CN108757195B - EGR rate control device based on worm and gear driving variable venturi tube and control method thereof - Google Patents
EGR rate control device based on worm and gear driving variable venturi tube and control method thereof Download PDFInfo
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- CN108757195B CN108757195B CN201810849237.5A CN201810849237A CN108757195B CN 108757195 B CN108757195 B CN 108757195B CN 201810849237 A CN201810849237 A CN 201810849237A CN 108757195 B CN108757195 B CN 108757195B
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 239000007789 gas Substances 0.000 claims abstract description 113
- 239000002912 waste gas Substances 0.000 claims abstract description 66
- 238000010992 reflux Methods 0.000 claims abstract description 46
- 238000002485 combustion reaction Methods 0.000 claims abstract description 28
- 230000002829 reductive effect Effects 0.000 claims abstract description 21
- 230000007246 mechanism Effects 0.000 claims abstract description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 38
- 230000001965 increasing effect Effects 0.000 claims description 27
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 19
- 239000001569 carbon dioxide Substances 0.000 claims description 19
- 230000000694 effects Effects 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 5
- 238000011084 recovery Methods 0.000 claims description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 28
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0047—Controlling exhaust gas recirculation [EGR]
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
- F02M26/19—Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/46—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Exhaust-Gas Circulating Devices (AREA)
Abstract
The invention provides an EGR rate control device based on a worm and gear driving variable venturi tube and a control method thereof, comprising an exhaust gas recirculation system, wherein the air inlet end of a diesel engine is connected with a first air inlet pipe and a second air inlet pipe, the first air inlet pipe is communicated with the first venturi tube, the second air inlet pipe is communicated with the second venturi tube, a waste gas reflux main flow channel is communicated with a first waste gas reflux pipe and a second waste gas reflux pipe, and the first waste gas reflux pipe and the second waste gas reflux pipe are fixedly connected with a worm; the control device further comprises a first stepping motor and a second stepping motor, and worm gears are fixed at the output ends of the first stepping motor and the second stepping motor; the worm and gear mechanism is utilized to change the relative positions of the exhaust gas reflux pipe and the venturi tube which are correspondingly arranged, so that the flow section of the venturi tube is changed to meet the EGR rate control, the combustion temperature in the cylinder is reduced on the premise of not changing the dynamic property of the diesel engine, the NOx in the exhaust gas is reduced, and the emission is reduced.
Description
Technical Field
The invention relates to a control method of an EGR rate of a diesel engine for a vehicle, in particular to a control method of an EGR rate based on a worm gear driving variable venturi tube, which belongs to the technical field of vehicle emission reduction and is an EGR rate control device based on the worm gear driving variable venturi tube.
Background
EGR, i.e., exhaust gas recirculation (Exhaust Gas Recirculation), is a technique (method or technique) in which a part of exhaust gas is separated after combustion in an internal combustion engine and introduced into the intake side to be burned again. The main purpose is to reduce nitrogen oxides (NOx) in exhaust gas and increase fuel consumption rate when sharing partial load. The EGR rate is defined as the ratio of the amount of recirculated exhaust gas to the total amount of intake air drawn into the cylinder, and reasonable control of the EGR rate is extremely important for the purification of nitrogen oxides and overall emissions, and a method is needed to quantify the EGR rate in calibration tests to evaluate the effect of exhaust gas recirculation on engine performance. When the automobile starts, accelerates or loads, the exhaust NOx is rapidly increased due to higher combustion temperature in a diesel engine cylinder, the environment is polluted by exhaust, and meanwhile, the control accuracy of the EGR rate is not high enough under different working conditions, so that the emission cannot be improved, or the emission of the combustion NOx is aggravated. Therefore, the technical measures are adopted to reform the automobile with the existing EGR exhaust gas recirculation pipeline, improve the control of the EGR rate under different working conditions of the diesel engine and reduce the NO X emission, and have important significance.
