CN110486200A - Improved new-type EGR valve and its control method - Google Patents
Improved new-type EGR valve and its control method Download PDFInfo
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- CN110486200A CN110486200A CN201910855956.2A CN201910855956A CN110486200A CN 110486200 A CN110486200 A CN 110486200A CN 201910855956 A CN201910855956 A CN 201910855956A CN 110486200 A CN110486200 A CN 110486200A
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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]
- F02D41/0077—Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position
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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
- F02M26/47—Sensors specially adapted for EGR systems for determining the characteristics of gases, e.g. composition the characteristics being temperatures, pressures or flow rates
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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
- F02M26/52—Systems for actuating EGR valves
- F02M26/53—Systems for actuating EGR valves using electric actuators, e.g. solenoids
- F02M26/54—Rotary actuators, e.g. step motors
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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
- F02M26/65—Constructional details of EGR valves
- F02M26/66—Lift valves, e.g. poppet valves
- F02M26/67—Pintles; Spindles; Springs; Bearings; Sealings; Connections to actuators
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Analytical Chemistry (AREA)
- Exhaust-Gas Circulating Devices (AREA)
Abstract
The invention discloses a kind of improved new-type EGR valves, shell including being equipped with valve chamber, shell is equipped with the EGR cycle gas entrance being connected to respectively with valve chamber and the outlet of EGR cycle gas, valve body is movably installed in valve chamber, shell end is equipped with the valve drive device with valve body transmission connection, pressure test device is also equipped on shell, the test side of pressure test device is connected to valve chamber；Also disclose the control method of the valve, after EGR valve receives the open command that Engine ECU is assigned, valve drive device pushes valve rod first to generate quantitative displacement according to the start-up parameter demarcated in Engine ECU, then the pressure difference data in pressure test device real-time detection valve chamber, and feed back to Engine ECU, Engine ECU calculates the exhaust gas flow by EGR valve according to the pressure difference data of real-time detection, then real-time control valve drive device works, to change valve location, it realizes and the real-time closed-loop of exhaust gas flow is controlled, keep engine EGR rate control more accurate, keep engine performance more stable.
Description
Technical Field
The invention relates to the technical field of engine control, in particular to an improved novel EGR valve and a specific control method of the EGR valve.
Background
With the increasing requirements of environmental emission regulations, the technology development of an EGR valve (exhaust gas recirculation valve) capable of effectively reducing the emission of an engine is rapid, and the EGR valve has the functions of reintroducing part of exhaust gas discharged by the combustion of the engine into an air inlet manifold, participating in the combustion again, reducing the oxygen content in the intake air, so as to reduce the temperature of a combustion chamber, improve the working efficiency of the engine, improve the combustion environment, reduce the emission of NOX, reduce the detonation and prolong the service life of the engine. Therefore, the EGR valve is an important means for reducing the NOx emission of the engine, and the EGR system is generally applied to advanced engines at home and abroad at present, wherein the structural form and the arrangement position of the EGR valve as an important component of the EGR system have important influence on the whole system.
The EGR valve used at present mainly has two types, namely a butterfly valve and a lift valve, the working principles of the butterfly valve and the lift valve are similar, and the adjustment of the flow area ratio in a pipeline is realized through the position of a valve plate so as to achieve the purpose of adjusting the introduction amount of exhaust. The butterfly valve is limited by an internal structure, and when air flows pass through the butterfly valve, the butterfly valve can impact a valve plate to cause the valve plate to vibrate, so that the butterfly valve cannot accurately control the flow of waste gas; the poppet valve is easy to form interception due to a small flow surface at a single valve, thereby influencing the throughput of exhaust gas, and also being difficult to accurately control the introduction amount of the exhaust gas, thereby reducing the stability and reliability of the operation of the engine.
Disclosure of Invention
The invention aims to solve the technical problem of providing an improved novel EGR valve which can accurately detect the flow of exhaust gas in the valve, further accurately control the introduction amount of the exhaust gas and improve the performance of an engine.
In order to solve the technical problems, the technical scheme of the invention is as follows: the improved novel EGR valve comprises a shell provided with a valve cavity, wherein an EGR circulating waste gas inlet and an EGR circulating waste gas outlet are formed in the shell, the EGR circulating waste gas inlet and the EGR circulating waste gas outlet are respectively communicated with the valve cavity, a valve body used for communicating or separating the EGR circulating waste gas inlet and the EGR circulating waste gas outlet is movably arranged in the valve cavity, a valve body driving device connected with the valve body in a transmission mode is installed at the end of the shell, a pressure difference detection device is further installed on the shell, and a detection end of the pressure difference detection device is communicated to the valve cavity.
