US20140326325A1

US20140326325A1 - System and method for filling reductant tank

Info

Publication number: US20140326325A1
Application number: US14/336,257
Authority: US
Inventors: Brian M. Cole
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2014-07-21
Filing date: 2014-07-21
Publication date: 2014-11-06

Abstract

A method for filling a reductant tank is disclosed. The method includes creating a lower air pressure within the reductant tank than a pressure of an external reductant reservoir using the first valve, the second valve, and the venturi. The method also includes determining a level of a reductant in the reductant tank. The method further includes engaging the tank fill coupling mechanism with the external reductant reservoir. The method includes supplying the reductant from the external reductant reservoir into the reductant tank based on a pressure difference between the air pressure within the reductant tank and the pressure of the external reductant reservoir. The method also includes shutting-off the supply of the reductant based, at least in part, on the level of the reductant in the reductant tank. The method further includes disengaging the tank fill coupling mechanism from the external reductant reservoir.

Description

TECHNICAL FIELD

The present disclosure relates to an aftertreatment system, more specifically to a system and method for filling a reductant tank of the aftertreatment system.

BACKGROUND

An exhaust aftertreatment system associated with an engine may include a reductant supply system for delivery of a reductant into an exhaust stream of the engine. The reductant supply system may include a tank for storing the reductant, a pump, a reductant injector, and reductant delivery conduits. The reductant delivery conduits may fluidly connect various components of the reductant supply system for flow of the reductant therethrough. The reductant from the tank may be supplied to the reductant injector via the pump.
Reductant tanks generally require periodic refilling. The reductant tanks are refilled using an external reductant reservoir. The external reductant reservoir includes a pump. The reductant from the external reductant reservoir is pressurized and introduced into the reductant tank by the pump present at an external location.
U.S. Publication Application Number 2012/279576 describes a motor vehicle includes a tank for storing a liquid reducing agent suppliable to the exhaust system of an internal-combustion engine, and an air delivery device, by which an excess pressure can be built-up in a cushion of air situated in the tank above the reducing agent level. Via the air delivery device, alternatively, a vacuum is generatable in the air cushion, which vacuum supports feeding of the agent into the tank. Via the vacuum in the air cushion, reducing agent can also be returned from a pipe, which leads the reducing agent to the exhaust system, back into the tank, and/or additional liquid reducing agent can be transferred from a storage tank by way of a supply duct.

SUMMARY OF THE DISCLOSURE

In one embodiment of the present disclosure, a method for filling a reductant tank is disclosed. The method includes connecting an injector supply conduit to the reductant tank and an injector. The method also includes providing a driving fluid source in fluid communication with the reductant tank via a dose driving conduit. The method further includes connecting a purge conduit with the driving fluid source and the reductant tank. The method includes providing a first valve in fluid communication with the reductant tank via the dose driving conduit and the purge conduit. The method also includes providing a second valve in fluid communication with the reductant tank via the purge conduit. The method further includes providing a venturi in fluid communication with the first valve and the second valve. The method includes providing a tank fill coupling mechanism in fluid communication with the reductant tank via a fill conduit. The method also includes creating a lower air pressure within the reductant tank than a pressure of an external reductant reservoir using the first valve, the second valve, and the venturi. The method further includes determining a level of a reductant in the reductant tank. The method includes engaging the tank fill coupling mechanism with the external reductant reservoir. The method also includes supplying the reductant from the external reductant reservoir into the reductant tank based on a pressure difference between the air pressure within the reductant tank and the pressure of the external reductant reservoir. The method further includes shutting-off the supply of the reductant based, at least in part, on the level of the reductant in the reductant tank. The method includes disengaging the tank fill coupling mechanism from the external reductant reservoir.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary engine system, according to an embodiment of the disclosure;

FIG. 2 is a schematic view of a reductant supply system associated with an aftertreatment system of the engine system, according to an embodiment of the disclosure; and

FIG. 3 is a flowchart for a method of filling a reductant tank.

