CN105587383A - SCR metering module - Google Patents

Abstract

Provided is an SCR metering module. The SCR metering module is characterized in that the SCR metering module comprises a urea tank, a solenoid driving pump, a controller, a nozzle, a filter, a support and a pallet; working liquid enters the solenoid driving pump; high-voltage liquid outputted by a liquid discharge channel is sprayed in a vaporific shape via the nozzle; and the sprayer acts as a check valve closed by spring force or an electromagnetic valve. The SCR metering module is advantaged by being high in metering precision, fine in inject effect, easy in structure and convenient in replacement and maintenance and helps to reduce cost of a metering and spraying system after air exhaust.

Description

A kind of SCR metering module

Technical field

The invention belongs to exhaust gas aftertreatment techniques field, be specifically related to engine exhaust and purify NOx SCR (SCR) metering injection system.

Background technology

Be accompanied by becoming increasingly conspicuous of environmental problem, energy-saving and emission-reduction have become the of paramount importance theme of Engine Industry, world many countries is all constantly released a series of engine and vehicular emission standards, to this, vehicle taking internal combustion engine as power needs better combustion control system, and discharge post-treatment system is installed in the hope of meeting more and more stricter emission request. For example, the engine including spark ignition type put-put also adopts electronic fuel injection technology and exhaust three-element catalytic treatment technology as automobile engine; The direct spray petrol engine in cylinder of Diesel engine or lean burn, for noxious pollutants such as the NOx in reduction tail gas, employing can be carried out NOx selective catalysis reduction (SCR=SelectiveCatalyticReduction) technology of catalytic reduction processing under oxygen-enriched environment.

SCR technology is passed through in the metered injection NOx selective reduction agent of catalyst converter upstream, and for example aqueous solution of urea of 32.5% weight concentration (be also diesel exhaust gas treatment fluid DEF=DieselExhaustFluid, or add blue liquid AdBlue) is processed exhaust. Specifically, when DEF enters after the exhaust pipe of engine, resolve into ammonia by exhaust high temperature, after mixing with exhaust, enter SCR catalyst. Under the effect of catalyst, ammonia will with engine exhaust in NOx etc. there is catalytic reduction reaction, make NOx be decomposed into harmless N2, H2O. If the NOx content in DEF emitted dose and exhaust does not match, so otherwise NOx can not be by abundant reduction decomposition, discharge capacity increases, or remaining many ammonias is discharged in atmosphere, causes secondary pollution. Therefore SCR system must need the SCR metering jetting device that precision is higher.

US Patent No. 20090301067A1 discloses a kind of metering jetting device and method thereof. Metering jetting device is the plunger displacement pump nozzle of a solenoid-activated, is arranged on blast pipe, needs an additional low-lift pump to provide hydraulic fluid for it from DEF fluid reservoir, and need to take cooling provision normally to work. In addition the scheme that, provides a kind of pump-mouth end to control respectively in the operation of the disclosed SCR metered injection of US Patent No. 8356471B2, system and method. Except measuring accuracy requires, due to the characteristic of urea itself, temperature control and the pipeline ice of device also be there are certain requirements.

For example, because aqueous solution of urea has electric conductivity, traditional injection metering system taking DC rotation electric pump as power source can not slip in hydraulic fluid works, therefore most prior aries adopt the external diaphragm pump driving taking direct current generator as power source, the complex structure of this system, except reliability, is also subject to the impact of environment larger, especially the ice-melt servicing unit of need of work complexity under low temperature environment, after-sale service is safeguarded also more difficult.

Prior art has adopted quite complicated system to address the above problem, for example special measuring pump is placed in outside aqueous solution of urea holding vessel, rely on complicated pipeline to connect each device, all pipelines all must wrap up electric heater unit and carry out ice-melt, cause system complex and cost is very high. In addition, injection unit with and the layout installation, maintenance of relevant device pipeline to change convenience be also a major issue, the cost of the more complicated this respect of system is also just higher. Therefore, about no matter succinct structure and application mode of SCR metering jetting device, or the precision of its metering injection system and stability are all very valuable research work.

