CN202250319U - Diesel engine tail gas aftertreatment system - Google Patents

Abstract

The present application discloses a diesel engine exhaust after-treatment system, which re-sends part of the exhaust gas into the diesel engine through an EGR valve for absorption and conversion, and the remaining nitrogen oxides in the exhaust gas are reduced and converted through an SCR reaction box; the opening of the EGR valve is adjusted to allow the exhaust gas to enter the cylinder of the diesel engine, and at the same time, the injection amount of urea in the SCR reaction box is adjusted to make the conversion rate of the nitrogen oxides in the remaining exhaust gas in the SCR reaction box reach a preset SCR target conversion rate, so that the content of nitrogen oxides in the exhaust gas reaches a preset target content, that is, the exhaust gas discharged by the diesel engine meets the requirements of the national exhaust emission standards.

Description

A diesel engine exhaust aftertreatment system

technical field

The present application relates to the technical field of intake and exhaust, in particular to a diesel engine exhaust aftertreatment system.

Background technique

As the country's requirements for emission standards become more and more stringent, the emission of diesel engines is far from reaching the national emission standards only by its internal purification function. Therefore, the exhaust after-treatment system of the diesel engine plays a key role in meeting the emission standards of the diesel engine.

At present, the diesel engine control systems on the market can only process the exhaust gas, or can only control the intake air, without considering the interaction between the intake air and the exhaust air. In the actual working process of a diesel engine, the intake air volume, fuel injection volume and the working conditions of the diesel engine have a decisive effect on the characteristics of the exhaust gas emitted; at the same time, the content of exhaust gas re-entering the diesel engine will affect the intake air characteristics. , and the injection amount of urea in the exhaust gas treatment has an impact. Therefore, in order to accurately control the emission standards of diesel engines, the interaction between intake air and exhaust air must be considered at the same time.

Utility model content

In order to solve the above technical problems, the embodiment of the present application provides a diesel engine exhaust post-treatment system to realize simultaneous control of the intake air and exhaust gas of the diesel engine. The technical solution is as follows:

A diesel engine exhaust aftertreatment system, including: exhaust gas recirculation EGR valve, mixer, variable cross-section turbo VGT supercharger, selective catalytic reduction SCR reaction box, intake air flow sensor and drive control unit DCU controller, wherein :

The VGT supercharger is used to compress the external air and send it into the cylinder of the diesel engine;

The intake air flow sensor is arranged at the intake manifold of the engine, and is used to collect the current total amount of intake air entering the cylinder of the engine;

The EGR valve is arranged between the exhaust pipe of the diesel engine and the mixer, and is used to re-send part of the exhaust gas into the diesel engine;

The mixer is used to mix part of the exhaust gas entering through the EGR valve and the outside air entering through the VGT supercharger before sending it into the diesel engine;

The SCR reaction box is used to reduce the exhaust gas that has not passed through the EGR valve to reduce the content of nitrogen oxides in the exhaust gas;

The DCU controller obtains the total amount of nitrogen oxides in the current tail gas emitted by the diesel engine under the current working condition according to the obtained current working condition information of the diesel engine and the current intake air amount, and the diesel engine currently The working condition information includes rotational speed information and fuel injection quantity information; and the opening degree of the EGR valve is calculated by using the total amount of nitrogen oxides, the preset up-to-standard content and the preset SCR target conversion rate, and adjusts the EGR valve to The calculated opening degree; and the DCU controller controls the reduction efficiency of the SCR reaction box to reach the preset SCR target conversion rate, and adjusts the VGT supercharger according to the obtained fuel injection quantity information Air intake.

Preferably, the above-mentioned diesel engine exhaust after-treatment system also includes: a nitrogen oxide sensor installed at the exhaust outlet of the SCR reaction box, used to collect the total amount of nitrogen oxides in the exhaust gas discharged from the SCR reaction box. amount, and provided to the DCU controller;

The DCU controller controls the injection amount of urea in the SCR reaction tank according to the received information about the total amount of nitrogen oxides provided by the nitrogen oxides, so as to adjust the reduction efficiency in the SCR reaction tank.

