US20150240683A1

US20150240683A1 - Reductant supply system

Info

Publication number: US20150240683A1
Application number: US14/190,750
Authority: US
Inventors: Jason W. Hudgens; Jinhui Sun
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2014-02-26
Filing date: 2014-02-26
Publication date: 2015-08-27

Abstract

A reductant supply system for an engine aftertreatment device is provided. The reductant supply system includes a tank configured to store a reductant. The reductant supply system includes a filter configured to receive the reductant from the tank. The filter defines a filtered volume therein. The reductant supply system includes a suction conduit in fluid communication with the filtered volume. The reductant supply system also includes a pump in fluid communication with the suction conduit. The pump is configured to pressurize the reductant. The reductant supply system further includes a return conduit configured to recirculate at least a part of the reductant pressurized by the pump to the filtered volume.

Description

TECHNICAL FIELD

The present disclosure relates to a reductant supply system, and more specifically to the reductant supply system for an aftertreatment device of an engine.

BACKGROUND

Currently used reductant delivery systems employ a return conduit used for recirculating excess reductant pressurized by a pump back to a tank. The excess reductant has been filtered by one or more filters present in the system before its return to the tank. Once returned to the tank, the filtered reductant may mix with the remaining unfiltered reductant. This mixture of the filtered reductant and the unfiltered reductant is required to be filtered before being supplied to the pump and/or other components of the system. Such a situation may result in repeated mixing of the filtered reductant with the unfiltered reductant and repeated filtration of the reductant. Hence, there is a need for an improved reductant supply system.
U.S. Pat. No. 6,912,846 discloses an apparatus for metering a urea or urea-water solution reducing agent into an exhaust gas stream. The apparatus includes means for delivering a reducing agent to a catalytic converter assembly for removing nitrogen oxides from the exhaust gases from an internal combustion engine. The means are connected via a line to a metering valve that regulates the metering. The means are connected via the line to a measuring element for measuring the pressure in the line, or for measuring a measurement variable correlating with the pressure. The means are connected via the line to a control means for ventilating the line by opening the metering valve, if a pressure drop in the line is detected by the measuring element. The control means include a memory for storing a performance graph, so that the metering valve can be opened for ventilation as a function of the magnitude of the pressure drop in the line.
However, the apparatus fails to address the need for an improved reductant supply system as discussed above.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a reductant supply system for an engine aftertreatment device is provided. The reductant supply system includes a tank configured to store a reductant. The reductant supply system includes a filter configured to receive the reductant from the tank. The filter defines a filtered volume therein. The reductant supply system includes a suction conduit in fluid communication with the filtered volume. The reductant supply system also includes a pump in fluid communication with the suction conduit. The pump is configured to pressurize the reductant. The reductant supply system further includes a return conduit configured to recirculate at least a part of the reductant pressurized by the pump to the filtered volume.
In another aspect of the present disclosure, a method of supplying a reductant to an engine aftertreatment device is provided. The method includes filtering the reductant by a filter. The filter defines a filtered volume therein. The method includes supplying the reductant from the filtered volume to a pump via a suction conduit. The method also includes pressurizing the reductant by the pump. The method further includes recirculating at least a part of the reductant pressurized by the pump to the filtered volume via a return conduit.
In yet another aspect of the present disclosure, a machine is provided. The machine includes an engine configured to generate an exhaust gas. The machine also includes an engine aftertreatment device configured to treat the exhaust gas. The engine aftertreatment device includes a Selective Catalytic Reduction (SCR) module. The machine further includes a reductant supply system. The reductant supply system includes a tank configured to store a reductant. The reductant supply system includes a filter configured to receive the reductant from the tank. The filter defines a filtered volume therein. The reductant supply system includes a suction conduit in fluid communication with the filtered volume. The reductant supply system includes a pump in fluid communication with the suction conduit. The pump is configured to pressurize the reductant. The reductant supply system includes a outlet conduit configured to receive the reductant pressurized by the pump. The reductant supply system includes a main filter provided in the outlet conduit. The main filter is configured to filter the reductant pressurized by the pump. The reductant supply system also includes a injector configured to receive a portion of the reductant filtered by the main filter via the outlet conduit. The injector is configured to dispense the reductant into the exhaust gas upstream of the Selective Catalytic Reduction (SCR) module of the engine aftertreatment device. The reductant supply system further includes a return conduit in fluid communication with the outlet conduit downstream of the main filter. The return conduit is configured to recirculate the rest of the reductant filtered by the main filter to the tank. The return conduit is in fluid communication with the filtered volume.
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 an exemplary engine system, according to an embodiment of the present disclosure;