Disclosure of Invention
The invention improves the problems, namely, the technical problem to be solved by the invention is that when the existing automobile with the exhaust gas recirculation system starts, accelerates or loads, the exhaust gas NOx is rapidly increased due to higher combustion temperature in a diesel engine cylinder, the exhaust gas NOx is discharged to pollute the environment, and meanwhile, the control precision of the EGR rate is not high enough under different working conditions, so that the emission cannot be improved.
The specific embodiments of the invention are: the utility model provides an EGR rate controlling means based on variable venturi of worm gear drive, includes exhaust gas recirculation system, exhaust gas recirculation includes diesel engine, has the waste gas backward flow sprue that is used for realizing waste gas recovery burning and is used for driving the waste gas backward flow subchannel of turbocharged work with diesel engine waste gas output UNICOM, its characterized in that: the diesel engine air inlet end is connected with a first air inlet pipe and a second air inlet pipe, the first air inlet pipe is communicated with a first Venturi tube, the second air inlet pipe is communicated with a second Venturi tube, the waste gas reflux main flow channel is communicated with a first waste gas reflux pipe and a second waste gas reflux pipe, and the first waste gas reflux pipe and the second waste gas reflux pipe are fixedly connected with worms; the control device further comprises a first stepping motor and a second stepping motor, and worm gears are fixed at the output ends of the first stepping motor and the second stepping motor;
the first waste gas return pipe is arranged towards the interior of the first venturi tube, and the worm wheel of the first stepping motor is matched with the worm on the first waste gas return pipe to drive the first waste gas return pipe to move towards or away from the interior of the first venturi tube, so that the flow section of the first venturi tube where the exhaust end of the first waste gas return pipe is positioned is changed;
the second waste gas return pipe is arranged towards the second venturi tube, and the worm wheel of the second stepping motor is matched with the worm on the second waste gas return pipe to drive the second waste gas return pipe to move towards or away from the second venturi tube, so that the flow section of the second venturi tube where the exhaust end of the second waste gas return pipe is positioned is changed;
the first venturi tube is also communicated with the second venturi tube, and an air inlet tube is also communicated with the first venturi tube and the second venturi tube.
Further, the maximum flow area of the first venturi is the same as the minimum flow area of the first venturi.
Further, an intercooler is arranged in the waste gas backflow main runner.
Further, a carbon dioxide concentration sensor is arranged in the first air inlet pipe, the second air inlet pipe, the air inlet pipe and the waste gas backflow main runner.
Further, electronic control valves are arranged in the first waste gas return pipe, the second waste gas return pipe, the first air inlet pipe and the second air inlet pipe.
Further, the first venturi tube where the exhaust end of the first exhaust gas return tube is located is coaxially arranged, and the second exhaust gas return tube is coaxially arranged with the second venturi tube.
The invention also comprises an EGR rate control method based on the variable venturi driven by the worm gear, which comprises the following steps of:
The method comprises the steps of firstly switching on a power supply to preheat an air inlet end carbon dioxide concentration sensor and an air outlet end carbon dioxide concentration sensor, switching on a central control unit ECU, switching on the carbon dioxide concentration sensor and the air outlet end carbon dioxide concentration sensor, switching on an intercooler, switching on a first stepping motor and a second stepping motor, and switching on a power supply after all electronic systems are stable;
In the control process, if the current working condition is just started or a low-speed working condition, the air inflow of the diesel engine is smaller, the combustion process is mild, the combustion temperature in the cylinder is moderate, the amount of NOx in exhaust gas is smaller, the EGR backflow should be closed at the moment, the normal combustion of high-internal gas is ensured, the third electronic control valve and the fourth electronic control valve are closed, and the first electronic control valve and the second electronic control valve are opened, so that sufficient air is ensured to enter the cylinder of the diesel engine for combustion;