Preferably, the DCU controller includes: an acquisition circuit, an analog-to-digital conversion circuit, a logic processing unit, and a drive circuit, wherein:

The collection circuit is used to collect the operating parameter information of the system, and the operating parameter information includes at least the current intake air volume information;

The analog-to-digital conversion circuit is connected to the acquisition circuit, and is used to convert the analog information collected by the acquisition circuit into digital information;

The logic processing unit is connected to the analog-to-digital conversion circuit, and is used to generate a corresponding adjustment control signal according to the information provided by the analog-to-digital conversion circuit and provide it to the driving circuit;

The drive circuit is used to drive the EGR valve, the VGT supercharger and the SCR reaction box to work after receiving the adjustment control signal.

Preferably, the logic processing unit includes:

An acquisition unit, configured to obtain the content of nitrogen oxides in the current exhaust gas emitted by the diesel engine under the current working condition according to the obtained rotational speed information, fuel injection quantity information and air intake quantity of the diesel engine;

The calculation unit is used to calculate the content of nitrogen oxides that can be converted by the SCR reaction box by using the preset up-to-standard content and the preset SCR target conversion rate, and use the obtained nitrogen oxides in the current exhaust gas The content and the content of the nitrogen oxides that can be converted by the SCR reaction box are calculated to obtain the opening value of the EGR valve;

a first control signal generating unit, configured to generate a control signal for adjusting the EGR valve according to the opening value of the EGR valve;

a second control signal generating unit, configured to generate a control signal for adjusting the VGT supercharger according to the obtained fuel injection quantity information;

The third control signal generating unit controls the urea content of the SCR reaction tank according to the preset SCR target conversion rate, and generates a control signal for adjusting the urea injection amount in the SCR reaction tank.

Preferably, the SCR reaction tank includes: a urea tank, a urea pump, an SCR tank, a urea tank heating module and a urea pipe heating module, wherein,

The urea tank is used to store urea solution;

The input end of the urea pump is connected to the urea tank through a urea pipe, the output end of the urea pump is connected to the SCR tank through a nozzle, and the urea pump is used to provide the urea solution in the urea tank to the The SCR box;

The urea tank heating module is arranged in the urea tank, and is used to heat the urea tank when the temperature in the urea tank is lower than a first preset temperature;

The urea pipe heating module is arranged on the urea pipe, and is used for heating the urea pipe when the temperature of the urea pipe is lower than the second preset temperature.

Preferably, the SCR reaction tank further includes: a urea temperature sensor in the urea tank for collecting the temperature of the urea solution in the urea tank; an ambient temperature sensor for detecting the temperature of the environment where the urea pipe is located;

The logic processing unit includes: a urea temperature detection unit, configured to send a urea tank heating control signal to the driving circuit when detecting that the temperature information provided by the urea temperature sensor is lower than a first preset temperature value; A detection unit, configured to send a urea pipe heating control signal to the drive circuit when the temperature information provided by the ambient temperature sensor is lower than a second preset temperature;

The drive circuit includes a urea tank heating drive circuit, used to drive the urea tank heating module to heat and defrost the urea tank after receiving the urea tank heating control signal; After the urea pipe heating control signal, drive the urea pipe heating module to heat and defrost the urea tank.

Preferably, the SCR reaction tank further includes a liquid level sensor set in the urea tank, and a pressure sensor set in the urea pump;

The logic processing unit further includes: a urea pump pressure detection unit, configured to send a urea pump start control signal to the drive circuit when it detects that the pressure information provided by the pressure sensor is higher than a preset pressure value;

A urea liquid level detection unit, configured to send an alarm signal when detecting that the liquid level information in the urea tank provided by the liquid level sensor is lower than a preset liquid level value;

The drive circuit further includes: a urea pump drive circuit, configured to drive the urea pump after receiving the start control signal of the urea pump, and inject the urea solution in the urea tank into the SCR tank.

Preferably, the above-mentioned diesel engine exhaust post-treatment system further includes: a communication module, configured to communicate with the engine electronic control unit in the diesel engine to obtain the current working condition information of the engine, the working condition information including the engine speed information, fuel injection quantity information and torque information.

Preferably, the above-mentioned diesel engine exhaust after-treatment system also includes:

The monitoring and protection module is used to monitor the operation state of the diesel engine exhaust after-treatment system, and ensure the safe operation of the diesel engine exhaust after-treatment system when the diesel engine exhaust after-treatment system operates abnormally.