As a preferred technical scheme, the valve cavity is provided with a cylindrical valve cavity inlet section communicated with the EGR circulating exhaust gas inlet and a cylindrical valve cavity outlet section communicated with the EGR circulating exhaust gas outlet, the inner diameter of the valve cavity inlet section is smaller than that of the valve cavity outlet section, and a valve cavity diffusion section with the inner diameter gradually increased along the gas advancing direction is communicated between the valve cavity inlet section and the valve cavity outlet section.
Preferably, the differential pressure detecting device comprises a differential pressure sensor fixedly mounted on the housing, the differential pressure sensor is provided with two pressure detecting ends, one of the pressure detecting ends corresponds to the small port of the valve cavity diffusion section or the valve cavity inlet section, and the other pressure detecting end corresponds to the large port of the valve cavity diffusion section.
As the preferred technical scheme, the valve body include the axial suit in the valve rod in the casing, valve rod one end with valve body drive arrangement connects, the cover is equipped with valve plate and direction slider along gas advancing direction in proper order on the valve rod, the valve plate with between the direction slider spacing cover is equipped with auxiliary spring on the valve rod, the valve plate with the sealed sliding fit in little port department of valve chamber diffusion section.
According to the preferable technical scheme, a guide sleeve is sleeved on the outer side of the EGR circulating exhaust gas outlet in the valve cavity in a limiting mode, one end, close to the EGR circulating exhaust gas outlet side, of the guide sleeve is arranged in a closed mode, the guide sliding block is in sliding fit with the guide sleeve, and the valve rod penetrates through the closed end of the guide sleeve and is fixedly connected with the guide sliding block.
As a preferable technical scheme, the valve body driving device comprises a servo motor fixedly installed at the end part of the shell, and the valve rod is connected to a power output end of the servo motor.
As the preferred technical scheme, the casing tip is located servo motor's inboard is installed and is used for the shutoff the sealed blanking cover of cavity, the valve rod runs through sealed blanking cover sets up, the other end demountable installation of casing has the sleeve to keep off the lid.
Preferably, the EGR circulation exhaust gas inlet and the EGR circulation exhaust gas outlet are disposed at both sides of the housing, and the EGR circulation exhaust gas inlet is located between the servo motor and the EGR circulation exhaust gas outlet.
The invention also relates to a control method of the novel EGR valve, wherein the valve body driving device and the differential pressure sensor are respectively connected to an engine ECU, the method comprises the following steps,
step one, bench test
Starting an engine, testing theoretical gas flow q corresponding to the EGR valve under each power running state of the engine in each temperature environment, forming a theoretical parameter table of temperature, power and theoretical gas flow q, and storing the theoretical parameter table into an engine ECU (electronic control Unit);
step two, setting the starting position of the valve plate
In the engine ECU, the starting parameters of the valve body driving device when the engine is started are calibrated in advance, and the valve rod or the valve plate and the starting parameters correspond to quantitative displacement parameters;
when the valve body driving device receives a starting instruction sent by the engine ECU, the valve body driving device is started and operated according to a starting parameter calibrated in the engine ECU, the valve rod or the valve plate is driven to generate quantitative displacement, the valve plate moves towards the valve cavity outlet section, the EGR circulating exhaust gas inlet, the valve cavity inlet section, the valve cavity outlet section and the EGR circulating exhaust gas outlet are communicated, and part of exhaust gas discharged by the engine enters an air inlet manifold of the engine through the EGR valve, so that the exhaust gas is recycled;
step three, pressure difference detection
After the valve rod or the valve plate generates quantitative displacement, one pressure detection end detects the gas pressure at the gas inlet end of the valve cavity diffusion section, the other pressure detection end detects the gas pressure at the gas outlet end of the valve cavity diffusion section, the pressure difference sensor determines a pressure difference delta p according to two detected pressure values and transmits the pressure difference delta p to the engine ECU;
step four, calculating the gas flow
And the engine ECU calculates the actual gas flow of the EGR valve according to the received pressure difference, and the calculation formula is as follows:
wherein,
qm-mass flow rate, actual mass of gas passing through said EGR valve per unit time;
c-the outflow coefficient;
beta is the ratio of the cross section area of the outlet to the cross section area of the inlet of the diffusion section of the valve cavity;
