CN107701305B - Free piston engine with variable stroke - Google Patents
Free piston engine with variable stroke Download PDFInfo
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- CN107701305B CN107701305B CN201711073840.0A CN201711073840A CN107701305B CN 107701305 B CN107701305 B CN 107701305B CN 201711073840 A CN201711073840 A CN 201711073840A CN 107701305 B CN107701305 B CN 107701305B
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- engine
- piston
- linear motor
- variable
- stroke
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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
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B69/00—Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types
- F02B69/06—Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types for different cycles, e.g. convertible from two-stroke to four stroke
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B71/00—Free-piston engines; Engines without rotary main shaft
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
- H02K41/02—Linear motors; Sectional motors
Abstract
The invention discloses a free piston engine with variable stroke. The engine comprises a combustion chamber part, a spring chamber part, a permanent magnet linear motor part and an electronic control unit part, and realizes full flexible control of an intake valve and an exhaust valve by adopting a cam-free variable gas distribution mode and electromagnetically driving a gas distribution mechanism; the electronic control unit controls the displacement of the piston by adjusting the size and the direction of the electrified current of the permanent magnet linear motor coil, realizes the variable upper and lower dead points and the variable compression ratio of the piston, and realizes the real-time control of the valve opening time, the valve lift curve and the valve distribution duration by changing the control signal of the cam-free variable valve distribution mechanism. The invention has simple structure and high efficiency, realizes the full flexible control of each actuating mechanism of the engine and improves the energy-saving and environment-friendly performance of the engine.
Description
Technical Field
The invention relates to the technical field of vehicle engines, in particular to a free piston engine with a variable stroke.
Background
The reciprocating cycle engine is classified into two-stroke engines and four-stroke engines according to the number of strokes in one working cycle. A working cycle of the two-stroke internal combustion engine is divided into two strokes, wherein a first stroke piston moves from a bottom dead center to a top dead center to complete air intake and compression, a second stroke piston moves from the top dead center to the bottom dead center to complete work application and air exhaust, and one working cycle is finished. A working cycle of the four-stroke internal combustion engine is divided into four strokes, a first stroke piston moves from a top dead center to a bottom dead center to complete air intake, a second stroke piston moves from the bottom dead center to the top dead center to complete compression, a third stroke piston moves from the top dead center to the bottom dead center to complete work, and a fourth stroke piston moves from the bottom dead center to the top dead center to complete exhaust.
Compared with two engines, the two-stroke engine has the advantages that the piston of the two-stroke engine does work once after reciprocating, the power density is high, the number of times of the four-stroke engine doing work in unit time is twice that of the four-stroke engine, theoretically, the power can be twice that of the four-stroke engine, the structure of the two-stroke engine is compact, although the number of times of the two-stroke engine doing work in unit time is twice that of the four-stroke engine, the two-stroke engine has the advantages that the number of times of the two-stroke engine doing work in unit time is one time that of the four-stroke engine doing work, due to the large; the four strokes of the four-stroke engine are completely separated, the air exchange effect is good, the fuel utilization rate is high, the emission is low, but the power is lower than that of the two-stroke engine because the piston reciprocates twice to complete once work.
The free piston engine has no crank connecting rod mechanism, is simpler than the traditional engine, has less parts and small volume, has no lateral force when the engine piston moves, has smaller frictional resistance of the piston and has long service life. Because the engine is not constrained by a crank connecting rod mechanism, the positions of the upper dead point and the lower dead point of the piston are variable, the engine has a variable compression ratio, the fuel economy of the engine can be optimized and the emission can be reduced by combining different engine working conditions, and meanwhile, the capability of the engine to adapt to various fuels is realized.
There are three main approaches to implementing variable stroke technology: the first type is that two stroke cylinders are configured on the engine, and the two stroke cylinders and the four stroke cylinders are respectively and independently used for working according to actual requirements, namely a multi-cylinder cooperation mode is adopted, so that the utilization rate of the engine is low, and the weight and the cost of the engine are increased; the second type is to use a set of gas distribution system to satisfy two-stroke and four-stroke gas distribution simultaneously, a two-stroke gas distribution molded line, a four-stroke gas distribution molded line and a transition molded line for switching are arranged on a cam shaft, and the position of a variable cam is changed by using a hydraulic or mechanical driving mode to complete the switching of the gas distribution, so that the design and production difficulty is higher, the controllability is low, and good fuel economy cannot be obtained; the third is to change the structure of the engine cylinder block, combine the air distribution of the inlet and outlet valves of the four-stroke engine with the scavenging and scavenging of the two-stroke engine, and use the combination of closing and opening of different air passages to complete the work of each stroke.