It can be seen from the technical solutions provided by the above embodiments of the present application that the diesel engine exhaust post-treatment system re-sends part of the exhaust gas into the diesel engine for absorption conversion through the EGR valve, and the nitrogen oxides in the remaining exhaust gas are reduced and converted through the SCR reaction box; Adjust the opening of the EGR valve so that the exhaust gas enters the diesel engine. At the same time, adjust the injection amount of urea in the SCR reaction tank so that the conversion rate of nitrogen oxides in the remaining exhaust gas in the SCR reaction tank reaches the preset SCR target conversion rate. In this way, the content of nitrogen oxides in the discharged exhaust gas reaches the preset target content, that is, the exhaust gas discharged by the diesel engine meets the requirements of the national exhaust emission standards.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic structural view of a diesel engine exhaust aftertreatment system according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a DCU controller according to an embodiment of the present application.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described The embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

Please refer to Fig. 1, which shows a schematic structural view of a diesel engine exhaust after-treatment system according to an embodiment of the present application, the system comprising: a DCU controller 1, an EGR (Exhaust Gas Recirculation, exhaust gas recirculation) valve 2, a VGT (Variable Gemetry Turbocharger, variable cross-section turbocharging system) supercharger 3, SCR (Selective Catalytic Reduction, selective catalytic reduction) reaction box 4, mixer 5, intake air flow sensor 6, engine 7, of which:

The EGR valve 2 is arranged between the exhaust pipe of the engine 7 and the mixer 5, and is used to re-send part of the exhaust gas discharged by the engine into the engine, and absorb and convert the nitrogen oxides in the part of the exhaust gas.

The VGT supercharger 3 is used to compress the outside air and send it into the inside of the engine 7, and the intake air flow sensor 6 is arranged at the intake manifold of the engine 7 to collect the current flow rate entering the engine cylinder. gas volume.

The SCR reaction box 4 is used for reducing the nitrogen oxides in the exhaust gas discharged from the engine and sent into the engine cylinder without the EGR valve, so as to reduce the content of nitrogen oxides in the exhaust gas.

The mixer 5 is arranged at the intake manifold of the engine, and is used to mix the external air entering the engine cylinder through the VGT supercharger 3 and part of the exhaust gas entering the engine cylinder through the EGR valve 2 and then send it into the engine 7 .

The DCU controller 1 obtains the total amount of nitrogen oxides in the exhaust gas emitted by the diesel engine under the current working conditions, and calculates the EGR valve by using the total amount of nitrogen oxides, the preset up-to-standard content and the preset SCR target conversion rate The opening degree of the EGR valve is adjusted to the calculated opening degree, and the opening degree of the VGT supercharger 3 is adjusted according to the fuel injection quantity information, and the DCU controller controls the The amount of urea injected so that the reduction efficiency of the exhaust gas reaches the preset SCR target conversion rate.

During specific implementation, according to the obtained engine speed information and fuel injection quantity information, the concentration of nitrogen oxides under the current working condition is obtained, and according to the obtained engine fuel injection quantity information and the current intake air volume information, the diesel engine is obtained under the current working condition. The lower exhaust gas volume, and then calculate the total amount of nitrogen oxides in the current exhaust gas according to the concentration of the nitrogen oxides and the exhaust gas volume.

According to the preset up-to-standard content and the preset SCR target conversion rate, the total amount of nitrogen oxides that can be reduced and converted by the SCR reaction box 4 is calculated, and the DCU controller 1 adjusts the injection amount of urea in the SCR reaction box 4, so that the SCR reaction box The reduction efficiency in reaches the preset SCR target conversion rate.

The SCR reaction box uses the catalytic reduction reaction between urea and nitrogen oxides to convert nitrogen oxides into N2, and the nitrogen content in the urea required for conversion is the same as the nitrogen content in the nitrogen oxides that need to be converted.

The preset SCR target conversion rate can be set according to the actual operating conditions of the diesel engine. Since the reduction efficiency in the SCR reaction box is related to temperature, it should be set in conjunction with the temperature of the exhaust gas entering the SCR reaction box. The preset SCR target conversion rate mentioned above can be set according to the working conditions of the diesel engine.