If the current working condition is medium load, the combustion of the gas in the cylinder is more intense, the NOx amount in the exhaust gas is relatively high, the third electronic control valve is opened, the fourth electronic control valve is closed, the second electronic control valve is closed, the first electronic control valve is opened, the exhaust gas flows into the first venturi tube with low EGR rate gradient and smaller pipeline flow cross section area from the first exhaust gas reflux tube, when the current working condition EGR rate is lower than the standard, the first stepping motor drives the worm gear mechanism to drive the first exhaust gas reflux tube to move into the first venturi tube, the pressure at the position where the pipeline cross section area in the first venturi tube is reduced, the exhaust gas reflux pressure difference is increased, the exhaust gas reflux amount is increased, and the EGR rate is increased;
When the EGR rate of the current working condition is higher than that of the standard working condition, the first stepping motor drives the worm gear mechanism in a reversing way to drive the first waste gas return pipe to move in the direction deviating from the first venturi tube, so that the pressure at the position where the cross section area of the pipeline of the first venturi tube is increased, the waste gas return pressure difference is reduced, the waste gas return quantity is reduced, and the EGR rate is reduced;
If the working condition is a high-load working condition or a full-load working condition at present, the combustion intensity of the gas in the cylinder reaches the maximum, the NOx amount in the exhaust gas reaches the maximum, the three electronic control valves are closed at the moment, the fourth electronic control valve is opened, the second electronic control valve is opened, the first electronic control valve is closed, the exhaust gas flows into the second venturi tube with high EGR rate gradient and larger pipeline flow cross section from the second exhaust gas return tube, and at the moment, the air inflow of the second venturi tube with large caliber is increased due to the fact that the air inflow of the second venturi tube is increased under the high working condition; if the current EGR rate is lower than the standard, the second stepping motor is driven to rotate because the EGR rate is improved to reach the best emission, so that the second waste gas return pipe moves towards the second venturi tube, the waste gas return pressure difference is increased, and the effect of increasing the EGR rate is achieved; if the current EGR rate is higher than the standard, the ECU drives the second stepping motor to rotate reversely, so that the second waste gas return pipe moves rightwards, waste gas return pressure difference is reduced, and the effect of reducing the EGR rate is achieved.
Compared with the prior art, the invention has the following beneficial effects: a variable venturi tube is additionally arranged on an air inlet pipeline of the diesel engine, and a stepping motor is used for driving a worm gear mechanism so that under different working conditions, an accurate exhaust gas reflux pressure difference is formed to achieve an accurate control EGR rate.
In addition, in the embodiment of the invention, the flow cross sections of the two groups of venturi tubes sequentially form different gradients to meet the pressure difference gradients under different working conditions, so that accurate control is formed.
Drawings
FIG. 1 is a schematic diagram of the hardware architecture of the present invention.
Fig. 2 is a schematic diagram of a circuit connection structure according to the present invention.
Description of the embodiments
The invention will be described in further detail with reference to the drawings and the detailed description.
As shown in fig. 1, an EGR rate control device based on a worm gear driving variable venturi of the present invention is based on an existing vehicle system with an exhaust gas recirculation system, and the existing exhaust gas recirculation system generally includes a diesel engine 10 (internal combustion engine), an exhaust gas recirculation main runner 201 communicating with an exhaust gas output end of the diesel engine for realizing exhaust gas recovery combustion, and an exhaust gas recirculation sub runner 202 for driving a turbo-charging operation, where the exhaust gas recirculation sub runner 202 is mainly for coaxially driving a turbocharger 30 to realize that more air enters the internal combustion engine for air entering.
