English:
[0001] Diesel engine exhaust pollutants can be reduced by injecting a treatment fluid into the engine's exhaust stream. Such systems typically use a reductant dosing unit or "RDU" as part of a selective catalytic reduction or "SCR" system. In order for a selective catalytic reduction system to work effectively, however, the dosing device or dosing unit that injects a diesel exhaust fluid (DEF) is preferably operated when the exhaust gas and exhaust system is at elevated temperatures that support hydrolysis and thermolysis. The farther from an engine that an RDU is, the longer it takes for the exhaust gas and exhaust system to elevate to operating temperature, which lengthens the time it takes for a selective catalytic reduction system to work properly. Stated another way, the closer that a reductant dosing unit is to an engine, the more effective it will be.
[0002] Locating an RDU close to the engine subjects the device to very high temperatures. Prior art SCR systems therefore surround a diesel exhaust fluid injector with a cooled liquid, typically engine coolant, in order to limit the RDU's internal temperature.
[0003] While liquid-cooled diesel exhaust fluid injectors are known, they do not provide heat dissipation to the inlet portion of an RDU, i.e., he portion immediately adjacent to, and frequently inserted into, the exhaust stream of an engine. Extending the coolant jacket completely around the reductant dosing unit would be an improvement over the prior art.
[0004] FIG. 1 is a cross-sectional view of a thermally-controlled inlet reductant dosing unit;
[0005] FIG. 2 is an isolated portion of the cross-sectional view shown in FIG. 1, showing portions of a thermal conduction path through which heat from a diesel exhaust fluid is conducted into a coolant;
[0006] FIG. 3 A is an exploded view of the reductant dosing unit shown in FIG. 1;
[0007] FIG. 3B is a perspective view of the reductant dosing unit; and
[0008] FIGS. 4A and 4B illustrate welding of the diesel exhaust fluid injector portion to a coolant housing and welding of an inlet cap to the housing.
[0009] FIG. 1 is a cross-sectional view of a thermally-controlled inlet reductant dosing unit 100. The dosing unit 100 comprises an electrically-operated fluid injector 102, preferably a diesel exhaust fluid injector, most of which is located inside a cavity 106 that is inside a coolant housing 104. A cover 106 is welded to a housing flange 108, the flange being located at the top 109 of the housing 104. A first weld 150 is formed around a lower flange 112 of the housing 104 and a tube-shaped output port seal the cavity 106.
[0010] The housing 104 and its internal cavity 106 enable engine coolant 122 to flow over and around metal surfaces of the cavity 106, including metal surfaces 118 that are sized, shaped and arranged to make direct and indirect mechanical and thermal contact with the injector 102.
[0012] FIG. 2 is an enlargement of a portion of the interface between the housing and injector. A thermal conduction path 200 comprises the metal side wall 202 of the housing 104 in direct contact with an outside surface 204 of the injector 102. Heat from the diesel exhaust fluid (DEF) 206 that is absorbed by the injector 102, is conducted downwardly, in the direction of the arrow identified by reference numeral 250, and away from the injector 102 to engine coolant flowing through the housing 104 and exiting the outlet port 126.
[0013] FIG. 3A is an exploded view of the dosing unit 100. It shows the axial alignment of the injector 102 with the coolant housing 104 and cover 106. The cap, injector and housing have center lines, co-incident with an axis 303.
[0015] The injector 102 has a DEF output port 306 directly below and aligned with the inlet port 304. Except for the connector 306, the entire injector 102, is inserted into the cavity 106 in the coolant housing 104. The DEF output orifice of the housing is centered and axially arranged and aligned with the DEF input port as well as the output port and output port of the injector 102. It is also aligned with the cover 106 of the cavity. FIG. 3B is a perspective view of the assembled dosing unit 100.
[0017] As best seen in FIG. 1, the housing 104 includes a substantially tube-shaped sleeve portion 170, which extends inwardly from the circular output orifice 124 of the housing. The sleeve portion 170 is sized and shaped to provide a clearance fit between it and the exterior surfaces of the output port 126 of the injector 102. The sleeve portion 170 also provides an excellent heat conductor, enabling the diesel exhaust fluid temperature to be determined by engine coolant temperature.
[0018] Those of ordinary skill in the art should also recognize from FIG. 3A that the diesel exhaust fluid that flows through the injector travels in essentially a straight line and parallel to the axis 303, at least between the pipe portion of the cover and the output orifice of the housing. The dosing unit 100 thus minimizes mechanical losses that would otherwise be caused by redirecting or rerouting exhaust fluid through the injector.
[0019] A method of controlling the temperature of a diesel exhaust fluid injector can be essentially characterized as enclosing the electrically operated exhaust fluid injector into a coolant bath inside a cavity of a housing, the cavity being provided with and coupled to an inlet port and outlet port through which engine coolant can flow. By flowing or pumping coolant through the housing and thus through the cavity, the temperature of the diesel exhaust fluid can be controlled when engine temperatures are high. Similarly, the diesel exhaust fluid can be warmed or heated if necessary by engine coolant, the temperature of which might exceed that of the diesel exhaust fluid. The method of controlling the temperature of a diesel exhaust fluid injector thus necessarily includes flowing or routing a heat transfer fluid into and out of the cavity and around the structures that route or carry diesel exhaust fluid into an engine exhaust stream. In a preferred embodiment, such a heat transfer fluid is engine coolant. Engine coolant is typically made up of a mixture of water and ethylene glycol and equivalents.