Then according to the total amount of nitrogen oxides in the current exhaust gas and the total amount of nitrogen oxides that can be reduced and converted by the SCR reaction box 4, the content of nitrogen oxides that need to be sent into the engine by the EGR valve 2 is calculated, The query obtains the corresponding EGR rate, and then obtains the corresponding opening degree of the EGR valve 2 .

The corresponding relationship between the content of nitrogen oxides absorbed by the EGR valve and the EGR rate, and the corresponding relationship between the EGR rate and the opening of the EGR valve are obtained through multiple test calibrations.

Adjust the EGR valve to the opening value, and at the same time, adjust the opening of the VGT supercharger, so that the air content entering the cylinder of the diesel engine matches the fuel injection quantity.

Since the content of air entering the cylinder of the diesel engine through the VGT supercharger and the content of exhaust gas entering the cylinder of the diesel engine through the EGR valve play a decisive role in the content of nitrogen oxides produced by the diesel engine, therefore, while adjusting the EGR valve, it must be Adjust the VGT supercharger so that the air content entering the cylinder of the diesel engine matches the fuel injection quantity, thereby reducing the emission of nitrogen oxides from the diesel engine.

Preferably, a nitrogen oxide sensor 10 is arranged at the tail gas discharge pipe of the SCR reaction box 4 to collect the content of nitrogen oxides in the tail gas emitted by the diesel engine, and provide it to the DCU controller 1, when the content of the nitrogen oxides in the tail gas When the emission standard specified by the national standard is exceeded, the injection amount of urea in the EGR valve and the SCR reaction tank is adjusted to reduce the content of nitrogen oxides in the exhaust gas emitted by the diesel engine, so that the exhaust gas emitted by the diesel engine meets the standard.

The following is a specific example to illustrate

Assuming that the preset SCR target conversion rate is 80%, and the preset up-to-standard content is 1.4 g/cycle, the current nitrogen oxide content in the exhaust gas obtained is 10 g/cycle.

Based on the preset standard content and the preset SCR target conversion rate, the total amount of nitrogen oxides that can be reduced and converted by the SCR reaction box 4 is calculated as: 1.4/(1-80%)=7g/cycle. The total amount of urea needed is then determined according to the nitrogen content in the total amount of reduced and converted nitrogen oxides.

The content of nitrogen oxides that need to be fed into the engine through the EGR valve 2 is: 10g/cycle-7g/cycle=3g/cycle, and then query to obtain the opening of the EGR valve corresponding to 3g/cycle.

If you use the existing traditional exhaust gas control system, only the SCR reaction system, if the content of nitrogen oxides in the current exhaust gas is still 10g/cycle, and the preset content is still 1.4g/cycle, you must increase the SCR reaction box 4 To reduce the reduction efficiency, that is, inject a large amount of urea into the SCR reaction box 4, it is easy to cause incomplete reduction reaction, form ammonia gas and leak it.

In the diesel engine exhaust post-treatment system provided in the embodiment of the present application, part of the exhaust gas is re-sent into the diesel engine for absorption conversion through the EGR valve, and the nitrogen oxides in the remaining exhaust gas are reduced and converted through the SCR reaction box; the opening of the EGR valve is adjusted, Let the exhaust gas enter the diesel engine, and at the same time, adjust the injection amount of urea in the SCR reaction tank, so that the conversion rate of nitrogen oxides in the remaining exhaust gas in the SCR reaction tank reaches the preset SCR target conversion rate, so that the nitrogen oxides in the exhaust gas can be oxidized The content of the substance reaches the preset target content.

Preferably, referring to Fig. 1, the diesel engine exhaust aftertreatment system also includes a cooler 8 arranged between the EGR valve 2 and the exhaust pipe of the engine 7, for cooling the exhaust gas that is about to enter the engine; The cooler 9 between the VGT supercharger 3 and the mixer 5 is used to cool the compressed air.