In this embodiment, the air inlet end of the diesel engine is connected to a first air inlet pipe 110 and a second air inlet pipe 120, the first air inlet pipe 110 is communicated with a first venturi tube 111, the second air inlet pipe 120 is communicated with a second venturi tube 121, the exhaust gas reflux main flow channel 130 is communicated with a first exhaust gas reflux pipe 131 and a second exhaust gas reflux pipe 132, and the first exhaust gas reflux pipe 131 and the second exhaust gas reflux pipe 132 are fixedly connected with a worm 140; the control device further comprises a first stepping motor 410 and a second stepping motor 420, wherein worm gears are fixed at the output ends of the first stepping motor and the second stepping motor;
The first exhaust gas return pipe 131 is arranged towards the inside of the first venturi tube 111, and the worm wheel of the first stepping motor is matched with the worm on the first exhaust gas return pipe to drive the first exhaust gas return pipe to move towards or away from the inside of the first venturi tube, so that the flow section of the first venturi tube where the exhaust end of the first exhaust gas return pipe is positioned is changed;
the second waste gas return pipe is arranged towards the second venturi tube, and the worm wheel of the second stepping motor is matched with the worm on the second waste gas return pipe to drive the second waste gas return pipe to move towards or away from the second venturi tube, so that the flow section of the second venturi tube where the exhaust end of the second waste gas return pipe is positioned is changed;
The present invention uses the first stepping motor 410 and the second stepping motor 420 as the energy source power response speed and speed are fast, and simultaneously uses the worm gear mechanism as the transmission device, which has the advantages of realizing self-locking, so that the first exhaust gas return pipe 131 and the second exhaust gas return pipe 132 can not interfere the axial positions of the first venturi tube 111 and the second venturi tube 121 where the first exhaust gas return pipe 131 and the second exhaust gas return pipe 132 are located because of the air inlet, and generally, the first exhaust gas return pipe 131 and the second exhaust gas return pipe 132 are coaxially arranged corresponding to the first venturi tube 111 and the second venturi tube 121 respectively.
Meanwhile, the first stepping motor 410 and the second stepping motor 420 can generate back electromotive force to inhibit abnormal operation of the worm gear mechanism, meanwhile, as the pressure in a pipeline with gradually reduced cross section area is smaller and larger and smaller, the back electromotive force is generated by changing different flow sections of the first exhaust gas return pipe 131 and the second exhaust gas return pipe 132 in the first venturi tube 111 and the second venturi tube 121 to generate exhaust gas return flow with enough pressure difference, so that the EGR rate under different working conditions is controlled to enable the combustion of the diesel engine 10 to be more reasonable, the in-cylinder combustion temperature is reduced on the premise of not changing the dynamic property of the diesel engine 10, the NO X in the exhaust gas is reduced, and the emission is reduced.
The first venturi tube 111 and the second venturi tube 121 are structured such that the pressure in the conduit having a gradually decreasing cross-sectional area is smaller and larger, so that the flow-back amount of the exhaust gas generating a sufficient pressure difference is generated by changing the different flow-back sections of the first venturi tube 111 and the second venturi tube 121 where the first exhaust gas return pipe 131 and the second exhaust gas return pipe 132 are located.
The first venturi tube and the second venturi tube are also communicated with an air inlet tube 60, an air inlet end carbon dioxide concentration sensor 701 is arranged in the air inlet tube 60 which is connected with the first venturi tube 111 and the second venturi tube 121 in parallel, and a first electronic control valve 801 and a second electronic control valve 802 are respectively arranged at the exhaust ends of the first venturi tube and the second venturi tube.
In order to reduce the waste heat discharged from the diesel engine 10, the exhaust gas recirculation main flow path 201 is generally provided with an intercooler 203, the exhaust gas recirculation main flow path 201 is connected in series with an exhaust end carbon dioxide concentration sensor 702, and the air inlet ends of the first exhaust gas recirculation pipe 131 and the second exhaust gas recirculation pipe 132 are respectively connected with a third electronic control valve 803 and a fourth electronic control valve 804.
In this embodiment, the exhaust gas reflux main flow channel 201 discharges the exhaust gas through the first exhaust gas reflux pipe 131 and the second exhaust gas reflux pipe 132 respectively through the three-way pipeline, the connection parts of the first exhaust gas reflux pipe 131 and the second exhaust gas reflux pipe 132 of the three-way pipe and the first exhaust gas reflux pipe 131 and the second exhaust gas reflux pipe 132 can be sleeved with the bearing, so that one end of the first exhaust gas reflux pipe 131 and one end of the second exhaust gas reflux pipe 132 extending into the three-way pipe can be moved, and the first exhaust gas reflux pipe 131 and the second exhaust gas reflux pipe 132 extend into the air inlet pipe and the air inlet pipe to be in sliding fit towards one end of the first venturi pipe 111 and the second venturi pipe 121.
The carbon dioxide concentration sensor in the present embodiment may use an infrared carbon dioxide sensor.
In the present embodiment, the maximum flow cross-sectional area of the first venturi tube 111 is equal to the minimum flow cross-sectional area of the second venturi tube 121, so that the control of the cross-sections of the venturi tubes constituting different gradients can be realized.
