CN108194207B - Variable compression ratio system of internal combustion engine and internal combustion engine - Google Patents
Variable compression ratio system of internal combustion engine and internal combustion engine Download PDFInfo
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- CN108194207B CN108194207B CN201810138602.1A CN201810138602A CN108194207B CN 108194207 B CN108194207 B CN 108194207B CN 201810138602 A CN201810138602 A CN 201810138602A CN 108194207 B CN108194207 B CN 108194207B
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 98
- 238000007906 compression Methods 0.000 title claims abstract description 73
- 230000006835 compression Effects 0.000 title claims abstract description 72
- 239000000446 fuel Substances 0.000 claims description 32
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000295 fuel oil Substances 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000003921 oil Substances 0.000 claims description 4
- 230000009977 dual effect Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 38
- 238000002347 injection Methods 0.000 description 17
- 239000007924 injection Substances 0.000 description 17
- 230000000694 effects Effects 0.000 description 15
- 238000000889 atomisation Methods 0.000 description 11
- 239000002912 waste gas Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 230000009286 beneficial effect Effects 0.000 description 7
- 230000008859 change Effects 0.000 description 7
- 238000011217 control strategy Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010763 heavy fuel oil Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000005414 inactive ingredient Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 230000003313 weakening effect Effects 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
- F02D15/00—Varying compression ratio
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
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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
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
- F02D13/0223—Variable control of the intake valves only
- F02D13/0226—Variable control of the intake valves only changing valve lift or valve lift and timing
-
- 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
- F02D41/30—Controlling fuel injection
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2700/00—Mechanical control of speed or power of a single cylinder piston engine
- F02D2700/03—Controlling by changing the compression ratio
- F02D2700/035—Controlling by changing the compression ratio without modifying the volume of the compression space, e.g. by changing the valve timing
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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
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
Abstract
The invention discloses a variable compression ratio system of an internal combustion engine and the internal combustion engine, and relates to the field of auxiliary systems of internal combustion engines. The system comprises an auxiliary connecting pipe, an auxiliary air passage and a variable auxiliary air valve; the auxiliary air passage is arranged on a cylinder cover connected with the cylinder, the auxiliary air passage is connected with the air inlet branch pipe through an auxiliary connecting pipe, the variable auxiliary valve is assembled in the auxiliary air passage, the maximum lift and the maximum duration of the variable auxiliary valve respectively correspond to 0.3-0.5 times of the maximum lift and the maximum duration of the air inlet valve, the variable auxiliary valve is driven by a variable valve system, and the variable valve system is connected with the ECU; under the high-load stable working condition, the ECU can output an instruction to a variable valve timing control variable auxiliary valve of a variable valve system to open at the initial stage of compression; the mixed gas with a specific proportion can be stored between the auxiliary air passage and the air inlet passage for the next working cycle, so that the effective compression ratio of the internal combustion engine is reduced; the internal combustion engine comprises the internal combustion engine variable compression ratio system, so that the internal combustion engine is prevented from knocking under the high-load stable working condition.
Description
Technical Field
The invention relates to the field of auxiliary systems of internal combustion engines, in particular to a variable compression ratio system of an internal combustion engine and the internal combustion engine.
Background
The compression ratio refers to the compression degree of gas in the cylinder after the piston moves from the bottom dead center to the top dead center; EGR is a process 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. Multiple injection techniques can change the trade-off relationship of traditional engine NOx and PM emissions.
In order to improve fuel economy, prevent knocking, reduce engine exhaust pollution, researchers have proposed variable compression ratio, exhaust gas recirculation technology, multiple injection technology, in which the variable compression ratio has a complicated structural design, internal EGR control accuracy is lacking,the external EGR structure and the controller are complex, and multiple injections have high demands on the system. The compression ratio has an important influence on the performance of the internal combustion engine, the higher the compression ratio is, the higher the thermal efficiency is, the variable compression ratio hopes that the internal combustion engine has higher compression ratio at low load, so that the thermal efficiency and the fuel economy of the internal combustion engine are improved, and the internal combustion engine is easy to start on fire; the internal combustion engine has lower compression ratio under the condition of large load, so that the internal combustion engine is prevented from knocking, and the engine is protected. Whereas EGR can control the combustion rate to achieve low temperature combustion, NO x To a certain extent, the emissions of (2) are well attenuated, wherein the EGR control strategy is: the EGR is turned off or turned on slightly at cold or idle, turned on slightly during light acceleration or low speed cruise control, and applied at medium load. When the engine requires high power and high rotation speed, the engine should be shut down or a small amount of EGR should be used to ensure good dynamic performance of the engine; multiple injections may achieve a more desirable combustion profile.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a variable compression ratio system of an internal combustion engine and the internal combustion engine, which realize that the variable compression ratio technology is adopted under the high-load stable working condition, have low effective compression ratio, prevent the internal combustion engine from knocking and protect the internal combustion engine.