FIG. 2 is a schematic representation of a reductant supply system, according to an embodiment of the present disclosure;

FIG. 3 is a schematic representation showing a return conduit in fluid communication with a supply conduit within a filtered volume of the reductant, according to an embodiment of the present disclosure;

FIG. 4 is another schematic representation showing the return conduit in fluid communication with the supply conduit within the filtered volume of the reductant, according to another embodiment of the present disclosure; and

FIG. 5 is a flowchart of a method of working of the reductant supply system, according to an 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 similar parts. FIG. 1 illustrates an exemplary engine system 100 according to one embodiment of the present disclosure. The engine system 100 illustrated in the accompanying figure may be employed in any machine (not shown) such as a dump truck. The machine may embody any other type of machine that performs an operation associated with an industry, such as mining, construction, farming, transportation, or any other industry known in the art. For example, the machine may be an off-highway truck, an earth moving machine, such as a wheel loader, an excavator, an articulated truck, a backhoe, a motor grader, a material handler and so on. In one embodiment, the term “machine”, as used herein, may also refer to a stationary equipment, such as a generator, that employs the engine system 100 to generate electricity.
The engine system 100 includes an engine 102 which is adapted to combust a fuel to release the chemical energy therein and convert that energy to mechanical power. The engine 102 may be a compression ignition engine that combusts diesel fuel. Alternatively, the engine 102 may include a spark ignition engine that is configured to combust gasoline or other fuels such as ethanol, bio-fuel, natural gas and so on.
An intake manifold 104 is disposed in association with the engine 102 and in fluid communication with combustion chambers (not shown) of the engine 102, in order to direct intake air used in the combustion process to the engine 102. The intake manifold 104 may be configured to receive intake air from an intake line 106. The intake line 106 in turn may draw atmospheric air through an air intake filter 108. A turbocharger 110 is also present in the intake line 106 in order to increase an amount of intake air supplied to the engine 102.
An exhaust manifold 112 is provided on the engine 102 and is in fluid communication with the combustion chambers. It should be noted that the arrangement of the intake manifold 104 and the exhaust manifold 112 may vary based on the application. Further, exhaust gases flowing through the exhaust manifold 112 may be directed to an exhaust line 114 and to be further released into the atmosphere.
The engine 102 includes an aftertreatment device 116 provided in fluid communication with the exhaust manifold 112 via the exhaust line 114. The aftertreatment device 116 is configured for reducing the emissions present in the exhaust gas produced by the combustion process. More specifically, the aftertreatment device 116 may include one or more components, or a combination thereof, such as an exhaust gas recirculation (EGR) module (not shown), a diesel oxidation catalyst (DOC) 118, a diesel particulate filter (DPF) 120, a reductant supply system 122, a selective catalytic reduction (SCR) module 124, an ammonia oxidation (AMOX) catalyst module 126 and so on. The SCR module 124 is configured to convert emission compounds such as Nitrogen Oxides (NOx) to Nitrogen (N2) and Water (H2O) by way of catalytic reduction using a suitable reductant. It should be noted by one of ordinarily skilled in the art that the aftertreatment device 116 may include additional components not described herein. The components of the aftertreatment device 116 may be in fluid communication with each other as per system design and requirements.
The present disclosure relates to the reductant supply system 122. The reductant supply system 122 is fluidly coupled to the SCR module 124 for providing a regulated dose of the reductant in a stream of the exhaust gas. The reductant supply system 122 includes a tank 128, a pump 130 and an injector 132 which will be explained in detail with reference to FIG. 2. Referring to FIG. 2, a schematic representation of the reductant supply system 122 for the aftertreatment device 116 of the engine 102 is illustrated. The reductant supply system 122 includes the tank 128. The tank 128 is configured to store the reductant (not shown). The reductant may be any reductant known in the art, such as diesel exhaust fluid (DEF) that may include an ammonia based solution such as urea and so on, used for reducing the emissions present in the exhaust gas. The reductant supply system 122 includes a filter 202 provided within the tank 128. The filter 202 defines a filtered volume 310, 406 (shown in FIGS. 3 and 4) of the reductant therein. It should be noted that the filtered volume 310, 406 of the reductant is also present outside the filter 202 and/or the tank 128 and will be explained in detail with relation to other components of the reductant supply system 122. The filter 202 is configured to provide filtration of the reductant before the reductant is extracted from the tank 128.
