Exhaust aftertreatment system

Abstract

An exhaust aftertreatment system for treating exhaust gas emitted from an internal combustion engine (12), the exhaust aftertreatment system comprising: a catalyst component; and an exhaust treatment fluid supply system (16, 22, 116) for injecting an exhaust treatment fluid into an exhaust stream at a location upstream of the catalyst component, the exhaust treatment fluid supply system (16, 22, 116) comprising: a tank (26, 126) for holding the exhaust treatment fluid; a supply channel (46, 146) receiving the exhaust treatment fluid from the tank (26, 126) and supplying the exhaust treatment fluid to a supply manifold (38, 138); a plurality of injection valves (42, 142) receiving the exhaust treatment fluid from the supply manifold (38, 138) and metering the exhaust treatment fluid into the exhaust stream; a bypass valve (36, 136) that selectively allows a portion of the exhaust treatment fluid in the supply channel (46, 146) to return to the tank (26, 126) through a bypass channel (50, 150) without flowing through the injection valves (42, 142); and a control module (52, 152) that controls the bypass valve (36, 136) and the injectors (42, 142) based on a first fluid pressure in the supply channel (46, 146) and a second fluid pressure between an inlet of the supply manifold (38, 138) and the injectors (42, 142).

Description

REGIONThe present disclosure relates to an exhaust aftertreatment system for an internal combustion engine, a fluid delivery system for injecting exhaust treatment fluid into a stream of exhaust gas, and a method.BACKGROUNDThis section provides background information to the present disclosure and does not necessarily represent the prior art.Emission regulation requirements dictate that engines include exhaust aftertreatment systems to eliminate or at least substantially minimize the emissions of, for example, particulates and NOx. To remove or reduce emissions of particulates and NOx, exhaust aftertreatment systems may include components such as a particulate filter (e.g., a diesel particulate filter (DPF)), a selective catalyst reduction (SCR) component, and a diesel oxidation catalyst (DOC) component.SCR and DOC components generally cooperate with fluid delivery systems that inject a fluid (e.g., a hydrocarbon fluid, urea, or other reagent) into the exhaust stream for treating the exhaust gas before the exhaust gas enters the SCR or DOC components. For example, in SCR, a reductant solution containing urea may be injected into the exhaust stream prior to entering the SCR component. In DOC, a hydrocarbon reductant, such as diesel fuel, is injected into the exhaust stream prior to entering the DOC component.The fluid delivery systems include the integration of injectors, pumps, filters, valves, and other necessary control devices to control the dosing of each of these fluids into the exhaust stream. Generally, fluid delivery systems for, for example, low, medium and high weight trucks may include a single injection source for dosing the fluid into the exhaust stream. Large engine fluid delivery systems for locomotives, marine and stationary applications may include multiple injection sources for injecting the fluid into the exhaust stream. Solving various problems, such as maintaining proper injection pressure, system stability, sufficient reductions in harmful emissions (e.g., particulates and NOx), cost, and maintenance, can be difficult in constructing these industrial applications. The principles of the present disclosure provide more precise control of the fluid pressure at the injectors so that the size of the fluid's spray droplets can be more accurately regulated within a narrower tolerance range.In the prior art, U.S. Pat. No. 8,920,757 B1 discloses a reducing agent metering system and method for post-treatment of the engine gas. It is provided that opening and closing of a metering valve in the reducing agent metering system is controlled in such a way that the pressure oscillations in the metering system are damped. The metering valve is opened in response to the metering command exceeding a minimum threshold and the differential pressure across the metering valve exceeding a differential pressure threshold.Furthermore, a reducing agent supply device having a reducing agent injection valve is known from the prior art according to US 2013 / 0118155 A1. The reducing agent supply device includes an injection valve fixed to an exhaust pipe of a reduction catalyst. The apparatus further includes a cooling water circulation passage, a flow control valve, a temperature sensor, and a controller.SUMMARYThis section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.In one embodiment, the present disclosure provides an exhaust aftertreatment system for treating exhaust gas emitted from an internal combustion engine. The exhaust aftertreatment system may include a catalyst component and an exhaust treatment fluid delivery system for injecting an exhaust treatment fluid into an exhaust stream at a location upstream of the catalyst component. The exhaust treatment fluid delivery system may include a tank for holding the exhaust treatment fluid, a delivery passage, one or more injectors (e.g., 1-10 injectors or more), a bypass valve, and a control module. The supply passage receives the exhaust treatment fluid from the tank and supplies the exhaust treatment fluid to a supply manifold. The plurality of injectors receive the exhaust treatment fluid from the supply manifold and meter the exhaust treatment fluid into the exhaust flow. The bypass valve selectively allows a portion of the exhaust treatment fluid in the supply passage to return to the tank through a bypass passage without flowing through the injectors. The control module controls the bypass valve and the injectors based on a