US20160376968A1

US20160376968A1 - Header unit for reductant tank

Info

Publication number: US20160376968A1
Application number: US14/753,499
Authority: US
Inventors: Dongming Tan; Brian M. Cole; Shawn R. Herold; Kevin L. Dea; Theron Cassidy; Matthew F. Fahrenkrug; Douglas A. Long; James J. Driscoll
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2015-06-29
Filing date: 2015-06-29
Publication date: 2016-12-29

Abstract

A header unit for a reductant tank is provided. The header unit includes a reductant draw conduit extending into an interior space of the reductant tank. The reductant draw conduit is configured to draw a reductant from the reductant tank. The reductant draw conduit includes at least one expansion opening provided along a length thereof. The header unit also includes a valve element coupled to the reductant draw conduit. The valve element includes a main body member defining a channel therethrough. The main body member circumferentially surrounds at least a portion of the reductant draw conduit corresponding to the at least one expansion opening. The main body member is made of an elastomeric material configured to accommodate an expansion thereof.

Description

TECHNICAL FIELD

The present disclosure relates to a header unit, and more particularly to the header unit for a reductant tank.

BACKGROUND

An exhaust aftertreatment system associated with an engine may include a reductant supply system. The reductant supply system delivers a reductant into an exhaust stream of the engine. The reductant supply system may include a reductant tank for storing the reductant, a pump, a reductant injector, and reductant draw conduits. The reductant draw conduits may fluidly connect the reductant tank with the reductant injector. The reductant from the reductant tank may be supplied to the reductant injector via the pump.
The reductant flowing through the reductant supply system of the aftertreatment system experiences freezing in cold environments. For example, the trapped reductant within the reductant draw conduit may freeze and expand close to an inlet end, an outlet end, and a middle portion of the reductant draw conduit. The expansion of reductant applies force on the reductant draw conduit leading to a failure of the reductant draw conduit due to bulging and/or cracking. Such failure may require replacement or servicing of the reductant draw conduit, thereby increasing maintenance cost associated with the aftertreatment system.
U.S. Published Application Number 2011/0047972, hereinafter referred to as '972 application, describes a device and method for metering a reducing agent into an exhaust gas system of a motor vehicle. The '972 application describes an internal-combustion engine exhaust gas system having a storage tank that stores the reducing agent, a supply pipe that connects the storage tank to a metering unit which introduces the reducing agent into the exhaust gas system. Also, a pump mechanism within the supply pipe conveys the reducing agent and a pressure sensor detects the pressure in the supply pipe downstream of the pump. A first valve system is arranged in the supply pipe. A section of the return pipe is located at a higher level than the return pipe to form a storage volume for air present in the supply pipe. A second valve system is arranged in the supply pipe to create, when the second valve system is closed, a storage volume for pressurized reducing agent by way of this pipe branch.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a header unit for a reductant tank is provided. The header unit includes a reductant draw conduit extending into an interior space of the reductant tank. The reductant draw conduit is configured to draw a reductant from the reductant tank. The reductant draw conduit includes at least one expansion opening provided along a length thereof. The header unit also includes a valve element coupled to the reductant draw conduit. The valve element includes a main body member defining a channel therethrough. The main body member circumferentially surrounds at least a portion of the reductant draw conduit corresponding to the at least one expansion opening. The main body member is made of an elastomeric material configured to accommodate an expansion thereof.
In another aspect of the present disclosure, a reductant supply system is provided. The reductant supply system includes a reductant tank having an interior space. The reductant supply system also includes a heat exchanger in thermal communication with the interior space of the reductant tank. The reductant supply system further includes a pump configured to draw a reductant from the interior space of the reductant tank. The reductant supply system includes a header unit attached to the reductant tank. The header unit includes a reductant draw conduit extending into the interior space of the reductant tank. The reductant draw conduit is configured to draw reductant from the reductant tank. The reductant draw conduit includes at least one expansion opening provided along a length thereof. The header unit also includes a valve element coupled to the reductant draw conduit. The valve element includes a main body member defining a channel therethrough. The main body member circumferentially surrounds at least a portion of the reductant draw conduit corresponding to the at least one expansion opening. The main body member is made of an elastomeric material configured to accommodate an expansion thereof. The header unit further includes a coolant loop coupled to the heat exchanger. The coolant loop extends into the interior space of the reductant tank. The coolant loop includes a coolant supply line configured to supply a coolant flow into the reductant tank. The coolant loop also includes a coolant outlet line configured to discharge the coolant flow from the reductant tank.
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 schematic view of an exemplary engine system, according to one embodiment of the present disclosure;

