GB2548129A

GB2548129A - Injector arrangement for reductant supply systems

Info

Publication number: GB2548129A
Application number: GB1604058.6A
Authority: GB
Inventors: S Gharpure Siddharth
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2016-03-09
Filing date: 2016-03-09
Publication date: 2017-09-13
Anticipated expiration: 2036-03-09
Also published as: GB201604058D0; GB2548129B

Abstract

An after-treatment system injector 112' includes an injector housing 140 and an injector nozzle 142. The housing includes inlet and outlet coolant ports 128, 132, and a coolant passage 146 extending there between. The passage is substantially U-shaped and includes first and second substantially parallel (or minimally inclined) sections 148 150, and a connecting section 152. The passage extends around at least a portion of the injector nozzle, and the injector is arranged such that the connecting section of the passage is provided lower in elevation relative to the injector nozzle. The injector may be part of a reductant system which also includes a coolant circuit with a coolant tank. A method of installing the injector may comprise coupling the inlet and outlet ports to a coolant circuit. The inlet and outlet ports may be positioned higher relative to the injector nozzle. The injector nozzle may comprise one, six, or an even number of injector holes.

Description

Injector Arrangement for Reductant Supply Systems Technical Field [0001] The present disclosure relates to the field of after-treatment systems in machines. More particularly, the present disclosure relates to an arrangement of reductant injectors in after-treatment systems that assist in cooling of the reductant injectors, without affecting the reductant injector’s dosing performance.

Background [0002] After-treatment systems are commonly applied to treat exhaust gases of engines. After-treatment systems typically include a number of injectors that inject a reductant fluid into a stream of exhaust gas. During operations, tips of the injectors, which generally embody injector nozzles, are subjected to considerably high temperature conditions of the exhaust gas. Such high temperature conditions may damage the tips. To mitigate tip damage, a coolant from a coolant circuit is made to flow through a coolant passage structured within the injectors. Such coolant passages may be structured relatively closely around the injector nozzle so as to impart conductive cooling to the tips, during operations.

[0003] During an engine shutdown, a coolant pump driven by an associated engine may gradually come to a halt as the engine attains 0 rpm. Consequently, a pumped coolant flow to the injectors may cease. In such situations, the tips may remain exposed to the high temperature conditions of a persisting exhaust gas and a heat mass of the associated after-treatment system and the engine. As a result, a coolant remaining within the coolant passage is t5φically subjected to the high temperature conditions and may start to vaporize. This vaporized coolant may be trapped in certain sections of the coolant passage. A trapped vaporized coolant restricts effective replenishment of the coolant passage with condensed coolant from the coolant circuit. Moreover, the trapped vaporized coolant may act as an insulator, generally significantly affecting the injectors’ heat transfer capability.

Summary of the Invention [0004] Various aspects of the present disclosure disclose an after-treatment system. The after-treatment system includes an injector having an injector housing and an injector nozzle. The injector housing includes an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port. The coolant passage is substantially U-shaped. The coolant passage includes a first section, a second section substantially parallel to the first section, and a connecting section that fluidly couples the first section to the second section. The coolant passage extends around at least a portion of the injector nozzle. The injector is arranged such that the connecting section of the coolant passage is provided lower in elevation relative to the injector nozzle.

[0005] Certain aspects of the present disclosure disclose a method for installing an injector in an after-treatment system. The injector includes an injector housing and an injector nozzle. The injector housing including an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port. The coolant passage is substantially U-shaped and includes a first section, a second section, and a connecting section fluidly coupling the first section to the second section. The first section is substantially parallel to the second section. The coolant passage extends around at least a portion of the injector nozzle. The method includes arranging the injector such that the connecting section is provided lower in elevation relative to the injector nozzle. The method also includes coupling of the inlet coolant port and the outlet coolant port of the coolant passage to a coolant circuit of the after-treatment system.