first fluid pressure in the supply passage and a second fluid pressure between an inlet of the supply manifold and the injectors.In some embodiments, the control module controls the bypass valve to achieve a predetermined fluid pressure in the supply passage that is higher than a desired fluid pressure at the injectors.In some embodiments, the control module controls the bypass valve and the injectors to account for a head due to differences in vertical height between the injectors and one or more pumps of the fluid delivery system.In some embodiments, the aftertreatment system includes a recirculation passage that recirculates non-injected exhaust treatment fluid from the injectors to the tank and allows for cooling of the injectors.In some embodiments, the exhaust treatment fluid delivery system includes a recirculation valve disposed along the recirculation passage between a recirculation manifold and the bypass passage.In some embodiments, the control module controls the recirculation valve based on a third fluid pressure in the recirculation passage.In some embodiments, the bypass valve and the recirculation valve are pulse width modulated.In some embodiments, the exhaust treatment fluid delivery system includes a valve bypass line that allows fluid to bypass the recirculation valve.In some embodiments, the valve bypass line includes a check valve that permits fluid flow through the valve bypass line in a first direction from a first location between the recirculation valve and the tank and a second location between the recirculation valve and the recirculation manifold, and inhibits fluid flow through the valve bypass line in a second direction opposite the first direction.In some embodiments, the exhaust treatment fluid delivery system includes a pump for pressurizing the delivery manifold and inlet lines of the injectors.In some embodiments, the exhaust treatment fluid is a hydrocarbon exhaust treatment fluid. The hydrocarbon exhaust treatment fluid may be atomized at a location adjacent to the catalyst component.In some embodiments, the catalyst component is an oxidation catalyst component.In some embodiments, the exhaust treatment fluid is a urea exhaust treatment fluid. The urea exhaust treatment fluid may be atomized at a location adjacent to the catalyst component.In some embodiments, the catalyst component is an SCR catalyst.In some embodiments, the exhaust aftertreatment system includes a urea quality sensor disposed upstream of at least one of the injectors.In some embodiments, the plurality of injectors inject the exhaust treatment fluid into a common exhaust stream.In some embodiments, the plurality of injectors inject the exhaust treatment fluid into separate exhaust streams associated with a plurality of internal combustion engines.In another embodiment, the present disclosure provides a fluid delivery system for injecting exhaust treatment fluid into a stream of exhaust gas emitted from an internal combustion engine. The fluid delivery system may include a tank for holding the exhaust treatment fluid, a delivery passage, a delivery manifold, one or more injectors, a recirculation passage, a bypass passage, and first and second pressure sensors. The supply passage receives the exhaust treatment fluid from the tank. The supply manifold receives the exhaust treatment fluid from the supply passage. The plurality of injectors receive the exhaust treatment fluid from the supply manifold. The exhaust treatment fluid is recirculated from the injectors to the tank through the recirculation passage. The bypass passage connects the supply passage to the recirculation passage and may include a bypass valve that controls fluid flow therebetween. The first pressure sensor may measure a first pressure of the exhaust treatment fluid in the supply passage. The bypass valve is controlled based on the first pressure. The second pressure sensor may measure a second pressure of the exhaust treatment fluid in the supply manifold. The injectors may be controlled based on the second pressure.In some embodiments, the bypass valve is controlled to achieve a predetermined fluid pressure in the supply passage that is higher than a desired fluid pressure at the injectors.In some embodiments, the fluid delivery system includes a recirculation valve disposed along the recirculation passage between a recirculation manifold and the bypass passage.In some embodiments, the recirculation valve is controlled based on a third pressure in the recirculation passage.In some embodiments, the bypass valve and the recirculation valve are pulse width modulated.In some embodiments, the fluid delivery system includes a valve bypass line that allows fluid to bypass the recirculation valve.In some embodiments, the valve bypass line includes a check valve that permits fluid flow through the valve bypass line in a first direction from a first location between the recirculation valve and the tank and a second location between the recirculation valve and the recirculation manifold. The check valve prevents fluid flow through the valve bypass line in a second direction opposite the first direction.In some embodiments, the fluid delivery system includes a pump for pressurizing the delivery manifold and inlet lines of the injectors.In some embodiments, the exhaust treatment fluid is a hydrocarbon exhaust treatment fluid. The hydrocarbon exhaust treatment fluid may be injected into an exhaust stream at a location adjacent a catalyst component.In some embodiments, the catalyst component is an oxidation catalyst component.In some embodiments, the exhaust treatment fluid is a urea exhaust treatment fluid. The urea exhaust treatment fluid may be injected at a location adjacent to a catalyst component.In some embodiments, the catalyst component is an SCR catalyst.In some embodiments, the