The invention is realized by the following technical scheme:
the invention discloses a variable compression ratio system of an internal combustion engine, which comprises an auxiliary connecting pipe, an auxiliary air passage and a variable auxiliary air valve, wherein the auxiliary connecting pipe is connected with the auxiliary air passage; the auxiliary air passage is arranged on a cylinder cover connected with the cylinder, the auxiliary air passage is connected with the air inlet branch pipe through an auxiliary connecting pipe, the variable auxiliary valve is assembled in the auxiliary air passage, the maximum lift and the maximum duration of the variable auxiliary valve respectively correspond to 0.3-0.5 times of the maximum lift and the maximum duration of the air inlet valve, the variable auxiliary valve is driven by a variable valve system, and the variable valve system is connected with the ECU; under the high-load stable working condition, the ECU is used for outputting a command to the variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve to be opened at the initial stage of compression.
Preferably, the ECU is capable of outputting a command to the variable valve system to control the opening of the variable auxiliary valve in the forced exhaust phase at the variable valve timing of the variable valve system under the steady-state condition of medium and low load.
Preferably, the auxiliary connecting pipe is a reducer with a volume, wherein the necking end of the auxiliary connecting pipe is connected with the air inlet branch pipe, and one end of the auxiliary connecting pipe, which is far away from the necking end, is connected with the auxiliary air passage.
Preferably, the auxiliary connecting pipe is provided with a flow sensor, the flow sensor is used for measuring the flow of gas flowing through the auxiliary air passage, the flow sensor is connected with the ECU, and a flow signal of the flow sensor is an input signal of a closed-loop control system arranged in the ECU.
Preferably, the intake valve includes a first intake valve and a second intake valve respectively fitted in the intake passage, both of which are driven by the camshaft, wherein the ECU can output a command to the variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve to open at the initial stage of intake.
Preferably, an injector is mounted in the auxiliary air passage, the injector being connected to an oil supply system, the oil supply system being connected to the ECU control unit, wherein the injector is a single fuel or dual fuel injector and injects liquid before the initial stage of intake.
Further preferably, the liquid is one or more of fuel oil, water or ethanol.
Preferably, the engine further comprises an exhaust passage arranged on the cylinder cover, a main exhaust valve is arranged in the exhaust passage, the exhaust passage is connected with an exhaust branch pipe, and the exhaust branch pipe is connected with an exhaust main pipe.
The invention also discloses an internal combustion engine, which comprises the variable compression ratio system of the internal combustion engine.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention discloses a variable compression ratio system of an internal combustion engine, which comprises an auxiliary connecting pipe, an auxiliary air passage and a variable auxiliary air valve, wherein the auxiliary connecting pipe is connected with the auxiliary air passage; the auxiliary air passage is communicated with the air inlet pipe through the auxiliary connecting pipe, the maximum lift and the longest duration of the variable auxiliary valve respectively correspond to 0.3-0.5 times of the maximum lift and the longest duration of the air inlet valve, the variable auxiliary valve is driven by the variable valve system, the variable valve system is connected with the ECU, the ECU is beneficial to outputting instructions to the variable valve system under the high-load stable working condition, the variable valve timing of the variable valve system controls the variable auxiliary valve to be opened at the initial stage of compression, and the mixed gas (considering the residual exhaust gas quantity) with a specific proportion can be stored in the auxiliary air passage and the air inlet passage for the next working cycle, so that the effective compression ratio of the internal combustion engine under the high-load stable working condition is reduced, the knocking tendency is reduced, and the internal combustion engine is protected.