[0006] One aspect of the present disclosure discloses a reductant system for an after-treatment system. The after-treatment system includes a housing assembly. The reductant system includes a coolant circuit and a reductant injector. The coolant circuit includes a coolant tank. The reductant injector includes an injector housing and an injector nozzle. The injector housing including an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port. The inlet coolant port and the outlet coolant port are connected to the coolant circuit. The inlet coolant port is in fluid communication with the coolant tank. The coolant passage is substantially U-shaped. The coolant passage includes a first section and a second section. The second section is substantially parallel to the first section. The reductant injector includes a connecting section that fluidly couples the first section to the second section. The coolant passage extends around at least a portion of the injector nozzle. The reductant injector is arranged to the housing assembly such that the connecting section of the coolant passage is provided lower in elevation relative to the injector nozzle.

Brief Description of the Drawings [0007] FIG. 1 is a schematic view of an exemplary after-treatment system with a reductant system, in accordance with the concepts of the present disclosure; [0008] FIG. 2 is a housing assembly of the after-treatment system of FIG. 1, in accordance with the concepts of the present disclosure; [0009] FIG. 3 is a diagrammatic view of an injector applied within the after-treatment system of FIG. 1, in accordance with the concepts of the present disclosure; [0010] FIG. 4 is an embodiment of the injector of FIG. 3, in accordance with the concepts of the present disclosure; and [0011] FIG. 5 is a flow chart illustrating an exemplary method for installing the injector with the after-treatment system, in accordance with the concepts of the present disclosure.

Detailed Description [0012] Referring to FIG. 1, there is shown a block diagram of an after-treatment system 100. The after-treatment system 100 is applied for treating exhaust gases of an engine 102. The after-treatment system 100 includes a Diesel Particulate Filter (DPF) 104 and a Selective Catalyst Reduction Module (referred to as SCR module 106) that facilitate treatment of exhaust gases of the engine 102, prior to an emission of the exhaust gases into the environment. An exhaust conduit 108 is fluidly connected between the DPF 104 and the SCR module 106. The exhaust conduit 108 includes a mixing chamber 110. In addition, the exhaust conduit 108 facilitates accommodation of a number of injectors 112. A fluid reductant tank 114 is fluidly connected with tbe injectors 112 for reductant delivery. The fluid reductant tank 114 stores a Diesel Emission Fluid (DEF). Additionally, the after-treatment system 100 includes and works in conjunction with a cooling system 116 that facilitates injector cooling during operations.

[0013] The engine 102 may be an internal combustion engine having a multicylinder engine configuration. Tbe engine 102 may be applicable in macbines, general heavy machineries, and conventional mobile equipment. For example, off-highway trucks, mining trucks, skid steer loaders, wheel loaders, track type tractors, excavators, dozers, wheel loaders, etc. The present disclosure also envisions an extended application of the engine to stationary machines, such as power generation systems and other electric power generating machines. Although the present disclosure contemplates employment of a multi-cylinder diesel engine, an equivalent application of the aspects of the present disclosure may be directed to other engine types as well.

[0014] As part of the after-treatment system 100, the DPF 104 may be selected from one of widely available DPFs in the art. The DPF 104 may be fluidly connected to an exhaust port 118 of the engine 102 to receive exhaust gas from the engine 102 in a raw, untreated state. Upon reception of the exhaust gases, the DPF 104 is configured to filter or separate soot or diesel particulate matter from the inflowing exhaust gas.

[0015] The exhaust conduit 108 is fluidly connected to the DPF 104 and is positioned downstream to the DPF 104 (along an exhaust gas flow direction. A).

The exhaust conduit 108 may he shaped and structured as conventionally known, and may he configured to receive a filtered exhaust gas from the DPF 104. The mixing chamber 110 within the exhaust conduit 108 generally embodies an enclosed space, facilitating an effective mix of the filtered exhaust gases from the DPF 104 with the DEF. Although not limited, typical reductant fluids or DBFs may include anhydrous ammonia, aqueous ammonia, or urea.

[0016] The SCR module 106 is fluidly connected further downstream to the exhaust conduit 108. The SCR module 106 includes a catalyst, such as titanium oxide, and other active catalytic components of oxides of base metals to convert nitrogen oxides in the exhaust gases into diatomic nitrogen and water. Base metals may include, but are not limited to, vanadium, molybdenum, and/or tungsten. As with the DPF 104, the SCR module 106 may also be chosen from among the widely known SCR modules available.

[0017] The cooling system 116 includes a coolant circuit 120. The coolant circuit 120 is adapted to facilitate cooling of the injectors 112. The coolant circuit 120 includes a coolant reservoir 122, a fluid pump 124, and a coolant tank 126.