epsilon-coefficient of expansion;
s-outlet cross-sectional area of the EGR valve;
delta p is the pressure difference, and the pressure difference between the inlet and the outlet of the diffusion section of the valve cavity;
ρ -density, gas density at the inlet of the EGR valve;
the expansion coefficient epsilon is calculated by the formula:
wherein,
beta is the ratio of the cross section area of the outlet to the cross section area of the inlet of the diffusion section of the valve cavity;
κ -isentropic index;
τ -pressure ratio, the ratio of the EGR valve inlet pressure to outlet pressure;
step four, contrast adjustment
Calculating the actual gas flow q obtained in the step threemComparing the theoretical gas flow q with the theoretical gas flow q stored in the engine ECU under the corresponding temperature and the corresponding power;
when the actual gas flow rate q ismWhen the gas flow rate is less than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate to move along the gas advancing direction, so that the opening degree of the valve plate is increased until the actual gas flow rate q is reachedmTheoretical gas flow q;
when the actual gas flow rate q ismTheoretical gas flowWhen the quantity q is measured, the engine ECU controls the valve body driving device to keep the current state, namely the current opening degree of the valve plate is kept;
when the actual gas flow rate q ismWhen the gas flow rate is larger than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate to move reversely along the gas advancing direction, so that the opening degree of the valve plate is reduced until the actual gas flow rate q is reachedmTheoretical gas flow q.
As an improvement to the above technical solution, the range of the outflow coefficient c is: 0 < the efflux coefficient c < 2.
Due to the adoption of the technical scheme, the invention has the following technical effects: the valve body is driven by the valve body driving device to generate linear displacement so as to control the size of a gap between the valve body and the valve cavity, thereby controlling the flow of the circulating waste gas, and meanwhile, the pressure difference in the valve cavity is detected by the pressure difference detection device, and the real-time waste gas flow passing through the EGR valve is calculated. The specific process is that after the EGR valve receives an opening instruction issued by an engine ECU, a valve body driving device pushes a valve rod to generate quantitative displacement firstly according to a calibrated starting parameter in the engine ECU, then a pressure difference detection device detects pressure difference data in a valve cavity in real time and feeds the pressure difference data back to the engine ECU, the engine ECU calculates the exhaust gas flow passing through the EGR valve according to the pressure difference data detected in real time, then the valve body driving device is controlled to work in real time, the position of the valve is changed, real-time closed-loop control of the exhaust gas flow is realized, the EGR rate of the engine is controlled more accurately, and the performance of the engine is more stable.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein:
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a top view of an embodiment of the present invention;
FIG. 3 is a side view of an embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view of an embodiment of the present invention;
in the figure: 1-a shell; 2-valve cavity inlet section; 3-an outlet section of the valve cavity; 4-valve cavity diffusion section; 5-EGR circulating exhaust gas inlet; 6-EGR circulating exhaust gas outlet; 7-a valve stem; 8-a valve plate; 9-a guide slide block; 10-an auxiliary spring; 11-a guide sleeve; 12-a servo motor; 13-sealing the plugging cover; 14-sleeve shield cap; 15-differential pressure sensor; 16-pressure detection end.
Detailed Description
The invention is further illustrated below with reference to the figures and examples. In the following detailed description, certain exemplary embodiments of the present invention are described by way of illustration only. Needless to say, a person skilled in the art realizes that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims.
As shown in fig. 1, 2, 3 and 4, the new-type EGR valve of modified, including the casing 1 that is equipped with the valve pocket, specifically, the valve pocket be equipped with cylindrical valve pocket inlet section 2 of EGR circulation waste gas entry 5 intercommunication, with cylindrical valve pocket outlet section 3 of EGR circulation waste gas export 6 intercommunication, the internal diameter of valve pocket inlet section 2 is less than the internal diameter of valve pocket outlet section 3, valve pocket inlet section 2 with it has the gradually big valve pocket diffusion section 4 of internal diameter along the gas direction of advance to communicate between the valve pocket outlet section 3, and it is thus clear that valve pocket overall structure is similar to venturi tube, through reducing structure valve pocket diffusion section 4 sets up, is convenient for detect pressure signal in the valve pocket to realize the accurate control of EGR valve flow.