The reductant supply system 122 includes a suction conduit 204 provided within the tank 128. The suction conduit 204 is provided in fluid communication with the filter 202. Accordingly, the suction conduit 204 is provided in fluid communication with the filtered volume 310, 406 of the reductant within the tank 128. The suction conduit 204 is configured to provide a passage to the filtered volume 310, 406 such that the reductant may flow out of the tank 128.
The reductant supply system 122 includes the pump 130. The pump 130 is provided in fluid communication with the suction conduit 204. The pump 130 is configured to receive the reductant from the suction conduit 204 and pressurize the reductant. The pump 130 may be any pump known in the art such as a centrifugal pump, a piston pump, a screw pump, a diaphragm pump and so on. In the illustrated embodiment, the pump 130 is located external to the tank 128. In an alternative embodiment the pump 130 may be located within the tank 128. Accordingly, in such an alternative embodiment the pump 130 may be any type of submersible pump known in the art.
The reductant supply system 122 includes an outlet conduit 206. The outlet conduit 206 is provided in fluid communication with the pump 130. The outlet conduit 206 is configured to receive the pressurized reductant from the pump 130. The outlet conduit 206 includes a reversing valve 208 provided upstream and downstream of the pump 130 such that the reductant flows towards as well as away from the pump 130 through the reversing valve 208. The reversing valve 208 disclosed herein is a solenoid type of the reversing valve 208. In other embodiments, the reversing valve 208 may be any other hydraulic reversing valve known in the art operated by mechanical, electrical and/or electromechanical means. The reversing valve 208 is configured to control a reversal of a flow of the reductant from the tank 128 towards the pump 130 and vice versa based on operational requirements of the system.
The outlet conduit 206 includes a main filter 210 provided downstream of the pump 130. The main filter 210 is configured to filter the pressurized reductant received from the pump 130. The outlet conduit 206 includes a pressure gauge 212 provided downstream of the pump 130 and/or the main filter 210. The pressure gauge 212 is configured to determine a pressure of the reductant in the outlet conduit 206 downstream of the pump 130. The pressure gauge 212 may be any pressure gauge known the art. Further, a location of the pressure gauge 212 disclosed herein is merely exemplary and may vary as per system design and requirements without deviating from the scope of the disclosure. The outlet conduit 206 is further provided in fluid communication with the injector 132 of the aftertreatment device 116. The injector 132 may be communicably coupled to a controller (not shown).
Additionally, the controller may be communicably coupled to one or more sensors (not shown) provided upstream and/or downstream of the SCR module 124. The sensors may be configured to generate signals indicative of concentration of constituents in the exhaust gas. The controller may be configured to determine a required volume of the reductant per unit of time based on the signals received from the sensors. Further, the controller may be configured to actuate the injector 132 accordingly. The injector 132 is configured to receive a portion of the reductant filtered by the main filter 210 from the outlet conduit 206. The injector 132 is also configured to dispense or inject the reductant into the exhaust gas upstream of the SCR module 124.
The reductant supply system 122 also includes a return conduit 216. The return conduit 216 is provided in fluid communication with the outlet conduit 206 downstream of the main filter 210. In another embodiment, the return conduit 216 may be provided in fluid communication with the outlet conduit 206 upstream of the main filter 210. The return conduit 216 is further provided in fluid communication with the filtered volume 310, 406 of the reductant and will be explained in detail with reference to FIGS. 3 and 4. The return conduit 216 is configured to recirculate a rest of the reductant filtered by the main filter 210 to the tank 128. The rest of the reductant may refer to a portion of the reductant that remains from the filtered reductant after the required amount is