[0018] The coolant reservoir 122 acts as a coolant supply source for the injectors 112 and stores a coolant in a liquid state. The coolant reservoir 122 is fluidly connected to an inlet coolant port 128 (FIGS. 2, 3, and 4) of the injectors 112 through a fluid line assembly 130. Such a connection facilitates delivery of a coolant to the injectors 112 from the coolant reservoir 122, along a coolant flow direction, B. The coolant reservoir 122 is also fluidly connected with the coolant tank 126 and is adapted to receive a quantity of phase separated, condensed coolant from the coolant tank 126 at the completion of a coolant running cycle.

[0019] The fluid pump 124 is assembled to the fluid line assembly 130 and positioned between the coolant reservoir 122 and the injectors 112. The fluid pump 124 enables coolant from the coolant reservoir 122 to be drawn and pumped to the injectors 112, providing the injectors 112 with a coolant flow that bears a requisite degree of pressure. The fluid pump 124 may be driven by the engine 102 and act as a primary power source for coolant supply within the coolant circuit 120. The fluid pump 124 is adapted to circulate coolant for periodic reuse along a coolant flow direction, B, throughout the coolant circuit 120. In various implementations, the fluid pump 124 may embody a variable displacement pump, a fixed displacement pump, or other pump-t5φes, as has been known and applied in the art.

[0020] The coolant tank 126 is airanged and fluidly connected with an outlet coolant port 132 (FIGS. 2, 3, and 4) of the injectors 112, further downstream to the injectors 112, along the coolant flow direction, B. The coolant tank 126 may be arranged at an altitude (or elevation) relative to the injectors 112, making it is possible for the coolant tank 126 to be used as a phase separation tank. By way of this arrangement, the coolant tank 126 may receive a coolant carrying heat from the injectors 112, facilitate phase separation of the coolant, and return a condensed coolant to the coolant reservoir 122. As aforementioned, the coolant tank 126 is fluidly connected to the coolant reservoir 122 by a fluid loop 168 that ensures return and recirculation of the coolant within the coolant circuit 120.

[0021] The injectors 112 may be reductant injectors. The injectors 112 may be one or more in number that are applicable for installation into generic multicylinder engine configurations. The number of injectors may vary depending upon an engine size as emissions from larger engines may require additional quantities of DBF to neutralize constituents of the filtered exhaust gas. As the depicted embodiment pertains to a relatively large-scale engine, four injectors are exemplarily included. Nevertheless, a variation in the number of injectors 112 may be contemplated. Correspondingly, the exhaust conduit 108 may include provisions for accommodating the injectors 112. In an embodiment, the injectors 112 are threadably engaged with the exhaust conduit 108, although other engagement measures, such as those attained by a luer-lock fastening functionality, etc., are possible. The injectors 112 are fluidly connected to the fluid reductant tank 114 to receive a generally continuous supply of DEF via a set of conduit flow lines 134. In an embodiment, each injector among the injectors 112 may include a dedicated DEF supply line, although a common rail may be provided to equalize pressurized injection within the mixing chamber 110. A DEF supply may be facilitated by a DEF pump (not shown). The injectors 112, fluid reductant tank 114, conduit flow lines 134, and the coolant circuit 120, also form a part of a reductant system 144 of the after-treatment system 100.

[0022] The injectors 112 are configured to inject a predetermined quantity or dosage of DEF, generally periodically, into the mixing chamber 110. A DEF injection may be such that a fine atomized spray of DEF is introduced into the mixing chamber 110 to facilitate an effective mix of DEF with the exhaust gas. Moreover, the injectors 112 may he positioned at an incline to the mixing chamber so as to inject DEF at an angle to the exhaust gas. This positioning is to ensure a thorough mix and reaction of the atomized spray with the exhaust gas, facihtating proper combustion of exhaust gas soot, preventing unbumt fuel exhaustion, and effectively lowering the concentration of nitrogen oxides of the exhaust gas.

