CN109339944B - Miniature free piston generator - Google Patents

Abstract

The invention provides a miniature free-piston generator, comprising a stator and a magnetic piston, the piston is a magnetically opposed piston, a stator winding and an excitation winding are arranged on the wall of the stator, and the magnetic piston is symmetrically placed inside the stator, so The left magnetic piston is located between the first pressure chamber and the first intake chamber, the right magnetic piston is located between the second pressure chamber and the second intake chamber, the intermediate piston is located in the combustion chamber, and the combustion chamber is symmetrical There is a combustion chamber exhaust port; the piston rod connecting the middle piston and the left magnetic piston is the first reducing rod, and the first pressure chamber is communicated or blocked with the combustion chamber through the movement of the piston; the middle piston The piston rod connected with the piston rod of the right magnetic piston is the second reducing rod, and the second pressure chamber is communicated or blocked with the combustion chamber through the movement of the piston. The invention realizes the process of air intake from the air intake chamber to the pressure chamber, and ensures the filling performance of the air intake.

Description

A miniature free-piston generator

technical field

The invention relates to the field of internal combustion engines or the field of power generation, in particular to a miniature free-piston generator.

Background technique

The free-piston engine is a new type of engine that has been gradually developed in recent years. It cancels the crank and connecting rod mechanism of the traditional engine, and the piston only performs reciprocating linear motion. The movement law of the piston is determined by the operating conditions of the engine. Because of the simple structure and easy miniaturization of free-piston engine, the miniaturized free-piston engine has become another new research field in the world. The mechanical structure of the micro-free piston engine does not have the crank connecting rod, air valve and other mechanisms of the traditional internal combustion engine, and the free piston is not constrained by mechanical force in the cylinder, so it has a very high work performance. Due to the limitation of the way the miniaturized free-piston engine can output power externally, the micro-free-piston generator formed by organically combining the micro-engine and the power generation device has become the mainstream research direction. Most of the existing micro-power generation systems use thermoelectric materials for thermoelectric conversion, and use thermoelectric materials on the surface of the burner to directly convert thermal energy into electrical energy. This power generation method has high requirements on thermoelectric materials and has a very limited lifespan. The micro-free piston generator stands out among many micro-power devices due to its advantages of high volume efficiency, high energy conversion rate, and long working life, and has become a research hotspot of domestic and foreign scientific research institutions.

As we all know, the working efficiency of a two-stroke engine depends to a large extent on the intake effect and scavenging efficiency of the engine. For the micro free piston generator, due to the large intake resistance of the micro combustion chamber, it is easy to appear in the working process. Insufficient exhaust gas and other problems, so improving the intake and scavenging effects of the internal combustion engine part can greatly improve its power generation efficiency. Secondly, due to the particularity of the size of the micro-generator, the fuel will generate high-temperature and high-pressure exhaust gas after combustion in the micro-combustion chamber. The energy in this part of the exhaust gas accounts for about 40% of the total energy of the fuel, and the utilization of this part of the energy can be very efficient. Maximize the efficiency of micro-generators. Conventional conventional size engines already have relatively mature technologies for exhaust gas preheating and utilization, such as exhaust gas turbocharging technology, exhaust gas thermoelectric power generation technology, etc., but these technologies are not suitable for miniaturized power units. In addition, in all the patents disclosed so far, the exhaust gas treatment part of the micro-power device is not considered. Most of the existing designs of micro-free piston generators use external components to boost intake air, which makes the device integration low and needs to consume external work at the same time. There are also a few designs that use optimized device structure arrangement to realize the air intake process of the micro-generator. For example, the Chinese patent uses an air duct to connect the pressure chamber with the air inlet, and the air intake is realized when the combustion chamber and the pressure chamber generate negative pressure. The end piston lacks a rigid connection and the actual gas is compressible, so the pressure rise in the pressure chamber is not obvious, and then the intake air boosting effect is not obvious. Secondly, in this design, the exhaust gas preheating and intake system is set inside the device, which is not conducive to the development of miniaturization; moreover, when the exhaust gas passes through the narrow exhaust pipe, it will lose a large part of its own heat, making the exhaust gas The effect of preheating the intake air is poor. Another example is that the Chinese patent design fails to consider the micro-engine scavenging process, so the exhaust effect of this design is poor, and the combustion exhaust gas is easy to remain in the combustion chamber, which affects the working ability of the device. In addition, the design does not consider the recycling and treatment of high-temperature exhaust gas, resulting in energy waste and environmental pollution problems.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the present invention provides a micro free piston generator, which can achieve supercharged air intake and good scavenging effect, and design an air intake preheating system and an exhaust gas treatment system at the same time. Utilize the waste heat of the intake air and reduce the emission of harmful substances. The dual combustion chamber and three-piston structure are adopted in the design, and the intake air is squeezed into the combustion chamber through the extrusion action of the piston. The supercharged intake air can not only ensure sufficient intake air, but also achieve a good scavenging effect; The structural arrangement of the combustion chamber in the middle of the end pressure chamber greatly shortens the power stroke of the piston in the middle of the combustion chamber and avoids excessive heat dissipation loss caused by the scattered arrangement of the combustion chamber. The exhaust gas generated in the micro-combustion chamber first passes through the intake preheating system, and then transfers heat to the fresh intake air through the heat exchanger. Harmful substances such as CO and NO _X contained in the exhaust gas are treated by the exhaust gas treatment system to reduce the emission of harmful substances.