supplied to the injector 132. The return conduit 216 includes a throttling device 218. The throttling device 218 may be communicably coupled to the controller. The throttling device 218 is configured to throttle and/or control the reductant recirculated to the filtered volume 310, 406 based on the determined required volume of the reductant per unit of time. The return conduit 216 also includes a check valve 220 provided between the throttling device 218 and the tank 128. The check valve 220 is configured to regulate the reductant recirculated to the filtered volume 310, 406. The check valve 220 is also configured to provide a unidirectional flow path for the rest of the reductant flowing via the return conduit 216 from the outlet conduit 206 to the tank 128.
The reductant supply system 122 includes a coolant conduit 222. The coolant conduit 222 is provided in fluid communication with a coolant system 224 of the engine 102. The coolant conduit 222 may be configured to provide cooling or heating, as per system design and requirements, to one or more components of the reductant supply system 122 such as the tank 128, the pump 130, the suction conduit 204, the outlet conduit 206, the return conduit 216, the injector 132 and/or other components of the reductant supply system 122 and/or the aftertreatment device 116. For example, in a cold environment the reductant present in the tank 128 may freeze. In such a case, the coolant conduit 222 may provide heat to the frozen reductant. The heat may thaw the frozen reductant and enable it to flow through the reductant supply system 122. In another embodiment, the injector 132, which is in fluid communication with the exhaust gas, may get heated to high temperatures. In such an embodiment, the coolant conduit 222 may provide cooling to the injector 132. The coolant conduit 222 may include other components including, but not limited to, one or more valves and filters, without deviating from the scope of the present disclosure.
Referring to FIG. 3, a schematic representation of an embodiment showing the return conduit 216 in fluid communication with the suction conduit 204 within the filtered volume 310 of the reductant is illustrated. In the exemplary embodiment of FIG. 3, the filter 202 is a pickup filter 301. The suction conduit 204 includes a partition 302. The partition 302 is configured to at least partly divide the suction conduit 204 into a first portion 304 and a second portion 306 within the filtered volume 310.
The first portion 304 is in fluid communication with the pump 130. The second portion 306 is in fluid communication with the return conduit 216. Additionally, the second portion 306 is also in fluid communication with the first portion 304 within the filtered volume 310 of the reductant. The suction conduit 204 includes an opening 312. The opening 312 is provided in the suction conduit 204 such that the opening 312 is surrounded by the filtered volume 310 of the reductant. The opening 312 is configured to receive the filtered volume 310 into the suction conduit 204. It should be noted that the return conduit 216 may be provided in fluid communication with the suction conduit 204 in other ways not described herein and may not limit the scope of the disclosure. For example, in one embodiment (not shown), the return conduit 216 may be provided in direct fluid communication with the suction conduit 204 outside the filtered volume 310 but within the tank 128. In another embodiment (not shown), the return conduit 216 may be provided in direct fluid communication with the suction conduit 204 outside the filtered volume 310 and outside the tank 128.
Referring to FIG. 4, a schematic representation of another embodiment showing the return conduit 402 in fluid communication with the suction conduit 404 within the filtered volume 406 of the reductant is illustrated. In an embodiment, as illustrated in FIG. 4, the filter 408 is a sock filter 410. The sock filter 410 may be provided around the pickup filter 412. The sock filter 410 may be configured to provide the filtered volume 406 of the reductant around the pickup filter 412 and to prevent contamination and mixing of the filtered volume 406 with the rest of the reductant present within the tank 128. The suction conduit 404 includes an opening 414. The opening 414 is provided in the suction conduit 404 such that the opening 414 is surrounded by the filtered volume 406 of the reductant. The opening 414 is configured to receive the filtered volume 406 into the suction conduit 404.
Referring to FIGS. 3 and 4, the return conduit 216, 402 includes an air vent 308, 416 respectively. The air vent 308, 416 is configured to prevent vapor lock during startup of the reductant supply system 122. The air vent 308, 416 is also configured to provide self priming of the pump 130 during startup of the reductant supply system 122.