Disclosure of Invention
The invention aims to provide a variable stroke free piston engine which can freely switch between a two-stroke engine and a four-stroke engine and has a variable compression ratio, can meet different working condition requirements, has better fuel economy and dynamic property, and can meet the work of different fuels.
The technical solution for realizing the purpose of the invention is as follows: a free piston engine with variable stroke, which comprises four parts of a combustion chamber, a spring chamber, a permanent magnet linear motor and an electronic control unit, wherein:
the combustion chamber part comprises a variable valve mechanism, an engine cylinder cover, an engine cylinder body, a piston and a spark plug, wherein the variable valve mechanism changes a valve lift, a valve opening moment and a valve opening duration under the control of the electronic control unit, so that the full-flexible control of engine valve distribution is realized;
the spring chamber part comprises a spring and a bracket, wherein the spring is fixed between the engine piston and the linear motor, the spring is compressed when the piston descends to limit the displacement of the piston and store energy, and the spring provides return energy when the piston ascends;
the permanent magnet linear motor part comprises a linear motor shell and a coil rotor, wherein coils in the coil rotor are arranged in a concentric solenoid mode, the coil rotor of the linear motor is fixedly connected with an engine piston, and an electronic control unit controls the displacement of the engine piston by adjusting the size and the direction of the electrifying current of the coil of the linear motor;
when the engine works, the electronic control unit controls the gas distribution, oil injection, ignition and piston displacement of the engine in real time according to different requirements, so that the engine can work under different strokes and different loads.
Furthermore, the top dead center and the bottom dead center of the piston are variable, and the compression ratio is variable.
Further, the linear motor shell is made of a permanent magnet.
Furthermore, a working gap is reserved between the inner side of the linear motor shell and the coil rotor of the linear motor, so that the coil rotor can move up and down.
Compared with the prior art, the invention has the following remarkable advantages: (1) a camshaft gas distribution mechanism and a crank connecting rod mechanism are eliminated, the structure is simple, and the utilization rate is high; (2) the cam-free variable valve actuating mechanism replaces a camshaft valve actuating mechanism, and the linear motor drives and replaces a crank connecting rod mechanism, so that the full flexible control of each actuating mechanism of the engine is realized, the engine can realize stroke change and compression ratio change under the control of an Electronic Control Unit (ECU), and the engine can be freely switched between two strokes and four strokes; (3) the fuel oil can meet the requirements of different working conditions, has better fuel oil economy and dynamic property, and can meet the work of different fuels.
Drawings
FIG. 1 is a schematic diagram of a variable stroke free piston engine according to the present invention.
FIG. 2 is a schematic diagram of the operating conditions of a four-stroke engine.
FIG. 3 is a schematic diagram of a two-stroke engine operating condition.
Detailed Description
The invention discloses a stroke-variable free piston engine, which comprises a combustion chamber, a spring chamber, a permanent magnet linear motor and an electronic control unit, wherein:
the combustion chamber part comprises a variable valve mechanism 1, an engine cylinder cover 2, an engine cylinder body 5, a piston 4 and a spark plug 3, wherein the variable valve mechanism 1 changes a valve lift, a valve opening moment and a valve opening duration under the control of an electronic control unit, so that the full-flexible control of engine valve distribution is realized;
the spring chamber part comprises a spring 7 and a bracket 8, wherein the spring 7 is fixed between the engine piston 4 and the linear motor, the spring 7 is compressed when the piston 4 descends to limit the displacement of the piston 4 and store energy, and the spring 7 provides return energy when the piston 4 ascends;
the permanent magnet linear motor part comprises a linear motor shell 9 and a coil mover 10, wherein coils in the coil mover 10 are arranged in a concentric solenoid mode, the coil mover 10 of the linear motor is fixedly connected with the engine piston 4, and the electronic control unit controls the displacement of the engine piston 4 by adjusting the size and the direction of the electrifying current of the coil of the linear motor;
when the engine works, the electronic control unit controls the gas distribution, oil injection, ignition and the displacement of the piston 4 of the engine in real time according to different requirements, so that the engine can work under different strokes and different loads.
Further, the top and bottom dead centers of the piston 4 are variable, and the compression ratio is variable.
Further, the material of the linear motor housing 9 is a permanent magnet.
Further, a working gap is left between the inner side of the linear motor housing 9 and the coil mover 10 of the linear motor, so that the coil mover 10 can move up and down.
