CN106150619B - Urea injection assembly - Google Patents

Abstract

A urea injection assembly includes a housing, a filter assembly, and a pump assembly. The housing includes a receiving cavity that receives the filter assembly. The filter assembly includes a filler block, a filter cartridge, and a cover that are received in the receiving cavity. The pump assembly comprises a first pump shell, a second pump shell and a pump, wherein the first pump shell comprises a channel communicated with an outlet of the pump and an air channel positioned below the channel, and a one-way valve is arranged in the air channel. The second pump shell comprises a first connecting pipe communicated with the inlet of the pump and a second connecting pipe connected with the air outlet channel; when the urea injection assembly is emptied, the one-way valve is opened, at least a portion of compressed air enters the liquid path from the air path and only the urea solution located downstream of the pump is emptied, thereby saving cost. In addition, the filling block is added, so that the volume of the containing cavity for containing urea solution is reduced, and damage caused by urea freezing is reduced.

Description

Urea injection assembly

Technical Field

The invention relates to a urea injection assembly, and belongs to the technical field of engine tail gas aftertreatment.

Background

Existing urea injection systems include air-assisted and non-air-assisted. Among other things, non-air assisted urea injection systems typically include a pump, a filter, a metering nozzle connected to the pump, and a number of sensors. Such urea injection systems often have very high demands on the metering nozzle, which is easily affected in metering accuracy by the high temperatures of the exhaust gases, even burnt out by the high temperatures, as the metering nozzle is mounted on the exhaust pipe. Air-assisted urea injection systems introduce compressed air to enhance the effectiveness of urea atomization, which has been favored by many manufacturers.

In addition, the urea solution can freeze and expand in volume under cold conditions, so how to empty the residual urea solution in the system and reduce the risk of freezing the system is also a problem to be solved by the system.

Disclosure of Invention

The invention aims to provide a urea injection assembly with low cost and a emptying function.

In order to achieve the above purpose, the invention adopts the following technical scheme: the urea injection assembly comprises a shell, a filter assembly, a pump assembly, a heating assembly and a wire harness assembly, wherein the filter assembly is arranged in the shell, the pump assembly is used for pumping urea solution, the heating assembly is provided with a heating defrosting function, the wire harness assembly is used for heating and defrosting, the urea injection assembly comprises a liquid path for circulating urea solution and a gas path for circulating compressed air, the liquid path comprises a urea inlet joint and a urea outlet joint, the gas path comprises a gas inlet joint and a gas outlet joint, the shell comprises a mounting part, the mounting part is provided with a containing cavity communicated with the urea inlet joint and an air outlet channel communicated with the gas outlet joint, and the filter assembly comprises a filling block contained in the containing cavity, a filter element positioned above the filling block and a cover body matched with the filter element; the pump assembly comprises a pump shell and a pump positioned in the pump shell, wherein the pump is provided with an inlet and an outlet, the pump shell comprises a first pump shell and a second pump shell matched with the first pump shell, the first pump shell comprises a channel communicated with the outlet of the pump and an air passage positioned below the channel, a one-way valve is arranged in the air passage, and the second pump shell comprises a first connecting pipe communicated with the inlet of the pump and a second connecting pipe connected with the air outlet channel; when the urea injection assembly normally injects, the one-way valve is closed, and compressed air leaves from the second connecting pipe, the air outlet channel and the air outlet connector; when the urea injection assembly empties, the one-way valve opens, at least a portion of the compressed air from the air passage into the liquid path and empties only urea solution downstream of the pump.

As a further improved technical scheme of the invention, the mounting part comprises a first through hole and a second through hole positioned below the first through hole, the first through hole and the second through hole are obliquely arranged at an angle of 45 degrees, the first connecting pipe is inserted into the first through hole, and the second connecting pipe is inserted into the second through hole.

As a further improved technical scheme of the invention, the shell is provided with a mounting boss, the mounting boss comprises a notch, a stop wall positioned above the notch and a first jack positioned below the notch, and the first jack is communicated with the air outlet channel; the wire harness assembly is provided with a second pressure sensor mounted on the mounting boss, the second pressure sensor comprises a second main body part, a second detection part extending downwards beyond the second main body part and a second positioning protrusion extending downwards from the second main body part, the second detection part is contained in the first jack, the second positioning protrusion is clamped in the notch after rotating, and the stop wall limits the second positioning protrusion to move upwards in the vertical direction.