FIG. 2 is a perspective view of an exemplary reductant tank having a header unit, according to one embodiment of the present disclosure;

FIG. 3 is a perspective view of the reductant draw conduit and a valve element, according to one embodiment of the present disclosure;

FIG. 4 is a perspective view depicting the valve element during a suction operation of the reductant through the reductant draw conduit;

FIG. 5 is a perspective view depicting the valve element during an expansion of the valve element; and

FIG. 6 is a perspective view of a reductant draw conduit and a valve element, according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Referring to FIG. 1, a block diagram of an exemplary engine system 100 is illustrated, according to one embodiment of the present 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. According to one 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 engines 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 (not shown), 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 (not shown) 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 exiting the exhaust manifold of the engine 102. The exhaust gas flow 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 before exiting the engine system 100.
In the illustrated embodiment, the aftertreatment system 104 includes a first module 106 that is fluidly connected to an exhaust conduit 108 of the engine 102. During engine operation, the first module 106 is arranged to internally receive engine exhaust gas from the exhaust conduit 108. The first module 106 may contain various exhaust gas treatment devices, such as, a Diesel Oxidation Catalyst (DOC) 110 and a Diesel Particulate Filter (DPF) 112, but other devices may be used. The first module 106 and the components found therein are optional and may be omitted for various engine applications in which the exhaust treatment function provided by the first module 106 is not required.
The exhaust gas flow provided to the first module 106 by the engine 102 may first pass through the DOC 110 and then through the DPF 112 before entering a transfer conduit 114. The aftertreatment system 104 includes a reductant supply system 116. A reductant is injected into the transfer conduit 114 by a reductant injector 118. The reductant may be a fluid, such as, Diesel Exhaust Fluid (DEF). The reductant may include urea, ammonia, or other reducing agent known in the art.
Referring to FIG. 2, the reductant is contained within a reductant tank 120. The reductant tank 120 defines an interior space. Parameters related to the reductant tank 120 such as size, shape, location, and material used may vary according to system design and requirements. Further, the reductant injector 118 may be communicably coupled to a controller (not shown). Based on control signals received from the controller, the reductant from the reductant tank 120 is provided to the reductant injector 118 by a pump 122. The pump 122 is configured to draw the reductant from the interior space of the reductant tank 120. In one embodiment, the reductant supply system 116 may include two or more reductant injectors 118. The number of the reductant injector 118 may vary based on the type of application.
As the reductant is injected into the transfer conduit 114, the reductant mixes with the exhaust gas passing therethrough, and is carried to a second module 124. Further, the transfer conduit 114 is configured to fluidly interconnect the first module 106 with the second module 124, such that, the exhaust gas flow from the engine 102 may pass through the first and second modules 106, 124 in series before being released at a stack 126 connected downstream of the second module 124. The second module 124 encloses a Selective Catalytic Reduction (SCR) module 128 and an Ammonia Oxidation Catalyst (AMOX) 130. The SCR module 128 operates to treat exhaust gases exiting the engine 102 in the presence of ammonia, which is provided after degradation of a urea-containing solution injected into the exhaust gases in the transfer conduit 114. The AMOX 130 is used to convert any ammonia slip from the downstream flow of the SCR module 128 before exiting the exhaust gas through the stack 126.
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 aftertreatment system design are possible without deviating from the scope of the disclosure.
FIG. 2 is a perspective view of the reductant tank 120. The reductant tank 120 includes a header unit 202. In one embodiment, the reductant tank 120 may include more than one header unit 202 based on the type of application. The header unit 202 may be threadably coupled with a top portion of the reductant tank 120. Alternatively, the header unit 202 may be welded, bolted, or brazed to the reductant tank 120.