Further, under the middle-low load stable working condition, the variable valve timing of the variable valve system can control the variable auxiliary valve to be opened in the forced exhaust stage, so that the method is beneficial to receiving a part of waste gas for the next working cycle in the forced exhaust stage, realizes the change of the EGR rate and keeps the original high compression ratio, and the EGR can control the combustion rate, reduces the oxygen concentration in a cylinder and the highest combustion temperature to realize low-temperature combustion, and achieves the purpose of reducing NO x The exhaust effect keeps the original high compression ratio, and can improve the thermal efficiency and the fuel economy of the internal combustion engine under the low-load stable working condition.
Further, the auxiliary connecting pipe is a reducing pipe with a volume, the necking end of the auxiliary connecting pipe is connected with the air inlet branch pipe, one end of the auxiliary connecting pipe, which is far away from the necking end, is connected with the auxiliary air passage, so that the necking effect is beneficial to being generated, the necking effect can enable the fresh mixed gas stored in the part to generate an acceleration effect when the next working cycle enters the air cylinder, the injection effect can be generated on the back-in air inlet, and the effect of improving the air inlet efficiency is realized.
Further, through the flow sensor that is equipped with on the auxiliary connection pipe, flow sensor's flow signal is the input signal of the closed loop control system that sets up in ECU, is convenient for measure the gas flow who flows through auxiliary air flue (will flow into gas flow in the jar), gives ECU with gas flow signal, gives variable valve system through the ECU instruction, and variable valve timing control variable auxiliary valve lift of variable valve system changes (the variable auxiliary valve is opened and is accepted a part of waste gas and be used for next duty cycle in forced exhaust stage) realizes improving EGR precision and keeps original high compression ratio.
Further, the first inlet valve and the second inlet valve are conveniently driven by the valve driving device; the control strategy, namely the ECU, outputs an instruction to the variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve to be opened in the air inlet stage, so that three air inlet valves (an air inlet valve I, an air inlet valve II and a variable auxiliary valve) are realized, the air flow passing area is enlarged, and the air inlet efficiency is improved.
Further, an oil injector is arranged in the auxiliary air passage, is a single-fuel or dual-fuel oil injector and injects liquid before the initial stage of air intake; still more preferably, the liquid is one or more of fuel, water or ethanol, which is favorable for realizing secondary injection in the EGR process, and the exhaust gas temperature is utilized to improve the atomization quality of the fuel, so that the emission of NOx pollutants of the internal combustion engine is well weakened to a certain extent.
Further, through the exhaust branch pipe, the whole structure is arranged reasonably.
The invention also discloses an internal combustion engine, which comprises the internal combustion engine variable compression ratio system, has reasonable structural design, can realize low effective compression ratio under the high-load stable working condition, prevents the internal combustion engine from knocking and protects the internal combustion engine.
Drawings
FIG. 1 is a schematic top view of the structure of the present invention;
fig. 2 is a schematic diagram of the control strategy of the present invention.
Wherein: 1. a cylinder head; 2. a cylinder; 3. an air inlet branch pipe; 4. an air inlet channel; 5. an inlet valve I; 6. an air inlet valve II; 7. an exhaust branch pipe; 8. an exhaust passage; 9. a main exhaust valve; 10. an auxiliary connection pipe; 11. an auxiliary airway; 12. a variable auxiliary valve; 13. a flow sensor; 14. an ejector.