The EGR control device for driving the variable venturi tube by using the worm gear can realize the control of the EGR, and comprises the following control steps:
(1) The method comprises the steps of switching on a power supply, preheating an air inlet end carbon dioxide concentration sensor 701 and an air outlet end carbon dioxide concentration sensor 702, switching on a central control unit ECU, switching on the carbon dioxide concentration sensor 701 and the air outlet end carbon dioxide concentration sensor 702, switching on an intercooler 203, switching on a first stepping motor 410 and a second stepping motor 420, and switching on an ignition switch of a diesel engine 10 after all electronic systems are stable; namely, the corresponding optimal EGR rates (three-dimensional space curves of the corresponding EGR rates under the current torque and the vehicle speed) of the tested diesel engine under different working conditions are compared, so that corresponding electric signals are output to control the forward and reverse rotation of the first stepping motor 410 and the second stepping motor 420, the passage sections of the first venturi tube 111 and the second venturi tube 121 are changed, and the optimal EGR rate conforming to the current working condition is achieved.
Specifically, in the control process, if the current working condition is just started or a low-speed working condition, at this time, the air inflow of the diesel engine 10 is smaller, the combustion process is more moderate, the in-cylinder combustion temperature is more moderate, the amount of NOx in the exhaust gas is less, at this time, the recirculation of EGR should be closed to ensure the normal combustion of high-internal gas, at this time, the third electronic control valve 803 and the fourth electronic control valve 804 are closed, and the first electronic control valve 801 and the second electronic control valve 802 are opened to ensure that a sufficient amount of air enters the cylinder of the diesel engine 10 to be combusted;
If the current medium load working condition is that the combustion of the in-cylinder gas is more severe, the NOx amount in the exhaust gas is relatively high, the third electronic control valve 803 is opened, the fourth electronic control valve 804 is closed, the second electronic control valve 802 is closed, the first electronic control valve 801 is opened, the exhaust gas flows into the first venturi tube 111 with low EGR rate gradient (smaller pipeline flow cross section) from the first exhaust gas reflux tube 131, when the current working condition EGR rate is lower than the standard, the first stepping motor 410 drives the worm gear mechanism to drive the first exhaust gas reflux tube 131 to move into the first venturi tube 111, the pressure at the position where the pipeline cross section area in the first venturi tube 111 is reduced, the exhaust gas reflux pressure difference is increased, the exhaust gas reflux amount is increased, and the EGR rate is increased;
When the EGR rate of the current working condition is higher than that of the standard working condition, the first stepping motor 410 reversely drives the worm gear mechanism to drive the first waste gas return pipe 131 to move in the direction away from the first venturi tube 111, so that the pressure at the position where the cross section area of the pipeline of the first venturi tube 111 is increased, the waste gas return pressure difference is reduced, the waste gas return quantity is reduced, and the EGR rate is reduced;
If the current high load working condition or the full load working condition is adopted, the combustion intensity of the gas in the cylinder reaches the maximum, the NOx amount in the exhaust gas reaches the maximum, the three electronic control valve 803 is closed, the fourth electronic control valve 804 is opened, the second electronic control valve 802 is opened, the first electronic control valve 801 is closed, the exhaust gas flows into the second venturi tube 121 with high EGR rate gradient (larger pipeline flow cross section area) from the second exhaust gas return pipe 131, at the moment, the air inflow of the exhaust gas is required to be increased under the high working condition, so that the flow rate of the large-caliber second venturi tube 121 is also increased, and if the current EGR rate is lower than the standard, the second stepping motor 420 is required to be driven to rotate because the EGR rate is increased to reach the best emission, so that the second exhaust gas return pipe 132 moves towards the second venturi tube 121, the exhaust gas return pressure difference is increased, and the EGR rate increasing effect is achieved; if the current EGR rate is higher than the standard, the ECU drives the second stepping motor 420 to reverse, so that the second exhaust gas return pipe 132 moves rightward, reducing the exhaust gas return pressure difference, and achieving the effect of reducing the EGR rate.