As a further improved technical scheme of the invention, the first pump shell comprises a first matching part and a first extending part extending forwards from the first matching part, the first matching part comprises a cavity positioned in the first pump shell, a first concave part connected with the cavity and the air passage positioned below the first concave part, and the first extending part is provided with the passage penetrating front and back and communicated with the first concave part; the second pump shell comprises a second matching part fixed with the first matching part and a second extending part extending backwards from the second matching part, the second extending part is provided with a second concave part penetrating through the second matching part, and the first connecting pipe and the second connecting pipe extending backwards from the second concave part, the front end of the pump is accommodated in the first concave part, and the rear end of the pump is accommodated in the second concave part.

As a further improved embodiment of the present invention, the first pump casing is made of a metal material, and the second pump casing is made of an insulating material.

As a further improved technical scheme of the invention, the pump is a plunger pump and comprises a return spring, a piston assembly, a one-way valve assembly, a coil and a contact pin, wherein the piston assembly is pressed against the return spring, the one-way valve assembly is positioned at the front end of the piston assembly, the coil is wrapped at the periphery of the piston assembly, and the contact pin is connected with the coil; the second pump case includes a pin portion extending rearward from an upper end of the second fitting portion and located above the second extending portion, through which the pin passes.

As a further improved technical scheme of the invention, the first pump shell comprises a protruding part extending upwards from the first extending part, wherein the protruding part comprises a groove penetrating up and down, a stop part positioned at one side of the groove and a second jack communicated with the channel and penetrating upwards; the urea injection assembly comprises a first pressure sensor arranged on the protruding portion, the first pressure sensor comprises a first main body portion, a first detection portion extending downwards beyond the first main body portion and a first positioning protrusion extending downwards from the first main body portion, the first detection portion is contained in the second insertion hole, the first positioning protrusion is clamped in the groove after rotating, and the stop portion limits the first positioning protrusion to move upwards in the vertical direction.

As a further improved technical scheme of the invention, the air passage comprises a horizontal air passage and a vertical air passage, and the one-way valve is accommodated in the horizontal air passage.

As a further development of the invention, the urea injection assembly comprises a rubber gasket under the first extension, and the pump assembly comprises a fixing ring for fixing the pump housing to the housing.

As a further improved technical scheme of the invention, the first matching part further comprises a convex part positioned on the side surface, the convex part comprises an air inlet hole positioned in the middle and threaded holes positioned on the upper side and the lower side of the air inlet hole, the air inlet hole is matched with the air passage, the urea injection assembly further comprises an air pressure valve arranged on the convex part, and the air pressure valve is fixed through a screw fixed in the threaded holes.

Compared with the prior art, the filling block is added, so that the volume for containing urea solution in the containing cavity is reduced, and the damage of volume expansion caused by urea freezing to a system is reduced; in addition, based on the design, the invention only empties the urea solution at the downstream of the pump, and does not empty the urea solution at the upstream, thereby saving the cost.

Drawings

FIG. 1 is a schematic perspective view of a urea injection assembly of the present invention.

Fig. 2 is a schematic perspective view of another angle of fig. 1.

Fig. 3 is a partial perspective view of fig. 1, in which the upper housing is not shown.

Fig. 4 is a top view of fig. 3.

Fig. 5 is a partially exploded perspective view of fig. 3.

Fig. 6 is a partially exploded perspective view of the alternative angle of fig. 5.

Fig. 7 is a further exploded perspective view of fig. 6.

Fig. 8 is a further exploded perspective view of fig. 7.

Fig. 9 is a partially exploded perspective view of fig. 3.

Fig. 10 is a top view of the lower housing of fig. 3.

Fig. 11 is a perspective view of the rubber gasket of fig. 6.

Fig. 12 is a perspective view of the pump assembly of fig. 3.

Fig. 13 is a perspective view of the other angle of fig. 12.

Fig. 14 is a perspective view of the further angle of fig. 12.

Fig. 15 is an exploded perspective view of fig. 12.

Fig. 16 is a schematic cross-sectional view of fig. 15.

Fig. 17 is a schematic cross-sectional view of the pump assembly of fig. 12.

Fig. 18 is a perspective view of the first pressure sensor of fig. 3.

Fig. 19 is a perspective view of the second pressure sensor of fig. 3.

Fig. 20 is a top view of the first and second pressure sensors of fig. 3 in an initial installed position.

