Patent ID: 12203485

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of exemplary embodiments to illustrate the principles of the invention. The embodiments are provided to illustrate aspects of the invention, but the invention is not limited to any embodiment. The scope of the invention encompasses numerous alternatives, modifications, and equivalents. The scope of the invention is limited only by the claims.

While numerous specific details are set forth in the following description to provide a thorough understanding of the invention, the invention may be practiced according to the claims without some or all of these specific details.

Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes and are not intended to limit the scope of the claims.

FIG.1is a block diagram of an example system100including a DEF pump110, main DEF tank120, dosing tank130, SCR system140, flow control valve160, and relief valve170.

DEF pump110is connected to main DEF tank120via supply122to allow DEF pump110to pull, or suction, DEF from main DEF tank120into inlet270. Outlet280of DEF pump110is connected to flow control valve160via supply line128. Flow control valve160is connected to dosing tank130via supply line132to allow DEF to flow to dosing tank130. The output136of dosing tank130is connected to SCR system140via supply line134. Relief valve170is connected to input124of main DEF tank120via return line126to allow unused DEF to be returned to main DEF tank120.

When a centerline166of DEF pump110is located above main DEF tank120, DEF pump110is designed to self prime and operate even under conditions where the fluid level in main DEF tank120is at a minimum level, or threshold, and DEF pump interior parts are dry. The suction required to lift the fluid from the tank to inlet270is a function of a height164of DEF pump110above main DEF tank120, atmospheric pressure pushing on the fluid in main DEF tank120, and back pressure on outlet280of DEF pump110. One of skill in the art will understand how to calculate the required suction.

FIG.2illustrates an example SCR system140including an input from engine142, an oxidation catalyst144, a urea dosing system146, a urea SCR148, and an NH2oxidate catalyst150.

Engine142is connected to oxidation catalyst144. The output of oxidation catalyst144to connected to urea dosing system146, which in turn is connected to urea SCR148. Supply line134from dosage tank130is connected to the input of urea dosing system146. Urea SCR148is connected to NH2oxidate catalyst150.

FIGS.3-6illustrate an example DEF pump110including an inverter assembly210, inverter housing212, speed sensor220, pressure sensor230, CAN connector240, inverter cooling pipe250, mounting feet260, inlet270, outlet280, lifting ring282, power connector284, and motor290.

Inverter assembly210comprises a microcontroller211and memory213. In one embodiment, inverter assembly210is a PWM inverter assembly such as the design disclosed in U.S. Pat. No. 8,707,932, which is incorporated herein in its entirety.

Inverter cooling pipe250is integrated into inverter housing212to allow DEF to flow past the most sensitive and highest heat-producing electronic parts in inverter assembly210, such as MOSFETs, pulling heat away in the process. In one embodiment, inverter cooling pipe250comprises stainless steel.

As shown inFIG.3, inverter assembly210is used to control DEF pump110, which has a bus communication capability, such as a CAN bus communication capability, that will allow DEF pump110to be connected to a Controller Area Network (CAN bus)242, or other network, in a vehicle248(as shown inFIG.4). A CAN connector240is integrated into inverter housing212. In one embodiment, connector240comprises materials such as thermoplastic or polyimide to make it environmentally rugged.

FIG.4illustrates DEF pump110may be connected to a vehicle248, such as a locomotive, that has an engine control module (ECM)244, which is a computer system that analyzes data and controls numerous aspects of the vehicle's performance. In one or more embodiments, vehicle248has a CAN bus242, which is a bus standard allowing microcontrollers and other devices to communicate with each other using a message-based protocol. DEF pump diagnostics can be transmitted from inverter assembly210to ECM244via CAN bus242, which can be connected to inverter assembly210with connector240.

Multi-mode control of DEF pump110can be achieved using CAN bus commands. Modes of operation may include, among others, standby, high-speed priming, running, reverse or purge, closed-loop pressure control, or open-loop speed control.