In this embodiment, the load condition of the automobile engine is determined by using the existing vehicle wheel rotation speed sensor module and the accelerator opening sensor module.
The beneficial effects of the invention are as follows:
1. the control method can select the experimental pipeline through the opening and closing selection of the electromagnetic valve, so as to achieve the flow control under different working conditions.
2. The control method uses the stepping motor as a power source, and the worm and gear mechanism is driven, so that the transient accurate control can be achieved, the control efficiency is high, the speed is high, the self-locking is realized, and the stability and the safety are good.
3. The variable venturi tube is adopted to accurately control the EGR rate under different working conditions, and the control precision of the current EGR rate is high through accurate feedback of the carbon dioxide concentration sensor.
Any of the above-described embodiments of the present invention disclosed herein, unless otherwise stated, if they disclose a numerical range, then the disclosed numerical range is the preferred numerical range, as will be appreciated by those of skill in the art: the preferred numerical ranges are merely those of the many possible numerical values where technical effects are more pronounced or representative. Since the numerical values are more and cannot be exhausted, only a part of the numerical values are disclosed to illustrate the technical scheme of the invention, and the numerical values listed above should not limit the protection scope of the invention.
If the terms "first," "second," etc. are used herein to define a part, those skilled in the art will recognize that: the use of "first" and "second" is used merely to facilitate distinguishing between components and not otherwise stated, and does not have a special meaning.
Meanwhile, if the above invention discloses or relates to parts or structural members fixedly connected with each other, the fixed connection may be understood as follows unless otherwise stated: detachably fixed connection (e.g. using bolts or screws) can also be understood as: the non-detachable fixed connection (e.g. riveting, welding), of course, the mutual fixed connection may also be replaced by an integral structure (e.g. integrally formed using a casting process) (except for obviously being unable to use an integral forming process).
In addition, terms used in any of the above-described aspects of the present disclosure to express positional relationship or shape have meanings including a state or shape similar to, similar to or approaching thereto unless otherwise stated.
Any part provided by the invention can be assembled by a plurality of independent components, or can be manufactured by an integral forming process.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical scheme of the present invention and are not limiting; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (4)
1. The utility model provides an EGR rate controlling means based on variable venturi of worm gear drive, includes exhaust gas recirculation system, exhaust gas recirculation system includes diesel engine, has the waste gas backward flow sprue that is used for realizing waste gas recovery burning and is used for driving the waste gas backward flow subchannel of turbo charging work with diesel engine waste gas output UNICOM, its characterized in that: the diesel engine air inlet end is connected with a first air inlet pipe and a second air inlet pipe, the first air inlet pipe is communicated with a first Venturi tube, the second air inlet pipe is communicated with a second Venturi tube, the waste gas reflux main flow channel is communicated with a first waste gas reflux pipe and a second waste gas reflux pipe, and the first waste gas reflux pipe and the second waste gas reflux pipe are fixedly connected with worms; the control device further comprises a first stepping motor and a second stepping motor, and worm gears are fixed at the output ends of the first stepping motor and the second stepping motor;
the first waste gas return pipe is arranged towards the interior of the first venturi tube, and the worm wheel of the first stepping motor is matched with the worm on the first waste gas return pipe to drive the first waste gas return pipe to move towards or away from the interior of the first venturi tube, so that the flow section of the first venturi tube where the exhaust end of the first waste gas return pipe is positioned is changed;
the second waste gas return pipe is arranged towards the second venturi tube, and the worm wheel of the second stepping motor is matched with the worm on the second waste gas return pipe to drive the second waste gas return pipe to move towards or away from the second venturi tube, so that the flow section of the second venturi tube where the exhaust end of the second waste gas return pipe is positioned is changed;
the first venturi tube is also communicated with the second venturi tube, and an air inlet tube is also communicated with the first venturi tube and the second venturi tube;
The maximum flow area of the first venturi tube is the same as the minimum flow sectional area of the first venturi tube;
An intercooler is arranged in the waste gas backflow main runner;
The first air inlet pipe, the second air inlet pipe, the air inlet pipe and the waste gas reflux main flow channel are internally provided with a carbon dioxide concentration sensor.