[0023] The injectors 112 include injector tips (or simply tips 136) projected into the mixing chamber 110. The tips 136 facilitate injection of a predetermined quantity of DEF into the exhaust conduit 108, and, more particularly, into a stream of the exhaust gas. However, such an arrangement subjects the tips 136 to relatively high temperature conditions of the flowing exhaust gas. Because the tips 136 malfunction owing to such relatively high temperature conditions, repairs and replacements are generally sought.

[0024] Referring to FIG. 2, there is shown an arrangement principle of the injectors 112 and the coolant tank 126 in relation to a housing assembly 138 of the after-treatment system 100. For ease in understanding and depiction, only a singular injector 112 is shown, and the forthcoming description is focused towards a single injector alone. However, it may be contemplated that this description is equivalently applicable to each of the injectors 112, as discussed in FIG. 1.

[0025] Referring to FIG. 2, 3 and 4, the injector 112 includes an injector body, termed as an injector housing 140, and an injector nozzle 142. The injector housing 140 includes the inlet coolant port 128 and the outlet coolant port 132. The inlet coolant port 128 is configured to receive coolant from the coolant reservoir 122, while the outlet coolant port 132 is configured for a coolant release to the coolant tank 126 (FIG. 2). The injector housing 140 includes a coolant passage 146 (FIGS. 3 and 4) structured and fluidly extending between the inlet coolant port 128 and the outlet coolant port 132.

[0026] Referring to FIGS. 3 and 4, the coolant passage 146 is substantially U-shaped. To this end, the coolant passage 146 includes a first section 148, a second section 150, and a connecting section 152. Both the first section 148 and the second section 150 may be substantially straight passages. The first section 148 fluidly extends from the inlet coolant port 128, while the second section 150 fluidly extends to the outlet coolant port 132. Although the first section 148 and the second section 150 are minimally inclined towards a central portion of the injector 112 (that includes the injector nozzle 142), the first section 148 and the second section 150 may be largely parallel to each other, as shown. The connecting section 152 may also be a substantially straight passage defined within the injector housing 140. The connecting section 152 is fluidly connected between the first section 148 and the second section 150, facilitating fluid communication between the inlet coolant port 128 and the outlet coolant port 132, and thereby imparting the substantial U-shaped profile to the coolant passage 146. This U-shaped profile enables the coolant passage 146 to extend around and inclusively encompass at least a portion of the injector nozzle 142 positioned substantially centrally to the injector 112. Such a coolant passage configuration allows coolant to flow from the coolant reservoir 122 into the coolant passage 146, receive heat from the tips 136, and reduce the temperature therein, during operation. The inlet coolant port 128 and outlet coolant port 132 respectively provide for inflow and outflow of coolant.

[0027] The injector 112 is generally triangular shaped with a first vertex portion 154, a second vertex portion 156, and a third vertex portion 158. In general, it may he assumed that the triangle shaped profile of the injector 112 conforms to an isosceles configuration, with a segment formed and defined hy the first vertex portion 154 and the second vertex portion 156 being substantially symmetrical and equivalent to a segment formed by the first vertex portion 154 and the third vertex portion 158. Further, the injector 112 includes a longitudinal axis 160 that passes through the first vertex portion 154, and generally defining a right angle with the connecting section 152. The longitudinal axis 160 may embody or represent an injector median, with the injector nozzle 142 positioned along the longitudinal axis and forming a general centroid of the injector 112. The longitudinal axis 160 generally forms an injector dividing line and establishes said symmetry across the longitudinal axis 160. Further, a horizontal axis 162 passes through the injector nozzle 142, as shown.

[0028] An arrangement between the injector 112 and the housing assembly 138 will now be discussed. The injector 112 is arranged and mounted to the housing assembly 138 such that the connecting section 152 of the coolant passage 146 (shown in FIGS. 3 and 4) is provided lower in elevation relative to the injector nozzle 142. Additionally, the inlet coolant port 128 and the outlet coolant port 132 is also arranged at an elevation relative to the injector nozzle 142 (as may be understood by viewing FIGS. 2, 3, and 4, together), therefore locating the inlet coolant port 128 and the outlet coolant port 132 above the connecting section 152, as well. By having the connecting section 152 positioned below the injector nozzle 142, the connecting section 152 is also imparted with a position that is generally lower than the horizontal axis 162. Moreover, the coolant circuit 120 may be altogether arranged above the coolant passage 146 and the connecting section 152. Such an arrangement of the injector 112 may be termed as ‘lowered position’ for ease in reference, hereinafter. In the depicted embodiment (FIG. 2), the injector 112 is positioned in the lowered position such that the longitudinal axis 160 is perpendicular to the horizontal axis 162, ensuring parallelity between the connecting section 152 and the horizontal axis 162.