An EGR circulating exhaust gas inlet 5 and an EGR circulating exhaust gas outlet 6 are formed in the shell 1, and the EGR circulating exhaust gas inlet 5 and the EGR circulating exhaust gas outlet 6 are respectively communicated with the valve cavity. The EGR circulating exhaust gas inlet 5 is connected to an exhaust pipe of an engine, the EGR circulating exhaust gas outlet 6 is connected to an intake manifold of the engine, the EGR valve is connected with an engine pipeline through the EGR circulating exhaust gas inlet 5 and the EGR circulating exhaust gas outlet 6, and part of exhaust gas discharged by the engine is introduced into an intake system of the engine through the EGR valve and recycled so as to improve the temperature environment of a combustion chamber.
The EGR circulation waste gas inlet 5 and the EGR circulation waste gas outlet 6 are movably arranged in the valve cavity, and a valve body driving device in transmission connection with the valve body is arranged at the end of the shell 1. Specifically, the valve body comprises a valve rod 7 axially sleeved in the housing 1, one end of the valve rod 7 is connected with the valve body driving device, and the valve body driving device can drive the valve rod 7 to move back and forth along the axial direction of the housing 1 so as to control the communication and the stop of the valve cavity with the EGR circulating exhaust gas inlet 5 and the EGR circulating exhaust gas outlet 6, thereby realizing the functions of transmitting power and controlling the ventilation area of the valve cavity.
The valve rod 7 is gone up and is equipped with valve plate 8 and direction slider 9 along gas advancing direction in proper order, valve plate 8 with between the direction slider 9 the valve rod 7 upper limit position cover is equipped with auxiliary spring 10, valve plate 8 with the sealed sliding fit of little port department of valve pocket divergent section 4, consequently valve plate 8 is round platform shape structure. When the valve body driving device drives the valve body to open, the valve rod 7 drives the valve plate 8 and the guide slide block 9 to move towards one side far away from the valve body driving device, the auxiliary spring 10 is compressed, a gap is formed between the valve plate 8 and the valve cavity diffusion section 4, waste gas enters the valve cavity outlet section 3 through the valve cavity inlet section 2 and the valve cavity diffusion section 4 and is conveyed into an air inlet manifold of an engine through the EGR circulating waste gas outlet 6, and in the process, the auxiliary spring 10 can play a certain damping role and simultaneously store energy; when the engine stops, under valve body drive arrangement's the effect, valve rod 7 drives valve plate 8 with direction slider 9 orientation is close to valve body drive arrangement's one side removes, auxiliary spring 10 releases, until valve plate 8 reset with the sealed laminating of little port department of valve pocket divergent section 4 turns off the EGR valve, at this in-process, auxiliary spring 10 releases its potential energy of storing, plays the boosting the effect of valve plate 8 return, and guarantees the leakproofness after valve plate 8 closes.
In this embodiment the valve cavity is located the spacing cover in the outside of EGR circulation exhaust gas outlet 6 is equipped with guide sleeve 11, guide sleeve 11 is close to the one end of EGR circulation exhaust gas outlet 6 side seals the setting, guide slider 9 sliding fit in guide sleeve 11, valve rod 7 runs through guide sleeve 11's blind end with guide slider 9 fixed connection. The guide sleeve 11 can guide the valve rod 7 to move when the valve plate 8 is opened, so that the valve plate 8 in motion is not deviated or abraded. In addition, one end of the auxiliary spring 10 abuts against the outer side of the closed end of the guide sleeve 11, and the other end of the auxiliary spring 10 abuts against the end face of the valve plate 8, so that the limiting installation of the auxiliary spring 10 is realized.
The valve body driving device comprises a servo motor 12 fixedly installed at the end part of the shell 1, the valve rod 7 is connected to a power output end of the servo motor 12, the servo motor 12 is a small motor and becomes a power source for valve body action to drive the valve rod 7 to rotate and simultaneously generate linear displacement, the servo motor 12 has high-precision adjusting capacity, and the accurate control of the EGR valve on the exhaust gas flow can be improved. The end of the shell 1 is located the inside of the servo motor 12 is provided with a sealing plug 13 for plugging the cavity, the valve rod 7 runs through the sealing plug 13, the other end of the shell 1 is detachably provided with a sleeve blocking cover 14, the sealing plug 13 is matched with the sleeve blocking cover 14 to realize the sealing of the two ends of the valve cavity, and simultaneously, the sleeve blocking cover 14 is matched with the annular bulge in the valve cavity and is also right for the guide sleeve 11 to play a role of limiting and fixing.