Preferably, referring to FIG. 1 , in the diesel engine air intake and exhaust control system, the SCR reaction box 4 includes: a urea tank 41, a urea pump 42, an SCR tank 43, a urea tank heating module 44, and a urea pipe heating module 45 , urea temperature sensor 47, ambient temperature sensor 48, urea solution pressure sensor 49, liquid level sensor 50, wherein:

The urea tank 41 and the urea pump 42 are connected through a urea pipe 46 , and the urea pump 42 and the nozzle 51 arranged on the SCR tank are used to spray the urea solution in the urea tank into the SCR tank 43 .

A urea tank heating module 44 is arranged on the urea tank 41 to heat the urea tank 41 when the temperature inside the urea tank 41 is lower than a first preset temperature.

When the temperature of the urea tank is low, urea crystallization may occur in the urea tank. Therefore, a urea tank heating module is required to defrost the urea tank. Specifically, the urea tank heating module can be realized by an electric heating wire.

A urea pipe heating module 45 is arranged on the urea pipe 46 to heat the urea pipe 46 when the temperature inside the urea pipe 46 is lower than the second preset temperature.

When the ambient temperature is too low, the urea solution in the urea tube is likely to crystallize, so the urea tube needs to be heated. Specifically, the urea tube heating module can be realized by an electric heating wire.

The urea temperature sensor 47 is arranged in the urea tank 41 to collect temperature information of the urea tank 41 .

The ambient temperature sensor 48 is arranged at the urea pipe 46 to collect temperature information of the environment where the urea pipe is located.

The urea solution pressure sensor 49 is arranged in the urea pump 42 to collect the pressure of the urea solution in the urea pump.

The liquid level sensor 50 is arranged in the urea tank 41 to collect the liquid level information of the urea solution in the urea tank.

The diesel engine air intake and exhaust control system also includes an exhaust gas temperature sensor 11 arranged on the exhaust gas intake pipe of the SCR reaction box for collecting the temperature information of the exhaust gas entering the SCR reaction box. The reaction efficiency is related to the temperature. When the temperature is low, the reaction rate of the catalytic reaction is very low. Therefore, when the temperature of the exhaust gas reaches above 200 degrees Celsius, the SCR reaction box will perform the catalytic reduction reaction.

Please refer to FIG. 2, which shows a schematic structural diagram of a DCU controller, which includes: an acquisition circuit 110, an analog-to-digital conversion circuit 120, a logic processing unit 130, and a drive circuit 140, wherein:

The collection circuit 110 is used to collect the operating parameter information of the system, and the operating parameter information includes at least the current intake air volume information.

The analog-to-digital conversion circuit 120 is connected to the acquisition circuit 110 and is used to convert the analog information collected by the acquisition circuit into digital information and provide it to the logic processing unit 130 .

The logic processing unit 130 is configured to generate a corresponding adjustment control signal according to the information provided by the analog-to-digital conversion circuit 120 and send it to the driving circuit 140 .

The logic processing unit 130 includes: an acquisition unit 131, a calculation unit 132, a first control signal generation unit 133, a second control signal generation unit 134, and a third control signal generation unit 135, wherein:

The obtaining unit 131 is configured to obtain the content of nitrogen oxides in the current exhaust gas emitted by the diesel engine under the current working condition according to the obtained rotational speed information, fuel injection quantity information and air intake quantity of the diesel engine.

The calculation unit 132 is used to calculate the content of nitrogen oxides that can be converted by the SCR reaction box by using the preset standard content and the preset SCR target conversion rate, and use the obtained nitrogen oxide content in the current exhaust gas content and the content of nitrogen oxides that can be converted by the SCR reaction box, and calculate the opening value of the EGR valve.

The first control signal generating unit 133 is configured to generate a control signal for adjusting the EGR valve according to the opening value of the EGR valve;

The second control signal generating unit 134 is configured to generate a control signal for adjusting the VGT supercharger according to the obtained information about the fuel injection quantity;

The third control signal generation unit 135 controls the urea content of the SCR reaction tank according to the preset SCR target conversion rate, and generates a control signal for adjusting the reduction efficiency of the SCR reaction tank.

The urea temperature detection unit 136 sends a urea tank heating control signal to the driving circuit when detecting that the temperature information provided by the urea temperature sensor is lower than a first preset temperature value.