DETAILED DESCRIPTION

Various embodiments of the disclosure will now be described with reference to the drawings, wherein like reference numbers refer to like elements, unless specified otherwise. Referring to FIG. 1, a block diagram of an exemplary engine system 100 is illustrated, according to an embodiment of the disclosure. The engine system 100 includes an engine 102, which may be an internal combustion engine such as a reciprocating piston engine or a gas turbine engine, for example. According to an embodiment of the disclosure, the engine 102 is a spark ignition engine or a compression ignition engine such as a diesel engine, a homogeneous charge compression ignition engine, or a reactivity controlled compression ignition engine, or other compression ignition engine known in the art. The engine 102 may be fueled by gasoline, diesel fuel, biodiesel, dimethyl ether, alcohol, natural gas, propane, hydrogen, combinations thereof, or any other combustion fuel known in the art.
The engine 102 may include other components such as, a fuel system, an intake system, a drivetrain including a transmission system, and so on. The engine 102 may be used to provide power to any machine including, but not limited to, an on-highway truck, an off-highway truck, an earth moving machine, an electric generator, and so on. Further, the engine system 100 may be associated with an industry including, but not limited to, transportation, construction, agriculture, forestry, power generation, and material handling.
The engine system 100 includes an exhaust aftertreatment system 104 fluidly connected to an exhaust manifold of the engine 102. The aftertreatment system 104 is configured to treat an exhaust gas flow 106 exiting the exhaust manifold of the engine 102. The exhaust gas flow 106 contains emission compounds that may include Nitrogen Oxides (NOx), unburned hydrocarbons, particulate matter, and/or other combustion products known in the art. The aftertreatment system 104 may be configured to trap or convert NOx, unburned hydrocarbons, particulate matter, combinations thereof, or other combustion products in the exhaust gas flow 106 before exiting the engine system 100.
The aftertreatment system 104 may include a reductant supply system 108. The reductant supply system 108 is configured to dispense a reductant in the exhaust gas flow 106. The aftertreatment system 104 may also include a Selective Catalytic Reduction (SCR) module 110 provided downstream of the reductant supply system 108. The SCR module 110 is configured to reduce a concentration of NOx in the exhaust gas flow 106. The SCR module 110 may include a catalyst for facilitating the reaction, reduction, or removal of NOx from the exhaust gas flow 106 passing through the SCR module 110. The SCR module 110 may have a honeycomb or other structure made from or coated with an appropriate material. The material may be an oxide, such as vanadium oxide or tungsten oxide, coated on an appropriate substrate, such as titanium dioxide. The SCR module 110 may have a monolithic structure or may include multiple banks based on system requirements.
According to an embodiment of the disclosure, the aftertreatment system 104 may include a filter (not shown), such as, for example, a Diesel Particulate Filter (DPF), provided upstream of the SCR module 110. The DPF may be coated with a suitable catalyst to promote oxidation of any particulate matter in the exhaust gas flow 106 that may be trapped in the DPF. Additionally, in another embodiment, the aftertreatment system 104 may further include a Diesel Oxidation Catalyst (DOC). In such an embodiment, the DOC may be positioned upstream of the SCR module 110, in an exhaust flow direction. Alternatively, the aftertreatment system 104 may omit the DPF and include only the SCR module 110. In yet another embodiment, a combined DPF/SCR catalyst (not shown) may be used.
Further, the aftertreatment system 104 may include one or more Nitrous Oxide (NOx) sensors 112. The NOx sensors 112 may be located at varying locations within the aftertreatment system 104. For example, the NOx sensors 112 may be located upstream and/or downstream of the SCR module 110. The NOx sensors 112 may be configured to measure the concentration of NOx compounds in the exhaust gas flow 106 passing through the aftertreatment system 104. Similarly, other additional sensors, such as, a pressure sensor and a temperature sensor may also be included in contact with the exhaust gas flow 106 without any limitation. The aftertreatment system 104 disclosed herein is provided as a non-limiting example. It will be appreciated that the aftertreatment system 104 may be disposed in various arrangements and/or combinations relative to the exhaust manifold. These and other variations in the aftertreatment system design are possible without deviating from the scope of the disclosure.
As shown in FIG. 1, the reductant supply system 108 includes a reductant tank 114 and an injector 116 for supplying the reductant in an exhaust conduit 118 of the engine system 100. The reductant tank 114 is provided in fluid communication with the injector 116. The reductant tank 114 is configured to store the reductant therein. The reductant may be a fluid, such as, Diesel Exhaust Fluid (DEF). Alternatively, the reductant may include urea, ammonia, or other reducing agent known in the art. Parameters related to the reductant tank 114 such as size, shape, location, and material used may vary according to system design and requirements.