As shown inFIG.3, mounting feet260may be attached to motor290and can be used to attach DEF pump110to a vehicle248(FIG.4).

FIG.6shows an example DEF pump110comprising drive shaft bushings300, drive shaft310, pump body cover (fluid manifold)320, shaft seal330, shaft seal seat338, pump body housing340, pump body insert314, gears350, inverter assembly210, and motor290. Motor290comprises a rotor (not shown). In one or more embodiments, drive shaft bushings300are PEEK bushings.

Motor290is separated from the pumping fluid (DEF fluid) because of the fluid's corrosiveness and conductivity. The separation is accomplished with a mechanical shaft seal330. Since motor290cannot be cooled with the pumping fluid, Type-H stator windings are used to provide the highest standard temperature rating for motor290.

In one embodiment, motor290is oversized relative to the pumping requirement for normal operation so that DEF pump110is more capable of breaking free from crystalized urea. For example, in one embodiment, motor290has a 0.5 Hp rating and produces 5.9 foot-pounds of torque at 0 RPM despite the need for only 0.03 Hp and 0.2 foot-pounds of torque necessary for producing 2 gpm at 10 psi.

As shown inFIG.7, a robust motor frame296allows pump body housing340and inverter housing212(as shown inFIGS.5and6) containing inverter assembly210to be mounted directly to front of motor290, and motor290to be mounted directly to a chassis of vehicle248, such as the chassis of a locomotive. Motor frame296comprises mounting feet260that are integrated into a solid cast housing of motor frame296and a motor mounting face298. In one or more embodiments, motor frame296further comprises a heat exchanger286for improved passive cooling and a shaft310. In one or more embodiments, heat exchanger286comprises fins287. In one or more embodiments, shaft310is a 316 stainless steel shaft. This design increases the manufacturability of DEF pump110, and eliminates the need for shimming in most cases.

By designing the parts of DEF pump110to be self-aligning, shimming is not required and no special measurements are required for aligning the parts during manufacture. To eliminate alignment issues, an assembly can be used where motor shaft310extends all the way into pump body housing340and into a drive gear351(FIG.3), and applies torque via a shaft key (not shown) as opposed to a press-fit interface. This configuration eliminates the need for a separate pump head shaft and a rotating coupling to connect motor shaft310to the pump head shaft and the associated alignment challenges. Gears350shown inFIG.3comprise a drive gear351(right gear) and an idler gear353(left gear). Pump body housing340mounts directly to motor mounting face298.

DEF pump110is able to prime itself when dry because of the design and tolerances of gears350, pump body cavity (not shown), which is the cavity in the pump body insert in which the gears are located, and various seal interfaces. For example, in one or more embodiments, gears350, pump body insert314, wear plate324, and pump body cover320are designed with tolerances so that there is 0.0005-0.002 inches of clearance between gears350and all surrounding walls of pump body insert314. The ability to vary the speed of DEF pump110and run it at a higher-than-required speed for a fixed amount of time or until pressure at outlet280of DEF pump110is above a specified threshold also improves the ability of DEF pump110to self-prime.

A DEF-specific pressure sensor230can be integrated into the outlet side of DEF pump110. This will allow microcontroller211in inverter assembly210to determine if the pump is running dry, as well as achieve closed-loop pressure control if necessary.

A speed sensor220can be integrated into DEF pump110. In one or more embodiments, speed sensor220is a hall-effect speed sensor. Speed sensor220and a set of magnets (not shown) potted into drive shaft310allow microcontroller211in inverter assembly210to monitor the speed of gears350and detect if DEF pump110has seized. If DEF pump110has seized and a “locked-rotor” is detected, microcontroller211in inverter assembly210will attempt to restart DEF pump110using higher current for a specified amount of time, and then rest for a specified amount of time to cool down. DEF pump110repeats this process until it is shut off. This prevents motor290and inverter assembly210from overheating and potentially damaging other components. It also increases the likelihood of DEF pump110recovering from urea crystallization without having to be flushed with clean water.