injectors inject the exhaust treatment fluid into a common exhaust stream.In some embodiments, the injectors inject the exhaust treatment fluid into separate exhaust streams associated with multiple internal combustion engines.In another embodiment, the present disclosure provides a method that may include supplying exhaust treatment fluid from a tank to a supply manifold; controlling an injector that receives the exhaust treatment fluid from the supply manifold based on a first fluid pressure in the supply manifold; selectively allowing a portion of the exhaust treatment fluid to bypass the injector; and controlling an amount of the exhaust treatment fluid allowed to bypass the injector based on a second fluid pressure upstream of the supply manifold.In some embodiments, the method includes measuring the second fluid pressure with a pressure sensor disposed along a supply passage that supplies exhaust treatment fluid from the tank to the supply manifold.In some embodiments, controlling the injector includes adjusting a pulse width modulation duty cycle of the injector.In some embodiments, controlling the amount of exhaust treatment fluid permitted to bypass the injector includes adjusting a pulse width modulation duty cycle of a bypass valve.In some embodiments, the method includes controlling a backpressure of fluid at the injector with a recirculation valve disposed in a recirculation passage through which exhaust treatment fluid is recirculated from the injector to the tank.In some embodiments, controlling backpressure of fluid at the injector with the recirculation valve includes controlling the recirculation valve based on a third fluid pressure in the recirculation passage.In some embodiments, the method includes selectively allowing exhaust treatment fluid to bypass the recirculation valve.In some embodiments, the method includes detecting fluid leaks by pumping fluid through the return passage to a return manifold.In some embodiments, controlling the recirculation valve includes adjusting a pulse width modulation duty cycle of the recirculation valve.In some embodiments, supplying exhaust treatment fluid comprises supplying a hydrocarbon exhaust treatment fluid.In some embodiments, the method includes injecting the hydrocarbon exhaust treatment fluid into an exhaust stream adjacent to an oxidation catalyst.In some embodiments, supplying exhaust treatment fluid comprises supplying a urea exhaust treatment fluid.In some embodiments, the method includes injecting the urea exhaust treatment fluid into an exhaust stream adjacent to an SCR catalyst.In some embodiments, the method includes controlling a plurality of injectors that receive the exhaust treatment fluid from the supply manifold based on the first fluid pressure in the supply manifold.In some embodiments, the method includes injecting the exhaust treatment fluid into a single exhaust stream with the plurality of injectors.In some embodiments, the method includes injecting the exhaust treatment fluid into a plurality of exhaust streams with the plurality of injectors. Each of the exhaust streams may be associated with a plurality of internal combustion engines.In some embodiments, the method includes returning non-injected exhaust treatment fluid from the injector to the tank.Further areas of applicability will become apparent from the description provided herein. The description and specific examples in the present summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.DRAWINGSThe drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. FIG. 1 is a schematic illustration of an exhaust aftertreatment system according to the principles of the present disclosure; FIG. 2 is a schematic illustration of a fluid delivery system of the exhaust aftertreatment system of FIG. 1 ; FIG. 3 is a schematic illustration of a control module that controls a valve and injectors of the fluid delivery system of FIG. 2 ; FIG. 4 is a schematic illustration of another fluid delivery system in accordance with the principles of the present disclosure; and FIG. 5 is a schematic illustration of a control module that controls valves and injectors of the fluid delivery system of FIG. 4.Throughout the several views of the drawings, corresponding reference numerals indicate corresponding parts.DETAILED DESCRIPTIONExemplary embodiments will now be described more fully with reference to the accompanying drawings.Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed as limiting the scope of the disclosure. In some embodiments, well-known methods, well-known device structures, and well-known technologies are not described in detail.The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an", and "the / s" are intended to include the plural forms as well, unless the context expressly indicates otherwise. The terms "comprises," "comprises(d)," "includes(d)," and "has(d)" are meant to be inclusive and therefore indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, methods, and steps described herein are not to be understood as requiring their performance in the particular order discussed or illustrated, unless specifically indicated as the order of performance. It will be further understood that further or alternative steps may be employed.When an element or layer is described as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. On the other hand, when an element is described as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other wording used to describe the relationship between elements should be interpreted in a similar manner (for example, "between" versus "directly between", "next" versus "directly next", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or portion from another region, layer, or portion. