INTEGRATED SCR REDUCING AGENT STORAGE DEVICE
The invention discloses an integrated SCR reducing agent storage device. The integrated SCR includes a liquid storage box and a metering injection unit, the liquid storage box is used for storing reducing agent, the metering injection unit is integrated with the liquid storage box, the metering injection unit at least includes a pump body, and a membrane pump, a filter, a metering valve and a control unit all arranged on the pump body, and the metering injection unit is integrally arranged on the liquid storage box to inject the reducing agent under the control of the control unit, thus avoiding the use of pipes for suction, reflux and heating and of relevant pipe joints and decreasing the leakage risk of the reducing agent, meanwhile, the metering injection device is compact in structure, good is pressure stabilizing effect and accurate in control for injection of the reducing agent.
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The invention relates to a reducing agent storage and injection control device in a diesel exhaust treatment purification system, in particular to a reducing agent storage device in an integrated SCR (Selective Catalyst Reaction) system.
BACKGROUNDWith the increasing social requirement on environmental protection, our country has put more and more efforts into environmental protection and appropriate polices regarding vehicle emission have been put forward by relevant national departments, and especially, introduction of ‘National Standard IV’ results in more stringent control for vehicle emission, which means that the standard can be met only after 30%-50% of pollutant is reduced on the basis of ‘National Standard IV’, and ‘National Standard IV’ will come into force nationwide on 2012 in accordance with normal standard implementation procedure.
Now, it is acknowledged that the technology of selective catalytic reduction (SCR) has dominated among vehicle emission post-treatment technologies, that is, a reducing agent (referred to as ‘Ad-Blue’ in this field) is quantitatively injected into an exhaust pipe by atomization and the primary harmful gas NOX in exhaust gas is converted through an SCR catalyst into nitrogen and water which are then discharged out, thus the purpose of exhaust purification is achieved, and this is also the commonest technical route for reaching the ‘National Standard IV’.
An SCR system generally includes a urea box, a metering injection pump, a nozzle and the like, however in the prior art, the modular units above are all independent of each other, just as disclosed in the China patent CN101240729A entitled Diesel Vehicle Emission and Urea Box Reactor, and connection among the urea box, the metering injection pump and other devices is realized by means of pipes and pipe joints. This typically will lead to the shortcomings below:
1. Mutual independence of the units and a large number of pipes (including pipes for suction, reflux and the like) result in great difficulty in arrangement, and pipe junctions are liable to be polluted, which brings difficult protection and also the hidden risk of leakage.
2. There is a high possibility of icing the reducing agent in various pipes under an environment with a relatively low temperature, and ice melting is difficult.
3. The system cost is high, and a large arrangement space is required by the units.
4. During practical mounting on vehicle, the matching effect in assembly is poor because the units are independent of each other and provided by different manufacturers, and pipe connection is carried out after all the units are properly mounted, which causes great difficulty in mounting and high possibility of pollution.
SUMMARY OF THE INVENTIONThe objective of the invention is to overcome the shortcomings in the prior art and provides an integrated SCR reducing agent storage device with high degree of integration, compact structure, good easiness in ice melting and great convenience for maintenance.
To fulfill the objective above, the technical proposal below is presented in the invention: the integrated SCR reducing agent storage device includes a liquid storage box and a metering injection unit, the liquid storage box is used for storing reducing agent, and the metering injection unit is integrated with the liquid storage box.
Preferably, the integrated SCR reducing agent storage device further includes a transition plate, and the metering injection unit is integrated with the liquid storage box via the transition plate.
The integrated SCR reducing agent storage device includes a water heating unit for heating the liquid storage box and the metering injection unit.
The metering injection unit further includes a cover body, a pump body, a membrane pump, a filter and a metering valve, the cover body is buckled on the pump body, a closed space is formed between the cover body and the pump body, and the membrane pump is at least arranged in the closed space.
The integrated SCR reducing agent storage device further includes a transition plate, and the metering injection unit is integrated with the liquid storage box via the transition plate.
The metering injection unit includes a water heating unit, the water heating unit is downwards extended into the liquid storage box from the transition plate and is used for heating the liquid storage box and the metering injection unit.
The water heating unit includes a water inlet pipe, a water outlet pipe, and a water circulation pipe arranged in the metering injection unit, the pipes are connected with each other, and the water inlet pipe and the water outlet pipe are extended into the liquid storage box.