The selection of corrosive-resistant materials for parts of DEF pump110that come into contact with DEF can prevent or limit corrosion. In one or more embodiments, pump body insert314comprises 316 stainless steel. In one or more embodiments, gears350comprise 30 percent carbon-filled PEEK. In one or more embodiments, pump body cover320comprises 316 stainless steel. As illustrated inFIG.8, shaft seal330comprises a spring334, a moving portion336, and a stationary portion337. In one or more embodiments, spring334, moving portion336, and stationary portion337each comprises 304 stainless steel, fluoroelastomer, ceramic, and/or silicon carbide. In one embodiment, spring334in shaft seal330comprises 304 stainless steel because 304 stainless provides a good balance between corrosion resistance and suitability for springs. Stationary portion337of shaft seal330is pressed into shaft seal seat338(FIG.6). Stationary portion337of shaft seal330comprises one face of the rotating face-to-face seal interface that comprises silicon carbide or ceramic.

Stationary portion337of shaft seal330comprises fluoroelastomer, ceramic, and/or silicon carbide, and moving seal336comprises fluoroelastomer, ceramic, and/or silicon carbide. In one or more embodiments, inverter cooling pipe250comprises 316 stainless steel.

As shown inFIG.6, in one or more embodiments, two O-rings (not shown) are used at an interface between cooling pipe250and pump body cover320. As shown inFIG.9, in one or more embodiments, three O-rings (not shown) are used at a wear plate to pump body cover interface420. In one or more embodiments, one O-ring is used at an idler shaft to pump body insert interface430. In one or more embodiments, one O-ring is used at a pump body cover to pump body insert interface440. In one or more embodiments, one O-ring is used at a pump body insert to shaft seal seat interface450. In one or more embodiments, the O-rings comprise EPDM or fluoroelastomer. The O-rings provide seals.

Stainless steel moving on stainless steel can cause galling, and plastic running on plastic can cause plastic welding. Therefore, in one or more embodiments, all bearing interfaces, except shaft seal330, utilize dissimilar material pairing (i.e., stainless steel running on PEEK or vice-versa). PEEK does not readily absorb water and is dimensionally stable over a large temperature range. In one or more embodiments, the PEEK is 30 percent carbon to increase wear resistance and decrease friction.

DEF pump110is designed to achieve IP67 minimum ingress protection rating, but also allow any moisture collected inside electrical components, such as motor290and inverter assembly210, to drain via strategically placed drain ports, or drain holes.FIGS.10and11show an inverter drain port292, andFIG.12shows motor drain ports294. In one or more embodiments, drain ports292,294are labyrinthed.

The inverter electronics are fully potted. In one or more embodiments, speed sensor220and pressure sensor230are waterproof.

In one or more embodiments, DEF pump110is designed so that components most prone to wear during pump operation, such as pump body insert314, cover wear plate324, and gears350, are easily removable and relatively inexpensive to replace reducing the cost and level of effort required to refurbish DEF pump110. The method of attachment, simplicity, and size of cover wear plate324make it easy to remove. In one or more embodiments, cover wear plate324comprises a 4 inch by 5 inch by 0.020 inch thick, work-hardened, 316 stainless steel sheet and is held in place by four screws that clamp it between pump body cover320and pump body housing340. Gears350are easy to remove because they simply slide off drive shafts310and idler shaft311(FIG.6) once pump body cover320and cover wear plate324are removed

To decrease EMI radiating from DEF pump110, all main components should be well connected electrically to each other according to a planned grounding scheme. Inverter housing212, shown inFIGS.3and12, can comprise aluminum and inverter cover214, shown inFIG.13can be anodized aluminum. However, in one or more embodiments, portions of these parts can be masked before anodization or machined after anodization so that their various part-to-part interfaces provide good electrical conduction and minimize EMI leakage. In one or more embodiments, for all the aluminum parts, if a particular part-to-part interface serves as an electrical conductor (ground path), the anodization is left off in that area. For example, in one or more embodiments, portions of aluminum inverter cover214and inverter housing212can be masked. This masking may be done on various areas on inverter housing212and on the portion of inverter cover plate214that comes in direct contact with inverter housing212.