Fig. 21 is a top view of the first and second pressure sensors of fig. 3 in a final installed position.

Fig. 22 is a cross-sectional view taken along line A-A of fig. 4 and showing the direction of flow.

Fig. 23 is a partial enlarged view of the circled portion in fig. 22.

FIG. 24 is similar to FIG. 23 but does not show the first connector tube assembly.

Fig. 25 is a cross-sectional view taken along line B-B of fig. 4, and indicates the flow direction.

Fig. 26 is a cross-sectional view taken along line C-C of fig. 4 and identifies the direction of flow.

Fig. 27 is a cross-sectional view taken along line D-D of fig. 4 and indicates the direction of flow.

Detailed Description

Referring to fig. 1 to 9, the present invention discloses a urea injection assembly 100, which includes a housing 1, a filter assembly 2 disposed in the housing 1, a pump assembly 3 for pumping urea solution, a heating assembly 4 having a heating and thawing function, a wire harness assembly 6, and the like. In the illustrated embodiment of the invention, the urea injection assembly 100 is used in an air-assisted urea injection assembly, which includes a liquid path 101 (shown with reference to the solid arrow in fig. 4) and a gas path 102 (shown with reference to the open arrow in fig. 4). It will be appreciated that the liquid path 101 and the gas path 102 are finally collected at a nozzle (not shown) to spray atomized urea solution into the exhaust pipe, and the exhaust gas is purified. As for the collection of the liquid path 101 and the gas path 102, the two modes of internal mixing and external mixing are generally known to those skilled in the art, and are not described herein.

In the illustrated embodiment of the invention, the housing 1 comprises a lower housing 11 and an upper housing 12 assembled with the lower housing by means of screws 10. Referring to fig. 3, an annular recess 111 and a sealing ring 112 clamped in the annular recess 111 are provided on the top of the lower housing 11 to improve the sealing performance of the upper housing 12 and the lower housing 11 after assembly.

Referring to fig. 5, the lower housing 11 is a substantially rectangular parallelepiped and includes a bottom wall 13 and four side walls connected to the bottom wall 13. The four side walls include a first side wall 14, a second side wall 15 opposite the first side wall 14, a third side wall 16 connecting the first side wall 14 and the second side wall 15, and a fourth side wall 17 opposite the third side wall 16. The bottom wall 13 and the four side walls together define a receiving space 18 for receiving the filter assembly 2, the pump assembly 3, the heating assembly 4, the wire harness assembly 6, etc. The first side wall 14 is provided with a first mounting hole 141, a second mounting hole 142, a third mounting hole 143, and a harness hole 144. In the illustrated embodiment of the present invention, the first, second and third mounting holes 141, 142 and 143 are circular holes, and the harness hole 144 is a square hole. Wherein the first mounting hole 141 is used for mounting a urea outlet joint 145, the second mounting hole 142 is used for mounting a gas inlet joint 146, the third mounting hole 143 is used for mounting a gas outlet joint 147, and the wire harness hole 144 is used for mounting a wire harness joint 148. In addition, the lower housing 11 is also provided with a urea inlet joint 149 injection molded with the first side wall 14.

In the illustrated embodiment of the invention, the urea outlet connection 145, gas inlet connection 146, gas outlet connection 147, harness connection 148 and urea inlet connection 149 are all located on the same side of the housing 1 for ease of assembly. In addition, the urea inlet joint 149 is adjacent to the third side wall 16 and the urea outlet joint 145 is adjacent to the fourth side wall 17. The gas inlet connection 146 and the gas outlet connection 147 are located between the urea outlet connection 145 and the urea inlet connection 149, wherein the gas inlet connection 146 is located proximate to the urea outlet connection 145 and the gas outlet connection 147 is located proximate to the urea inlet connection 149 so as to substantially reverse the orientation of the liquid circuit 101 to the orientation of the gas circuit 102. The harness connector 148 is located between the urea outlet connector 145 and the gas inlet connector 146.

Referring to fig. 6, 10 and 24, the urea outlet joint 145 includes a head portion 1451, a neck portion 1452 extending downward from the head portion 1451, a locking portion 1453 extending downward from the neck portion 1452, and an outlet tube 1454 extending downward from the locking portion 1453. The head 1451 is wider than the other portions so that the head 1451 is caught inside the first sidewall 14 when the other portions pass through the first mounting hole 141. The head 1451 is provided with a first notch 1455. The neck 1452 is caught in the first mounting hole 141, and the neck 1452 is provided with a second recess 1456 communicating with the first recess 1455. The outer periphery of the locking portion 1453 is provided with an external thread 1457 engaged with a nut 1459, and the inside of the locking portion 1453 is provided with a receiving hole 1458 communicating with the outlet tube 1454.