The water heating unit further includes a water inlet joint and a water outlet joint, the water inlet joint and the water outlet joint are arranged on the pump body, and the water inlet joint, the water inlet pipe, the water outlet pipe, the water circulation pipe and the water outlet joint are communicated with each other.
The integrated SCR reducing agent storage device further includes a sensing component arranged in the liquid storage box, and the sensing components is composed of a liquid level sensor and a first temperature sensor.
The heat insulating sleeve is further arranged on the water inlet pipe.
A multi-section liquid flow pipe for circulation of the reducing agent is formed in the pump body.
The metering injection unit further includes a first pressure sensor and a second pressure sensor arranged at the two ends of the metering valve.
The metering injection unit further includes a control unit, and the control unit is electrically connected with the membrane pump and the metering valve to control injection of the reducing agent.
The integrated SCR reducing agent storage device further includes a second temperature sensor arranged in the pump body.
Compared with the prior art, the integrated SCR reducing agent storage device of the invention has the advantages:
1) superior design scheme and high degree of integration;
2) the use of pipes for suction, reflux and heating and of relevant pipe joints is avoided and the leakage risk of the reducing agent is decreased;
3) heated engine cooling water passes by the metering pump and the liquid storage box directly, which avoids using a water heating device or an electric heating device for heating the metering pump independently;
4) a heat insulating sleeve is wrapped on the upper portion of the water inlet pipe to heat the reducing agent at the bottom at first, which brings good heating effect and helps timely ice melting and suction of the reducing agent;
5) the metering pump and the urea box are structurally integrated, so the occupied space is small and the cost is relatively low, meanwhile, convenient disassembly and mounting and excellent matching effect are achieved due to the modularized arrangement.
6) a filtration cavity and a pressure stabilizing cavity are integrally designed, thus bringing compact structure and good pressure stabilizing effect and contributing to control for the metering valve;
7) a cyclone mixing cavity is employed to achieve the purposes of small pressure loss, good stirring and atomization effects and low possibility of crystallization blockage.
The technical proposal in the preferred embodiment of the invention will be described below in a clear and complete way with reference to the drawings of the invention.
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In the metering injection unit as shown in
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In this embodiment, an injection hole portion at one end of the metering valve 5 stretches into the mixing cavity 6, an air throttle orifice 61 is arranged on the inner wall of the mixing cavity 6, the other end of the air throttle orifice is communicated with an air source, the air throttle orifice 61 is tangent to the inner wall of the mixing cavity 6 and provides an inlet of compressed air source for air-liquid mixing in the mixing cavity 6, and in the process of injecting the reducing agent by the metering valve 5, a high-speed airflow tangentially enters the mixing cavity 6 via the air throttle orifice 61.
Based on the principle of cyclone separator, when a tangent airflow enters the mixing cavity 6, an outward rotation airflow and an inward rotation airflow are formed in the cavity, the outward rotation airflow is rotated in a manner of cavity wall adherence and is blown in a direction away from the liquid outlet joint, i.e. in a direction towards the metering valve 5, the inward rotation airflow, which moves in a direction opposite to the outward rotation airflow, is formed when the tangent airflow reaches the top of the mixing cavity 6, at the same time, when the airflows are converged at the injection hole of the metering valve 5, the injected reducing agent is fully stirred by the inward rotation airflow under the action of the injection pressure from the metering valve and is then blown downwards and injected out through the liquid outlet joint, urea aqueous solution can be formed into homogeneous suspension due to the stirring effect in the mixing cavity 6, thus reducing the crystallization risk and contributing to forming homogeneous spray at an atomization nozzle at the downstream of the liquid outlet joint so as to improve the effect of selective catalytic reaction.
One end of the mixing cavity 6, which is far away from the metering valve 5, is communicated with the liquid outlet joint 18 on the sidewall of the pump body via the liquid flow pipe 16 in the pump body, and the liquid outlet joint 18 is connected with an exhaust pipe 77 via an injection pipe and a nozzle 76. Preferably, the position of the liquid outlet joint 18 is lower than that of the metering valve 5, an acute angle is formed between the axis of the mixing cavity 6 and the horizontal direction, that is to say, the mixing cavity 6 is arranged obliquely, preferably a 20-degree angle formed between the mixing cavity 6 and the horizontal direction, in this way, after the injection operation comes to an end, the reducing agent is not refluxed to block off the injection hole of the metering valve, instead, it flows downwards (i.e. the direction of the liquid outlet joint) under the action of gravity even if there is reducing agent remaining in the mixing cavity.