In this embodiment, the housing 1 is further provided with a differential pressure detection device, and a detection end of the differential pressure detection device is communicated to the valve cavity. Specifically, the differential pressure detecting device includes a differential pressure sensor 15 fixedly mounted on the housing 1, the differential pressure sensor 15 is provided with two pressure detecting ends 1616, one of the pressure detecting ends 16 corresponds to the small port of the valve cavity diffusing section 4 or corresponds to the valve cavity inlet section 2, and the other pressure detecting end 16 corresponds to the large port of the valve cavity diffusing section 4. The differential pressure sensor 15 is used for detecting the gas pressure at two ports of the valve cavity diffusion section 4, calculating the pressure difference and transmitting the pressure difference to the engine ECU, and the engine ECU processes the pressure difference to form a control signal of the servo motor 12, so that the left and right displacement adjustment of the valve plate 8 is realized, the purpose of adjusting the gas flow of the EGR valve is achieved, and the engine is operated in the best state. In order to facilitate connection of the EGR valve to each pipeline on the engine, the EGR circulation exhaust gas inlet 5 and the EGR circulation exhaust gas outlet 6 are arranged on two sides of the housing 1, and the EGR circulation exhaust gas inlet 5 is located between the servo motor 12 and the EGR circulation exhaust gas outlet 6.
In the present embodiment, in use, the valve body driving device and the differential pressure sensor 15 are respectively connected to an engine ECU, and the specific control method thereof includes the following steps:
step one, bench test
Starting an engine, testing the theoretical gas flow q corresponding to the EGR valve under each power running state of the engine in each temperature environment, forming a theoretical parameter table of temperature, power and theoretical gas flow q, and storing the theoretical parameter table into the engine ECU.
Step two, setting the starting position of the valve plate
In the engine ECU, the starting parameters of the valve body driving device when the engine is started are calibrated in advance, and the valve rod 7 or the valve plate 8 and the starting parameters correspond to quantitative displacement parameters.
When the valve body driving device receives a starting instruction sent by the engine ECU, the valve body driving device is started and operated according to a starting parameter calibrated in the engine ECU, the valve rod 7 or the valve plate 8 is driven to generate quantitative displacement, the valve plate 8 moves towards the valve cavity outlet section 3, the EGR circulating waste gas inlet 5, the valve cavity inlet section 2, the valve cavity outlet section 3 and the EGR circulating waste gas outlet 6 are communicated, and partial waste gas discharged by the engine enters an air inlet manifold of the engine through the EGR valve, so that the recycling of the waste gas is realized.
Step three, pressure difference detection
After the valve rod 7 or the valve plate 8 generates quantitative displacement, one pressure detection end 16 detects the gas pressure at the gas inlet end of the valve cavity diffusion section 4, the other pressure detection end 16 detects the gas pressure at the gas outlet end of the valve cavity diffusion section 4, the pressure difference sensor 15 determines a pressure difference deltap according to the two detected pressure values, and transmits the pressure difference deltap to the engine ECU.
Step four, calculating the gas flow
And the engine ECU calculates the actual gas flow of the EGR valve according to the received pressure difference, and the calculation formula is as follows:
wherein,
qm-mass flow rate, actual mass of gas passing through said EGR valve per unit time;
c-outflow coefficient, which is a coefficient representing the relationship between the actual flow passing through the device and the theoretical flow, wherein the specific value range of the outflow coefficient c is as follows: the outflow coefficient c is more than 0 and less than 2;
beta-the ratio of the outlet cross-sectional area to the inlet cross-sectional area of the valve cavity diffuser section, wherein the inlet cross-sectional area of the valve cavity diffuser section 4 is a fixed value, the outlet cross-sectional area of the valve cavity diffuser section 4 is a variable value, and the specific value of the area is determined by the specific position of the valve plate 8 on the valve cavity diffuser section 4. The specific determination method comprises the following steps: the area of the valve cavity diffusion section 4 at the large end face of the valve plate 8 is subtracted by the area of the large end face of the valve plate 8, namely the gap sectional area generated between the valve cavity diffusion section 4 and the large end face of the valve plate 8 in the moving process of the valve rod 7, and the value can be automatically measured and calculated under the matching of the engine ECU and the servo motor 12;
epsilon-coefficient of expansion;
s-outlet cross-sectional area of the EGR valve;
delta p is the pressure difference, and the pressure difference between the inlet and the outlet of the diffusion section of the valve cavity;
rho-density, the density of the gas at the inlet of the EGR valve, specific values that can be obtained by means of conventional techniques in the field of engine technology.