Detailed Description
The invention is described in further detail below with reference to the attached drawing figures:
referring to fig. 1 and 2, a variable compression ratio and EGR adjusting system of an internal combustion engine includes a cylinder head 1, a cylinder 2, an intake manifold 3, an intake duct 4, an intake valve one 5, an intake valve two 6, an exhaust manifold 7, an exhaust duct 8, a main exhaust valve 9, an auxiliary connection pipe 10, an auxiliary air passage 11, a variable auxiliary valve 12, and a flow sensor 13;
the cylinder cover 1 is arranged on the cylinder 2, the air inlet channel 4, the air outlet channel 8 and the auxiliary air channel 11 are all arranged on the cylinder cover 1, the air inlet branch pipe 3 is connected with the cylinder 2 through the air inlet channel 4 on the cylinder cover 1, the air inlet valve I5 and the air inlet valve II 6 are respectively assembled in the air inlet channel 4, the air inlet valve I5 and the air inlet valve II 6 are driven by a common cam shaft, the air outlet branch pipe 7 is connected with the cylinder 2 through the air outlet channel 8, the air outlet branch pipe 7 is connected with an air outlet manifold, the auxiliary connecting pipe 10 is connected with the cylinder 2 through the auxiliary air channel 11 on the cylinder cover 1, the variable auxiliary valve 12 is assembled in the auxiliary air channel 11, the cam profile of the variable auxiliary valve 12 is based on the cam shaft cam driving the air inlet valve, the cam profile of the variable auxiliary valve 12 is redesigned by the same proportion, and the contact stress is properly optimized and matched with the distribution phase, the cam shaft action angle, the valve size, the valve opening speed and the seating speed determined by the original cam shaft (the cam shaft of the air inlet valve), so that the maximum lift of the variable auxiliary valve 12 is 0.3-0.5 times of the maximum lift of the air inlet valve, the maximum duration of the variable auxiliary valve 12 is 0.3-0.5 times of the maximum duration of the variable valve duration, and the variable valve driving system is connected with the variable valve system; the auxiliary connecting pipe 10 is a reducing pipe with a certain volume, the necking end of the auxiliary connecting pipe 10 is connected to the air inlet branch pipe 3, one end of the auxiliary connecting pipe 10 far away from the necking end is connected with the air inlet branch pipe 3, the compressed mixed gas (considering the residual waste gas amount, but most of fresh air) in the tapered auxiliary connecting pipe 10 has a small speed increase (the necking effect can cause the part of stored mixed gas to generate acceleration effect when the part of stored mixed gas enters the air cylinder 2 in the next working cycle), the injection effect can be caused on the back-in air inlet, and the air inlet efficiency is slightly improved; the auxiliary connecting pipe 10 is provided with a flow sensor 13, the flow sensor 13 is used for measuring the flow of gas flowing through the auxiliary air passage 11, the flow sensor 13 is connected with the ECU, wherein, the flow signal of the flow sensor 13 is an input signal of a closed-loop control system arranged in the ECU, and the auxiliary connecting pipe is used for connecting the auxiliary air passage 11 with the ECU10 is provided with a flow sensor 13 which is convenient for measuring the flow of the gas flowing through the auxiliary air passage 11 (the flow of the gas discharged into the cylinder 2), transmitting a gas flow signal to the ECU, giving an instruction to the variable valve system through the ECU, and controlling the lift change of the variable auxiliary valve 12 through the variable valve lift of the variable valve system (the variable auxiliary valve 12 is opened to accept a part of the exhaust gas for the next working cycle in the forced exhaust stage) so as to achieve the improvement of the EGR precision and maintain the original high compression ratio. Under the high-load stable working condition, the ECU can output an instruction to a variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve 12 to be opened at the initial stage of compression, so that the mixed gas (considering the residual waste gas quantity, but most of fresh air) at the initial stage of compression is stored between the auxiliary air passage 11 and the air inlet passage 4 for the next working cycle (4 strokes of one working cycle, air inlet, compression, acting and exhaust, and the next working cycle is repeated again from the air inlet), thereby reducing the effective compression ratio of the internal combustion engine, preventing the internal combustion engine from knocking and protecting the internal combustion engine; under the middle-low load stable working condition, the variable valve timing of the variable valve system can control the variable auxiliary valve 12 to be opened in the forced exhaust stage, so that the opening of the variable auxiliary valve 12 in the forced exhaust stage is beneficial to receiving a part of waste gas for the next working cycle under the middle-low load stable working condition, the change of the EGR rate is realized, the original high compression ratio is kept, the EGR can control the combustion rate, the oxygen concentration in the cylinder 2 and the highest combustion temperature are reduced to realize low-temperature combustion, and the NO is reduced x The exhaust effect keeps the original high compression ratio, and can improve the thermal efficiency and the fuel economy of the internal combustion engine under the low-load stable working condition.