During specific implementation, the temperature information collected by the urea temperature sensor 47 is provided to the urea temperature detection unit 136 after being collected and converted by the collection circuit 110 and the analog-to-digital conversion circuit 120 in the DCU controller. The first preset temperature may be set as the crystallization temperature of the urea solution.

The ambient temperature detection unit 137 is configured to send a urea pipe heating control signal to the drive circuit when the temperature information provided by the ambient temperature sensor is lower than a second preset temperature.

During specific implementation, the ambient temperature information collected by the ambient temperature sensor 48 is provided to the ambient temperature detection unit 137 after being collected and converted by the acquisition circuit 110 and the analog-to-digital conversion circuit 120 in the DCU controller. The second preset temperature can also be set as the crystallization temperature of the urea solution.

In addition, when it is detected that the ambient temperature is lower than minus 11 degrees Celsius, the diesel engine exhaust after-treatment system is turned off.

A urea solution pressure detection unit 138, configured to send a urea pump control signal to the driving circuit when detecting that the pressure information provided by the pressure sensor is higher than a preset pressure value;

The urea liquid level detection unit 139 is configured to send an alarm signal when detecting that the liquid level information in the urea tank provided by the liquid level sensor is lower than a preset liquid level value;

The drive circuit 140 at least includes an EGR valve drive circuit 141 , a VGT supercharger drive circuit 142 , an SCR reaction tank drive circuit 143 , a urea tank heating drive circuit 148 , a urea tube heating drive circuit 149 , and an alarm drive circuit 150 .

The EGR valve drive circuit 141 controls the EGR valve to open to a corresponding opening degree after receiving the adjustment control signal sent by the logic processing unit 130 .

During specific implementation, according to the EGR valve driving circuit

The VGT supercharger drive circuit 142, after receiving the adjustment control signal sent by the logic processing unit 130, drives the VGT supercharger to compress the air, thereby adjusting the intake air volume sent into the engine to meet the requirements of the fuel injection volume. need.

Specifically, according to the obtained current diesel engine speed information, fuel injection quantity information and EGR valve opening information, the opening degree of the VGT is obtained by querying, and the opening value is provided to the VGT supercharger drive circuit to generate The electrical signal controls the VGT supercharger to reach the opening value.

The corresponding relationship between the VGT opening value and the current diesel engine speed information, fuel injection quantity information and EGR valve opening information is obtained through multiple test calibrations.

The SCR reaction box driving circuit 143, after receiving the adjustment control signal sent by the logic processing unit 130, makes the SCR reaction box perform a catalytic reduction reaction to reach a preset SCR target conversion rate.

The drive circuit of the SCR reaction box includes: a urea pump drive circuit 144 and a nozzle drive circuit 145, wherein the urea pump drive circuit 144 includes a gas-assisted urea pump drive circuit 146 and a non-air-assisted urea pump drive circuit 147, wherein the nozzle drive circuit 145 and the non-air-assisted urea pump drive circuit 147 jointly realize urea injection.

The air-assisted urea pump drive circuit 146, when the air-assisted urea pump drive circuit receives the adjustment control signal, generates a PWM pulse drive signal to drive the urea pump to work, because when the urea pump is working, there is always compressed air flowing through it The nozzle is driven by compressed air to realize the injection of urea.

The non-air-assisted urea pump drive circuit 147, when the non-air-assisted urea pump drive circuit receives the adjustment control signal, generates a PWM pulse drive signal to drive the urea pump to work. When the pressure of the urea pump is detected to reach the set value value, the nozzle drive circuit 145 opens the nozzle to realize urea injection.

The urea tank heating driving circuit 148 is used to drive the urea tank heating module 44 to heat the urea tank.

The urea pipe heating driving circuit 149 is used to drive the urea pipe heating module 45 to heat the urea pipe.

The alarm driving circuit 150 generates an alarm signal after receiving the alarm signal sent by the liquid level detection unit 139 . The warning signal can be an audible warning signal and/or a light warning signal.

Preferably, the DCU controller also includes a communication module 160 and a monitoring and protection module 170, wherein the communication module 160 is used for communication between the DCU controller and the engine electronic control unit, so as to obtain the Working condition information, the working condition information includes: engine speed information, fuel injection quantity information and torque information.