Summary of the invention

The present invention is directed to the problems referred to above, object to be to be to provide a kind of measuring accuracy high, jeting effect is good, simple in structure, changes, metering jetting device easy to maintenance, and further reduces the cost of exhaust aftertreatment metering injection system.

For achieving the above object, the present invention takes following technical scheme: a kind of SCR metering jetting device, it is characterized in that, and comprise urea tank, solenoid-activated pump, controller, nozzle, filter, support and pallet.

Described solenoid-activated pump comprises a solenoid driving device and a plunger assembly. Described spiral piping arrangement comprises coil, yoke, magnetic resistance and armature, and wherein yoke and armature are made up of permeability magnetic material, and magnetic resistance is made up of non-magnet material. Described plunger assembly comprises plunger, sleeve and return spring, and plunger coordinates formation force feed volume with sleeve, and force feed volume connects liquid feed valve and liquid valve, and liquid enters liquid feed valve from liquid inlet channel, inputs tapping channel by force feed volume from liquid valve. Described return spring can act on plunger or sleeve.

Described controller provides driving signal for spiral piping arrangement, and modal control method is the mode of taking PWM to drive. Owing to driving the effect of signal and return spring, plunger and sleeve, in the state of doing relatively reciprocating motion, alternately change force feed volume size.

Return spring in such scheme can be replaced to provide sleeve or the needed power of plunger return by another one spiral piping arrangement.

Hydraulic fluid enters solenoid-activated pump through filter, and the highly pressurised liquid after being exported by tapping channel is vaporific ejection by nozzle, and described nozzle can be a check valve of being closed by spring force, can also be a magnetic valve.

Further, can comprise a high-voltage tube between tapping channel and solenoid pump, described high-voltage tube is made up of metal or macromolecular material, can be the rigid pipe of sizing, can be also flexible flexible pipe. Described solenoid pump can be that nozzle can be also the injector being installed on discharge duct. In addition, need to just can enter through a filter inner space of solenoid-activated pump from the liquid of urea box.

Described support is the link of a stainless steel material, comprises temperature sensor, liquid level sensor etc. Support one end is a solenoid-activated pump fixed station, and the other end is for fixed tray. Controller is installed on pallet and comprises various lead-in wires duct with pipeline. Support also can a support being made up of ice-melt pipe, and ice-melt liquid is engine coolant, and its liquid inlet and outlet is arranged on pallet. Solenoid pump can or be placed horizontally in liquid reserve tank by support vertical, and wherein one end of fixed tray is fixed on liquid reserve tank, and controller exposes to liquid reserve tank, and one end of stationary solenoids jet pump is positioned at the bottom of liquid reserve tank.

A kind of selectable scheme is: comprise a gas-liquid mixed chamber, first liquid sprayed in gas-liquid mixed chamber by nozzle, and liquid sprays in waste pipe through an injector after mixing with gas again, to strengthen atomizing effect. In addition, after liquid has sprayed, pressure-air can be delayed and close, and to clear away the residual liquid mixing in carrier pipe, avoids it to freeze or crystalline solid is separated out transfer pipeline is resulted in blockage and damaged. Described injector can be a simple throttling hole type nozzle, can be also a swirl nozzle that does not contain nozzle group valve. Obstruction and damage that this scheme is conducive to the atomization of liquid and increases the content of blast pipe oxygen and can avoid liquid to freeze to transfer pipeline.

Another ejection schemes that is applied to SCR system is: nozzle is directly installed on discharge duct, liquid is directly sprayed in the exhaust pipe of engine by nozzle by high-voltage tube, and described nozzle can be that the lift valve that an anti-coking and pollution capacity are strong can be also a magnetic valve. In order to prevent that high-voltage tube from freezing, need to arrange deicing device along high-voltage tube, for example carry out ice-melt by the mode of electrical heating or engine cooling water heating.

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Brief description of the drawings

Fig. 1 is one of SCR metering module example structure schematic diagram provided by the invention.

Fig. 2 is two of SCR metering module example structure schematic diagram provided by the invention.

Fig. 3 is three of SCR metering module example structure schematic diagram provided by the invention.