Referring to fig. 6, the bottom wall 13 is provided with a pair of protrusions 131 disposed at intervals and a receiving groove 132 formed between the pair of protrusions 131, wherein each protrusion 131 is provided with a concave surface 133 inclined toward the receiving groove 132 and a fixing hole 134 located outside the concave surface 133. In the illustrated embodiment of the invention, the bottom of the receiving groove 132 is just flush with the upper surface of the bottom wall 13. The receiving groove 132 is disposed to be inclined at an angle of approximately 45 degrees.

The lower housing 11 further comprises a mounting portion 19 adjacent to the third side wall 16, the mounting portion 19 connecting the first side wall 14 and the second side wall 15. The mounting portion 19 is provided with a receiving chamber 191 communicating with the urea inlet joint 149, and the receiving chamber 191 penetrates the second side wall 15. The mounting portion 19 is further provided with a first through hole 192 adjacent to the second side wall 15 and facing the accommodation groove 132, and a second through hole 193 located below the first through hole 192, wherein the first through hole 192 and the second through hole 193 are arranged side by side in the vertical direction. In the illustrated embodiment of the present invention, the first through hole 192 is inclined at an angle of 45 degrees as the second through hole 193. In addition, the mounting portion 19 further includes an air outlet passage 194 communicating with the second through hole 193, the air outlet passage 194 communicating with the air outlet joint 147. The mounting portion 19 is provided with a mounting boss 195 adjacent the first side wall 14. The mounting boss 195 includes a recess 1951 open to the fourth side wall 17 and a stopper wall 1952 located above the recess 1951, the recess 1951 being upwardly penetrating. The mounting portion 19 is further provided with a first insertion hole 1953 communicating with the outlet passage 194 and penetrating upward, and a screw hole 1954 located at a lower right side of the first insertion hole 1953.

Referring to fig. 7 and 25, the filter assembly 2 includes a filler block 21, a filter element 22 disposed above the filler block 21, and a cover 23 engaged with the filter element 22, which are sequentially accommodated in the accommodating chamber 191. In the illustrated embodiment of the present invention, the cover 23 is in threaded engagement with the mounting portion 19, so as to facilitate disassembly, replace the filter element 22, and save maintenance costs. Referring to fig. 20, the filter assembly 2 of the present invention is shown as an outside-in inside-out type, that is, in use, urea solution flows upward from the gap between the filling block 21 and the receiving chamber 191, then the urea solution permeates through the filter element 22 from outside to inside, and finally leaves from the outlet 231 to enter the first through hole 192.

In cold conditions, the urea solution freezes and expands in volume. In order to reduce the risk that the urea solution may burst the mounting portion 19 after freezing, the invention employs an anti-freeze design, i.e. the filling block 21 is added. In addition, as the filling block 21 is added, the volume in the receiving chamber 191 for receiving urea solution is correspondingly smaller, which also reduces the requirement for the pumping capacity of the pump assembly 3, simplifying the design. In the illustrated embodiment of the invention, the filler piece 21 is a non-deformable hard plastic to save costs. Of course, it will be appreciated that in other embodiments, the filler 21 may be made of a soft material having a certain elasticity.

Referring to fig. 4, the pump assembly 3 is disposed obliquely in the housing 1, substantially parallel to a diagonal line of the housing 1. Referring to fig. 12 to 17, the pump assembly 3 includes a pump housing 31, a pump 32 positioned within the pump housing 31, and a securing ring 33 for securing the pump housing 31 to the bottom wall 13. The pump housing 31 can provide good protection for the pump 32 therein.

The pump housing 31 includes a first pump housing 311 and a second pump housing 312 that is coupled to the first pump housing 311. In the illustrated embodiment of the invention, the first pump housing 311 is made of a metallic material, on the one hand, capable of withstanding the high pressure at the pump outlet; on the other hand, the heat dissipation is facilitated, so that the influence of the heat on the precision of the pump 32 is reduced; the second pump housing 312 is substantially made of an insulating material (e.g., plastic) to facilitate passage of the pins 321 of the pump 32 therethrough, avoiding short circuits, as will be described in greater detail below. Although the second pump housing 312 is basically made of an insulating material, a metal nut having an internal thread may be inserted at the position of the screw hole in order to improve the assembly strength.

