Patent Application
20120275773
The present disclosure relates to an apparatus and a method of control for heating a reductant in an exhaust treatment system.
This section provides background information related to the present disclosure which is not necessarily prior art. Selective Catalytic Reduction (SCR) is a widely accepted technology for treating emission of nitrogen oxides (NOx) from lean engine exhaust. The most common, commercially available SCR deNOx system is urea-SCR which uses aqueous urea solution and employs a thermolysis/hydrolysis procedure to generate ammonia (NH3) from urea for NOx reduction over the SCR catalyst. The major challenges for the liquid urea system are its relatively high hardware costs and complicated control requirements. Another disadvantage is that the urea solution contains excess water (more than needed for hydrolysis), which necessitates a large storage tank. Still yet, another disadvantage is that reductants, such as urea, may freeze within the storage tank. If such a reductant is unable to thaw, a reductant pump may not prime and there is potential for a reductant injector on the exhaust pipe to fail.
What is needed then is a device and method for heating a reductant.
This section provides a general summary of disclosure material, and is not a comprehensive disclosure of full scope or of all disclosure features. A reductant heating system may include a reductant tank, a reductant tank flange and a hollow tube residing within the reductant tank that passes through the reductant tank flange in a first location to carry coolant into the reductant tank. The hollow tube may pass through the reductant tank flange at a second location to carry coolant from the reductant tank. The reductant heating system may further include a resistive wire wrapped around the hollow tube within the reductant tank and an electrical supply cord located outside of the reductant tank that supplies electrical power to the resistive wire. A temperature detector may be disposed within the reductant tank to detect a temperature within the reductant tank and govern electricity flow to the resistive wire. The temperature detector may be wired in-line in the resistive wire and may be a thermal switch attached to the hollow tube. Alternatively, the temperature detector may be a thermocouple that senses a temperature within the reductant tank. Heating the resistive wire heats a reductant within the tank.
A 120 volt electrical source may supply electrical energy to a 120 electrical supply cord that supplies power to the resistive wire. A controller may be disposed outside of the reductant tank and may be wired in-line with the electrical supply cord and receive communications from the thermocouple. An engine block heater may also be electrically wired to the 120 volt electrical source such that both, the engine block heater and the resistive wire are powered by 120 volt household or commercial power source. The engine block heater and the resistive wire may be operated at the same time.
A method of controlling a reductant heating system may entail providing a hollow tube, such as for passage of an engine coolant, wrapped with a resistive wire into a reductant tank, providing an electrical supply cord located outside the reductant tank that supplies electricity to the resistive wire located inside the reductant tank, providing a temperature detector in-line in the resistive wire, and connecting the electrical supply cord to a 120 volt electrical source.
The method of controlling a reductant heating system may further entail detecting a temperature with the temperature detector and closing electrical contacts within the temperature detector permitting electricity to flow through the resistive wire, thus heating the resistive wire and interior volume of the reductant tank, including a reductant. The method may further entail detecting a temperature with the temperature detector and opening electrical contacts within the temperature detector thereby causing electricity to stop flowing through the resistive wire thereby preventing any supply of heat.
The temperature detector may be a thermocouple and the method may further entail providing a controller in-line with the electrical supply cord, and providing a communication wire between the thermocouple and the controller. The method may then involve detecting a temperature with the thermocouple and providing a signal from the thermocouple to the controller and permitting electricity to flow through the resistive wire. Alternatively, providing a signal from the thermocouple to the controller may cause the controller to control in such a way thereby preventing electricity from flowing through the resistive wire.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to
A fuel tank 30 may be mounted to vehicle 12 to store fuel, such as diesel fuel, for engine 14. Fuel tank 30 may supply fuel to engine 14 via a fuel supply line 32 such that fuel may be selectively supplied to combustion chambers of engine 14. A reductant tank 34 also may be mounted to vehicle 12 and may store a reductant such as urea, or the like. In one example, and with reference including
As depicted in
Other components of reductant heating system 50 may include a resistive heating wire 62, which may be wrapped around tubing within reductant tank 34. When resistive heating wire 62 is energized with electricity, heat produced by electrical resistance transfers to tubing of u-tube 56 and surrounding frozen or liquid reductant, as will be further explained later. Resistive heating wire 62 may be circular in cross-section or may be relatively flat or oval in cross-section. Other cross-sectional shapes of resistive heating wire 62 are conceivable. While resistive heating wire 62 may be located inside a volume of reductant tank 34, a 120 volt electrical supply cord 64 may be located outside of a volume of reductant tank 34 and carry or supply electricity to resistive heating wire 62. Controller 66 may be located in an in-line fashion within 120 volt electrical supply cord 64, which may be divided into two electrical branches as depicted in
One-hundred twenty (120) volt electrical supply cord 64 may derive its electrical energy through a 120 volt electrical plug 70, which may be the same or similar to those used in residential or commercial businesses in the United States or equivalent outside of the USA. 120 volt electrical supply cord 64 may also supply or provide electrical energy to electrical cord 72 which supplies electrical energy to a block heater 74, which may reside in an engine block of engine 14.