The internal combustion engine in the system is provided with double inlet valves: an inlet valve I5 and an inlet valve II 6; single exhaust valve: a main exhaust valve 9, with the addition of a variable auxiliary valve 12; the variable auxiliary valve 12 is controlled to be opened in the initial stage of air intake by changing a control strategy, namely, an ECU (electronic control Unit) outputs an instruction to a variable valve system, so that three air inlet valves (an air inlet valve I5, an air inlet valve II 6 and a variable auxiliary valve 12) are realized, the air flow passing area is enlarged, and the air inlet efficiency is improved; the variable valve system can be selected from VTEC mechanism of Honda company; the auxiliary air passage 11 is internally provided with the fuel injector 14, the fuel injector 14 is connected with the fuel supply system, the fuel supply system is connected with the ECU control unit, wherein the fuel injector 13 is a single fuel or dual fuel injector and injects liquid before the initial stage of air intake, thereby being beneficial to realizing secondary injection in the EGR process, enabling fuel to enter the auxiliary air passage 11 and the air inlet passage 4 along with EGR waste gas for good atomization, realizing combustion similar to a separated combustion chamber, improving the atomization quality of the fuel by utilizing the temperature of the waste gas, and ensuring the atomization effect of the fuel; the temperature in the cylinder 2 is reduced, the emission of NOx pollutants of the internal combustion engine is well weakened to a certain extent, and meanwhile, the original compression ratio of the internal combustion engine is maintained, so that the heat efficiency is improved, and the emission performance of the internal combustion engine is improved.
Referring to the control strategy diagram (valve lift curve) of fig. 2, in the high-load stable working condition of the internal combustion engine, the control strategy is as follows: changing the variable valve timing of the variable valve system to move the duration of the variable compression ratio lift curve of the variable auxiliary valve 12 to the initial stage of the compression stroke (the end of the intake stroke), and receiving a part of the mixture (the mixture is stored between the auxiliary air passage 11 and the intake passage 4 for the next duty cycle), thereby reducing the effective compression ratio of the internal combustion engine; when the internal combustion engine is under a low-load stable working condition, the control strategy adopts the following technical scheme: changing the variable valve timing of the variable valve system again to enable the exhaust gas recirculation of the variable auxiliary valve 12 to move to the forced exhaust stage of the exhaust stroke with the lift curve duration, and receiving a part of exhaust gas as the exhaust gas of the EGR through the auxiliary connecting pipe 10 for the next working cycle, so as to realize the change of the EGR rate under the middle-low load stable working condition, and simultaneously maintain the original compression ratio of the internal combustion engine, thereby improving the thermal efficiency and the emission performance of the internal combustion engine; after the main exhaust valve 9 is closed (the temperature and pressure are not high in the later period of exhaust, the fuel is guaranteed not to self-ignite), secondary injection is carried out, and the secondary injection fuel enters the auxiliary air passage 11 and the air inlet passage 4 along with the exhaust gas of the EGR to carry out good atomization, so that the combustion similar to a separated combustion chamber is realized; the duration of the lift of the variable auxiliary valve 12 with abrupt change of the high and low working conditions is moved between the exhaust stroke and the intake stroke, and the transient response is required to be better, and the variable valve timing mechanism is durable and firm.
The compression ratio has an important influence on the performance of the internal combustion engine, the higher the compression ratio is, the higher the thermal efficiency is, the variable compression ratio hopes that the internal combustion engine has higher compression ratio at low load, so that the thermal efficiency and the fuel economy of the internal combustion engine are improved, and the internal combustion engine is easy to start on fire; the internal combustion engine has lower compression ratio under the condition of large load, so that the internal combustion engine is prevented from knocking, and the internal combustion engine is protected. The EGR can improve the air inlet temperature and the compression finishing temperature, meanwhile, the inactive ingredients contained in the EGR are used for controlling the combustion rate to realize low-temperature combustion, secondary injection is realized in the EGR process, the exhaust gas temperature is used for improving the atomization quality of the fuel oil, and the exhaust gas temperature has a good weakening effect on the emission of NOx pollutants of the internal combustion engine to a certain extent. The invention can realize the beneficial effects of the technology and can not interfere with each other.