The exhaust conduit 118 is fluidly connected to the exhaust manifold of the engine 102, the injector 116, and the SCR module 110. The exhaust conduit 118 is configured to provide a passage 120 for the exhaust gas flow 106 therethrough. The injector 116 is configured to dispense the reductant into the exhaust gas flow 106. In an embodiment of the disclosure, the reductant supply system 108 may include one or more pairs of the injectors 116. The number of the injector 116 may vary based on the type of application.
FIG. 2 is a schematic view of the reductant supply system 108, according to an embodiment of the disclosure. An injector supply conduit 122 is arranged and configured to fluidly connect the reductant tank 114 and the injector 116 such that the reductant drawn from the reductant tank 114 may be delivered to the injector 116 via the injector supply conduit 122. An in-tank filter 124 is provided within the reductant tank 114. The in-tank filter 124 may include, for example, a sock filter or other filter configuration known in the art. An in-line filter 126 may be disposed in the injector supply conduit 122. More particularly, the in-line filter 126 is positioned between the injector 116 and the reductant tank 114. The in-line filter 126 disclosed herein may be any type of filter known to a person of ordinary skill in the art.
The injector supply conduit 122 may be fluidly connected to a pressure manifold 128 associated with the injector 116. The pressure manifold 128 is provided downstream of the reductant tank 114 and the in-line filter 126. The pressure manifold 128 is configured to collect the reductant received from the reductant tank 114 and distribute the reductant to the injector 116. During a dosing operation, a controller 130 may send a control signal to open the injector 116 for a predetermined time period in order to allow the reductant to be injected into the exhaust gas flow 106. An injector pressure sensor 132 may be connected to the pressure manifold 128. The injector pressure sensor 132 is configured to generate and send a signal indicative of an injection pressure of the injector 116 to the controller 130.
A driving fluid source 134 is provided in fluid communication with the reductant tank 114. The driving fluid source 134 is configured to supply a driving fluid. In an embodiment of the disclosure, the driving fluid source 134 may include an air compressor for delivering pressurized air, a storage pressure vessel, or combinations thereof. The air compressor may be any type of known positive displacement compressor or a turbo machine. Alternatively, the driving fluid source 134 may be any other component serving the purpose of supplying a pressurized source of the driving fluid.
A first valve 136 is provided downstream of the driving fluid source 134. The first valve 136 is configured to fluidly connect the driving fluid source 134 with the reductant tank 114 via a dose driving conduit 140 or a purge conduit 142, depending on a configuration of the first valve 136. The first valve 136 disclosed herein may be any type of a known 3-way, 2-position valve configured to connect the driving fluid source 134 to the dose driving conduit 140 or the purge conduit 142. In one example, the first valve 136 may be a 3-way, 2-positon ball valve. Alternatively, the first valve 136 may be a 3-way, 3-position valve.
During a reductant dosing operation, the first valve 136 may be in a first configuration such that the first valve 136 effects fluid communication between the driving fluid source 134 and the reductant tank 114 through the dose driving conduit 140 via a valve passage 148. Further, in this configuration, the first valve 136 is configured to block fluid communication between the driving fluid source 134 and the injector supply conduit 122 via the purge conduit 142.
During a purge operation, the first valve 136 may be in a second configuration such that the first valve 136 is configured to effect fluid communication between the driving fluid source 134 and the reductant tank 114 via the purge conduit 142 and a valve passage 152, and block fluid communication between the driving fluid source 134 and the reductant tank 114 via the dose driving conduit 140. Actuation of the first valve 136 between the first and second configurations may be done manually or through the controller 130. The controller 130 may actuate the first valve 136 via an electrical actuator, such as a solenoid, a pneumatic actuator, a hydraulic actuator, or other actuator known in the art. The reductant delivery and purge operations will be explained in detail later in this section.
The dose driving conduit 140 and the purge conduit 142 may be connected to a top portion of the reductant tank 114 with respect to gravity. A reductant tank pressure sensor 144 may be connected to the dose driving conduit 140 and upstream of the reductant tank 114. Further, the reductant tank pressure sensor 144 may be operatively coupled to the controller 130. The reductant tank pressure sensor 144 is configured to measure the pressure within the reductant tank 114.