The monitoring and protection module 170 is used to monitor the operating state of the diesel exhaust after-treatment system, and ensure the safe operation of the diesel exhaust after-treatment system when the diesel exhaust after-treatment system operates abnormally.

Specifically, the monitoring and protection module 170 includes a fault diagnosis module and an OBD (On-BoardDiagnostics, on-board automatic diagnosis system) diagnosis module, wherein:

When the fault diagnosis module, when the diesel engine exhaust after-treatment system is abnormal, the fault diagnosis module can judge the cause of the failure of the system, and light the fault indicator light to remind the staff that the diesel engine exhaust after-treatment system fails, and according to Perform corresponding operations according to the cause of the failure, for example, limit the output torque of the engine, and limit the output torque of the engine to a very low level when a serious failure occurs in the system.

When the OBD diagnosis module detects that the exhaust gas discharged by the diesel engine exceeds the standard, the OBD indicator light is turned on to remind the staff that the exhaust gas emitted by the diesel engine exceeds the standard, and at the same time, the fault information is stored in the memory, and the fault in the memory can be read during maintenance. The maintenance personnel can accurately determine the nature and location of the fault according to the fault code.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. The system embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without creative effort.

The above description is only the specific implementation of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present application, some improvements and modifications can also be made. It should be regarded as the protection scope of this application.

Claims (9)

1. diesel engine vent gas after-treatment system; It is characterized in that; Comprise: exhaust gas recirculatioon EGR valve, mixer, variable cross section turbine VGT pressurized machine, SCR SCR reaction chamber, intake flow sensor and driving control unit DCU controller, wherein:

Said VGT pressurized machine is used for sending in the cylinder of said diesel engine after the ambient air compression;

Said intake flow sensor, the intake manifold who is arranged on said motor locates, and is used to gather the current air inlet total amount that gets in this cylinder;

Said EGR valve is arranged between the tail gas discharging pipe and mixer of said diesel engine, is used for part tail gas is sent in the said diesel engine again;

Said mixer is used for sending in the said diesel engine with the part tail gas that gets into through said EGR valve and after the ambient air that said VGT pressurized machine gets into mixes;

Said SCR reaction chamber is used for the tail gas that does not pass through the EGR valve is carried out reduction reaction, reduces the content of nitrogen oxide in the tail gas;

Said DCU controller; Current working information and said current air inlet total amount according to the said diesel engine that obtains; Obtain the total amount of nitrogen oxide in the current tail gas that discharges under the said diesel engine current working, said diesel engine current working information comprises rotary speed information and fuel injection quantity information; And utilize the total amount of this nitrogen oxide, preset content up to standard and preset SCR Target Transformation rate, and calculate the aperture of said EGR valve, regulate said EGR valve to the said aperture that calculates; And the reduction efficiency that this DCU controller is controlled said SCR reaction chamber reaches said preset SCR Target Transformation rate, and the air inflow of regulating said VGT pressurized machine according to the said fuel injection quantity information that obtains.

2. diesel engine vent gas after-treatment system according to claim 1; It is characterized in that; Also comprise: the NOx sensor that is installed in the tail gas delivery outlet of said SCR reaction chamber; Be used for gathering the total amount of nitrogen oxide from the tail gas that said SCR reaction chamber is discharged, and offer said DCU controller;

The total amount information of the nitrogen oxide that the said nitrogen oxide that said DCU controller basis receives provides, the emitted dose of urea in the control SCR reaction chamber is to regulate the reduction efficiency in the SCR reaction chamber.

3. diesel engine vent gas after-treatment system according to claim 1 is characterized in that, said DCU controller comprises: Acquisition Circuit, analog to digital conversion circuit, Logical processing unit, drive circuit, wherein:

Said Acquisition Circuit is used to gather the trip information of this system, and this trip information comprises at least, current air inflow information;

Analog-digital conversion circuit as described links to each other with said Acquisition Circuit, is used for converting the analog information that said Acquisition Circuit collects into numerical information;

Said Logical processing unit links to each other with analog-digital conversion circuit as described, is used for the information that provides according to analog-digital conversion circuit as described, produces the corresponding control signal of regulating and also offers said drive circuit;

Said drive circuit, be used to receive said adjusting control signal after, drive said EGR valve, said VGT pressurized machine and the work of said SCR reaction chamber.