As shown in FIGS. 2 and 3, the header unit 202 includes a reductant draw conduit 204. The reductant draw conduit 204 extends into the interior space of the reductant tank 120. The reductant draw conduit 204 is arranged and configured to draw the reductant from the reductant tank 120. The reductant draw conduit 204 includes at least one expansion opening 312 provided along a length thereof. In one example, the reductant draw conduit 204 may include a number of expansion openings 312. As shown in the accompanying figures, the reductant draw conduit 204 includes two expansion openings 312 provided diametrically opposite to each other. In another example, the reductant draw conduit 204 may include four or more expansion openings 312 provided equidistant from each other around a circumference of the reductant draw conduit 204 without limiting the scope of the present disclosure. Further, a heat exchanger 206 is provided in association with the header unit 202. The heat exchanger 206 is in thermal communication with the interior space of the reductant tank 120. The heat exchanger 206 is configured to receive a coolant flow therein. The coolant flow is configured to exchange heat with the reductant present within the reductant tank 120, thereby increasing a temperature of the reductant in the reductant tank 120.
The coolant may be any engine coolant that is configured to cool the engine 102. The coolant is generally at a temperature which is higher than that of the reductant, due to heat transfer between the coolant and various engine parts. Further, a coolant loop 208 is coupled to the heat exchanger 206. The coolant loop 208 extends into the interior space of the reductant tank 120. The coolant loop 208 includes a coolant supply line 210. The coolant supply line 210 is configured to introduce the coolant flow into the heat exchanger 206. The coolant loop 208 also includes a coolant outlet line 212. The coolant outlet line 212 is configured to discharge the coolant flow from the heat exchanger 206.
Based on an actuation signal received from the controller, a coolant flow valve (not shown) may be actuated and the coolant flow may be introduced into the heat exchanger 206 via the coolant supply line 210. A coolant pump (not shown) may be provided in fluid communication with the heat exchanger 206. The coolant pump may be configured to pump and deliver the coolant from a source such as a coolant tank (not shown) to various components of the aftertreatment system 104. One of ordinary skill in the art will appreciate that various additional components (not shown), such as a level sensor, a temperature sensor, or a fill port may be added or certain components could be removed depending on the application of the reductant tank 120.
The reductant draw conduit 204 may be fluidly coupled to a reductant supply conduit 214. The reductant supply conduit 214 is configured to fluidly couple the reductant draw conduit 204 with the reductant injectors 118, via the pump 122. The pump 122 is configured to pump and pressurize the reductant from the reductant tank 120 and supply the pressurized reductant to the reductant injector 118.
In cold environments, the reductant in the reductant draw conduit 204 tends to freeze leading to an expansion thereof. In order to accommodate the expansion of the reductant, the header unit 202 includes a valve element 300. The valve element 300 is coupled to the reductant draw conduit 204. The valve element 300 presents an additional volume for the reductant during expansion, based on an expansion of a main body member 302 of the valve element 300. More particularly, the main body member 302 is made of an elastomeric material that accommodates a change in volume of the reductant retained within the reductant draw conduit 204 during freezing thereof. Referring to FIGS. 3, 4, and 5, the valve element 300 defines a central axis X-X′. The valve element 300 is coupled and provided along the reductant draw conduit 204. In one example, the valve element 300 is positioned at a location on the reductant draw conduit 204 that has a tendency to undergo freezing last as compared to other locations on the reductant draw conduit 204. In the illustrated embodiment, only a single valve element 300 is disposed along the length of the reductant draw conduit 204. However, based on system requirements, additional number of the valve elements 300 may be disposed along the length of the reductant draw conduit 204.
The valve element 300 includes the main body member 302. The elastomeric material of the main body member 302 is capable of expansion and contraction based on a material property thereof. In one embodiment, the main body member 302 is made of rubber. The elastomeric material of the valve element 300 is configured to exert a radially inward restoring force on an outer wall 316 of the reductant draw conduit 204 with respect to the central axis X-X′ of the valve element 300 due to the material property of the valve element 300. The main body member 302 has a cylindrical cross section having a wall 304 of thickness “T”. The thickness “T” is defined such that a ratio of the thickness “T” of the wall 304 to a diameter “D” of the reductant draw conduit 204 is approximately 1:2.
The main body member 302 includes a channel 306 defined therethrough. The channel 306 is embodied as a through aperture. The reductant draw conduit 204 passes through the channel 306 of the main body member 302. Further, a diameter of the channel 306 is approximately equal to the diameter “D” of the reductant draw conduit 204. The main body member 302 includes an outer surface 308 and an inner surface 310 defined on the wall 304 of the main body member 302. The inner surface 310 is defined by the channel 306 of the main body member 302. The main body member 302 circumferentially surrounds at least a portion of the reductant draw conduit 204 corresponding to the expansion opening 312 such that the expansion openings 312 provides fluid communication between the reductant draw conduit 204 and the main body member 302.