[0029] In an embodiment, it is also possible that the injector 112 is angularly positioned relative to the housing assembly 138, in the lowered position. Such positioning may satisfy spatial constraints. However, the positioning may be such that the longitudinal axis 160 of the injector 112 is positioned relative to the horizontal axis 162 within an angular range defined anywhere between 45 degrees to 135 degrees. Such a range may be required when the after-treatment system 100 is employed in machines that require mobility and stationing on uphill and downhill slopes bearing an incline up to 45 degree to the horizontal axis 162. By defining this range, it is still possible for the connecting section 152 to remain below the horizontal axis 162 (and the injector nozzle 142). Additionally, it may be assumed that in such positioning a width, W, (FIG. 2) of the housing assembly 138 is generally parallel to the horizontal axis 162, or a horizontal plane (not shown).

[0030] Referring again to FIGS 3 and 4, a variation in the injector nozzle 142 is discussed. The variation involves and pertains to a variation of injector holes (or nozzle jets) provided within the injector nozzle 142. The variation facilitates a modular positioning of the injectors, such as injectors 112, while ensuring that a dosing performance of the injectors into the mixing chamber 110 (FIG. 1) remain unaffected. For ease in reference and understanding, the variations are discussed separately for injectors 112’ and 112”. Both the injectors 112’ and 112” may represent and be similar in form and function to the injector 112 discussed in FIGS. 1 and 2.

[0031] Referring to FIG. 3, there is shown an injector 112’ having an injector nozzle 142’ with a singular injector hole 164. The singular injector hole 164 is generally centrally positioned relative to the injector nozzle 142’. Such a provision enables the injector 112’ to be mounted to the housing assembly 138 in different configurations involving infinite angular variations. However, an arrangement of the injector 112’ may be limited within the angular range of 45 degrees to 135 degrees, as aforementioned.

[0032] Referring to FIG. 4, there is shown an injector 112” with an injector nozzle 142” having six injector holes 166. The six injector holes 166 are generally centrally positioned relative to the injector nozzle 142”, with each injector hole among the six injector holes 166 being positioned equilaterally, thus imparting a generally hexagonal configuration to the injector nozzle 142”. Such a provision enables the injector 112” to be mounted to the housing assembly 138 in generally different configurations, but involving angular variations of 60 degrees. The arrangement of the injector 112” may be limited within the angular range of 45 degrees to 135 degrees, as aforementioned.

[0033] With the embodiments covering the singular injector hole 164 and the six injector holes 166, it is possible for the injector 112’, 112” to be positioned at varied angular positions, without affecting a dosing performance of the injector 112’, 112”. Dosing performance may involve a characterized spray pattern and an angle of DEF injection. In certain embodiments, it is also possible that the injector nozzle 142 accommodates a different set of injector holes, other than those described above, such as having an alternate, even number of injector holes.

[0034] Referring to FIG. 5, there is shown a flowchart 500 depicting an exemplary method for installing the injector 112’, 112” to the housing assembly 138 of the after-treatment system 100. The method is discussed in connection with FIGS. 2, 3, and 4. The method initiates at stage 502.

[0035] At stage 502, an operator arranges the injector 112’, 112” in the lowered position such that the connecting section 152 is provided lower in elevation relative to the injector nozzle 142. This arrangement may comply with the number of injector holes 164, 166 provided within the injector nozzle 142. In an example, if there are six injector holes 166 (as disclosed in FIG. 4), the operator may position the injector 112” at an angle that may he varied in 60 degrees. However, the operator may restrict the injector’s positioning hy having the longitudinal axis 160 of the injector 112” positioned within 45 degrees and 135 degrees to the horizontal axis 162, such as 90 degrees (see FIG. 2). Such a restriction is to ensure that a position of the injector nozzle 142’, 142” remains at an elevation to the connecting section 152 even if a machine, which incorporates the after-treatment system 100, is mobile or stationed uphill or downhill with an incline of 45 degrees to the horizontal axis 162. The method proceeds to stage 504.