2. The EGR rate control device based on the worm gear and worm driving variable venturi according to claim 1, wherein the first exhaust gas return pipe, the second exhaust gas return pipe, the first intake pipe, and the second intake pipe are internally provided with electronic control valves.
3. The EGR rate control device based on a worm gear and worm drive variable venturi according to claim 1, wherein the first venturi where the exhaust end of the first exhaust gas return pipe is located is coaxially arranged, and the second exhaust gas return pipe is coaxially arranged with the second venturi.
4. An EGR rate control method based on a worm wheel and worm screw driving variable venturi tube, comprising using an EGR rate control apparatus based on a worm wheel and worm screw driving variable venturi tube according to claim 2, characterized by comprising the steps of:
The method comprises the steps of firstly switching on a power supply to preheat an air inlet end carbon dioxide concentration sensor and an air outlet end carbon dioxide concentration sensor, switching on a central control unit ECU, switching on the carbon dioxide concentration sensor and the air outlet end carbon dioxide concentration sensor, switching on an intercooler, switching on a first stepping motor and a second stepping motor, and switching on a power supply after all electronic systems are stable;
In the control process, if the current working condition is just started or a low-speed working condition, the air inflow of the diesel engine is smaller, the combustion process is mild, the combustion temperature in the cylinder is moderate, the amount of NOx in exhaust gas is smaller, the EGR backflow should be closed at the moment, the normal combustion of high-internal gas is ensured, the third electronic control valve and the fourth electronic control valve are closed, and the first electronic control valve and the second electronic control valve are opened, so that sufficient air is ensured to enter the cylinder of the diesel engine for combustion;
If the current working condition is medium load, the combustion of the gas in the cylinder is more intense, the NOx amount in the exhaust gas is relatively high, the third electronic control valve is opened, the fourth electronic control valve is closed, the second electronic control valve is closed, the first electronic control valve is opened, the exhaust gas flows into the first venturi tube with low EGR rate gradient and smaller pipeline flow cross section area from the first exhaust gas reflux tube, when the current working condition EGR rate is lower than the standard, the first stepping motor drives the worm gear mechanism to drive the first exhaust gas reflux tube to move into the first venturi tube, the pressure at the position where the pipeline cross section area in the first venturi tube is reduced, the exhaust gas reflux pressure difference is increased, the exhaust gas reflux amount is increased, and the EGR rate is increased;
When the EGR rate of the current working condition is higher than that of the standard working condition, the first stepping motor drives the worm gear mechanism in a reversing way to drive the first waste gas return pipe to move in the direction deviating from the first venturi tube, so that the pressure at the position where the cross section area of the pipeline of the first venturi tube is increased, the waste gas return pressure difference is reduced, the waste gas return quantity is reduced, and the EGR rate is reduced;
If the working condition is a high-load working condition or a full-load working condition at present, the combustion intensity of the gas in the cylinder reaches the maximum, the NOx amount in the exhaust gas reaches the maximum, the three electronic control valves are closed at the moment, the fourth electronic control valve is opened, the second electronic control valve is opened, the first electronic control valve is closed, the exhaust gas flows into the second venturi tube with high EGR rate gradient and larger pipeline flow cross section from the second exhaust gas return tube, and at the moment, the air inflow of the second venturi tube with large caliber is increased due to the fact that the air inflow of the second venturi tube is increased under the high working condition; if the current EGR rate is lower than the standard, the second stepping motor is driven to rotate because the EGR rate is improved to reach the best emission, so that the second waste gas return pipe moves towards the second venturi tube, the waste gas return pressure difference is increased, and the effect of increasing the EGR rate is achieved; if the current EGR rate is higher than the standard, the ECU drives the second stepping motor to rotate reversely, so that the second waste gas return pipe moves rightwards, waste gas return pressure difference is reduced, and the effect of reducing the EGR rate is achieved.
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| CN208587233U (en) * | 2018-07-28 | 2019-03-08 | 福州大学 | A kind of EGR rate control device driving variable Venturi tube based on worm and gear |
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