As shown in the accompanying figures, the valve element 300 includes a support member 314. The support member 314 is provided in a surrounding contacting relationship with the main body member 302. The support member 314 is configured to provide support to the main body member 302 against a portion of the outer wall 316 of the reductant draw conduit 204. The support member 314 may include a wire 318. The wire 318 may embody a cable, cord, splice, and the like. The wire 318 may be made of a metal or a non-metal. The wire 318 is wrapped around the main body member 302 in a helical configuration. Alternatively, any other configuration may be used to wrap the wire 318 around the main body member 302.
A positioning element 320 is provided in surrounding contact with the outer wall 316 of the reductant draw conduit 204 and the valve element 300. In one embodiment, a pair of the positioning elements 320 (see FIGS. 4 and 5) is provided near a top end and a bottom end respectively of the valve element 300. The positioning element 320 is configured to vertically position the valve element 300 along the length of the reductant draw conduit 204. More particularly, the positioning element 320 may restrict any vertical movement of the valve element 300 along the length of the reductant draw conduit 204. In the illustrated example, the positioning element 320 is a C-clip or a circlip. Alternatively, the positioning element 320 may include any mechanical retention element configured to securely hold the main body member 302 in place and avoid any movements thereof. Although, the accompanying figures illustrate a pair of the positioning elements 320 associated with the valve element 300, the valve element 300 may include a single positioning element, located at either the top end or the bottom end of the valve element 300 based on system requirements.
As shown in FIG. 4, during operation of the engine system 100, a suction force is created by the pump 122 (see FIGS. 1 and 2) in order to draw the reductant from the reductant tank 120 (see FIG. 2) via the reductant draw conduit 204. Based on the drawing of the reductant through the reductant draw conduit 204, a suction force acting on the reductant draw conduit 204 causes a radially inward force “F1” to be exerted on the outer wall 316 of the reductant draw conduit 204 by the valve element 300 with respect to the central axis X-X′ of the valve element 300. The radially inward force “F1” causes the main body member 302 to press against the outer wall 316 of the reductant draw conduit 204. This pressing of the main body member 302 causes a portion of the inner surface 310 (see FIG. 2) of the main body member 302 which is in communication with the expansion openings 312 to extend inwards and into the reductant draw conduit 204, through the expansion openings 312. This may allow sealing between the valve element 300 and the reductant draw conduit 204 when the level of the reductant in the reductant tank 120 is below a level of the valve element 300 with respect to the reductant draw conduit 204.
Referring to FIG. 5, when the reductant present within the reductant draw conduit 204 freezes, the reductant expands in an outward direction with respect the central axis X-X′ of the valve element 300. As the reductant within the reductant draw conduit 204 expands, a pressure build-up in the reductant draw conduit 204 causes the valve element 300 to expand. Due to the pressure build-up, a radially outward force “F2” is exerted by a portion of the reductant present within the reductant draw conduit 204 with respect to the central axis X-X′ of the valve element 300. The radially outward force “F2” causes the valve element 300 to present the additional volume for accommodation of the reductant within the reductant draw conduit 204. Further, in such conditions, any additional reductant present within the reductant draw conduit 204 may exit the reductant draw conduit 204 back into the reductant tank 120.
FIG. 6 illustrates another embodiment of the present disclosure. In this embodiment, the reductant draw conduit 604 has a split piece configuration. More particularly, the reductant draw conduit 604 includes a first section 608 and a second section 610. The second section 610 is in fluid communication with the reductant in the reductant tank 120. Whereas, the first section 608 is coupled with the reductant supply conduit 214 (see FIG. 1).
The valve element 600 is positioned between and fluidly connected to the first section 608 and the second section 610 respectively. Further, the first and second sections 608, 610 of the reductant draw conduit 604 include expansion openings 612, 614 respectively. The expansion openings 612, 614 fluidly communicate with the channel 606 of the main body member 602. The working of the valve element 600 of FIG. 6 is similar to that of the valve element 300 described with reference to FIGS. 3 to 5. The valve element 600 presents the additional volume to accommodate the expansion caused by the freezing of the reductant retained within the reductant draw conduit 604.