The present invention achieves the above technical purpose through the following technical means.

A miniature free-piston generator includes a stator and a magnetic piston, the piston is a magnetically opposed piston, a stator winding and an excitation winding are arranged on the wall of the stator, the magnetic piston is symmetrically placed inside the stator, and the magnetic piston includes A left magnetic piston, a right magnetic piston and an intermediate piston, the left magnetic piston is located between the first pressure chamber and the first intake chamber, and the right magnetic piston is located between the second pressure chamber and the second intake chamber, so The intermediate piston is located in the combustion chamber, and the combustion chamber is provided with a combustion chamber exhaust port at the symmetrical position; the first pressure chamber is communicated with the first intake chamber and the second pressure chamber is respectively connected with the second intake chamber;

The piston rod connecting the middle piston and the left magnetic piston is a first reducing rod, and the first pressure chamber is communicated or blocked with the combustion chamber through the movement of the piston;

The piston rod connecting the intermediate piston and the piston rod of the right magnetic piston is a second reducing rod, and the movement of the piston makes the second pressure chamber communicate or block the combustion chamber.

Further, the diameter of the first reducing rod is gradually changed from the left magnetic piston to the middle piston; the diameter of the second reducing rod is gradually changed from the right magnetic piston to the middle piston.

Further, it also includes a gas collection box, the gas collection box is respectively connected with the first air inlet cavity and the second air inlet cavity; the gas collection box is provided with a preheating system for preheating the gas entering the gas collection box .

Further, the preheating system includes a heat exchange tube, the inlet of the heat exchange tube and the exhaust port of the combustion chamber; the heat exchange tube is wound inside the gas collecting box.

Further, the outlet of the heat exchange tube is connected to the exhaust gas treatment system.

Further, the exhaust port of the combustion chamber is connected to an exhaust gas treatment system.

Further, one-way valves are respectively provided on the pipelines between the first pressure chamber and the first air intake chamber and the second pressure chamber and the second air intake chamber.

Further, the one-way valve includes an I-shaped valve core and a partition plate, and the partition plate is located on the pipeline between the second pressure chamber and the second air intake chamber or between the first pressure chamber and the first air intake chamber; so A movable I-shaped valve core is arranged in the middle of the partition plate, and at least two through holes are arranged on the partition plate; the two ends of the I-shaped valve core are different in length, and the I-shaped valve core The movement between the middle of the separators makes the through holes on the separators conduct or block.

The beneficial effects of the present invention are:

1. The miniature free-piston generator of the present invention can achieve air intake boosting without external boosting components. The microgenerator is arranged symmetrically on the left and right, and has a simple structure. Such a structural design is more suitable for the development of miniaturization.