4. diesel engine vent gas after-treatment system according to claim 3 is characterized in that, said Logical processing unit comprises:

Acquiring unit is used for rotary speed information, fuel injection quantity information and air inlet amount according to the said diesel engine that obtains, the content of nitrogen oxide in the current tail gas that obtains to discharge under the said diesel engine current working;

Computing unit; Be used to utilize said preset content up to standard and preset SCR Target Transformation rate; Calculate the content of the nitrogen oxide that said SCR reaction chamber can change; And utilize the content of the nitrogen oxide in the said current tail gas that obtains and the content of the nitrogen oxide that said SCR reaction chamber can be changed, calculate the opening value of EGR valve;

The first control signal generation unit is used for the opening value according to said EGR valve, produces the control signal of regulating said EGR valve;

The second control signal generation unit is used for producing the control signal of regulating said VGT pressurized machine according to the said fuel injection quantity information that obtains;

The 3rd control signal generation unit, the urea content according to said preset SCR Target Transformation rate control SCR reaction chamber produces the control signal of regulating the urea-spray amount in the said SCR reaction chamber.

5. diesel engine vent gas after-treatment system according to claim 3 is characterized in that, said SCR reaction chamber comprises: urea box, urea pump and SCR case, and urea box heating module and urea pipe heating module, wherein,

Said urea box is used for the storage uncorrectable cellulose solution;

The input end of said urea pump is connected with said urea box through the urea pipe, and said urea delivery side of pump is connected with said SCR case through nozzle, and this urea pump is used for the urea liquid of said urea box is offered said SCR case;

Said urea box heating module is arranged in the said urea box, is used for when the temperature in the urea box is lower than first preset temperature, said urea box being heated;

Said urea pipe heating module is arranged on the said urea pipe, is used for when the residing temperature of urea pipe is lower than second preset temperature, said urea pipe being heated.

6. diesel engine vent gas after-treatment system according to claim 5 is characterized in that:

Said SCR reaction chamber also comprises: the urea temperature transducer in the said urea box is set, the temperature that is used for gathering said urea box urea liquid; Environment temperature sensor is used to detect the temperature of urea pipe environment of living in;

Said Logical processing unit comprises: the urea temperature detecting unit, be used for when the temperature information that detects said urea temperature transducer and provide is lower than first preset temperature value, and send urea box heating control signal to said drive circuit; The ambient temperature detection unit when temperature information that being used to detect said environment temperature sensor provides is lower than second preset temperature, sends urea pipe heating control signal to said drive circuit;

Said drive circuit comprises urea box heat driven circuit, be used to receive said urea box heating control signal after, drive said urea box heating module and said urea box is heated thaw; Urea pipe heat driven circuit, be used to receive said urea pipe heating control signal after, drive said urea pipe heating module and said urea box is heated thaw.

7. diesel engine vent gas after-treatment system according to claim 5 is characterized in that:

Said SCR reaction chamber also comprises, is arranged on the liquid level sensor in the said urea box, and is arranged on the pressure transducer in the said urea pump;

Said Logical processing unit also comprises: the urea pump pressure sensing cell, be used for when the pressure information that detects said pressure transducer and provide is higher than preset pressure value, and send urea pump start-up control signal to said drive circuit;

The urea level detection unit is used for when the liquid level information that detects the said urea box that said liquid level sensor provides is lower than preset level value, sending alarm signal;

Said drive circuit also comprises: the urea pump drive circuit, be used to receive the said urea pump of said urea pump start-up control signal rear driving, and the spraying urea liquid in the urea box is mapped in the said SCR case.

8. diesel engine vent gas after-treatment system according to claim 4; It is characterized in that; Also comprise communication module; Be used for said diesel engine in engine electric-controlled unit communicate, obtain the current working information of said motor, this work information comprises rotary speed information, fuel injection quantity information and the torque information of motor.

9. diesel engine vent gas after-treatment system according to claim 4 is characterized in that, also comprises:

The monitoring and protection module is used to monitor the running state of this diesel engine vent gas after-treatment system, and when this diesel engine vent gas after-treatment system operation exception, guarantees the safe operation of this diesel engine vent gas after-treatment system.

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