In an alternate embodiment, inverter housing212can comprise stainless steel. The advantage to using stainless steel is that the cooling DEF flow could be run directly through ports in inverter assembly210eliminating the need for inverter cooling pipe250. The downside is that it would be heavier and more expensive compared with an aluminum housing.

In one embodiment, the motor phase wires are enclosed in a metal conduit315(FIG.6) that protects the motor phase wires and minimizes EMI radiation. In an alternate embodiment, the motor phase wires are enclosed in a sheet metal cover317(FIG.17) that protects the motor phase wires and minimizes EMI radiation. Sheet metal cover317shown inFIG.17can be used in place of metal conduit315in any of the disclosed embodiments.

In one or more embodiments, DEF pump110is designed to be able to survive sub-zero Fahrenheit ambient temperatures and ambient temperatures above 150 degrees Fahrenheit for continuous operation.

In one or more embodiments, the combination of the type-H motor stator windings (not shown), inverter cooling pipe250that flows DEF next to the power electronics in inverter assembly210, and materials allow the pump to be able survive high ambient temperatures, such as temperatures up to 300 degrees F., for short durations, such as at least 30 minutes.

In one or more embodiments, DEF pump110can endure a high vibration environment. Screw lengths, screw strengths, number of screws, location of screws, size of screws are selected to withstand substantial vibration. Materials and material finishes chosen are selected to withstand substantial vibration. Motor frame296with integrated mounting feet260withstands vibration better than prior art implementations that used a lighter-duty motor with sheet metal mounting feet260. In one or more embodiments, all electrical connections are minimum IP67 rated.

In one or more embodiments, DEF pump110can endure exposure to rain and snow, exposure to high-pressure and high-temperature engine washing fluid, and exposure to dust and iron particles. In one or more embodiments, drain ports292,294are placed in strategic locations in case moisture does makes its way into locations that are sensitive to moisture. Further, in one or more embodiments, drain ports292,294have a labyrinth design so that high-pressure washing cannot reach sensitive components.

DEF pump110is capable of meeting the performance requirements for a typical locomotive life-to-engine-rebuild. In an example embodiment, DEF pump110is designed to last for at least six years and/or 30,000 hours, and DEF pump110is designed to withstand50,000start/stop cycles.

As shown inFIG.1, when in operation, DEF pump110pulls DEF from a large tank (e.g., a main DEF tank)120, pumps DEF to a smaller tank (e.g. a dosing tank)130, and circulates unused DEF back to large tank120.

FIG.14is a flow diagram illustrating an example control process500for controlling inverter assembly210to control DEF pump110. Input power is supplied at Step510. Then in Step520microcontroller211determines whether it has been less than a specified time period, such as 60 seconds, since DEF pump110was started. If it has been less than the specified time period since DEF pump110was started, high-speed priming is performed in Step530, which means DEF pump110runs at twice the standard speed for the specified time period and then control loops back to Step520. If in Step520, it is determined that DEF pump110has been running for the specified time period or longer, then the process proceeds to Step540and DEF pump110is run at standard speed.

At Step550, microcontroller211tests for locked rotor check max re-starts. If the result of the test in Step550is yes, then control proceeds to Step560and the microcontroller211shuts down DEF pump110, and microcontroller211does not try to restart DEF pump110. To restart DEF pump110after being shut down in Step560, power must be cycled. If the result of the test in Step550is no, then control proceeds to Step570and microcontroller211tests the dry run check max time.

In one or more embodiments, microcontroller211uses control process500to determine if the rotor is locked. If the rotor is locked, DEF pump110will cycle between trying to restart for a specified time period, such as 5 seconds, and resting for a period of time, such as 5 seconds. DEF pump110cycles between trying to restart and resting for 5 minutes. After 5 minutes, it will stop, requiring a cycling power off and on to restart.