The expansion coefficient epsilon is calculated by the formula:
wherein,
beta is the ratio of the outlet cross section area to the inlet cross section area of the valve cavity diffusion section 4;
kappa-isentropic index, which is a constant and is preset in the engine ECU;
τ -pressure ratio, the ratio of the EGR valve inlet pressure to outlet pressure, i.e. the ratio of the EGR loop exhaust gas inlet 5 pressure to the EGR loop exhaust gas outlet 6 pressure.
Step four, contrast adjustment
Calculating the actual gas flow q obtained in the step threemAnd comparing the theoretical gas flow q with the theoretical gas flow q stored in the engine ECU under the corresponding temperature and the corresponding power.
When the actual gas flow rate q ismWhen the gas flow rate is less than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate 8 to move along the gas advancing direction, so that the opening degree of the valve plate 8 is increased until the actual gas flow rate q is reachedmTheoretical gas flow q.
When the actual gas flow rate q ismWhen the theoretical gas flow rate q is reached, the engine ECU controls the valve body drive device to maintain the current state, that is, the current opening degree of the valve plate 8.
When the actual gas flow rate q ismWhen the gas flow rate is larger than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate 8 to move reversely along the gas advancing direction, so that the opening degree of the valve plate 8 is reduced until the actual gas flow rate q is reachedmTheoretical gas flow q.
The system through engine ECU builds, makes EGR valve wholly form the closed-loop control to the exhaust gas flow, makes the exhaust gas flow who enters into the engine more accurate, and real-time adjustment speed is faster to ensure that the performance of engine is more reliable and more stable.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. Improved novel EGR valve, including the casing that is equipped with the valve pocket, its characterized in that: the EGR circulation waste gas inlet and the EGR circulation waste gas outlet are arranged on the shell, the EGR circulation waste gas inlet and the EGR circulation waste gas outlet are respectively communicated with the valve cavity, a valve body used for communicating or separating the EGR circulation waste gas inlet and the EGR circulation waste gas outlet is movably arranged in the valve cavity, a valve body driving device connected with the valve body in a transmission mode is installed at the end of the shell, a pressure difference detection device is further installed on the shell, and the detection end of the pressure difference detection device is communicated to the valve cavity.
2. The improved new EGR valve as defined in claim 1 wherein: the EGR circulation waste gas inlet section is communicated with the EGR circulation waste gas outlet section, the inner diameter of the EGR circulation waste gas outlet section is smaller than that of the EGR circulation waste gas outlet section, and a valve cavity diffusion section with the inner diameter gradually increased along the gas advancing direction is communicated between the EGR circulation waste gas inlet section and the EGR circulation waste gas outlet section.
3. The improved new EGR valve as defined in claim 2 wherein: the pressure difference detection device comprises a pressure difference sensor fixedly installed on the shell, the pressure difference sensor is provided with two pressure detection ends, one of the pressure detection ends corresponds to the small port of the valve cavity diffusion section or corresponds to the valve cavity inlet section, and the other pressure detection end corresponds to the large port of the valve cavity diffusion section.
4. The improved new EGR valve as defined in claim 3 wherein: the valve body comprises a valve rod axially sleeved in the shell, one end of the valve rod is connected with the valve body driving device, a valve plate and a guide sliding block are sequentially sleeved on the valve rod along the gas advancing direction, an auxiliary spring is sleeved on the valve rod in a limiting manner between the valve plate and the guide sliding block, and the valve plate is in sealing sliding fit with a small port of the valve cavity diffusion section.
5. The improved new EGR valve as defined in claim 4 wherein: the EGR circulation waste gas outlet is located in the valve cavity, the outer side of the EGR circulation waste gas outlet is limited and sleeved with a guide sleeve, one end, close to the EGR circulation waste gas outlet side, of the guide sleeve is arranged in a closed mode, the guide sliding block is in sliding fit with the guide sleeve, and the valve rod penetrates through the closed end of the guide sleeve and is fixedly connected with the guide sliding block.