The first pump case 311 includes a first fitting portion 313, a first extension portion 314 integrally extending forward from the first fitting portion 313, and a protrusion portion 315 extending upward from the first extension portion 314. The first fitting portion 313 includes a chamber 3131 therein, a first recess 3132 connected to the chamber 3131, and an air passage 3133 under the first recess 3132. Referring to fig. 14, the first mating portion 313 further includes a protrusion 3134 located at a side surface, and the protrusion 3134 includes an air inlet 3135 located at the middle and screw holes 3136 located at the upper and lower sides of the air inlet 3135. In the illustrated embodiment of the invention, the inlet port 3135 communicates with the chamber 3131, which chamber 3131 in turn communicates with the air channel 3133, ultimately placing the inlet port 3135 in communication with the air channel 3133. Referring to fig. 15 and 16, the first pump housing 311 further includes a check valve 3137 received in the air passage 3133. Referring to fig. 17, in the illustrated embodiment of the invention, the air duct 3133 includes a horizontal air duct 3138 and a vertical air duct 3139, wherein the check valve 3137 is received in the horizontal air duct 3138.

The first extension 314 is provided with a channel 3141 penetrating from front to back and communicating with the first recess 3132. The air channel 3133 extends forward and upward to communicate with the channel 3141. In addition, the first extension 314 is further provided with notches 3142 located at both sides of the air passage 3133. The protrusion 315 includes a recess 3151 opened to the fourth side wall 17 and a stopper 3152 located at one side of the recess 3151, and the recess 3151 is vertically penetrated. The boss 315 is further provided with a second insertion hole 3153 communicating with the passage 3141 and penetrating upward.

The second pump housing 312 includes a second fitting portion 316, a pin portion 317 extending rearward from an upper end of the second fitting portion 316, and a second extension portion 318 extending rearward from the second fitting portion 316 and below the pin portion 317. The second fitting part 316 is connected to the first fitting part 313 by bolts 319 located at four corners. In order to enhance the sealing property, the second mating portion 316 is provided with a mounting groove 3161 surrounding an end surface thereof and a sealing ring 3162 retained in the mounting groove 3161. The second extension portion 318 is provided with a second recess portion 3181 penetrating the second fitting portion 316, a first connecting tube 3182 extending backward from the second recess portion 3181, and a second connecting tube 3183, wherein the first connecting tube 3182 is located at an upper end of the second connecting tube 3183, and the second connecting tube 3183 is connected with the air channel 3133.

Referring to fig. 16 and 17, in the illustrated embodiment of the invention, the pump 32 is a plunger pump, which includes a return spring 322, a piston assembly 323 that is pressed against the return spring 322, a check valve assembly 324 that is positioned at the front end of the piston assembly 323, and a coil 325 that is wrapped around the periphery of the piston assembly 323, and the contact pin 321 is connected to the coil 325 to provide electric power. The pump 32 is provided with an inlet 326 at its rear end and an outlet 327 at its front end.

Referring to fig. 9, the fixing ring 33 includes a first pressing portion 331, a second pressing portion 332 spaced from the first pressing portion 331, and a pair of assembling portions 333 connecting the first pressing portion 331 and the second pressing portion 332, wherein each of the first pressing portion 331 and the second pressing portion 332 has an arc-shaped inner surface to be matched with the first extending portion 314. The middle of the first pressing portion 331 and the second pressing portion 332 has a hollow portion 334, and the protruding portion 315 extends upward through the hollow portion 334. The fitting portion 333 is substantially flat plate-shaped and includes a mounting hole 335 corresponding to the fixing hole 134.

Referring to fig. 17, when assembled, the front end of the pump 32 is received in the first recess 3132, the rear end of the pump 32 is received in the second recess 3181, the inlet 326 of the pump 32 is in communication with the first connection pipe 3182, and the outlet 327 of the pump 32 is in communication with the channel 3141.

Further, when the pump housing 31 is mounted to the lower housing 11, the first adapter 3182 is received in the first through hole 192, and the second adapter 3183 is received in the second through hole 193. Finally, the pump housing 31 is fixed by means of the fixing ring 33 by means of screws 336 passing through the mounting holes 335 and the corresponding fixing holes 134.