Fig. 4 is one of solenoid-activated pump configuration of SCR metering module provided by the invention.

Fig. 5 be SCR metering module provided by the invention solenoid-activated pump configuration two.

Fig. 6 is one of nozzle arrangements of SCR metering module provided by the invention.

Fig. 7 be SCR metering module provided by the invention nozzle arrangements two.

Specific embodiment

Fig. 1 is one of SCR metering device example structure schematic diagram provided by the invention, example comprises a urea tank 1, a solenoid-activated pump 2, a nozzle 3, a controller 4, one is set to the gas-liquid mixed chamber 5 of one with solenoid-activated pump 2, one is mixed woven hose 10, one comprises temperature sensor 12, the support 6 of liquid level sensor 11, a pallet 7, an injector 8, a discharge duct 9 with SCR catalyst 18, be furnished with successively temperature sensor 17 and NOx or ammonia gas sensor 19 along exhaust stream direction, lay respectively at catalyst 18 both sides.

Described solenoid-activated pump 2 is fixed on support 6 one end, can be by support 6 vertical or be placed horizontally in urea box 1, concrete structure schematic diagram as described in Figure 4, comprise solenoid driving device 104, plunger assembly 103, return spring 101, pump end 113, filter 110, low pressure volume 119 and output housing 118.

Solenoid driving device 104 comprises coil 116, the first inner yoke 121a, the second inner yoke 121d, outside yoke 121b, outside yoke end 121c, magnetic gap 117 and armature 102a. Outside yoke 121b is by plastic deformation and the external magnetic end 121c locking of protruding 121b1, and coil 116 is also fixed on wherein simultaneously, and the first inner yoke 121a comprises that can be passed through an exhaust gas inside road 120 for fluid. Outside yoke 121b, outside yoke end 121c, the first inner yoke 121a and the second inner yoke 121d make by permeability magnetic material, and magnetic gap 117 is non-magnet material. Armature 102a has several along the straight trough 102e circumferentially distributing, to reduce reciprocating resistance.

Plunger assembly 103 comprises sleeve 114, plunger 102, liquid feed valve 106 and liquid valve 115. Sleeve 114 and plunger 102 close fit, form force feed volume 107. Described sleeve 114 can be designed to one with armature 102a, and adopts identical or different materials, sleeve 114 to be positioned at armature 102a inner side, comprises plunger hole 105, spout hole 106b1, liquid inlet channel 109. Plunger 102 comprises an end face 106b2, a tapping channel 102d, and one is positioned at the metering hole 102b in tapping channel 102d downstream, and one is positioned at the protruding 102c of end. Liquid feed valve 106 be one by check valve 106a and a combination valve that guiding valve 106b forms. Described check valve 106a is made up of valve member 106a1, valve spring 106a2 and valve seat 106a3, and valve seat 106a3 can be connected as a single entity with sleeve 114, is a conical seat surface that is positioned at liquid inlet channel 109 places and is communicated with it. The end face 106b2 that described guiding valve 106b comprises spout hole 106b1 and plunger 102. The switching of guiding valve 106b determines by the relative position of plunger 102, and in the time that plunger 102 moves to end face 106b2 and exceedes spout hole 102b peak, guiding valve 106b closes. If closing of described check valve 106a is later than the moment that spout hole 106b1 is blocked, the process that starts force feed liquid depends on closing of check valve 106a, otherwise the process that starts force feed liquid depends on blocking of spout hole 106b1. Described liquid valve 115 is a check valve, comprises fluid valve member 115a, fluid valve spring 115b and fluid valve seat 115c. Fluid valve seat 115c is fixed on plunger 102, fixes and can adopt the mode such as close-fitting or welding.

Pump end 113 comprises a pump end inlet 113c, a support bar 113a and a locating part 113b, liquid inlet channel 109 allows support bar 113a to stretch into and touch unidirectional valve member 106a1, locating part 113b is used for limiting armature 102a return, in armature 102a leaves a segment distance of pump end 113, support bar 113a keeps contacting and stoping it to take a seat with unidirectional valve member 106a1, so on the one hand can be in the time that armature 102a be returned to initial position, check valve 106a is held open state, make liquid have the more sufficient time to enter force feed volume 107, on the other hand, in armature 102a leaves a segment distance of pump end 113 forward movement, gas in force feed volume 107 can continue to discharge by check valve 106a, thereby ensure the measuring accuracy of liquid.