[0036] At stage 504, the operator couples the inlet coolant port 128 and the outlet coolant port 132 to the coolant circuit 120 of the after-treatment system 100. A coupling of the inlet coolant port 128 and the outlet coolant port 132 to the coolant circuit 120 may respectively correspond to the inlet coolant port 128 being fluidly coupled to the coolant reservoir 122 via the fluid pump 124, and the outlet coolant port 132 being fluidly coupled to the coolant tank 126.

Industrial Applicability [0037] In operation, the fluid pump 124 may facilitate pumping of the coolant across the coolant circuit 120. As a result, the coolant may flow through the coolant passage 146 of the injector 112’, 112”, extract heat of operation from the injector 112’, 112”, flow to the coolant tank 126 for phase separation, and be eventually returned to the coolant reservoir 122, for recirculation. During an engine shutdown, the fluid pump 124 may stop functioning, thereby halting a coolant supply to the injector 112’, 112”. Until an engine cool down, the injector 112’, 112” may sustain the relatively high temperature conditions of the exhaust gas and heat mass from the after-treatment system 100 and the engine 102. As a result, a coolant remaining within the coolant passage 146 may start to vaporize. Owing to the lowered position of the connecting section 152 (lower than the injector nozzle 142’, 142”), vaporized coolant formed within the coolant passage 146, and particularly within the connecting section 152, rises and flows out of the injector 112’, 112” into the coolant circuit 120. The vaporized coolant may flow out through the outlet coolant port 132 (or the inlet coolant port 128), exert vapor pressure on the condensed coolant of the coolant circuit 120, and force the condensed coolant into the coolant passage 146. As more and more vaporized coolant is formed, the vaporized coolant may flow out, he condensed, and flow hack into to the coolant passage 146, so as to replace subsequently formed vaporized coolant in the coolant passage 146. Therefore, a periodic replenishment of the injector 112’, 112” with condensed coolant may naturally occur.

[0038] A removal of the vaporized coolant is generally pertinent as vaporized coolant may act as an insulator, limiting an effective heat transfer capability of the injector 112’, 112”, and a prolonged persistence of which may potentially shorten injector life. In effect, a position of the injector 112’, 112” with the connecting section 152 located lower to the injector nozzle 142’, 142” disallows the vaporized coolant from being trapped within the coolant passage 146. Moreover, by having a singular injector hole 164 (FIG. 3), or multi-injector holes (such as the six injector holes 166, FIG. 4), the injector 112’, 112” is positionable in different configurations in the lowered position. Such an ability of the injector 112’, 112” also ensures performance neutrality. This is because in each of the different configurations, the injector 112’, 112” may provide a similar and unaffected dosing performance. Further, an ability of the injector 112’, 112” to be positioned in different configurations also helps address limitations associated with spatial constraints of machines that incorporate the after-treatment system 100.

[0039] A provision to have the connecting section 152 of the coolant passage 146 arranged below the injector nozzle 142’, 142” may be applicable when the injector 112’, 112” is installed in the after-treatment system 100, and when the after-treatment system 100 is installed in a machine. In that way, it is possible to attain a generally higher level of heat transfer capability, and which may be applicable in relatively large-scale engine systems that generate relatively higher levels of heat energy.

[0040] In an embodiment, such as when the after-treatment system 100 is installed in a machine that is operated generally on level ground, a requirement to place the injector 112’, 112” within 45 degrees and 135 degrees to the horizontal axis 162 may be negated. Therefore, the injector 112’ may assume any arbitrary position, but with the connecting section 152 remaining below the injector nozzle 142’, 142”.

[0041] It should be understood that the above description is intended for illustrative purposes only and is not intended to limit the scope of the present disclosure in any way. Thus, one skilled in the art will appreciate that other aspects of the disclosure may be obtained from a study of the drawings, the disclosure, and the appended claim.