2. In the miniature free-piston generator of the present invention, a pressure chamber and an intake chamber with variable volume are formed by the piston and the inner wall of the device, and the reciprocating motion of the piston changes the volume of the pressure chamber and the intake chamber, thereby realizing the intake air. The process of entering the air into the pressure chamber. The fresh charge is pressurized through the pressure chamber and then fed into the micro-combustion chamber to ensure the filling of the intake air.

3. The miniature free-piston generator according to the present invention delivers pressurized gas to the combustion chamber in the corresponding stroke through the difference between the diameter of the connecting rod with variable diameter and the diameter of the intake port of the combustion chamber. The scavenging passages and exhaust passages are arranged on the left and right sides of the combustion chamber, and the fresh gas enters the combustion chamber along the peripheral side of the connecting rod at the small diameter for scavenging, and the scavenging effect is similar to the quality of direct scavenging.

4. The miniature free-piston generator of the present invention is designed with an intake preheating system, which uses the waste heat in the exhaust gas to preheat the fresh intake air, reduces the compression ignition conditions of the fuel, avoids the strong collision between the piston and the bottom of the combustion chamber, and increases the service life of the device.

5. In the miniature free-piston generator of the present invention, the air inlet preheating system and the outer wall of the pipeline are all arranged with thermal insulation layers to reduce heat dissipation loss and waste heat.

6. The micro free-piston generator of the present invention is designed with an exhaust gas treatment system to avoid or reduce the emission of harmful substances such as CO caused by insufficient combustion.

7. The miniature free-piston generator of the present invention is a one-way valve designed for a micro-scale combustion chamber, which has a simple structure, is safe and reliable, and is easy to miniaturize, and avoids the phenomenon of backflow caused by excessive pressure in the pipeline or combustion chamber.

Description of drawings

FIG. 1 is a schematic structural diagram of the miniature free-piston generator according to the present invention.

Figure 2a is a schematic diagram of the internal structure of the one-way valve according to the present invention.

Figure 2b is a schematic diagram of the one-way valve closing according to the present invention.

Figure 2c is a schematic diagram of the opening and closing of the one-way valve according to the present invention.

3 is a schematic diagram of the working process of the micro-generator according to the present invention, (a) the start-up stage, the first combustion chamber is intake, (b) the first combustion chamber is compressed, the second combustion chamber is intake, (c) the first combustion chamber is The first combustion chamber is compressed and ignited, the second combustion chamber is saturated with intake air, (d) the second combustion chamber is compressed, the first combustion chamber is scavenged, the exhaust gas is preheated and the intake air is discharged through the exhaust gas treatment system, (e) the second combustion chamber is compressed On fire, the intake air of the first combustion chamber is saturated, (f) the first combustion chamber is compressed, the second combustion chamber is scavenged, the exhaust gas is preheated and the intake air is discharged through the exhaust gas treatment system, (g) the first combustion chamber is compressed and ignited.

In the picture:

1-current inverter; 2-piston; 3-excitation winding; 4-left stator winding; 5-first combustion chamber; 6-right stator winding; 7-second combustion chamber; 8-piston rod; 9-th 2-pressure chamber; 10-check valve; 11-first air inlet chamber; 12-first pressure chamber; 13-intake conduit; 14-insulation layer; 15-gas collection box; 16-air inlet; 17- Exhaust port of combustion chamber; 18-exhaust gas treatment system; 19-exhaust port; 20-heat exchange tube; 21-second intake chamber; 22-stator.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