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by context. Thus, a first element, component, region, layer, or portion discussed below could be referred to as a second element, component, region, layer, or portion without departing from the teachings of the example embodiments.FIG. 1 illustrates an exhaust aftertreatment system 10 for treating exhaust gas discharged from an internal combustion engine 12 into an exhaust passage 14. The exhaust aftertreatment system 10 may include a first fluid delivery system 16, a diesel oxidation catalyst (DOC) 18, a diesel particulate filter (DPF) 20, a second fluid delivery system 22, and an SCR catalyst 24. Although a single engine 12 is shown in FIG. 1 as expelling exhaust gas into the exhaust passage 14, in some embodiments, multiple internal combustion engines may expel exhaust gas into the exhaust passage 14 such that the exhaust aftertreatment system 10 may treat exhaust gas from all of these internal combustion engines. The plurality of internal combustion engines may operate simultaneously and / or independently of one another.The first fluid delivery system 16 may inject a hydrocarbon (e.g., diesel fuel) into the exhaust stream at or upstream of the DOC 18. The second fluid delivery system 22 may inject urea (or other reagent) into the exhaust stream at or downstream of the SCR catalyst 24. It should be appreciated that the specific components of the aftertreatment system 10 and the positioning of these components with respect to the fluid delivery systems 16, 22 may vary from the configuration described above and shown in FIG. 1. It should be understood that the principles of the present disclosure are applicable to such variations.FIG. 2 illustrates an example fluid delivery system. One or both of the first fluid delivery systems 16, 22 may be configured as shown in FIG. 2. Thus, the following description of the fluid delivery system shown in FIG. 2 may apply equally to the first and second fluid delivery systems 16, 22.As shown in FIG. 2, the fluid delivery system 16, 22 may include a tank 26, a filter 28, a temperature sensor 30, a pump 32, a first pressure sensor 34, a bypass valve 36, one or more delivery manifolds 38, a second pressure sensor 40, one or more injectors 42, and one or more return manifolds 44. The tank 26 may supply fluid to a supply passage 46 and receive fluid from a return passage 48. A bypass passage 50 may directly fluidly connect the supply passage 46 to the return passage 48. Although the fluid delivery system 16, 22 shown in FIG. 2 includes two injectors 42, it should be appreciated that the fluid delivery system 16, 22 could include any number of injectors 42. Additionally or alternatively, the fluid delivery system 16, 22 could include one or more injectors 42 that inject fluid into separate exhaust passages 14 associated with different multiple engines. Some such motors may always be running while others may be shut down, or all motors may be running simultaneously or shut down simultaneously. Thus, one or more of the injectors 42 may be deactivated while one or more other injectors 42 may inject fluid into an exhaust stream.The pump 32 can draw fluid stored in the tank 26 through the filter 28 and the temperature sensor 30. The temperature sensor 30 may detect a temperature of the fluid flowing therethrough and communicate the temperature data to a control module 52 continuously, periodically, or upon request (FIG. 3 ). From the pump 32, the fluid may flow through the first pressure sensor 34 and into the supply passage 46. The first pressure sensor 34 may detect a pressure of the fluid flowing therethrough and communicate the pressure data to the control module 52 continuously, periodically, or upon request. From the first pressure sensor 34, a portion or all of the fluid in the supply passage 46 may flow into the supply manifold 38. The second pressure sensor 40 may detect a pressure of the fluid in the supply manifold 38 and communicate the pressure data to the control module 52 continuously, periodically, or on demand.Fluid may be supplied from the supply manifold 38 to the injectors 42 via supply lines 54. In some embodiments of the fluid delivery system 22, one or more urea quality sensors 58 may be disposed along one or more delivery conduits 54. The urea quality sensor 58 may sense the concentration of urea (e.g., the ammonia content in the fluid) supplied to the injectors 42. The urea quality sensor 58 may be in communication with the control module 52. The control module 52 may change its control of the bypass valve 36, the injectors 42, and / or the pump 32 and / or shut down the pump 32 based on data from the urea quality sensor 58.A first portion of the fluid flowing through the supply conduits 54 is injected into the exhaust flow flowing through the exhaust passage 14. Excess fluid (non-injected fluid) at the injectors 42 flows through return lines 56 to the return manifold 44. the control module 52 may control the operation of the injectors 42 to control the amount of fluid injected into the exhaust flow based on data from the temperature sensor 30 and / or the first pressure sensor 34 and / or the second pressure sensor 40. In some embodiments, the injectors 42 may be pulse width modulated. From the return manifold 44, the fluid is returned to the tank 26 for storage therein and / or recirculation through the fluid delivery system 16, 22.The control module 52 may control operation of the bypass valve 36 to selectively allow a portion of the fluid in the supply passage 46 to flow directly through the bypass passage 50 to the recirculation passage 48. In some embodiments, the bypass valve 36 may be pulse width modulated. The control module 52 may control operation of the bypass valve 36 based on data from the temperature sensor 30 and / or the first pressure sensor 34 and / or the second pressure sensor 40.As described above, the control module 