INDUSTRIAL APPLICABILITY

Previously designed return conduits simply recirculated excess reductant pressurized by the pump back to the tank. The excess reductant that had been filtered by the main filter, the pickup filter and/or the sock filter was recirculated and mixed with the unfiltered reductant present in the tank. This lead to contamination of the previously filtered reductant with the unfiltered reductant within the tank. This mixture of the filtered reductant and the unfiltered reductant was then required to be filtered again before flowing to the pump and/or other components of the system.
The present disclosure relates to a method 500 of supplying the reductant to the aftertreatment device 116 of the engine 102. Referring to FIG. 5, a flowchart of the method 500 is illustrated. At step 502, the method 500 includes filtering the reductant by the filter 202, 408. The filter 202, 408 defines the filtered volume 310, 406 therein. At step 504, the method 500 includes supplying the reductant from the filtered volume 310, 406 to the pump 130 through the suction conduit 204, 404.
At step 506, the method 500 includes pressurizing the reductant by the pump 130. The aftertreatment device 116 of the engine 102 determines the requirement of the reductant. In an embodiment, the controller may determine the requirement of the reductant based on the signals received from the sensors. Based on the determined requirement, at least a part of the reductant pressurized by the pump 130 is supplied to the aftertreatment device 116. At step 508, the method 500 includes recirculating the rest of the reductant pressurized by the pump 130 to the filtered volume 310, 406 through the return conduit 216, 402. The reductant is recirculated to the filtered volume 310, 406 by throttling the reductant using the throttling device 218. Additionally, the reductant, recirculated to the filtered volume 310, 406, is regulated using the check valve 220 provided in the return conduit 216, 402. Further, the return conduit 216, 402 is fluidly coupled to the suction conduit 204, 404 within the filtered volume 310, 406 of the reductant for recirculating the rest of the reductant pressurized by the pump 130. More specifically, the return conduit 216, 402 is fluidly coupled to the suction conduit 204, 404 within the pickup filter 301, 412 and/or the sock filter 410.
The recirculation of the rest of the reductant within the filtered volume 310, 406 prevents repeated re-filtration of the reductant. As a result, a life span of the main filter 210, the filter 202, 408 used in the filtration of the reductant may increase considerably leading to longer service intervals and lowered maintenance costs. During a shut off period of the reductant supply system 122, the reductant present in the reductant supply system 122 may purge and return to the tank 128. Hence, during startup of the reductant supply system 122, priming of the pump 130 may be required. The air vent 308, 416 provided in the return conduit 216, 402 may provide self priming of the pump 130 and may prevent vapor lock during startup of the reductant supply system 122. Additionally, in one embodiment, as shown in FIG. 4, the sock filter 410 used around the pickup filter 412 provides a larger volume of the reductant to enable priming of the pump 130 during startup.
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 reductant supply system for an engine aftertreatment device, the reductant supply system comprising:

a tank configured to store a reductant;

a filter configured to receive the reductant from the tank, wherein the filter defines a filtered volume therein;

a suction conduit in fluid communication with the filtered volume;

a pump in fluid communication with the suction conduit, wherein the pump is configured to pressurize the reductant; and

a return conduit configured to recirculate at least a part of the reductant pressurized by the pump to the filtered volume.