The working principle of the invention is as follows:
in the invention, under the high-load stable working condition, the variable valve timing control variable auxiliary valve 12 of the variable valve system is opened at the initial stage of a compression stroke, a piston moves upwards in the compression process of an engine, mixed gas (considering the residual waste gas quantity, but most of fresh air) in a cylinder 2 flows into an auxiliary air passage 11 and an auxiliary connecting pipe 10 through the variable auxiliary valve 12, the variable auxiliary valve 12 is closed after the duration of one auxiliary valve (the variable auxiliary valve 12) passes, the mixed gas is stored between the auxiliary air passage and the air inlet passage, the mixed gas is sucked into the cylinder 2 again after the next working cycle starts, the effective compression ratio of the internal combustion engine under the high-load stable working condition is reduced, the effect of variable effective compression ratio is realized under the condition of high-load low compression ratio at the moment, the knocking tendency is reduced, the internal combustion engine is protected, the variable valve timing control variable auxiliary valve 12 of the variable valve system is opened in the forced exhaust stage of the exhaust stroke, during the exhaust process of the engine, the piston moves upward, the exhaust gas in the cylinder 2 flows into the auxiliary air passage 11 and the auxiliary connecting pipe 10 through the variable auxiliary valve 12, the gas is sucked into the cylinder 2 again after the next working cycle starts, EGR is realized and the high compression ratio is maintained, and the flow sensor 13 arranged on the auxiliary connecting pipe monitors the exhaust gas flow through the variable auxiliary valve 11 in real time, the variable valve lift of the variable valve system adjusts the opening lift of the variable auxiliary valve 12 through closed loop control, thereby controlling the exhaust gas flow through the variable auxiliary valve 12, thereby precisely controlling the EGR rate, the auxiliary air passage 11 is provided with the injector 14, the injector 14 can inject the same fuel oil or ethanol of the original engine, or water, or a mixture thereof. In-cylinder direct injection is carried out in the cylinder 2 as usual under the medium-low load stable working condition, if the injector 14 injects fuel after the variable auxiliary valve 12 is opened, the fuel has the atomization diffusion time of two engine strokes (intake stroke and compression stroke), and the hot exhaust gas for EGR passing through the variable auxiliary valve 12 can also improve the atomization quality of the fuel injected by the injector 14, thereby improving the thermal efficiency of the internal combustion engine, reducing the PM emission, and the fuel injection quantity in the auxiliary air passage 11 is 0.3-0.7 of the original engine fuel injection quantity, and the corresponding residual fuel is supplied by the in-cylinder direct injection. In-cylinder direct injection is performed in the cylinder 2 as usual under steady-state conditions of medium and low load, if the injector 14 sprays ethanol or water or a mixture of both after the variable auxiliary valve 12 is opened, this causes the liquids to have an atomization diffusion time of two engine strokes (intake stroke, compression stroke), and the hot exhaust gas for EGR passing through the variable auxiliary valve 12 also increases the atomization quality of the liquids sprayed by the injector 14, which on the one hand decreases the combustion temperature in the cylinder 2 and decreases the emission of nitrogen oxides, and on the other hand, the liquids pyrolyze ions that promote the combustion rate, increasing the combustion thermal efficiency.
The invention can realize that under the high-load stable working condition, the variable valve timing control variable auxiliary valve 12 of the variable valve system is opened at the initial compression stage, the mixed gas (considering the residual waste gas amount, but most of fresh air) of the cylinder 2 at the initial compression stage is stored between the air inlet channel 4 and the auxiliary air channel 11 for the next working cycle, the duration of the variable compression ratio lift curve of the variable auxiliary valve 12 is moved to the final air inlet stroke and the initial compression stroke, and the lift and the duration of the variable auxiliary valve 12 are changed (reduced) by redesigning the cam profile of the cam shaft, and a part of the mixed gas is accepted between the air inlet channel 4 and the auxiliary air channel 11, thereby changing the internal combustionThe effective compression ratio of the engine ensures that the internal combustion engine has lower effective compression ratio, prevents the internal combustion engine from knocking and protects the internal combustion engine; under the stable working condition of medium and low load, the variable valve timing control variable auxiliary valve 12 of the variable valve system realizes the change of the EGR rate and maintains the original high compression ratio, the EGR can control the combustion rate, and the oxygen concentration and the highest combustion temperature in the cylinder are reduced to realize low-temperature combustion, so as to reduce NO x The effect of the discharge; in addition, secondary injection is realized in the EGR realization process, and fuel enters the air inlet channel 4 along with the exhaust gas through the auxiliary structure, so that the fuel atomization effect is ensured; meanwhile, the original compression ratio of the internal combustion engine is maintained, so that the thermal efficiency is improved, and the emission performance of the internal combustion engine is improved.