6. The improved new EGR valve as defined in claim 4 wherein: the valve body driving device comprises a servo motor fixedly installed at the end part of the shell, and the valve rod is connected to the power output end of the servo motor.
7. The improved new EGR valve as defined in claim 6 wherein: the casing tip is located servo motor's inboard is installed and is used for the shutoff the sealed blanking cover of cavity, the valve rod runs through sealed blanking cover sets up, the other end demountable installation of casing has the sleeve to keep off the lid.
8. The improved new EGR valve as defined in claim 6 wherein: EGR circulation exhaust gas entry with EGR circulation exhaust gas export is located the both sides of casing, just EGR circulation exhaust gas entry is located servo motor with between the EGR circulation exhaust gas export.
9. The improved control method for a new EGR valve according to claim 4, wherein said valve body driving means and said differential pressure sensor are respectively connected to an engine ECU, characterized in that: comprises the following steps of (a) carrying out,
step one, bench test
Starting an engine, testing theoretical gas flow q corresponding to the EGR valve under each power running state of the engine in each temperature environment, forming a theoretical parameter table of temperature, power and theoretical gas flow q, and storing the theoretical parameter table into an engine ECU (electronic control Unit);
step two, setting the starting position of the valve plate
In the engine ECU, the starting parameters of the valve body driving device when the engine is started are calibrated in advance, and the valve rod or the valve plate and the starting parameters correspond to quantitative displacement parameters;
when the valve body driving device receives a starting instruction sent by the engine ECU, the valve body driving device is started and operated according to a starting parameter calibrated in the engine ECU, the valve rod or the valve plate is driven to generate quantitative displacement, the valve plate moves towards the valve cavity outlet section, the EGR circulating exhaust gas inlet, the valve cavity inlet section, the valve cavity outlet section and the EGR circulating exhaust gas outlet are communicated, and part of exhaust gas discharged by the engine enters an air inlet manifold of the engine through the EGR valve, so that the exhaust gas is recycled;
step three, pressure difference detection
After the valve rod or the valve plate generates quantitative displacement, one pressure detection end detects the gas pressure at the gas inlet end of the valve cavity diffusion section, the other pressure detection end detects the gas pressure at the gas outlet end of the valve cavity diffusion section, the pressure difference sensor determines a pressure difference delta p according to two detected pressure values and transmits the pressure difference delta p to the engine ECU;
step four, calculating the gas flow
And the engine ECU calculates the actual gas flow of the EGR valve according to the received pressure difference, and the calculation formula is as follows:
wherein,
qmmass flow rate, sheetActual mass of gas passing through the EGR valve in bit time;
c-the outflow coefficient;
beta is the ratio of the cross section area of the outlet to the cross section area of the inlet of the diffusion section of the valve cavity;
epsilon-coefficient of expansion;
s-outlet cross-sectional area of the EGR valve;
delta p is the pressure difference, and the pressure difference between the inlet and the outlet of the diffusion section of the valve cavity;
ρ -density, gas density at the inlet of the EGR valve;
the expansion coefficient epsilon is calculated by the formula:
wherein,
beta is the ratio of the cross section area of the outlet to the cross section area of the inlet of the diffusion section of the valve cavity;
κ -isentropic index;
τ -pressure ratio, the ratio of the EGR valve inlet pressure to outlet pressure;
step four, contrast adjustment
Calculating the actual gas flow q obtained in the step threemComparing the theoretical gas flow q with the theoretical gas flow q stored in the engine ECU under the corresponding temperature and the corresponding power;
when the actual gas flow rate q ismWhen the gas flow rate is less than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate to move along the gas advancing direction, so that the opening degree of the valve plate is increased until the actual gas flow rate q is reachedmTheoretical gas flow q;
when the actual gas flow rate q ismWhen the theoretical gas flow q is reached, the engine ECU controls the valve body driving device to keep the current state, namely the current opening degree of the valve plate;
when the actual gas flow rate q ismWhen the gas flow rate is larger than the theoretical gas flow rate q, the engine ECU controls the valve body driving device to drive the valve plate to move reversely along the gas advancing direction, so that the opening degree of the valve plate is reduced until the actual gas flow rate q is reachedmTheoretical gas flow q.
10. The method for controlling an improved new EGR valve as set forth in claim 9, wherein: the value range of the outflow coefficient c is as follows: 0 < the efflux coefficient c < 2.
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