In one or more embodiments, there is a flag for a “locked rotor”, a counter to record the number of restart attempts, and a flag to indicate when the number of restart attempts equals the maximum number of allowed tries. This keeps the motor and electronics from overheating.

In one or more embodiments, there is a flag for a “dry run” condition. In one or more embodiments, if this flag is high, or set, for a specified time period, such as 2 minutes, DEF pump110will shut down, at which point another flag will be set high indicating that DEF pump110has been shut-down due to an extended time running dry. This condition also requires a power cycle, or turning power off and on again, to clear the flags and restart. This prevents excessive wear of DEF pump110components due to dry running and/or overheating because there is no fluid cooling when DEF pump110is dry running.

If the result of the test in Step570is no, then control proceeds to Step540. If the result of the test in Step570is yes, then control proceeds to Step560.

In one embodiment, the main loop repeatedly checks whether the specified time period, such as 60 seconds, has passed since startup and determines how fast to run DEF pump110based on the result of that test. In another embodiment, an input to the pressure sensor is used to vary DEF pump110speed to attain a pressure target (seeFIG.15).

FIG.15is a flow diagram for an example dry-running diagnostic600. Step610checks whether the time since DEF pump110was started is greater than a specified time period, such as 1 second, commanded RPM is greater than a specified number of revolutions, such as 800, and measured pressure at outlet280is less than a minimum threshold. If the result of any of the tests in Step610is no, then Step620causes the system to return to main loop500. If the result of all of the tests in Step610is yes, then in Step630the dry-running flag is set and control proceeds to Step640. In Step640, microcontroller211tests whether DEF pump110has been dry running greater than a specified time period, such as 2 minutes. If the result of the test in Step640is yes, then in Step650DEF pump110is shut down, and microcontroller211does not try to restart DEF pump110. Power will have to be cycled to restart DEF pump110after it is shut down in Step650. If the result of the test in Step640is no, then in Step660control returns to main loop500.

FIG.16is a flow diagram for an example locked-rotor diagnostic700. In Step710, microcontroller211tests whether the time to startup is greater than a specified time period, such as 1 second, measured RPM is less than a specific number of revolutions, such as 200, current draw is greater than a specific current, such as 2 amps, number of amp spikes is less than a specific number, such as 5, and commanded RPM is greater than a specific number of revolutions, such as 333. The 2 amp threshold is compared to a rolling average of the measured current. An amperage spike is counted when the instantaneous amperage goes over a different threshold, which in one example embodiment is 3 amps. If all of the conditions are met or if the current draw is greater than a current threshold, such as 8 amps, then the result of the Step710test is yes, or true. If the result of the test in Step710is no, then in Step720control returns to main loop500to run DEF pump110with the standard amperage limit. If the result of the test in Step710is yes, then in Step730the locked rotor flag is set and then control proceeds to Step740. In Step740, microcontroller211attempts to run DEF pump110with the maximum rated amperage limit and then control proceeds to Step750. In Step750, the microcontroller211tests whether the locked rotor time is greater than a specified time period, such as 5 seconds. If the result of the test in Step750is no, then the control goes to Step740. If the result of the test in Step750is yes, then in Step760DEF pump110is stopped for a specified time period, such as 5 seconds. Then the control proceeds to Step770. In Step770, microcontroller211tests whether the number of re-start cycles is greater than or equal to a specific number of cycles, such as 30. If the result of the test in Step770is no, then control goes to Step710. If the result of the test in Step770is yes, then in Step780DEF pump110is shut down, and microcontroller211does not try to restart DEF pump110. After DEF pump110is shut down in Step780, the power must be cycled to restart DEF pump110.

The disclosed embodiments are illustrative, not restrictive. While specific configurations have been described, it is understood that the present invention can be applied to a wide variety of DEF pump designs and used with a wide variety of diesel and diesel-electric engines. There are many alternative ways to implement the invention.