In the illustrated embodiment of the invention, the positioning is already possible by means of the first connecting piece 3182 and the second connecting piece 3183 when the pump housing 31 is mounted on the lower housing 11. To avoid over-positioning, in the illustrated embodiment of the invention, the housing 1 further comprises a rubber gasket 135 located above the receiving groove 132 and supported on the concave surface 133. The rubber gasket 135 has an arc-shaped upper surface 1351, and a first positioning portion 1352 and a second positioning portion 1353 located on both sides of the upper surface 1351. The arcuate upper surface 1351 is configured to support the first extension 314 of the pump housing 31. The first positioning portion 1352 and the second positioning portion 1353 extend downward and are respectively retained at the front and rear ends of each bump 131. The rubber gasket 135 has a certain elasticity, and can absorb shock, and avoid over-positioning, etc.

Referring to fig. 4-9, 23 and 24, the urea injection assembly 100 further comprises a first connecting tube assembly 51 connecting the channel 3141 with the urea outlet fitting 145. The first connecting tube assembly 51 includes a throttle valve 511 received in the receiving hole 1458, a first end portion 512 received in the first and second recesses 1455 and 1456, a second end portion 513 received in the channel 3141, and a first connecting tube 514 connecting the first and second end portions 512 and 513. To enhance the seal, a seal ring 515 is provided on each of the first end 512 and the second end 513. In the illustrated embodiment of the present invention, the first end portion 512 and the first connecting tube 514 are two elements separately provided, and the first end portion 512 is provided with a first barb 5121 inserted into the first connecting tube 514; similarly, the second end 513 is also two separate elements from the first connecting tube 514, and the second end 513 is provided with a second barb 5131 inserted into the first connecting tube 514.

Referring to fig. 23, the urea outlet connection 145 is in communication with the first connection pipe assembly 51 for passing the pumped urea solution. Since the pump 32 has a relatively small pressure at the pump outlet at the initial stage of pressure build-up, a throttle valve 511 is provided in the illustrated embodiment of the present invention in order to allow quick identification of the pump outlet pressure. It will be appreciated that the outlet pressure will increase after the throttle 511 is provided.

In addition, referring to fig. 4-9 and 26, the urea injection assembly 100 further includes a second connecting tube assembly 52 connected to the gas inlet fitting 146.

Referring to fig. 4 to 9, the heating assembly 4 includes a first heating blanket 41 coated on the mounting portion 19, a second heating blanket 42 connected to the first heating blanket 41 by a harness 40, and a third heating blanket 43, wherein the first heating blanket 41, the second heating blanket 42, and the third heating blanket 43 are disposed in series. The heating assembly 4 is finally connected to the harness assembly 6 to provide electrical power. In the illustrated embodiment of the invention, the first heater blanket 41 is further provided with a shoulder 411 that wraps around the first through hole 192 and the second through hole 193. The second heating blanket 42 is wrapped in the notches 3142 at both sides of the first pump housing 311 to heat and defrost the urea solution at the pump outlet. The third heating blanket 43 is wrapped on the first connecting tube 514 to achieve heating and thawing. Referring to fig. 3, the heating assembly 4 further includes spacers 44 at the upper and lower ends of the first heating blanket 41, and the spacers 44 can fix the first heating blanket 41 after the lower case 11 is assembled with the upper case 12.

The wire harness assembly 6 includes a pneumatic valve 61 mounted on the pump housing 31, a first pressure sensor 62 mounted on the boss 315, and a second pressure sensor 63 mounted on the mounting boss 195. Wherein the pneumatic valve 61 is fixed by a screw fixed in the screw hole 3136. The air pressure valve 61 is communicated with the air inlet hole 3135, one end of the second connecting pipe assembly 52 is connected with the air inlet joint 146, and the other end is connected with the air pressure valve 61.

Referring to fig. 4 and 18, the first pressure sensor 62 is installed at the outlet of the liquid path 101 to detect the outlet pressure. The first pressure sensor 62 includes a first body 621, a first detecting portion 622 extending downward beyond the first body 621, a sealing ring 623 fitted over the first detecting portion 622, and a first positioning boss 624 extending downward from the first body 621. Referring to fig. 20 and 21, when assembling, the first detecting portion 622 and the sealing ring 623 are first inserted into the second insertion hole 3153, and then the first pressure sensor 62 is rotated toward the recess 3151, so that the first positioning protrusion 624 is locked in the recess 3151. At this time, the stopper 3152 can restrict the upward movement of the first positioning protrusion 624 in the vertical direction, thereby functioning as a limit function.