Further, the dose driving conduit 140 may include a pressure regulator 146 connected downstream of the first valve 136, and in association with the reductant tank 114. The pressure regulator 146 is configured to, at least in part, mitigate high pressure spikes in the reductant tank 114. In one embodiment, the pressure regulator 146 may be an electrically controlled pressure regulator in operative communication with the controller 130.
The purge conduit 142 may include a venturi 150 connected upstream of the reductant tank 114. An upstream side of the venturi 150 is fluidly connected to the first valve 136. The venturi 150 may include a converging-diverging nozzle or any other device known in the art for creating suction from a fluid flow. Further, a suction port 154 of the venturi 150 is fluidly connected to a second valve 138. The second valve 138 is provided in series fluid communication with the purge conduit 142, such that the second valve 138 is located downstream of the first valve 136 and upstream of the reductant tank 114. Operation of the second valve 138 may be used to apply suction to the reductant tank 114. The second valve 138 may be embodied as a 2-way valve.
During an operational state of the engine 102, the reductant supply system 108 may inject or dose a desired amount of the reductant into the exhaust gas flow 106. The injector 116 may receive the reductant from the reductant tank 114. As shown in FIG. 2, the first valve 136 is in the first configuration. The driving fluid source 134 is configured to introduce the driving fluid into the reductant tank 114 through the first valve 136, via the dose driving conduit 140.
The driving fluid may pressurize the reductant tank 114 to a given pressure. It should be noted that during the dosing operation, based on control signals received from the controller 130, the second valve 138 is in a closed position, so that pressure may build up in the reductant tank 114. In one embodiment, this pressure of the reductant tank 114 may be approximately equal to a pressure at which the reductant is introduced by the injector 116 into the exhaust gas flow 106. The controller 130 associated with the reductant supply system 108 may be configured to sense the pressure of the pressure manifold 128 and/or the injection pressure of the injector 116, via the injector pressure sensor 132. The controller 130 may be further configured to regulate an operation of the driving fluid source 134 or the operation of the first valve 136 in order to control a quantity of the driving fluid being introduced into the reductant tank 114.
The driving fluid introduced within the reductant tank 114 may increase a pressure of the reductant tank 114, further causing the reductant present in the reductant tank 114 to enter into the injector supply conduit 122. The reductant may flow through the in-tank and in-line filters 122, 124, and flow into the pressure manifold 128. The reductant may further be introduced by the injector 116 into the exhaust conduit 118.
Some quantity of the reductant may be retained in the components of the aftertreatment system 104. For example, the reductant may be retained in the reductant delivery lines, such as, the injector supply conduit 122. The purge conduit 142 of the reductant supply system 108 is configured to purge this reductant that is retained within the components of the aftertreatment system 104.
During the purge operation, the second valve 138 is actuated by the controller 130 and operates in an open position. The second valve 138 may release the pressure built up within the reductant tank 114 and vent the same to the atmosphere via the valve passage 156. When the pressure in the reductant tank 114 reaches a predetermined pressure value, for example, approximately 50 kPa, the first valve 136 is actuated by the controller 130 to operate in the second configuration. It should be noted that the first valve 136 may be operated in the second configuration for a predetermined time period or until negative pressure is created within the reductant tank 114. The controller 130 may send control signals to close the first valve 136 thereafter.
In this configuration of the first valve 136, the venturi 150 is in fluid communication with the driving fluid source 134 via the valve passage 152. On actuation of the driving fluid source 134, the driving fluid is delivered to the venturi 150 of the purge conduit 142 via the valve passage 152. Suction generated at the suction port 154 of the venturi 150 may cause the driving fluid collected in the top portion of the reductant tank 114 to be drawn into the valve passage 156 and vented outside the reductant tank 114. A negative pressure may be created within the reductant tank 114, thereby drawing fluid from flow passages of the reductant supply system 108 into the reductant tank 114. For example, reductant present in the injector supply conduit 122 may be drawn into the reductant tank 114 by suction generated at the venturi 150, thereby purging the injector supply conduit 122.