As shown in FIG. 1 , the miniature free-piston generator according to the present invention includes a stator 22 and a magnetic piston 2 , the piston 2 is a magnetically opposed piston, and the wall of the stator 22 is provided with a left stator winding and a right stator winding 6 and the excitation winding 3, the magnetic piston 2 is symmetrically placed inside the stator 22, the magnetic piston 2 includes a left magnetic piston, a right magnetic piston and an intermediate piston, the left magnetic piston is located in the first pressure chamber 12 and the first intake air. Between the chambers 11, the right magnetic piston is located between the second pressure chamber 9 and the second intake chamber 21, the intermediate piston is located in the combustion chamber, and divides the combustion chamber into the first combustion chamber 5 and the first combustion chamber 5 which are not communicated with each other. The second combustion chamber 7 is provided with a combustion chamber exhaust port 17 at the symmetrical position of the combustion chamber; the first pressure chamber 12 communicates with the first intake chamber 11 and the second pressure chamber 9 and the second intake chamber 21 respectively ; The piston rod 8 connecting the middle piston and the left magnetic piston is the first reducing rod, through the movement of the piston 2, the first pressure chamber 12 is communicated or blocked with the combustion chamber 5; the middle piston and the right magnetic piston are The piston rod 8 connected to the piston rod 8 is the second reducing rod, and the movement of the piston 2 makes the second pressure chamber 9 communicate or block the combustion chamber. The diameter of the first reducing rod changes from the left magnetic piston to the middle piston; the diameter of the second reducing rod changes from the right magnetic piston to the middle piston.

The air collecting box 15 is respectively communicated with the first air intake cavity 11 and the second air intake cavity 21 through the air intake duct 13; the air intake duct 13 is wrapped with a thermal insulation layer 14; the air collecting box 15 is provided with a preheating system , used to preheat the gas entering the gas collection box 15 . The air collecting box 15 is provided with an air inlet 16 for supplying air to the first air intake chamber 11 and the second air intake chamber 21 . The preheating system includes a heat exchange tube 20 , the inlet of the heat exchange tube 20 and the exhaust port 17 of the combustion chamber; the heat exchange tube 20 is wound inside the gas collecting box 15 . The outlet of the heat exchange tube 20 is connected to the exhaust gas treatment system 18 . The exhaust port of the exhaust gas treatment system 18 is connected to the exhaust gas collection tank.

As shown in FIG. 2 a , one-way valves 10 are respectively provided on the pipes between the first pressure chamber 12 and the first intake chamber 11 and the second pressure chamber 9 and the second intake chamber 21 . The one-way valve 10 includes an I-shaped valve core and a baffle, and the baffle is located in the pipeline between the second pressure chamber 9 and the second intake chamber 21 or the first pressure chamber 12 and the first intake chamber 11 . The middle of the partition plate is provided with a movable I-shaped valve core, and the partition plate is provided with at least two through holes; the lengths of both ends of the I-shaped valve core are different, and the I-shaped valve core is The movement of the valve core between the partitions makes the through holes on the partitions conduct or block. As shown in Figures 2b and 2c, the one-way valve 10 adopts an "I"-shaped structure, and the valve plates of the I-shaped valve core of different sizes are designed according to the pressure at both ends of the valve. When the small valve plate is closed, the one-way valve is opened, allowing the fluid from the side with higher pressure to flow to the side with lower pressure; when the large valve is closed, the one-way valve is closed, and no fluid is allowed to pass through the valve pipeline.

Working principle, the stator 22 and the piston 2 of the micro-free piston generator are made of heat-resistant materials with excellent magnetic properties and high resistivity. The piston 2 also acts as an armature, and the start of the generator is completed by electromagnetic force. The left stator winding 4 and the right stator winding 6 are respectively wound on the left half and the right half of the stator. The number of groups of the left stator winding 4 and the right stator winding 6 is related to the length of the micro-combustion chamber cylinder; the left stator winding 4 is inversely related to the current. The inverter 1 is connected in series, and the right stator winding 6 is connected in series with another current inverter. Under the excitation of the excitation winding, the piston moves linearly, and the piston cuts the magnetic field line to generate electric energy; when the load switch is closed and the battery switch is open, the generator Provides electrical energy for the load; when the load switch is open and the battery switch is closed, the power generated by the generator is delivered to the battery for storage.