Claims

Claims What is claimed is:

1. An after-treatment system comprising: an injector including an injector housing and an injector nozzle, the injector housing including an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port, the coolant passage being substantially U-shaped, the coolant passage including: a first section; a second section, substantially parallel to the first section; and a connecting section, fluidly coupling the first section to the second section, wherein the coolant passage extends around at least a portion of the injector nozzle, and the injector is arranged such that the connecting section of the coolant passage is provided lower in elevation relative to the injector nozzle.

2. The after-treatment system of claim 1, wherein the injector is a reductant injector.

3. The after-treatment system of claim 1 or 2, wherein the inlet coolant port and the outlet coolant port are arranged higher in elevation relative to the injector nozzle.

4. The after-treatment system of any preceding claim further comprising a coolant circuit including a coolant tank, the outlet coolant port being in fluid communication with the coolant tank.

5. The after-treatment system of any preceding claim, wherein the injector nozzle includes a single injector hole.

6. The after-treatment system of any of claims 1 to 4, wherein the injector nozzle includes six injector holes.

7. The after-treatment system of any of claims 1 to 4, wherein the injector nozzle includes an even number of injector holes.

8. The after-treatment system of any preceding claim, wherein the injector includes a longitudinal axis substantially perpendicular to the connecting section and passing through the injector nozzle, the longitudinal axis making an angle ranging between 45 degrees and 135 degrees relative to a horizontal axis of the injector passing through the injector nozzle.

9. The after-treatment system of claim 8, wherein the longitudinal axis makes an angle of 90 degrees with the horizontal axis.

10. A method for installing an injector in an after-treatment system, the injector including an injector housing and an injector nozzle, the injector housing including an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port, the coolant passage being substantially U-shaped including a first section, a second section, and a connecting section fluidly coupling the first section to the second section, the first section being substantially parallel to the second section, the coolant passage extending around at least a portion of the injector nozzle, the method comprising: arranging the injector such that the connecting section is provided lower in elevation relative to the injector nozzle; and coupling the inlet coolant port and the outlet coolant port to a coolant circuit of the after-treatment system.

11. The method of claim 10 further comprising positioning the injector such that a longitudinal axis of the injector makes an angle ranging hetween 45 degrees and 135 degrees relative to a horizontal axis of the injector, wherein the longitudinal axis passes through the injector nozzle and is substantially perpendicular to the connecting section, and the horizontal axis passes through the injector nozzle.

12. The method of claim 10 or 11 further comprising positioning the injector such that the longitudinal axis makes an angle of 90 degrees with the horizontal axis.

13. The method of any of claims 10 to 12, wherein arranging the connecting passage at a lower elevation relative to the injector nozzle corresponds to positioning the inlet coolant port and the outlet coolant port at a higher elevation relative to the injector nozzle.

14. A reductant system for an after-treatment system, the after-treatment system including a housing assembly, the reductant system comprising: a coolant circuit, with a coolant tank; a reductant injector including an injector housing and an injector nozzle, the injector housing including an inlet coolant port, an outlet coolant port, and a coolant passage extending between the inlet coolant port and the outlet coolant port, the inlet coolant port and the outlet coolant port being connected to the coolant circuit, the outlet coolant port being in fluid communication with the coolant tank, the coolant passage being substantially U-shaped, the coolant passage including: a first section; a second section, substantially parallel to the first section; a connecting section, fluidly coupling the first section to the second section, wherein the coolant passage extends around at least a portion of the injector nozzle, and the reductant injector is arranged to the housing assembly such that the connecting section of the coolant passage is provided lower in elevation relative to the injector nozzle.

15. The reductant system of claim 14, wherein the inlet coolant port and the outlet coolant port are arranged higher in elevation relative to the injector nozzle.

16. The reductant system of claim 14 or 15, wherein the injector nozzle includes a single injector hole.

17. The reductant system of claim 14 or 15, wherein the injector nozzle has six injector holes.

18. The reductant system of claim 14 or 15, wherein the injector nozzle has an even number of injector holes.

19. The reductant system of any of claims 14 to 18, wherein the reductant injector includes a longimdinal axis, substantially perpendicular to the connecting section and passing through the injector nozzle, and a horizontal axis passing through the injector nozzle, the longitudinal axis making an angle ranging between 45 degrees and 135 degrees relative to the horizontal axis.

20. The reductant system of claim 19, wherein the longitudinal axis makes an angle of 90 degrees with the horizontal axis.