52 is in communication with the first and second pressure sensors 34, 40, the temperature sensor 30, the bypass valve 36, and the injectors 42. The control module 52 may include, or be part of, for example, an ASIC (application specific integrated circuit); an electronic circuit; a processor (shared, dedicated, or grouped) and / or memory (shared, dedicated, or grouped) that executes one or more software or firmware programs, and / or a combined logic circuit, and / or other suitable components that provide the described functionality. The control module 52 may be or may include part of a control unit that controls one or more other vehicle systems. Alternatively, the control module 52 may be a control unit dedicated to the exhaust aftertreatment system 10 or the fluid delivery system 16, 22. In some embodiments, the control module 52 may be in communication with and control operation of the pump 32. In some embodiments, the control module 52 may control the pump 32 to achieve the desired flow rates and / or fluid pressures based on data received from one or more of the sensors 30, 34, 40 (e.g., vary a speed or duty cycle of the pump 32).Based on the data received from the first pressure sensor 34, the control module 52 may control the bypass valve 36 to achieve a first predetermined fluid pressure in the supply passage 46. The first predetermined fluid pressure may be a pressure that is above a desired target fluid pressure at one or more of the injectors 42. The first predetermined fluid pressure and / or the desired pressure at the injectors may be constant values or values that change based on operating conditions of the one or more engines 12 (e.g., engine speed, engine load, engine temperature, exhaust temperature, exhaust flow rate), and / or temperature data from the temperature sensor 30, for example.The control module 52 may adjust the pulse width modulation (PWM) duty cycle to achieve the first predetermined fluid pressure in the supply passage 46. That is, when the fluid pressure in the supply passage 46 (i.e., at the first pressure sensor 34) is higher than the first predetermined fluid pressure, the control module 52 may adjust the PWM duty cycle to allow more fluid to flow from the supply passage 46 through the bypass passage 50 to the return passage 48 (which leads back to the tank 26). When the fluid pressure in the supply passage 46 (i.e., at the first pressure sensor 34) is below the first predetermined fluid pressure, the control module 52 may adjust the PWM duty cycle to restrict fluid flow through the supply passage 46, thereby supplying more fluid to the supply manifold 38.Based on data received from the second pressure sensor 40, the control module 52 may control the PWM duty cycle of the injectors 42 to achieve a desired desired target pressure in the supply lines 54 proximate the injectors 42. That is, when the fluid pressure at the second pressure sensor 40 is below a second predetermined fluid pressure, the control module 52 may adjust the PWM duty cycle of the injectors 42 to reduce the amount of fluid injected into the exhaust stream 14. When the fluid pressure at the second pressure sensor 40 is higher than the second predetermined fluid pressure, the control module 52 may adjust the PWM duty cycle of the injectors 42 to increase the amount of fluid injected into the exhaust stream 14. The second predetermined fluid pressure may be a constant value or a value that changes based on operating conditions of the one or more engines 12 (e.g., engine speed, engine load, engine temperature, exhaust temperature, exhaust flow rate) and / or, for example, temperature data from the temperature sensor 30.It should be appreciated that it may be desirable at any time for one or more of the injectors 42 to inject fluid into the exhaust stream 14 while another or more of the injectors 42 are deactivated (i.e., not injecting fluid into the exhaust stream 14). In controlling the PWM duty cycle of the bypass valve 36 and / or one or more of the injectors 42, the control module 52 may consider whether one or more of the injectors 42 are deactivated at a given time and adjust the duty cycles of the injectors 42 during operation accordingly. In some embodiments, one or more injectors 42 may be operated at a different PWM duty cycle than one or more other injectors 42. In some embodiments, one or more of the injectors 42 may have a different opening size than one or more other injectors 42 for injecting different amounts of fluid at the same or different pressures.Referring to FIGS. 4 and 5, another fluid delivery system 116 is provided. The fluid delivery system 116 may be incorporated into the exhaust aftertreatment system 10 in place of one of the fluid delivery systems 16, 22. The structure and function of the fluid delivery system 116 may be similar or identical to those of the fluid delivery system 16, 22 described above, except for any exceptions described below and / or shown in the figures. Therefore, similar features will not be described in detail again.The fluid delivery system 116 may include a tank 126, a filter 128, a temperature sensor 130, a pump 132, a first pressure sensor 134 (disposed in a delivery passage 146), a bypass valve 136 (disposed in a bypass passage 150), one or more delivery manifolds 138, a second pressure sensor 140, one or more delivery lines 154, one or more injectors 142, one or more return lines 156, one or more return manifolds 144, a third pressure sensor 145, a return valve 147 (disposed in a return passage 148), and a check valve 149 (disposed in a valve bypass line 151). A control module 152 may be in communication with the first, second, and third pressure sensors 134, 140, 145, the temperature sensor 130, the bypass valve 136, the injectors 142, and the recirculation valve 147. The control