Filter 110 comprises inner skeleton 108, filter net cloth 111, filter inner chamber 112.

The course of work of described solenoid-activated pump is as follows:

At motion initial position, because effect and the locating part 113b of return spring 101 are close to, now check valve 106a is because support bar 113a effect is in opening, and spout hole 106b1 and force feed volume 107 are in connected state, the contained gas componant force feed volume 107 of easily escaping, is full of liquid in force feed volume 107. When starting to travel forward together with sleeve 114 under the effect of armature 102a in electromagnetic force, the segment fluid flow in force feed volume 107 is discharged by liquid inlet channel 109 and spout hole 106b1, comprising portion gas. When after armature 102a motion certain distance, spout hole 106b1 is blocked by the surface of plunger 102. Armature 102a continues motion, and force feed volume 106 constantly reduces, and in the time that the ball surface of unidirectional valve member 106a1 is seated at conical valve seat 106a3, feed liquor check valve 106a closes, and force feed process starts. Fluid pressure in force feed volume 107 raises gradually, and in the time acting on the pressure of liquid valve part 115a and can overcome the active force of fluid one-way valve spring 115b, fluid check valve 115 is opened, and liquid enters tapping channel 102d, and is exported by metering hole 102b.

When after the electromagnetic force disappearance acting on armature 102a, under the effect of return spring 101, armature 102a starts return-stroke, now because of the expansion of force feed volume 107 cause pressure drop then fluid check valve 115 close, check valve 106a opens, liquid enters rapidly force feed volume 107 under the effect of pressure reduction, armature 102a continues after the certain stroke of motion, first the supported bar 113a of motion that is feed liquor valve member 106a1 stops, next be that spout hole 106b1 is communicated with again with force feed volume 107, partially liq also can enter force feed volume 107 from spout hole 106b1, limited 113b of continuation return of armature 102a stops and stops, this end that circulates.

In said process, also can redesign spout hole 106b1, to such an extent as to closing with the close moment order of liquid feed valve 106a of spout hole 106b1 put upside down mutually.

In the above-mentioned course of work, liquid enters whole armature space 102d from filter inner chamber 112 by pump end liquid inlet channel 113c, and enter force feed volume 106 by liquid inlet channel 109, because of the dissipation heating of electric energy, cause partially liq to evaporate in armature space 102d, the steam evaporating enters low pressure volume 119 from exhaust gas inside road 120, and excretes by an exhaust bubble mouthful 119a who is positioned on output housing 118. A described exhaust bubble mouthful 119a comprises an installation step 119b, can be used for installing exhaust gas bubble pipe 20(as shown in the Examples), exhaust gas bubble pipe 20 extends to solution top, makes the more effective discharge pump housing of gas. Pipe outlet have one section of bending circular arc (can be also exit install one cross filter ruffle, as described in Example 2), not contaminated to ensure the interior clean solution of solenoid-activated pump 2, prevent that foul from entering.

Nozzle 3 is a ball-valve type nozzle, concrete structure is as shown in Fig. 6 a and 6b, comprise the front valve seat 301 of nozzle, valve member 307, nozzle rear valve base 306, nozzle group valve spring 305, spray orifice 303, before nozzle valve seat 301 comprise can with the conical seat surface of the ball face sealing of valve member 307, nozzle rear valve base 306 comprises a plane (in Fig. 6 b, nozzle back seat 306 planes are a confined planes) that can form with the plane of valve member 307 sealing, before nozzle, valve seat 301 and nozzle rear valve base 306 are by being welded to connect, after connection, leave therein for valve member 307 and open needed space, be provided with screen pack 308 in the porch of ball-valve type nozzle 3. tapping channel mesohigh urea arrives valve member 307 by screen pack 308, when after before valve member 307, pressure reduction is elevated to the active force that can overcome nozzle group valve spring 305, valve member 307 leaves the sealing cone of the front valve seat 301 of nozzle and is adjacent to the sealing plane of nozzle rear valve base 306, and at this moment urea liquid sprays by spray orifice 303.