To either cause electrical energy to activate or energize resistive wire 62 wrapped around tube 82 or to not activate and prevent electrical energy from energizing resistive wire 62 wrapped around tube 82, switch 90 may be a thermally-activated in-line switch that opens or closes switch contacts in accordance with a predetermined temperature to which switch 90 is subjected or exposed. Closing of contacts may permit electrical energy to flow through resistive wire 62 thereby heating reductant within reductant tank 34, while opening of contacts may prevent electrical energy from flowing through resistive wire 62 thereby preventing any heating of reductant within reductant tank 34.
Control within flowchart 200 proceeds to inquiry block 208 where an inquiry is made as to whether a temperature of reductant sensed by thermocouple 92 is less than a predetermined threshold temperature, such as a threshold “ON” temperature. If the response to the inquiry of inquiry block 208 is affirmative, then the method proceeds to block 210 where controller 66 permits the flow of electricity to resistive wire 62 wrapped around tube 82 within reductant tank 34. Flow of electricity causes heating of resistive wire 62 and tube 82 to heat reductant within reductant tank 34. However, if the response to the inquiry of inquiry block 208 is negative, then the method proceeds to block 212 where controller 66 prevents the flow of electricity to resistive wire 62 wrapped around tube 82 within reductant tank 34. With no flow of electricity to resistive wire 62, resistive wire 62 and tubing 82 do not heat within reductant tank 34, thereby preventing any heating of reductant within reductant tank 34 by resistive wire 62. Thus, reductant tank heat controller 66 may act as a gateway for electricity supplied to resistive wire 62 wrapped around tube 82, which may be formed into coolant u-tube 56, for example. Thus, controller 66 and thermocouple 92 communicate via communication wire 94.
Reductant heating system 50 may employ reductant tank 34, hollow tube 82 passing into and from reductant tank 34 that carries a flowing coolant, such as an engine coolant, resistive wire 62 wrapped around hollow tube 82, and temperature detector 90 disposed within reductant tank 34 to detect a temperature within reductant tank 34 and govern electricity flow to resistive wire 62. Reductant tank flange 58 may be arranged over a hole or aperture in reductant tank 34 such that hollow tube 82 residing within the reductant tank may pass through reductant tank flange 58 in a first location to carry coolant into reductant tank 34 and through reductant tank flange 58 at a second location to carry coolant from reductant tank 58. Coolant flowing through tube 82 may be an engine coolant that warms reductant within reductant tank 34 when engine 14 is running and engine 14 heats engine coolant. Coolant flowing through reductant tank flange 58 in a first location and through reductant tank flange 58 at a second location may be part of an engine coolant loop, which includes coolant circulating through a water jacket around engine block of engine 14.
Temperature detector 90 may be a thermal switch disposed in-line in resistive wire 62 to control electricity flow in accordance with a sensed temperature. Resistive wire 62 may be electrically connected to a 120 volt electrical source, such as at a household or commercial building. In some instances, resistive wire 62 only may be electrically connected to a 120 volt electrical source (i.e. household or commercial building current), and not vehicle-supplied or vehicle-generated current. The temperature detector may be thermocouple 92 and controller 66 may be wired in-line with 120 volt electrical source that communicates with the thermocouple. Controller 66 may be disposed outside of reductant tank 34. The temperature detector may be wired in-line in resistive wire 62. The temperature detector, regardless of whether it is a thermal switch or a thermocouple, may be attached to hollow tube 82.