Way of working:

As shown in Figure 3a, before the generator starts, the fresh homogeneous mixture in the collecting tank 15 enters the first intake chamber 11 and the first pressure chamber 12 through the intake conduit 13, and the first reducing rod makes the first pressure chamber 12 is communicated with the first combustion chamber 5, and the mixture in the first pressure chamber 12 enters the first combustion chamber 5 from the intake port of the combustion chamber. The battery switch is closed, and the current from the battery is converted into alternating current through the current inverter 1, and an alternating magnetic field is generated through the left stator winding 4 and the right stator winding 6, and the alternating magnetic field acts on the piston 2 to make it move. The starting work of the generator begins. The magnetic piston 2 is driven to the right by the electromagnetic force, and compresses the homogeneous mixture in the first combustion chamber 5 .

As shown in Figure 3b, in the process of compressing the homogeneous mixture in the first combustion chamber 5, when the piston runs to a certain position, the second reducing rod makes the second pressure chamber 9 communicate with the second combustion chamber 7; The fresh air mixture in the second pressure chamber 9 enters the second combustion chamber 7 from the combustion chamber intake port under the pressing action of the piston, and the intake operation of the second combustion chamber starts.

As shown in Figure 3c, the piston 2 moves to the left under the drive of electromagnetic force until the homogeneous mixture in the first combustion chamber 5 is compressed and ignited. Finish.

As shown in Figure 3d, after the first combustion chamber 5 is ignited, the piston returns to move to the right, prompting the piston to compress the homogeneous mixture in the second combustion chamber 7; when the piston runs to the right to a certain position, the exhaust gas of the combustion chamber is The port 17 is opened, the fresh mixture in the first pressure chamber 12 enters the first combustion chamber 5 from the combustion chamber intake port under the pressing action of the piston, and the fresh fuel pressurized by the first pressure chamber 12 enters the first combustion chamber 5. Sweep the exhaust gas; the exhaust gas enters the intake preheating system through the exhaust port 17, and the heat in the exhaust gas is transferred to the fresh air mixture in the collecting box 15 through the heat exchange effect of the heat exchanger 20; after preheating, it has a certain temperature The fresh gas enters the second intake chamber 21 through the intake duct 13, and the intake duct 13 and the surface of the gas collecting box are covered with thermal insulation materials to avoid energy loss due to heat exchange loss; the movement of the piston will cause the second intake The fresh mixed gas in the air cavity 21 is squeezed into the second pressure chamber 9; the exhaust gas discharged from the intake preheating system is transported to the exhaust gas treatment system 18. The function of the exhaust gas treatment system is to eliminate or reduce the emission of harmful substances such as CO in the exhaust gas, After the exhaust gas is treated by the exhaust gas treatment system, the exhaust gas is discharged to the outside of the device through the exhaust gas treatment exhaust port 19 .

As shown in Figure 3e, the piston is forced to move to the right until the homogeneous mixture of the second combustion chamber 7 is compressed and ignited. At the moment when the second combustion chamber 7 is ignited, the intake and exhaust of the first combustion chamber 5 are completed simultaneously. ; Similarly, the exhaust gas generated in the process is discharged from the exhaust port 17 and then discharged to the outside of the device through the intake air preheating system and the exhaust gas pretreatment system 18 .

As shown in Figure 3f, after the second combustion chamber 7 catches fire, the pressure of the combustion chamber increases sharply, which pushes the piston to move to the left, and urges the piston to compress the homogeneous mixed fuel in the first combustion chamber 5; when the piston moves to the left to a certain position At this time, the exhaust port 17 of the combustion chamber is opened, and the fresh intake air of the second pressure chamber 9 enters the second combustion chamber 7 from the combustion chamber intake port under the pressing action of the piston, and is pressurized by the second pressure chamber 9. The fresh fuel enters the second combustion chamber 7 to scavenge the exhaust gas; at the same time, the collecting box 15 feeds into the second intake chamber and the second pressure chamber 9; similarly, the exhaust gas discharged from the exhaust port 17 in this process It is discharged to the outside of the device through the intake air preheating system and the exhaust gas pretreatment system.

As shown in Fig. 3g, the piston 2 is forced to move to the left until the homogeneous mixed intake air of the first combustion chamber 5 is compressed and ignited. done at the same time.