Similarly, referring to fig. 4 and 19, the second pressure sensor 63 is installed at the outlet of the gas path 102 to detect the outlet pressure. The second pressure sensor 63 includes a second body portion 631, a second sensing portion 632 extending downward beyond the second body portion 631, a sealing ring 633 sleeved on the second sensing portion 632, a second positioning boss 634 extending downward from the second body portion 631, and a third positioning boss 635 extending rearward from the second body portion 631. Referring to fig. 20 and 21, when assembling, the second detecting portion 632 and the sealing ring 633 are first inserted into the first inserting hole 1953, and then the second pressure sensor 63 is rotated (e.g. rotated clockwise) toward the recess 1951, so that the second positioning protrusion 634 is snapped into the recess 1951. At this time, the stopper wall 1952 can restrict upward movement of the second positioning protrusion 634 in the vertical direction, thereby functioning as a stopper. Then, a screw 1955 is fixed in the screw hole 1954. So configured, the screw 1955 can interfere with the third positioning protrusion 635 to prevent the second pressure sensor 63 from rotating (e.g., counter-clockwise) away from the stop wall 1952.

Referring to fig. 18 to 21, in the illustrated embodiment of the present invention, the first pressure sensor 62 and the second pressure sensor 63 have the same structure, so as to save costs. The circuit portions of the air pressure valve 61, the first pressure sensor 62, and the second pressure sensor 63 are all connected to the harness connector 148 by a flat cable.

Referring to fig. 22, 25 to 27, the thick arrows represent the flow direction of urea solution, the thin solid arrows represent the flow direction of air, and the thin dotted arrows represent the flow direction of air during emptying. When the urea injection assembly 100 is in operation, with respect to the direction of the liquid path 101, the urea solution enters the filter assembly 2 from the urea inlet fitting 149, then enters the first through hole 192, is pressurized and output into the channel 3141 by the pump 32, then enters the first connecting tube 514, passes through the throttle 511, and finally exits from the urea outlet fitting 145.

With respect to the orientation of the air path 102, compressed air enters from the air inlet fitting 146, passes through the air pressure valve 61, and enters the chamber 3131 from the air inlet 3135. In normal conditions (not empty), the one-way valve 3137 closes, i.e. the air channel 3133 closes. Referring to fig. 22, at this time, the compressed air can only enter the second connection pipe 3183, then enter the second through hole 193 and the air outlet passage 194, and finally exit from the air outlet connector 147.

In the emptying state, please refer to fig. 22, at this time, the check valve 3137 is opened, at least a part of the compressed air enters the air channel 3133 (as indicated by the dashed arrow), and then is converged into the channel 3141, so as to empty the pipeline located behind the outlet of the pump in the urea flow direction, thereby reducing the risk of urea icing.

It should be noted that, since the filling block 21 is added in the present invention, the volume of the containing chamber 191 for containing the urea solution is reduced, and in this case, even if the piping in front of the outlet of the pump is not emptied, the low-temperature test can be performed, thereby greatly reducing the cost of the system design.

The above embodiments are only for illustrating the present invention and not for limiting the technical solutions described in the present invention, and the understanding of the present specification should be based on the description of the directivity of the present invention such as "front", "rear", "left", "right", "upper", "lower", etc., and although the present specification has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the present invention may be modified or equivalent by those skilled in the art, and all the technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered by the claims of the present invention.

Claims (10)