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The water heating unit 8 includes a water inlet joint 81, a water inlet pipe 82, a water outlet pipe 83, a water outlet joint 84 and a multi-section water circulation pipe 85, the water circulation pipe 85 includes a first flow passage 851 and a second flow passage 852 both arranged inside the pump body 12, and a third flow passage 853 formed between the lower surface 121 of the pump body 12 and the transition plate 3, and the first flow passage 851 and the second flow passage 852 are respectively connected with the water inlet joint 81 and the water outlet joint 84 arranged on the sidewall of the pump body.
The water inlet pipe 82 and the water outlet pipe 83 are formed in a manner of extending downwards from the lower side of the transition plate 3, the upper ends of the both are communicated with the third flow passage 853 of the water circulation pipe 85 respectively and the bottoms of the both are communicated with each other through a heat exchanger 87, and the water inlet joint 81, the water inlet pipe 82, the water outlet pipe 83 and the water outlet joint 84 are communicated with each other in sequence through the water circulation pipe 85 in order to impart a good heating on the reducing agent in the pump body 12 and the liquid storage box 2.
Preferably, the heat exchanger 87, which is formed on the bottom of the liquid storage box at the junction of the water inlet pipe 82 and the water outlet pipe 83, is a spiral structure for increasing the heating area, a heat insulating sleeve 88 is wrapped on the outer surface of the upper portion of the water inlet pipe 82, and the heat insulating sleeve 88 is arranged to avoid, when the heated cooling water flows by the upper portion of the water inlet pipe, loss of excessive heat, which in turn melts the ice at the bottom of the urea box at first in order to contribute to suction.
More preferably, the metering injection device of the invention further includes a ventilation pipe 79, and the ventilation pipe 79, the suction pipe 31 and the water inlet pipe 82 are all wrapped in the heat insulating sleeve 88.
As shown in
The control unit 17 is electrically connected with the membrane pump 13, the metering valve 5, and the first pressure sensor 14 and the second pressure sensor 15 mounted on the two ends of the metering valve 5 and the mixing cavity 6, wherein the first pressure sensor 14 is arranged at the upstream end of the metering valve 5, the second pressure sensor 15 is arranged at the downstream end of the metering valve 5, and according to a specified injection amount received by the control unit and a pressure difference between the two ends of the metering valve, the first pressure sensor 14 and the second pressure sensor 15 calculate the duty ratio of the starting pulse of the metering valve 5 to achieve the purpose of accurate metering.
The metering injection device in this embodiment further includes a compressed air unit 9, the compressed air unit 9 includes an air source 91, a second electromagnetic valve 92 and a reducing valve 93 which are serially connected in sequence, the second electromagnetic valve 92 is in circuit connection with the control unit 17, an air filter is further arranged at the downstream of the air source 91, the compressed air unit can not only provide air pressure for opening or closing of the membrane valve 71, but also provide compressed air for atomization of the reducing agent in the mixing cavity 6.
As shown in
When the control unit receives an engine ignition signal, the control unit 17 controls a motor in the membrane pump 13 to begin an emptying action at a certain fixed rotating speed, so that the reducing agent in the liquid flow pipe 16 is returned to the liquid storage box 2 through a reflux pipe, and about 30 seconds later, the control unit 17 controls the second electromagnetic valve 72 to open the air source and close an emptying loop, the membrane pump 13 continues working at this moment, the reducing agent is conveyed to the upstream of the metering valve 5 by the pump body after passing through the liquid flow pipe 16 and the filter 4, the pressure of the reducing agent increases ceaselessly, the motor of the membrane pump stops operating when a pressure value P1 of the first pressure sensor 14 at the upstream of the metering valve 5 reaches a set value, the control unit receives an injection request and controls the metering valve 5 to begin metering injection, and the second pressure sensor 15 is used for acquiring a pressure value P2 at the downstream of the metering valve to calculate the pressure difference, and for regulating the opening pulse width of the metering valve.
The pressure value (P1) of the first pressure sensor 14 is relatively small after the control unit 17 controls the compressed air unit to close a liquid return membrane and before injection, at this moment, the control unit 17 controls the motor in the membrane pump to operate at a preset rotating speed, and about 5 seconds later, the pressure value P1 in the filtration cavity reaches an injection pressure value; P1 will decrease after injection begins, specifically depending on the injection amount, and in order to keep P1 stable, the motor begins working and the reducing agent is supplemented into the filtration cavity to keep the P1 value stable, furthermore, during this procedure, the rotating speed of the motor is subjected to closed-loop control in accordance with the injection amount and the current P1 value, so as to achieve the purpose of accurate metering.