Engine block heater 74 may be electrically wired to 120 volt electrical source receptacle 88, which may supply electrical power to engine block heater 74 and resistive wire 62 at the same time through electrical supply cord 64. That is, engine block heater 74 and resistive wire 62 may not be powered by vehicle-generated electricity (e.g. a generator) and may not be powered by an on-board battery.
A method of controlling a reductant heating system 50 may entail providing hollow tube 82 wrapped with resistive wire 62 into reductant tank 34, providing electrical supply cord 64 located outside reductant tank 34 to supply electricity to resistive wire 62 located inside reductant tank 34, providing a temperature detector 90, 92, which may be in-line in resistive wire 62, and connecting electrical supply cord 64 to a 120 volt electrical source.
The method may further entail detecting a temperature with temperature detector 92 and closing electrical contacts within temperature detector 92 thereby permitting electricity to flow through resistive wire 62, or detecting a temperature with temperature detector 92 and opening electrical contacts within temperature detector 92 thereby preventing electricity from flowing through resistive wire 62. Temperature detector 92 may, for example, work on the principles of a bi-metallic strip such that one or more metal tabs move (e.g. closing or opening contact) as a result of temperature changes.
The temperature detector may be thermocouple 92 and the method may further entail providing controller 66 in-line with electrical supply cord 64, providing communication wire 94 between thermocouple 92 and controller 66, detecting a temperature with thermocouple 92, and providing a signal from thermocouple 92 to controller 66 and permitting electricity to flow through resistive wire 62 or providing a signal from thermocouple 92 to controller 66 and preventing electricity from flowing through resistive wire 62.
While the present disclosure may utilize 120 volt power supplied by a 120 volt household or commercial power source, an auxiliary power unit 214 (“APU”) may be utilized as an alternative to a 120 volt household or commercial power source. The auxiliary power unit 214 (“APU”) may be an on-board power unit. That is, an on-board power unit may be a power unit, such as an internal combustion engine coupled with an electrical generator that is completely contained upon a vehicle, with no wires or other connections to a residential or commercial building. More specifically, as depicted in
Auxiliary power unit 214 may be a gasoline or diesel engine and may employ a generator that is capable of providing a range of power. For example, auxiliary power unit 214 may supply 6500 Watts of power to power block heater 74 and reductant heating system 50. However, auxiliary power unit 214 may be sized to supply any level of power (e.g. watts) or a range of power, depending upon the electrical draw or load of block heater 74 and reductant heating system 50. Auxiliary power unit 214 may be equipped with electric start, remote start, remote glow plug if powered by a diesel engine, and may be equipped with 20 A breakers, for example, although precise configuration may be determined by the loads (e.g. block heater 74 and reductant heating system 50) to be supplied. An advantage of utilizing APU 214 is that vehicle 12 may be able to power block heater 74 and reductant heating system 50 even when 120 volt household or commercial power source is not available. Thus, vehicle 12 may be completely self-sustaining with regard to powering block heater 74 and reductant heating system 50. In one configuration, APU 214 may utilize an 11 HP diesel engine, which when equipped with a 6500 W generator, may generate 46 A at 120V, 23 A at 240V, and 8.3 A at 12V. Other power output configurations are conceivable. When APU 214 is operating and supplying electrical power to block heater 74 and reductant heating system 50, 120 volt electrical plug 70 will not be plugged into a 120 volt household or commercial power source.
There are multiple advantages of the present disclosure. One aspect is that the electrical heating wrap may be plugged into land-based electrical supply voltage (e.g. residential or commercially available 120 v voltage source) to permit heating of frozen, semi-frozen, or liquid reductant within reductant tank 34 at the same time that an engine block heater is operating from the same 120 volt electrical supply to warm an engine 14, such as a diesel engine used within a diesel road tractor, on-road equipment or off-road equipment. Another aspect is that instead of utilizing a land-based electrical supply voltage (e.g. residential or commercially available 120 v voltage source), APU 214 may utilize an on-board diesel or gasoline engine equipped with a power generator, which may generate the requisite amperes and voltage to power block heater 74 and reductant heating system 50. In such a manner, reductant within a reductant tank may thaw and will not be frozen and thus be waiting and ready to be used for NOx reduction upon starting of an engine employing reductant tank 34. Thus, waiting for frozen reductant to thaw will not be necessary which greatly reduces the time necessary for an emission control system 10 to begin emitting environmentally friendly exhaust from an exhaust tail pipe outlet.
Methods depicted in
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