The technical solution of the present invention will be described in detail with reference to specific examples.
Example 1
Referring to fig. 1, the invention relates to a variable stroke free piston engine, which comprises a combustion chamber part, a spring chamber part, a permanent magnet linear motor part and an electronic control unit part.
Wherein:
the combustion chamber part comprises a variable valve mechanism 1, an engine cylinder cover 2, an engine cylinder body 5, a piston 4 and a spark plug 3, wherein the variable valve mechanism 1 changes a valve lift, a valve opening moment and a valve opening duration under the control of an electronic control unit, so that the full-flexible control of engine valve distribution is realized; the top dead center and the bottom dead center of the piston 4 are variable, and the compression ratio is variable;
the spring chamber part comprises a spring 7 and a bracket 8, wherein the spring 7 is fixed between the engine piston 4 and the linear motor, the spring 7 is compressed when the piston 4 descends to limit the displacement of the piston 4 and store energy, and the spring 7 provides return energy when the piston 4 ascends;
the permanent magnet linear motor part comprises a linear motor shell 9 and a coil mover 10, wherein coils in the coil mover 10 are arranged in a concentric solenoid mode, the coil mover 10 of the linear motor is fixedly connected with the engine piston 4, and the electronic control unit controls the displacement of the engine piston 4 by adjusting the size and the direction of the electrifying current of the coil of the linear motor; the linear motor shell 9 is made of a permanent magnet; a working gap is reserved between the inner side of the linear motor shell 9 and a coil rotor 10 of the linear motor, so that the coil rotor 10 can move up and down;
when the engine works, the electronic control unit controls the gas distribution, oil injection, ignition and the displacement of the piston 4 of the engine in real time according to different requirements, so that the engine can work under different strokes and different loads.
The four-stroke engine operating conditions are shown in fig. 2:
and (3) power stroke: an Electronic Control Unit (ECU) controls a spark plug 3 to ignite, mixed working media in a cylinder start to burn, and the pressure in the cylinder rises to push a piston 4 to move from an upper dead point to a lower dead point so as to finish an acting stroke;
exhaust stroke: the piston 4 moves from a bottom dead center to a top dead center under the combined action of the spring 7 and the linear motor rotor 10, meanwhile, an Electronic Control Unit (ECU) gives an exhaust valve opening signal to the variable valve actuating mechanism 1, the variable valve actuating mechanism 1 opens an exhaust valve and keeps an opening state, the Electronic Control Unit (ECU) gives an exhaust valve closing signal to the variable valve actuating mechanism 1 when the exhaust stroke is finished, and the variable valve actuating mechanism 1 closes the exhaust valve and keeps a closing state to finish the exhaust stroke;
an intake stroke: the piston 4 moves from the top dead center to the bottom dead center under the action of the linear motor rotor 10, meanwhile, an Electronic Control Unit (ECU) gives an inlet valve opening signal to the variable valve actuating mechanism 1, the variable valve actuating mechanism 1 opens an inlet valve and keeps an open state, the Electronic Control Unit (ECU) gives an inlet valve closing signal to the variable valve actuating mechanism 1 when an inlet stroke is finished, and the variable valve actuating mechanism closes the inlet valve and keeps a closed state to finish the inlet stroke;
compression stroke: the piston 4 moves from the bottom dead center to the top dead center under the combined action of the spring 7 and the linear motor rotor 10, the air inlet valve and the exhaust valve are kept in a closed state, the oil injector receives an oil injection signal of the controller to inject oil and mix with fresh air, the compression stroke is completed, and one cycle is finished.
The working conditions of the two-stroke engine are shown in figure 3:
the first stage is as follows: an Electronic Control Unit (ECU) controls a spark plug 3 to ignite, mixed working media in a cylinder start to burn, the pressure in the cylinder rapidly rises to push a piston 4 to move from a top dead center to a bottom dead center to do work, a variable valve timing mechanism 1 opens an exhaust valve and an intake valve successively to start exhaust and intake in the piston movement process, and a first stage is finished when the piston 4 moves to a bottom dead center;
and a second stage: the piston 4 moves from the lower dead point to the upper dead point under the combined action of the spring 7 and the linear motor rotor 10, the variable air distribution mechanism 1 closes the exhaust valve and the air inlet valve successively to finish exhaust and air inlet, the oil injector receives an oil injection signal of the controller to inject oil and mix with fresh air, the piston 4 moves to the upper dead point to compress the mixed gas in the cylinder to finish the second stage, and one cycle is finished.