module 152 may control the operation of the bypass valve 136, the injectors 142, and the recirculation valve 147 based on data received from one or more of the sensors 130, 134, 140, 145. The structure and function of the control module 152, sensors 130, 134, 140, bypass valve 136, and injectors 142 may be similar or identical to those of the control module 52, sensors 30, 34, 40, bypass valve 36, and injectors 42 described above, except for any exceptions described below. Therefore, similar features will not be described in detail again. In some embodiments, one or more of the feed lines 154 may include a urea quality sensor 158. The structure and function of the urea quality sensor 158 may be similar or identical to those of the urea quality sensor 58 described above.The third pressure sensor 145 may detect a pressure of fluid in the return passage 148 and communicate this data to the control module 152 continuously, periodically, or upon request. Based on data from the third pressure sensor 145, the control module 152 may adjust the PWM duty cycle of the recirculation valve 147 to achieve a third predetermined fluid pressure in the recirculation passage 148. That is, when the fluid pressure in the feedback passage 148 (i.e., at the third pressure sensor 145) is higher than the third predetermined fluid pressure, the control module 152 may adjust the PWM duty cycle to allow more fluid to flow through the feedback passage 148. When the fluid pressure in the recirculation passage 148 (i.e., at the third pressure sensor 145) is below the third predetermined fluid pressure, the control module 152 may adjust the PWM duty cycle of the recirculation valve 147 to restrict fluid flow therethrough. The control of the recirculation valve 147 in this manner acts to adjust the backpressure at the injectors 142 and adjust an amount of heat transfer from the injectors 142 to the non-injected fluid. The third predetermined fluid pressure may be a constant value or a value that changes based on operating conditions of the one or more engines 12 (e.g., engine speed, engine load, engine temperature, exhaust temperature, exhaust flow rate) and / or, for example, temperature data from the temperature sensor 130.The valve bypass line 151 is connected to the recirculation passage 148 and allows fluid to bypass the recirculation valve 147 when the valves 136, 147 and the injectors are off (closed). Check valve 149 may allow fluid in return passage 148 to flow between tank 126 and return valve 147 through valve bypass line 151 to a location in return passage 148 between return valve 147 and return manifold 144. The check valve 149 may prevent fluid flow through the valve bypass line 151 in the opposite direction. In this way, during normal operation of the aftertreatment system 10 (where one or more of the injectors 142 are operating), the check valve 149 prevents fluid from bypassing the recirculation valve 147. The check valve 149 and the valve bypass line 151 allow the fluid delivery system 116 to be back-flushed (e.g., by pumping fluid from the tank 126 or air with an auxiliary pump (not shown) to the recirculation manifold 144 through the recirculation passage 148) to clean the fluid delivery system 116, check for leaks in the fluid delivery system 116, and / or flush liquid from one or more components or tubes of the fluid delivery system 116 to prevent the liquid from freezing there.Although the valves 36, 136, 147 and the injectors 42, 142 are pulse width modulated as described above, it should be appreciated that some or all of the valves 36, 136, 147 and / or the injectors 42, 142 may not be pulse width modulated in some embodiments. Instead, some or all of the valves 36, 136, 147 and / or injectors 42, 142 may be controlled by varying the valve positions between fully open and fully closed positions.Although not shown in the figures, in some embodiments, the fluid delivery system 16, 22, 116 may include an additional bypass valve (e.g., a PWM bypass valve) that selectively allows fluid at the delivery manifold 38, 138 or between the delivery manifold 38, 138 and the injectors 42, 142 to bypass the injectors 42, 142 and flow directly to the recirculation passage 48, 148. Such a valve may for example be advantageously integrated into a system with a large number of injection valves (e.g. 8 or more) supplied by the same supply manifold.Although the systems 16, 22, 116 are shown as having a single bypass valve 36, 136 and a single bypass passage 50, 150, in some embodiments, the systems 16, 22, 116 may include multiple bypass valves 36, 136 and / or multiple bypass passages 50, 150.Further, although the systems 16, 22, 116 as described above have recirculation passages 48, 148 that receive non-injected fluid from the injectors 42, 142, in some embodiments, the injectors 42, 142 may inject all of the fluid supplied thereto. That is, the injectors 42, 142 may not be equipped to receive reagent fluid for cooling and return to the tank 26, 126. In such embodiments, the systems 16, 22, 116 may not include return lines 56, 156 that fluidly couple the injectors 42, 142 to return manifolds 44, 144 and the tank 26, 126. In some embodiments, the injectors 42, 142 may include cooling jackets that receive a coolant fluid (e.g., a fluid other than urea or hydrocarbon fluid).It should be appreciated that the supply manifold 38, 138 and the return manifold 44, 144 could be formed from a common manifold block, or the supply manifold 38, 138 and the return manifold 44, 144 could be stand-alone and separate components.The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to the particular embodiment, but, where applicable, are interchangeable and may be used in a selected embodiment, even if not specifically shown or described. This can also be changed in various ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