Described controller 4 provides driving signal for solenoid pump 2, and modal control method is the mode of taking PWM to drive. Owing to driving the effect of signal and return spring 101, plunger 102 in the state of doing relatively reciprocating motion, alternately changes force feed volume 107 sizes with sleeve 114. It can be also a control module that comprises SCR system for receiving the metering module of main control unit working signal that controller 3 can be one, is installed on pallet 7. Pallet 7 is fixed on support 6 and is positioned at the one end at urea tank 1 top, is sealed by seal 15, and controller 4 exposes to urea tank.

The present embodiment gives the course of work of SCR system as follows.

The engine operating condition that controller 3 is sent according to engine main control unit (not shown), and exhaust gas temperature sensor 17, NOx or ammonia gas sensor 19, the signal of the interior temperature sensor 12 of urea tank 1, liquid level sensor 11 etc., calculates required urea solution flow, then judges whether urea solution spraying system can normally work, if can, just control solenoid jet pump 2 and work, the urea liquid pump in urea tank 1, to nozzle 3, is spurted into hybrid chamber 5. Meanwhile, pressure-air is inputted hybrid chamber 5 through Pressure gauge 13, magnetic valve 14, air inlet pipe 22 and air intake duct 21 and is mixed with jetting fluid wherein, between magnetic valve 14 and air inlet pipe 22, a check valve can be installed, and makes air-flow one-way trip. Mixed liquor is entered and is mixed woven hose 10a and 10b by tapping channel 23. Finally, by injector 8, mixed liquor is sprayed and entered in blast pipe 9 with the form of atomization, urea solution pyrolysis under the effect of engine exhaust 16 high temperature is ammonia, mixes and enters SCR catalyst 18 with engine exhaust 16, and result NOx wherein will be efficiently decomposed into harmless N₂And H₂O, reaches the object of evolution tail gas. After injection completes, air magnetic valve 14 can time-delay closing, to clean residual urine cellulose solution in pipeline.

In such scheme, injector 8 can be a simple throttling hole type nozzle, can be also a swirl nozzle that does not contain nozzle group valve. Obstruction and damage that this scheme is conducive to the atomization of liquid and increases the content of blast pipe oxygen and can avoid liquid to freeze to transfer pipeline.

Figure 2 shows that SCR metering device the second embodiment schematic diagram provided by the invention, with the invention provides one of first embodiment difference and be: described support 6 is a support being made up of ice-melt pipe 6a, ice-melt liquid can be engine coolant, and ice-melt liquid inlet 30 and liquid outlet 31 are arranged on pallet 7. This example with the invention provides two of the first embodiment difference and be: comprise one section of high-voltage tube 32 with snap joint, be connected with solenoid pump tapping channel 102d by snap joint 35, and enclose 33 by o and seal. Nozzle 3 can be connected with high-voltage tube with the form of injection moulding, also can connect by connecing soon mode. This example with the invention provides three of the first embodiment difference and be: gas-liquid mixed chamber 5 and pallet 7 are designed to one, are positioned at urea tank 1 outside.

Described in the present embodiment, solenoid-activated pump as shown in Figure 5, is with the main distinction of embodiment that Fig. 4 provides: the present embodiment solenoid-activated pump 1 has adopted plunger 102 and armature 102a to be synchronized with the movement, and the fixed structure of sleeve 114. Armature 102a is roughly a cylinder, comprises the through hole 201 that connects both ends of the surface. Described through hole 201 can have certain tapering, and the stability of its work, to feeding liquid under pressure Directional Extension, to realize the directed flow of liquid in inner space, is improved in the hole with tapering.