When heating is needed at a relatively low temperature, the control unit 17 controls the second electromagnetic valve 92 to open the water heating unit after receiving a low temperature signal from the temperature sensor in inductive sensors, the heated engine cooling water flows by the water inlet joint 81, the water inlet pipe 82, the water outlet pipe 83 and the water outlet joint 84 in sequence, which realizes heating not only for the metering injection unit, but also for the reducing agent in the liquid storage box 2.
The technical contents and features of the invention have been disclosed above, however, a variety of substitutions and modifications not departing from the spirit of the invention may still be made by those skilled familiar with the art based upon the instruction and disclosure of the invention, thus, the scope of the invention shall not be limited to the contents disclosed in the embodiments, instead, it shall include a variety of substitutions and modifications that do not depart from the invention and is covered by the claims of this patent application.
Claims
1. An integrated SCR reducing agent storage device, characterized in that: the integrated SCR reducing agent storage device includes a liquid storage box and a metering injection unit, the liquid storage box is used for storing reducing agent, and the metering injection unit is integrated with the liquid storage box.
2. The integrated SCR reducing agent storage device according to claim 1, characterized in that: the integrated SCR reducing agent storage device further includes a transition plate, and the metering injection unit is integrated with the liquid storage box via the transition plate.
3. The integrated SCR reducing agent storage device according to claim 1, characterized in that: the integrated SCR reducing agent storage device includes a water heating unit for heating the liquid storage box and the metering injection unit.
4. The integrated SCR reducing agent storage device according to claim 1, characterized in that: the metering injection unit further includes a cover body, a pump body, a membrane pump, a filter and a metering valve, the cover body is buckled on the pump body, a closed space is formed between the cover body and the pump body, and the membrane pump is at least arranged in the closed space.
5. The integrated SCR reducing agent storage device according to claim 4, characterized in that: the integrated SCR reducing agent storage device further includes a transition plate, and the metering injection unit is integrated with the liquid storage box via the transition plate.
6. The integrated SCR reducing agent storage device according to claim 5, characterized in that: the metering injection unit includes a water heating unit, the water heating unit is downwards extended into the liquid storage box from the transition plate and is used for heating the liquid storage box and the metering injection unit.
7. The integrated SCR reducing agent storage device according to claim 6, characterized in that: the water heating unit includes a water inlet pipe, a water outlet pipe, and a water circulation pipe arranged in the metering injection unit, the pipes are connected with each other, and the water inlet pipe and the water outlet pipe are extended into the liquid storage box.
8. The integrated SCR reducing agent storage device according to claim 7, characterized in that: the water heating unit further includes a water inlet joint and a water outlet joint, the water inlet joint and the water outlet joint are arranged on the pump body, and the water inlet joint, the water inlet pipe, the water outlet pipe, the water circulation pipe and the water outlet joint are communicated with each other.
9. The integrated SCR reducing agent storage device according to claim 7, characterized in that: the integrated SCR reducing agent storage device further includes a sensing component arranged in the liquid storage box, and the sensing components is composed of a liquid level sensor and a first temperature sensor.
10. The integrated SCR reducing agent storage device according to claim 7, characterized in that: a heat insulating sleeve is further arranged on the water inlet pipe.
11. The integrated SCR reducing agent storage device according to claim 4, characterized in that: a multi-section liquid flow pipe for circulation of the reducing agent is formed in the pump body.
12. The integrated SCR reducing agent storage device according to claim 4, characterized in that: the metering injection unit further includes a first pressure sensor and a second pressure sensor arranged at the two ends of the metering valve.
13. The integrated SCR reducing agent storage device according to claim 4, characterized in that: the metering injection unit further includes a control unit, and the control unit is electrically connected with the membrane pump and the metering valve to control injection of the reducing agent.
14. The integrated SCR reducing agent storage device according to claim 4, characterized in that: the integrated SCR reducing agent storage device further includes a second temperature sensor arranged in the pump body.
Type: Application
Filed: May 16, 2011
Publication Date: Mar 6, 2014
Applicant: SUZHOU POWERGREEN EMISSION SOLUTION SYSTEM CO., LTD. (Wujiang Jiangsu)
Inventor: Qingjun Hao (Wujiang Jiangsu)
Application Number: 13/823,540
International Classification: F01N 3/035 (20060101);