INDUSTRIAL APPLICABILITY

The valve element 300, 600 of the present disclosure is coupled to the reductant draw conduit 204, 604. Based on operational requirements, multiple valve elements 300, 600 may be disposed along the length of the reductant draw conduit 204, 604 to compensate for the expansion of the reductant. The valve element 300, 600 is positioned within the reductant tank 120.
The valve element 300, 600 disclosed herein is capable of relieving volumetric expansion of the reductant during freezing and can also hold vacuum during suction of the reductant from the reductant tank 120. The valve element 300, 600 reduces the possibility of failure of the reductant draw conduit 204, 604 in freezing conditions. The valve element 300, 600 includes inexpensive components and is easy to assemble with the reductant draw conduit 204, 604. Further, the valve element 300, 600 can be retrofitted to an existing aftertreatment system without substantially changing the design of the aftertreatment system.
While aspects 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 header unit for a reductant tank, the header unit comprising:

a reductant draw conduit extending into an interior space of the reductant tank, the reductant draw conduit configured to draw a reductant from the reductant tank, wherein the reductant draw conduit includes at least one expansion opening provided along a length thereof; and

a valve element coupled to the reductant draw conduit, the valve element comprising:

a main body member defining a channel therethrough, the main body member circumferentially surrounding at least a portion of the reductant draw conduit corresponding to the at least one expansion opening,

wherein the main body member is made of an elastomeric material configured to accommodate an expansion thereof.

2. The header unit of claim 1, wherein the reductant draw conduit includes a plurality of expansion openings provided along the length thereof.

3. The header unit of claim 1, wherein the elastomeric material of the valve element is configured to exert a radially inward restoring force on an outer wall of the reductant draw conduit with respect to a central axis of the valve element.

4. The header unit of claim 1, wherein the valve element is configured to exert a radially inward force on the reductant draw conduit with respect to a central axis of the valve element based on the drawing of the reductant from the reductant tank.

5. The header unit of claim 1, wherein the expansion of the valve element is based on a radially outward force with respect to a central axis of the valve element exerted thereon by a portion of the reductant present within the reductant draw conduit.

6. The header unit of claim 1, wherein a ratio of a thickness of a wall of the main body member of the valve element to a diameter of the reductant draw conduit is 1:2.

7. The header unit of claim 1, wherein the reductant draw conduit has a split piece configuration, such that the reductant draw conduit includes a first section and a second section.

8. The header unit of claim 7, wherein the valve element is positioned between and fluidly connected to the first section and the second section respectively.

9. The header unit of claim 1 further comprising a positioning element configured to vertically position the valve element along the length of the reductant draw conduit.

10. The header unit of claim 1 further comprising a support member provided on an outer wall of the valve element.

11. The header unit of claim 1, wherein the header unit further includes at least one additional valve element provided on the reductant draw conduit.

12. A reductant supply system comprising:

a reductant tank having an interior space;

a heat exchanger in thermal communication with the interior space of the reductant tank;

a pump configured to draw a reductant from the interior space of the reductant tank; and

a header unit attached to the reductant tank, the header unit comprising:

a reductant draw conduit extending into the interior space of the reductant tank, the reductant draw conduit configured to draw the reductant from the reductant tank, wherein the reductant draw conduit includes wherein the reductant draw conduit includes at least one expansion opening provided along a length thereof; and

wherein the main body member is made of an elastomeric material configured to accommodate an expansion thereof; and

a coolant loop coupled to the heat exchanger, the coolant loop extending into the interior space of the reductant tank, the coolant loop comprising:

a coolant supply line configured to supply a coolant flow into the reductant tank; and

a coolant outlet line configured to discharge the coolant flow from the reductant tank.

13. The reductant supply system of claim 12, wherein the elastomeric material of the valve element is configured to exert a radially inward restoring force on an outer wall of the reductant draw conduit with respect to a central axis of the valve element.

14. The reductant supply system of claim 12, wherein the valve element is configured to exert a radially inward force on the reductant draw conduit with respect to a central axis of the valve element based on the drawing of the reductant from the reductant tank.

15. The reductant supply system of claim 12, wherein the expansion of the valve element is based on a radially outward force with respect to a central axis of the valve element exerted thereon by a portion of the reductant present within the reductant draw conduit.

16. The reductant supply system of claim 12, wherein the reductant draw conduit has a split piece configuration, such that the reductant draw conduit includes a first section and a second section.

17. The reductant supply system of claim 16, wherein the valve element is positioned between and fluidly connected to the first section and the second section respectively.

18. The reductant supply system of claim 12 further comprising a positioning element configured to vertically position the valve element along the length of the reductant draw conduit.

19. The reductant supply system of claim 12 further comprising a support member provided on an outer wall of the valve element.

20. The reductant supply system claim 12, wherein the header unit further includes at least one additional valve element provided on the reductant draw conduit.