Described armature 102a and plunger 102 can be an entirety, also can be by connector 203 transmission of moving. Sleeve 114 is coaxially fixed on output housing 118, and sleeve 114 is provided with the spout hole 106b1 of side direction and axial straight consent 105 is communicated with. Plunger 102 precisions are slidably matched and are contained in sleeve 114, and its top contacts with armature 102a all the time by connector 203. Spout hole 106b1 and plunger end face 106b2 form liquid feed valve 106. Liquid valve 115 is made up of fluid valve member 115a, fluid valve spring 115b and fluid valve seat 115c, and fluid valve seat 115c is the conical surface coordinating with fluid valve member 115a, is positioned at sleeve 114 end 114a places. Return spring 101 is arranged between plunger 102 and armature space 102d bottom.

The liquid being entered by inlet 202 enters force feed volume 107 by spout hole 106b1, when armature 102a is subject to electromagnetic force driving descending, promote plunger 102 by connector 102b descending, once inhaling spout hole 106b1 is blocked by the wall of plunger 102, liquid feed valve 106 is closed, and force feed stroke starts, and the interior fluid pressure of force feed volume 107 raises, and then open liquid valve 115, pressure fluid arrives liquid outlet.

The present embodiment give the course of work of SCR system and the first embodiment basic identical. In this programme course of work, controller 13 judges whether to have occurred that according to the signal of temperature sensor in liquid reserve tank 144 urea solution freezes, freeze if existed, control cooling water that water valve (not shown) makes engine and enter circulating water heater 161 in liquid reserve tank with heating ice-melt.

Figure 3 shows that the SCR system embodiment schematic diagram taking non-compressed air SCR metered injection module provided by the invention as core, the force pipe 32b of diagram with external electric device 41 guides nozzle 3 by two pass joints 43 and connecting thread joint 43a into liquid high-pressure work liquid, electric heater unit 41 is controlled by controller 4, to ensure that external pipe temperature can not cause the DEF in force pipe 32b to freeze, and ice-melt under condition that may be icing. The deicing of the force pipe 32a of solenoid-activated pump inside is completed by circulating cooling liquid heat-exchanger rig.

Described nozzle can be the poppet valve arrangements that relies on opened by pressure, as shown in Figure 7a, can be also a magnetic valve, as shown in Figure 7b. Nozzle is fixed on discharge duct 9 by installation base 9a. Exhaust gas temperature sensor 17, catalyst 18, NOx sensor 19 is all arranged on the exhaust pipe of engine 9. Under the driving of solenoid-activated pump 2, DEF is by pulsed pump-in pressure pipe 32a and 32b from urea tank 1, and then eject the spraying of hollow type working solution from nozzle 3, principal direction and exhaust 16 directions that working solution spraying flows into the exhaust pipe of engine 9 are acute angle, therefore can enter catalyst 18 with good admixture with engine exhaust.

Above-mentioned example is only for the present invention is described, but do not limit the present invention, and all further change schemes based on Spirit Essence of the present invention all belong to the scope of the open and protection of the present invention.

Claims (8)

1. a SCR metering module, is characterized in that: comprise a solenoid-activated pump, a filter, a support, a pallet, liquid enters described solenoid-activated pump through filter, described solenoid-activated pump is fixed on one end of support, and described pallet is fixed on the other end of support.

2. SCR metering module as claimed in claim 1, is characterized in that: described support is a heating deicing device, and deicing device comprises heating tube, and in heating tube, solution is engine coolant, and the gateway of cooling fluid is separately fixed on described pallet.

3. SCR metering module as claimed in claim 2, is characterized in that: comprise a nozzle group valve.

4. SCR metering module as claimed in claim 3, is characterized in that: described nozzle group valve is a check valve of cutting out by spring force.

5. SCR metering module as claimed in claim 3, is characterized in that: described nozzle group valve is a magnetic valve.

6. SCR metering module as claimed in claim 4, is characterized in that: described nozzle group valve is directly fixed on described solenoid-activated pump.

7. the SCR metering module as described in claim 4 or 5, is characterized in that: comprise a high-voltage tube, high-voltage tube connects solenoid-activated pump and nozzle group valve.

8. the SCR metering module as described in claim 1-7, is characterized in that: comprise a gas-liquid mixed chamber, described nozzle group valve is connected with hybrid chamber, and liquid sprays in hybrid chamber by nozzle group valve.