[0020] The foregoing description is for purposes of illustration only. The true scope of the invention is set forth in the following claims.

中文:
[0001]可以通过将处理流体喷射到发动机的排出流中来还原柴油发动机排出污染物。此类系统通常使用还原剂剂量给送单元或“RDU”作为选择性催化还原或“SCR”系统的一部分。然而,为了使选择性催化还原系统有效地工作,喷射柴油机排出流体(DEF)的剂量给送设备或剂量给送单元优选地在排出气体和排出系统处于支持水解和热解的升高的温度时操作。RDU离发动机越远,则排出气体和排出系统升高到操作温度所花费的时间越长,这延长选择性催化还原系统正常工作所花费的时间。换句话说,还原剂剂量给送单元越靠近于发动机,则其将越有效。
[0002]靠近于发动机定位RDU会使设备经受极高温度。因此,现有技术的SCR系统采用冷却的液体(通常是发动机冷却剂)围绕柴油机排出流体喷射器,以便限制RDU的内部温度。
[0003]虽然已知液体冷却式柴油机排出流体喷射器,但是其并不向RDU的入口部分(即,紧邻于发动机的排出流并且经常插入到发动机的排出流中的部分)提供散热。使冷却剂夹套在还原剂剂量给送单元周围完全延伸将是优于现有技术的改进。
[0004]图1是热控入口还原剂剂量给送单元的横截面视图;
[0005]图2是图1中所示的横截面视图的隔离部分,其显示通过其来自柴油机排出流体的热被传导到冷却剂中的热传导路径的若干部分;
[0006]图3A是图1中所示的还原剂剂量给送单元的分解图;
[0007]图3B是还原剂剂量给送单元的透视图;并且
[0008]图4A和4B示出柴油机排出流体喷射器部分到冷却剂壳体的焊接以及入口帽到壳体的焊接。
[0009]图1是热控入口还原剂剂量给送单元100的横截面视图。剂量给送单元100包括电操作的流体喷射器102,优选地是柴油机排出流体喷射器,其大部分位于在冷却剂壳体104内部的腔106的内部。盖罩106焊接到壳体凸缘108,该凸缘位于壳体104的顶部109处。第一焊接部150形成在壳体104的下凸缘112周围,并且管形输出端口密封腔106。
[0010]壳体104及其内部腔106使得发动机冷却剂122能够在腔106的金属表面上和周围流动,该金属表面包括被尺寸设计、成形和布置成与喷射器102进行直接和间接机械和热接触的金属表面118。
[0012]图2是壳体和喷射器之间的界面的一部分的放大图。热传导路径200包括壳体104的与喷射器102的外表面204直接接触的金属侧壁202。由喷射器102吸收的来自柴油机排出流体(DEF)206的热沿由参考编号250标识的箭头的方向向下传导,并且远离喷射器102到达流过壳体104并且离开出口端口126的发动机冷却剂。
[0013]图3A是剂量给送单元100的分解图。其显示喷射器102与冷却剂壳体104和盖罩106的轴向对齐。帽、喷射器和壳体具有与轴线303一致的中心线。
[0015]喷射器102具有直接在入口端口304下方并且与入口端口304对齐的DEF输出端口306。除连接器306以外,整个喷射器102插入到冷却剂壳体104中的腔106中。壳体的DEF输出孔定在中心并且与DEF输入端口和输出端口以及喷射器102的输出端口轴向布置且对齐。其还与腔的盖罩106对齐。图3B是组装好的剂量给送单元100的透视图。
[0017]如图1中最佳可见的,壳体104包括大致管形套筒部分170,其从壳体的圆形输出孔124向内延伸。套筒部分170被尺寸设计和成形成在其和喷射器102的输出端口126的外表面之间提供间隙配合。套筒部分170还提供极佳的导热体,从而使得能够通过发动机冷却剂温度确定柴油机排出流体温度。
[0018]本领域普通技术人员根据图3A还应该认识到,流过喷射器的柴油机排出流体至少在盖罩的管道部分和壳体的输出孔之间沿实质上直线并且平行于轴线303行进。因此,剂量给送单元100最小化将原本由使排出流体重新引导或重新运送穿过喷射器所引起的机械损失。
[0019]一种控制柴油机排出流体喷射器的温度的方法可以实质上特征为将电操作的排出流体喷射器封闭到壳体的腔内部的冷却剂浴中,该腔设置有并且联接到入口端口和出口端口,发动机冷却剂可以流过该入口端口和出口端口。通过使冷却剂流过或泵送通过壳体、并且因此通过腔,可以在发动机温度高时控制柴油机排出流体的温度。类似地,如果需要,柴油机排出流体可以由发动机冷却剂加温或加热,发动机冷却剂的温度可能超过柴油机排出流体的温度。因此,控制柴油机排出流体喷射器的温度的方法必定包括使传热流体流动或运送(route)进出腔并且在将柴油机排出流体运送或运输到发动机排出流中的结构周围流动或运送。在优选实施例中,此传热流体是发动机冷却剂。发动机冷却剂通常由水和乙二醇及其等效物的混合物组成。
[0020]前述描述仅出于图解目的。在以下权利要求书中阐述本发明的真实范围。