An exhaust aftertreatment system for treating exhaust gas exhausted from an internal combustion engine (12), the exhaust aftertreatment system comprising: a catalyst component; and an exhaust treatment fluid delivery system (16, 22, 116) for injecting an exhaust treatment fluid into an exhaust stream at a location upstream of the catalyst component, the exhaust treatment fluid delivery system (16, 22, 116) comprising: a tank (26, 126) for holding the exhaust treatment fluid; a delivery passage (46, 146) receiving the exhaust treatment fluid from the tank (26, 126) and delivering the exhaust treatment fluid to a delivery manifold (38, 138); a plurality of injectors (42, 142) receiving the exhaust treatment fluid from the delivery manifold (38, 138) and metering the exhaust treatment fluid into the exhaust stream; a bypass valve (36, 136) that selectively allows a portion of the exhaust treatment fluid in the supply passage (46, 146) to return to the tank (26, 126) through a bypass passage (50, 150) without flowing through the injectors (42, 142); and a control module (52, 152) that controls the bypass valve (36, 136) and the injectors (42, 142) based on a first fluid pressure in the supply passage (46, 146) and a second fluid pressure between an inlet of the supply manifold (38, 138) and the injectors (42, 142).The exhaust aftertreatment system of claim 1, wherein the control module (52, 152) controls the bypass valve (36, 136) to achieve a predetermined fluid pressure in the supply passage (46, 146) that is higher than a desired fluid pressure at the injectors (42, 142).The exhaust aftertreatment system of claim 1, further comprising a return passage (48, 148) for returning non-injected exhaust treatment fluid from the injectors (42, 142) to the tank (26, 126).The exhaust aftertreatment system of claim 3, wherein the exhaust treatment fluid delivery system (16, 22, 116) comprises a recirculation valve (147) disposed along the recirculation passage (48, 148) between a recirculation manifold (44, 144) and the bypass passage (50, 150).The exhaust aftertreatment system of claim 4, wherein the control module (52) controls the recirculation valve (147) based on a third fluid pressure in the recirculation passage (48, 148).The exhaust aftertreatment system of claim 5, wherein the bypass valve (136) and the recirculation valve (147) are pulse width modulated.The exhaust aftertreatment system of claim 5, wherein the exhaust treatment fluid delivery system (16, 22, 116) comprises a valve bypass line (151) that allows fluid to bypass the recirculation valve (147).The exhaust aftertreatment system of claim 7, wherein the valve bypass line (151) comprises a check valve (149) that permits fluid flow through the valve bypass line (151) in a first direction from a first location between the recirculation valve (147) and the tank (126) and a second location between the recirculation valve (147) and the recirculation manifold (144), and inhibits fluid flow through the valve bypass line (151) in a second direction opposite the first direction.The exhaust aftertreatment system of claim 1, wherein the exhaust treatment fluid delivery system (16, 22, 116) comprises a pump (32, 132) for pressurizing the delivery manifold (38, 138) and inlet lines of the injectors (42, 142).The exhaust aftertreatment system of claim 1, wherein the exhaust treatment fluid is a hydrocarbon exhaust treatment fluid, wherein the hydrocarbon exhaust treatment fluid is atomized at a location adjacent to the catalyst component.The exhaust aftertreatment system of claim 10, wherein the catalyst component is an oxidation catalyst component.The exhaust aftertreatment system of claim 1, wherein the exhaust treatment fluid is a urea exhaust treatment fluid, wherein the urea exhaust treatment fluid is atomized at a location adjacent to the catalyst component.The exhaust aftertreatment system of claim 12, wherein the catalyst component is an SCR catalyst (24).The exhaust aftertreatment system of claim 12, further comprising a urea quality sensor disposed upstream of at least one of the injectors (42, 142).The exhaust aftertreatment system of claim 1, wherein the plurality of injectors (42, 142) inject the exhaust treatment fluid into a common exhaust stream.The exhaust aftertreatment system of claim 1, wherein the plurality of injectors (42, 142) inject the exhaust treatment fluid into separate exhaust streams associated with a plurality of internal combustion engines (12).A fluid delivery system for injecting exhaust treatment fluid into a stream of exhaust gas emitted from an internal combustion engine (12), the fluid delivery system comprising: a tank (26, 126) for holding the exhaust treatment fluid; a delivery passage (46, 146) receiving the exhaust treatment fluid from the tank (26, 126); a delivery manifold (38, 138) receiving the exhaust treatment fluid from the delivery passage (46, 146); a plurality of injectors (42, 142) receiving the exhaust treatment fluid from the delivery manifold (38, 138); a return passage (48, 148) through which exhaust treatment fluid from the injectors (42, 142) is returned to the tank (26, 126); a bypass passage (50, 150) connecting the supply passage (46, 146) to the return passage (48, 148) and comprising a bypass valve (36, 136) controlling fluid flow therebetween; a first pressure sensor (34, 134) measuring a first pressure of the exhaust treatment fluid in the supply passage (38, 138) based on which the bypass valve (36, 136) is controlled; a second pressure sensor (40, 140) measuring a second pressure of the exhaust treatment fluid in the supply manifold (38, 138) based on which the injectors (42, 142) are controlled.The fluid delivery system of claim 17, wherein the bypass valve (36, 136) is controlled to achieve a