Further, during the operation of the machine, a level of the reductant in the reductant tank 114 may decrease, based on usage thereof. A low level of the reductant within the reductant tank 114 may affect a performance of the aftertreatment system 104. The reductant tank 114 may include a tank level gauge 157. The tank level gauge 157 may determine a level of the reductant present within the reductant tank 114. In one embodiment, the tank level gauge 157 may include a float. Alternatively, the tank level gauge 157 may include a sensor, for example, an infrared sensor. The tank level gauge 157 may be communicably coupled to the controller 130. The controller 130 may be configured to display the level of the reductant present within the reductant tank 114 on a display present within an operator cabin, in order to make an operator of the machine aware of the level of the reductant in the reductant tank 114. When the level of the reductant present within the reductant tank 114 drops below a pre-determined level, the reductant tank 114 may need to be refilled. The reductant tank 114 is generally filled by an external reductant reservoir 164.
The reductant supply system 108 includes a tank fill coupling mechanism 158. The tank fill coupling mechanism 158 may include any type of a known quick connect coupling to provide fluid communication therethrough. The tank fill coupling mechanism 158 is connected to the reductant tank 114 via a fill conduit 160. A first end of the fill conduit 160 is connected to the tank fill coupling mechanism 158, whereas a second end protrudes within the reductant tank 114. The tank fill coupling may operate as a plug and play component such that the tank fill coupling mechanism 158 provided on the machine allows for quick and easy coupling with a nozzle (not shown) of the external reductant reservoir 164.
Further, the second end of the fill conduit 160 is provided with a third valve 162, such that the third valve 162 is disposed within the reductant tank 114. The third valve 162 may be embodied as any unidirectional valve known in the art, such that fluid flow is allowed into the reductant tank 114 and prevented out of the reductant tank 114. In one embodiment of the present disclosure, the third valve 162 may be an automatic shut-off valve. The third valve 162 may be coupled to the controller 130 such that on receiving control signals from the controller 130, the third valve 162 may block fluid flow into the reductant tank 114. The controller 130 may send these control signals to the third valve 162 when the level of the reductant within the reductant tank 114 exceeds a pre-set level.
The external reductant reservoir 164 is configured to store the reductant therein and serve as a supply for the reductant to the reductant tank 114. A reductant supply conduit 166 and the nozzle are attached to the external reductant reservoir 164. The external reductant reservoir 164 may be selectively connected to the reductant tank 114 based on an engagement of the nozzle with the tank fill coupling mechanism 158, allowing for reductant flow from the external reductant reservoir 164, through the reductant supply conduit 166, the nozzle, the tank fill coupling mechanism 158, the fill conduit 160, and into the reductant tank 114. The operation of filling the reductant into the reductant tank 114 will now be explained in detail.
As explained in reference to the purge operation, the second valve 138 is actuated by the controller 130, in order to de-pressurize the reductant tank 114. Further, the nozzle of the external reductant reservoir 164 may be connected with the tank fill coupling mechanism 158, thereby providing fluid communication between the external reductant reservoir 164 and the reductant tank 114. Based on the control signals from the controller 130, the first valve 136 is actuated to fluidly connect the driving fluid source 134 to the reductant tank 114 via the purge conduit 142. The air present within the reductant tank 114 may be drawn into the suction port 154 of the venturi 150 via the second valve 138 present in the purge conduit 142. Thus, a vacuum or negative pressure is created within the reductant tank 114. The air pressure of the reductant tank 114 is lesser than a pressure within the external reductant reservoir 164.
Due to the pressure difference between the reductant tank 114 and the external reductant reservoir 164, the reductant present within the external reductant reservoir 164 is drawn into the reductant tank 114, via the reductant supply conduit 166 and the fill conduit 160. In one embodiment, when the reductant within the reductant tank 114 exceeds the pre-set level, the third valve 162 may receive the control signals from the controller 130 to block or shut off fluid communication between the reductant tank 114 and the external reductant reservoir 164. This may indicate that the reductant tank 114 is filled to the desired level. The reductant supply conduit 166 may then be disconnected or disengaged from the tank fill coupling mechanism 158. The controller 130 may send control signals to close the first and second valves 136, 138 and/or to turn off a delivery of the driving fluid from the driving fluid source 134.