So far, the entire cyclic combustion process of the micro-generator is completed. The left and right intake and exhaust process and the combustion and expansion process of the mixture are completed alternately, and the magnetic piston 2 is pushed to reciprocate. When the magnetic piston reciprocates, according to the relative motion, it is equivalent to the movement of the coil wire to cut the magnetic field line, and a certain amount of current is generated. ; The energy released by the micro-engine through the compression and combustion of the mixture is converted into the mechanical energy of the piston, and then the mechanical energy of the piston is converted into electrical energy through the power generation device in the generator; the exhaust gas generated during the combustion process is passed through the intake preheating system. The function of preheating and intake air preheating can reduce the ignition conditions of the fuel, and then it is treated by the exhaust gas treatment system and discharged to the outside of the device. When the load switch is closed and the battery switch is open, the generator provides electrical energy for the load; when the load switch is open and the battery switch is closed, the power generated by the generator is sent to the battery for storage.

The embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or All modifications belong to the protection scope of the present invention.

Claims (8)

1. A miniature free-piston generator, comprising a stator (22) and a magnetic piston (2), the piston (2) is a magnetically opposed piston, and the wall of the stator (22) is provided with stator windings (4, 6) and the excitation winding (3), the magnetic piston (2) is symmetrically placed inside the stator (22), and it is characterized in that the magnetic piston (2) comprises a left magnetic piston, a right magnetic piston and a middle piston, the left magnetic The piston is located between the first pressure chamber (12) and the first intake chamber (11), the right magnetic piston is located between the second pressure chamber (9) and the second intake chamber (21), the intermediate piston Located in the combustion chamber, the combustion chamber is provided with a combustion chamber exhaust port (17) symmetrically; the first pressure chamber (12) and the first intake chamber (11) and the second pressure chamber (9) and the second The air intake chambers (21) are respectively communicated; The piston rod (8) connecting the intermediate piston and the left magnetic piston is a first reducing rod, and the first pressure chamber (12) is communicated or blocked with the combustion chamber (5) through the movement of the piston (2); The piston rod (8) connecting the intermediate piston and the right magnetic piston is a second reducing rod, and the second pressure chamber (9) is communicated or blocked with the combustion chamber through the movement of the piston (2). 2 . The miniature free-piston generator according to claim 1 , wherein the diameter of the first reducing rod is gradually changed from the left magnetic piston to the middle piston; the second reducing rod is from the right magnetic piston to the middle piston. 3 . Diameter gradient. 3. The miniature free-piston generator according to claim 1, characterized in that it further comprises a gas collecting box (15), the gas collecting box (15) is respectively connected with the first air inlet chamber (11) and the second air inlet chamber (11) The air cavity (21) is communicated; the air collecting box (15) is provided with a preheating system for preheating the gas entering the air collecting box (15). 4. The miniature free-piston generator according to claim 3, wherein the preheating system comprises a heat exchange tube (20), the inlet of the heat exchange tube (20) and the combustion chamber exhaust port (17) connection; the heat exchange tube (20) is wound inside the air collecting box (15). 5. The miniature free-piston generator according to claim 4, wherein the outlet of the heat exchange tube (20) is connected to the exhaust gas treatment system (18). 6. The miniature free-piston generator according to any one of claims 1-3, wherein the combustion chamber exhaust port (17) is connected to an exhaust gas treatment system (18). 7. The miniature free-piston generator according to any one of claims 1-3, characterized in that the first pressure chamber (12) is connected with the first air inlet chamber (11) and the second pressure chamber (9) A one-way valve (10) is respectively provided on the pipeline between the second air inlet chamber (21). 8. The miniature free-piston generator according to claim 7, characterized in that, the one-way valve (10) comprises an I-shaped valve core and a diaphragm, and the diaphragm is located between the second pressure chamber (9) and the On the pipeline between the second air inlet chamber (21) or the first pressure chamber (12) and the first air inlet chamber (11); a movable I-shaped valve core is arranged in the middle of the partition plate, and the partition plate is provided with a movable I-shaped valve core. There are at least 2 through holes on the plate; the two ends of the I-shaped valve core have different lengths, and the through holes on the partition plate are connected through the movement of the I-shaped valve core between the partition plates. or block.

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