2. The reductant supply system of claim 1, wherein the filter is disposed within the tank.

3. The reductant supply system of claim 1, wherein the filter is at least one of a sock filter and a pickup filter.

4. The reductant supply system of claim 1, wherein the return conduit comprises an air vent.

5. The reductant supply system of claim 1, wherein the return conduit is in fluid communication with the suction conduit within the filter.

6. The reductant supply system of claim 1, wherein the suction conduit comprises:

a partition configured to at least partly divide the suction conduit into a first portion and a second portion within the filtered volume,

wherein the first portion is in fluid communication with the pump;

wherein the second portion is in fluid communication with the return conduit; and

wherein the second portion is in fluid communication with the first portion within the filtered volume.

7. The reductant supply system of claim 1 further comprises a throttling device provided in the return conduit.

8. The reductant supply system of claim 7 further comprises a check valve provided in the return conduit between the throttling device and the tank.

9. The reductant supply system of claim 1 further comprises an outlet conduit configured to receive the reductant pressurized by the pump, wherein the return conduit is in fluid communication with the outlet conduit.

10. The reductant supply system of claim 1 further comprises a main filter configured to filter the reductant pressurized by the pump.

11. A method of supplying a reductant to an engine aftertreatment device, the method comprising:

filtering the reductant by a filter, wherein the filter defines a filtered volume therein;

supplying the reductant from the filtered volume to a pump via a suction conduit;

pressurizing the reductant by the pump; and

recirculating at least a part of the reductant pressurized by the pump to the filtered volume via a return conduit.

12. The method of claim 11 further comprises throttling the reductant recirculated to the filtered volume.

13. The method of claim 11 further regulating the reductant recirculated to the filtered volume by a check valve provided in the return conduit.

14. The method of claim 11 further comprises fluidly communicating the suction conduit and the return conduit within the filter.

15. The method of claim 11 further comprises:

determining a requirement of the reductant by the engine aftertreatment device;

supplying a portion of the reductant pressurized by the pump to the engine aftertreatment device based on the determined requirement; and

recirculating rest of the reductant pressurized by the pump to the filtered volume.

16. A machine comprising:

an engine configured to generate an exhaust gas;

an engine aftertreatment device configured to treat the exhaust gas, the engine aftertreatment device comprising a Selective Catalytic Reduction (SCR) module; and

a reductant supply system comprising:

a tank configured to store a reductant;

a suction conduit in fluid communication with the filtered volume;

a pump in fluid communication with the suction conduit, wherein the pump is configured to pressurize the reductant;

an outlet conduit configured to receive the reductant pressurized by the pump;

a main filter provided in the outlet conduit, wherein the main filter is configured to filter the reductant pressurized by the pump;

an injector configured to receive a portion of the reductant filtered by the main filter via the outlet conduit, wherein the injector is configured to dispense the reductant into the exhaust gas upstream of the Selective Catalytic Reduction (SCR) module of the engine aftertreatment device; and

a return conduit in fluid communication with the outlet conduit downstream of the main filter, wherein the return conduit is configured to recirculate rest of the reductant filtered by the main filter to the filtered volume.

17. The machine of claim 16, wherein the filter is one of a sock filter and a pickup filter.

18. The machine of claim 16, wherein the return conduit is in fluid communication with the suction conduit within the filter.

19. The machine of claim 16, wherein the suction conduit comprises:

a partition configured to at least partly divide the suction conduit into a first portion and a second portion within the filtered volume;

wherein the first portion is in fluid communication with the pump;

20. The machine of claim 16 further comprises a throttling device provided in the return conduit.