1. The utility model provides a urea injection subassembly, its include the casing, install in filter subassembly in the casing, be used for pumping urea solution's pump assembly, possess heating element and the pencil subassembly of heating defrosting function, urea injection subassembly is including the liquid way that supplies urea solution circulation and the gas circuit that supplies compressed air circulation, the liquid way includes urea inlet connection and urea outlet connection, the gas circuit includes gas inlet connection and gas outlet connection, the casing includes the installation department, the installation department be equipped with the holding chamber of urea inlet connection intercommunication and with the gas outlet channel of gas outlet connection intercommunication, its characterized in that: the filter assembly comprises a filling block accommodated in the accommodating cavity, a filter element positioned above the filling block and a cover body matched with the filter element; the pump assembly comprises a pump shell and a pump positioned in the pump shell, wherein the pump is provided with an inlet and an outlet, the pump shell comprises a first pump shell and a second pump shell matched with the first pump shell, the first pump shell comprises a channel communicated with the outlet of the pump and an air passage positioned below the channel, a one-way valve is arranged in the air passage, and the second pump shell comprises a first connecting pipe communicated with the inlet of the pump and a second connecting pipe connected with the air outlet channel; when the urea injection assembly normally injects, the one-way valve is closed, and compressed air leaves from the second connecting pipe, the air outlet channel and the air outlet connector; when the urea injection assembly empties, the one-way valve opens, at least a portion of the compressed air from the air passage into the liquid path and empties only urea solution downstream of the pump.

2. The urea injection assembly of claim 1, wherein: the installation department includes first through-hole and is located the second through-hole of first through-hole below, first through-hole with the second through-hole is 45 degrees angle slope settings, first takeover inserts in the first through-hole, the second takeover inserts in the second through-hole.

3. The urea injection assembly of claim 1, wherein: the shell is provided with a mounting boss, the mounting boss comprises a notch, a stop wall positioned above the notch and a first jack positioned below the notch, and the first jack is communicated with the air outlet channel; the wire harness assembly is provided with a second pressure sensor mounted on the mounting boss, the second pressure sensor comprises a second main body part, a second detection part extending downwards beyond the second main body part and a second positioning protrusion extending downwards from the second main body part, the second detection part is contained in the first jack, the second positioning protrusion is clamped in the notch after rotating, and the stop wall limits the second positioning protrusion to move upwards in the vertical direction.

4. The urea injection assembly of claim 1, wherein: the first pump shell comprises a first matching part and a first extending part extending forwards from the first matching part, the first matching part comprises a cavity arranged in the first matching part, a first concave part connected with the cavity and an air passage arranged below the first concave part, and the first extending part is provided with a channel penetrating front and back and communicated with the first concave part; the second pump shell comprises a second matching part fixed with the first matching part and a second extending part extending backwards from the second matching part, the second extending part is provided with a second concave part penetrating through the second matching part, and the first connecting pipe and the second connecting pipe extending backwards from the second concave part, the front end of the pump is accommodated in the first concave part, and the rear end of the pump is accommodated in the second concave part.

5. The urea injection assembly of claim 4, wherein: the first pump housing is made of a metal material, and the second pump housing is made of an insulating material.

6. The urea injection assembly of claim 5, wherein: the pump is a plunger pump and comprises a return spring, a piston assembly, a one-way valve assembly, a coil and a contact pin, wherein the piston assembly is in propping pressure with the return spring, the one-way valve assembly is positioned at the front end of the piston assembly, the coil is wrapped at the periphery of the piston assembly, and the contact pin is connected with the coil; the second pump case includes a pin portion extending rearward from an upper end of the second fitting portion and located above the second extending portion, through which the pin passes.

7. The urea injection assembly of claim 4, wherein: the first pump shell comprises a protruding part extending upwards from the first extending part, wherein the protruding part comprises a groove penetrating up and down, a stop part positioned at one side of the groove and a second jack communicated with the channel and penetrating upwards; the urea injection assembly comprises a first pressure sensor arranged on the protruding portion, the first pressure sensor comprises a first main body portion, a first detection portion extending downwards beyond the first main body portion and a first positioning protrusion extending downwards from the first main body portion, the first detection portion is contained in the second insertion hole, the first positioning protrusion is clamped in the groove after rotating, and the stop portion limits the first positioning protrusion to move upwards in the vertical direction.

8. The urea injection assembly of claim 7, wherein: the air passage comprises a horizontal air passage and a vertical air passage, and the one-way valve is accommodated in the horizontal air passage.

9. The urea injection assembly of claim 4, wherein: the urea injection assembly includes a rubber washer below the first extension, and the pump assembly includes a retaining ring to secure the pump housing to the housing.

10. The urea injection assembly of claim 4, wherein: the first matching part further comprises a protruding part positioned on the side face, the protruding part comprises an air inlet hole positioned in the middle and threaded holes positioned on the upper side and the lower side of the air inlet hole, the air inlet hole is matched with the air passage, the urea injection assembly further comprises an air pressure valve arranged on the protruding part, and the air pressure valve is fixed through screws fixed in the threaded holes.