INDUSTRIAL APPLICABILITY

The present disclosure describes a system and method for filling the reductant into the reductant tank 114, based on capabilities of the reductant tank 114 itself. Based on the creation of the low pressure within the reductant tank 114, the reductant from the external reductant reservoir 164 is drawn into the reductant tank 114. Thus, the filling of the reductant within the reductant tank 114 may be independent of an external motive force present at the external reductant reservoir 164.
FIG. 3 is a flowchart for a method 300 of filling the reductant tank 114. At step 302, the injector supply conduit 122 is connected to the reductant tank 114 and the injector 116. At step 304, the driving fluid source 134 is provided in fluid communication with the reductant tank 114 via the dose driving conduit 140. At step 306, the purge conduit 142 is connected with the driving fluid source 134 and the reductant tank 114. At step 308, the first valve 136 is provided in fluid communication with the reductant tank 114 via the dose driving conduit 140 and the purge conduit 142. At step 310, the second valve 138 is provided in fluid communication with the reductant tank 114 via the purge conduit 142. At step 312, the venturi 150 is provided in fluid communication with the first and second valves 136, 138. At step 314, the tank fill coupling mechanism 158 is provided in fluid communication with the reductant tank 114 via the fill conduit 160.
At step 316, the lower air pressure is created within the reductant tank 114 than the pressure of the reductant reservoir 164 using the first valve 136, the second valve 138, and the venturi 150. At step 318, the tank level gauge 157 is configured to determine the level of the reductant in the reductant tank 114. At step 320, the tank fill coupling mechanism 158 is engaged with the external reductant reservoir 164. At step 322, the reductant from the external reductant reservoir 164 is supplied into the reductant tank 114, based on a pressure difference between the air pressure within the reductant tank 114 and the pressure within the external reductant reservoir 164. At step 324, the supply of the reductant is shut-off based, at least in part, on the level of the reductant in the reductant tank 114. At step 326, the tank fill coupling mechanism 158 is disengaged from the external reductant reservoir 164.
The system and method of filling the reductant tank 114 disclosed herein does not require the additional motive force for reductant tank refilling purposes. Further, the system may be easily installed on existing machines with very few modifications. Also, the reductant tank 114 may be easily refilled on a worksite on which the machine is operating.
While embodiments of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

What is claimed is:

1. A method for filling a reductant tank, the method comprising:

connecting an injector supply conduit to the reductant tank and an injector;

providing a driving fluid source in fluid communication with the reductant tank via a dose driving conduit;

connecting a purge conduit with the driving fluid source and the reductant tank;

providing a first valve in fluid communication with the reductant tank via the dose driving conduit and the purge conduit;

providing a second valve in fluid communication with the reductant tank via the purge conduit;

providing a venturi in fluid communication with the first valve and the second valve;

providing a tank fill coupling mechanism in fluid communication with the reductant tank via a fill conduit;

creating a lower air pressure within the reductant tank than a pressure of an external reductant reservoir using the first valve, the second valve, and the venturi;

determining a level of a reductant in the reductant tank;

engaging the tank fill coupling mechanism with the external reductant reservoir;

supplying the reductant from the external reductant reservoir into the reductant tank based on a pressure difference between the air pressure within the reductant tank and the pressure of the external reductant reservoir;

shutting-off the supply of the reductant based, at least in part, on the level of the reductant in the reductant tank; and

disengaging the tank fill coupling mechanism from the external reductant reservoir.