The process of switching the engine from the four-stroke working condition to the two-stroke working condition is as follows: after receiving the stroke switching signal, the Electronic Control Unit (ECU) controls the engine to continue working under the four-stroke working state until the compression stroke is finished (the cycle is finished), and the two-stroke control mode is switched.
The process of switching the engine from the two-stroke working condition to the four-stroke working condition is as follows: and after receiving the stroke switching signal, an Electronic Control Unit (ECU) controls the engine to continue working under the two-stroke working state until the second stage is finished (the cycle is finished), and switches into a four-stroke control mode.
In conclusion, the variable stroke free piston engine can be freely switched between the two stroke and the four stroke, has variable compression ratio, can meet the requirements of different working conditions, has better fuel economy and dynamic property, and can meet the work of different fuels.
Claims (4)
1. A free piston engine with variable stroke is characterized by comprising four parts, namely a combustion chamber, a spring chamber, a permanent magnet linear motor and an electronic control unit, wherein:
the combustion chamber part comprises a variable valve mechanism (1), an engine cylinder cover (2), an engine cylinder body (5), a piston (4) and a spark plug (3), wherein the variable valve mechanism (1) changes a valve lift, a valve opening time and a valve opening duration under the control of an electronic control unit, so that the full-flexible control of engine valve distribution is realized;
the spring chamber part comprises a spring (7) and a bracket (8), wherein the spring (7) is fixed between the piston (4) of the engine and the linear motor, the spring (7) is compressed when the piston (4) descends, the displacement of the piston (4) is limited and energy is stored, and the spring (7) provides return energy when the piston (4) ascends;
the permanent magnet linear motor part comprises a linear motor shell (9) and a coil rotor (10), wherein coils in the coil rotor (10) are arranged in a concentric solenoid way, the coil rotor (10) of the linear motor is fixedly connected with an engine piston (4), and an electronic control unit realizes the control of the displacement of the engine piston (4) by adjusting the size and the direction of the electrifying current of the coil of the linear motor;
when the engine works, the electronic control unit controls the gas distribution, oil injection, ignition and piston (4) displacement of the engine in real time according to different requirements, so that the engine can work under different strokes and different loads.
2. The variable stroke free piston engine as claimed in claim 1 wherein top dead center and bottom dead center of the piston (4) is variable and the compression ratio is variable.
3. The variable stroke free piston engine according to claim 1 wherein the material of the linear motor housing (9) is a permanent magnet.
4. The variable stroke free piston engine according to claim 1, wherein a working gap is left between the inside of the linear motor housing (9) and the coil mover (10) of the linear motor, so that the coil mover (10) can move up and down.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711073840.0A CN107701305B (en) | 2017-11-05 | 2017-11-05 | Free piston engine with variable stroke |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711073840.0A CN107701305B (en) | 2017-11-05 | 2017-11-05 | Free piston engine with variable stroke |
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| CN107701305A CN107701305A (en) | 2018-02-16 |
| CN107701305B true CN107701305B (en) | 2019-12-27 |
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| CN109488471B (en) * | 2018-12-20 | 2021-09-03 | 南京理工大学 | Method for controlling stable operation process of free piston engine |
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| CN101979852A (en) * | 2010-11-24 | 2011-02-23 | 南京理工大学 | Free piston engine with independent compression and controllable inlet air thermodynamic parameter |
| US8555834B2 (en) * | 2011-03-22 | 2013-10-15 | Robert Bosch Gmbh | Device and method configured to control valve operation in a piston engine |
| CN103225539B (en) * | 2013-04-02 | 2015-06-17 | 清华大学 | Variable stroke engine |
| JP2017155620A (en) * | 2016-02-29 | 2017-09-07 | トヨタ自動車株式会社 | Variable cycle engine |
| CN106545380B (en) * | 2016-12-13 | 2018-10-19 | 大连理工大学 | A kind of locking-type multi-mode lever Variabale valve actuation system |
| CN107060942B (en) * | 2017-06-07 | 2019-04-09 | 大连理工大学 | A kind of compact multimode formula valve-driving system |
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Effective date of registration: 20210207 Address after: 225300 No. 999, Nanhuan West Road, Luotang street, Jiangyan District, Taizhou City, Jiangsu Province Patentee after: Jiangsu iridium Laide Drive System Co.,Ltd. Address before: 210094 Xuanwu District, Jiangsu, Xiaolingwei 200, Nanjing Patentee before: NANJING University OF SCIENCE AND TECHNOLOGY |
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