The variable compression ratio system of the internal combustion engine can be used for an HCCI internal combustion engine system, can be expanded to a multi-cylinder engine, and can use certain alternative fuels besides diesel fuel.
Claims (6)
1. A variable compression ratio system of an internal combustion engine, characterized by comprising an auxiliary connection pipe (10), an auxiliary air passage (11) and a variable auxiliary valve (12);
the auxiliary air passage (11) is arranged on the cylinder cover (1) connected with the cylinder (2), the auxiliary air passage (11) is connected with the air inlet branch pipe (3) through an auxiliary connecting pipe (10), the variable auxiliary valve (12) is assembled in the auxiliary air passage (11), the maximum lift and the maximum duration of the variable auxiliary valve (12) respectively correspond to 0.3-0.5 times of the maximum lift and the maximum duration of the air inlet valve, the variable auxiliary valve (12) is driven by a variable valve system, and the variable valve system is connected with the ECU;
the auxiliary connecting pipe (10) is a reducing pipe with a volume, wherein the necking end of the auxiliary connecting pipe (10) is connected with the air inlet branch pipe (3), and one end of the auxiliary connecting pipe (10) far away from the necking end is connected with the auxiliary air passage (11);
under the high-load stable working condition, the ECU can output an instruction to a variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve (12) to be opened at the initial stage of compression;
under the stable working condition of medium and low load, the ECU can output a command to a variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve (12) to be opened in the forced exhaust stage.
2. The variable compression ratio system of an internal combustion engine according to claim 1, characterized in that a flow sensor (13) is provided on the auxiliary connection pipe (10), the flow sensor (13) being for measuring the flow of gas through the auxiliary air passage (11), the flow sensor (13) being connected to the ECU, wherein the flow signal of the flow sensor (13) is an input signal of a closed loop control system provided in the ECU.
3. The variable compression ratio system of an internal combustion engine according to claim 1, characterized in that the intake valve includes a first intake valve (5) and a second intake valve (6) respectively fitted in the intake passage (4), both the first intake valve (5) and the second intake valve (6) being driven by a camshaft, wherein the ECU can output a command to the variable valve system, and the variable valve timing of the variable valve system controls the variable auxiliary valve (12) to open at an initial stage of intake.
4. A variable compression ratio system of an internal combustion engine according to any one of claims 1-3, characterized in that an injector (14) is fitted in the auxiliary air passage (11), the injector (14) being connected to an oil supply system, which is connected to the ECU control unit, wherein the injector is a single fuel or dual fuel injector and injects liquid before the initial stage of intake.
5. The variable compression ratio system of an internal combustion engine according to claim 4, wherein the liquid is one or more of fuel oil, water, or ethanol.
6. An internal combustion engine comprising the variable compression ratio system of the internal combustion engine according to any one of claims 1 to 5.
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| CN112145307A (en) * | 2020-09-03 | 2020-12-29 | 东风柳州汽车有限公司 | Variable compression ratio internal combustion engine and automobile thereof |
| CN114962018A (en) * | 2022-06-11 | 2022-08-30 | 重庆潍柴发动机有限公司 | Air intake and exhaust control method for four-stroke engine |
Citations (3)
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| CN1664342A (en) * | 2005-03-18 | 2005-09-07 | 上海绍博车辆动力装置科技有限公司 | Engine electric control EGR system for vehicle |
| CN104005860A (en) * | 2013-02-22 | 2014-08-27 | 现代自动车株式会社 | Variable compression engine |
| CN207879473U (en) * | 2018-02-10 | 2018-09-18 | 长安大学 | A kind of internal-combustion engine variable compression ratio system and internal combustion engine |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1664342A (en) * | 2005-03-18 | 2005-09-07 | 上海绍博车辆动力装置科技有限公司 | Engine electric control EGR system for vehicle |
| CN104005860A (en) * | 2013-02-22 | 2014-08-27 | 现代自动车株式会社 | Variable compression engine |
| CN207879473U (en) * | 2018-02-10 | 2018-09-18 | 长安大学 | A kind of internal-combustion engine variable compression ratio system and internal combustion engine |
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