predetermined fluid pressure in the delivery passage (46, 146) that is higher than a desired fluid pressure at the injectors (42, 142).The fluid delivery system of claim 17, further comprising a return valve (147) disposed along the return passage (48, 148) between a return manifold (44, 144) and the bypass passage (50, 150).The fluid delivery system of claim 19, wherein the recirculation valve (147) is controlled based on a third pressure in the recirculation passage (48, 148).The fluid delivery system of claim 20, wherein the bypass valve (36, 136) and the recirculation valve (147) are pulse width modulated.The fluid delivery system of claim 20, further comprising a valve bypass line (151) that allows fluid to bypass the recirculation valve (147).The fluid delivery system of claim 22, wherein the valve bypass line (151) comprises a check valve (149) that permits fluid flow through the valve bypass line (151) in a first direction from a first location between the recirculation valve (147) and the tank (126) and a second location between the recirculation valve (147) and the recirculation manifold (144), and inhibits fluid flow through the valve bypass line (151) in a second direction opposite the first direction.The fluid delivery system of claim 17, further comprising a pump (32, 132) for pressurizing the delivery manifold (38, 138) and inlet lines of the injectors (42, 142).The fluid delivery system of claim 17, wherein the exhaust treatment fluid is a hydrocarbon exhaust treatment fluid, wherein the hydrocarbon exhaust treatment fluid is injected into an exhaust stream at a location adjacent a catalyst component.The fluid delivery system of claim 25, wherein the catalyst component is an oxidation catalyst component.The fluid delivery system of claim 17, wherein the exhaust treatment fluid is a urea exhaust treatment fluid, wherein the urea exhaust treatment fluid is injected at a location adjacent to the catalyst component.The fluid delivery system of claim 27, wherein the catalyst component is an SCR catalyst (24).The fluid delivery system of claim 17, wherein the plurality of injectors inject the exhaust treatment fluid into a common exhaust stream.The fluid delivery system of claim 17, wherein the plurality of injectors (42, 142) inject the exhaust treatment fluid into separate exhaust streams associated with a plurality of internal combustion engines (12).A method comprising: supplying exhaust treatment fluid from a tank (26, 126) to a supply manifold (38, 138); controlling an injector (42, 142) that receives the exhaust treatment fluid from the supply manifold (38, 138) based on a first fluid pressure in the supply manifold (38, 138); selectively allowing a portion of the exhaust treatment fluid to bypass the injector (42, 142); and controlling an amount of the exhaust treatment fluid allowed to bypass the injector (42, 142) based on a second fluid pressure upstream of the supply manifold (38, 138).The method of claim 31, further comprising measuring the second fluid pressure with a pressure sensor (40, 140) disposed along a supply passage (46, 146) supplying exhaust treatment fluid from the tank (26, 126) to the supply manifold (38, 138).The method of claim 31, wherein controlling the injector (42, 142) comprises adjusting a pulse width modulation duty cycle of the injector (42, 142).The method of claim 31, wherein controlling the amount of exhaust treatment fluid permitted to bypass the injector (42, 142) comprises adjusting a pulse width modulation duty cycle of a bypass valve (36, 136).The method of claim 31, further comprising controlling a back pressure of fluid at the injector (42, 142) with a recirculation valve (147) disposed in a recirculation passage (48, 148) through which exhaust treatment fluid is recirculated from the injector (42, 142) to the tank (26, 126).The method of claim 35, wherein controlling the back pressure of fluid at the injector (42, 142) with the recirculation valve (147) comprises controlling the recirculation valve (147) based on a third fluid pressure in the recirculation passage (48, 148).The method of claim 36, further comprising selectively allowing exhaust treatment fluid to bypass the recirculation valve (147).The method of claim 37, further comprising detecting fluid leaks by pumping fluid through the return passage (48, 148) to a return manifold (44, 144).The method of claim 36, wherein controlling the recirculation valve (147) comprises adjusting a pulse width modulation duty cycle of the recirculation valve (147).The method of claim 31, wherein supplying exhaust treatment fluid comprises supplying a hydrocarbon exhaust treatment fluid.The method of claim 40, further comprising injecting the hydrocarbon exhaust treatment fluid into an exhaust stream adjacent to an oxidation catalyst.The method of claim 31, wherein supplying exhaust treatment fluid comprises supplying a urea exhaust treatment fluid.The method of claim 42 further comprising injecting the urea exhaust treatment fluid into an exhaust stream adjacent to an SCR catalyst (24).The method of claim 31, further comprising controlling a plurality of injectors (42, 142) that receive the exhaust treatment fluid from the supply manifold (38, 138) based on the first fluid pressure in the supply manifold (38, 138).The method of claim 44, further comprising injecting the exhaust treatment fluid into a single exhaust stream with the plurality of injectors (42, 142).The method of claim 44, further comprising injecting the exhaust treatment fluid into a plurality of exhaust streams with the plurality of injectors (42, 142), each of the exhaust streams belonging to a plurality of internal combustion engines (12).The method of claim 31, further comprising returning non-injected exhaust treatment fluid from the injector (42, 142) to the tank (26, 126).

Images