Reed valve for two-stroke aviation piston engine

Abstract

The utility model belongs to the technical field of aviation piston engines, and particularly relates to a reed valve for a two-stroke aviation piston engine, which comprises a valve seat and a valve body, and an electric heating sheet is arranged on an elastic valve sheet of the reed valve; the electric heating piece heats mixed gas entering the gas inlet in the starting stage of the aviation piston engine. Oil-gas mixture entering an engine cylinder is directly heated, and the mixed gas flows through the reed valve to quickly absorb heat mainly in a heat convection manner, so that the temperature of the mixed gas is increased, the evaporation rate of fuel oil is increased, the atomization quality of the fuel oil is improved, the mixed gas can be quickly ignited near a compression top dead center of an engine, and the combustion efficiency is improved. Quick starting of the two-stroke aviation piston engine is achieved, the starting success rate is greatly increased, and meanwhile the starting reliability in the low-temperature environment is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of aero-engine, specifically relates to a reed valve for two-stroke aero-piston engine. BACKGROUND

[0002] Two-stroke aero-piston engines are widely used in small fixed-wing unmanned aerial vehicles and other aerial vehicles due to their high power-to-weight ratio and simple structure. However, the existing two-stroke aero-piston engines have the following shortcomings due to their special structure during actual application:

[0003] Low starting success rate and slow warm-up speed: Two-stroke engines often exhibit instability during the starting phase, especially under cold conditions, with a high failure rate. Moreover, it takes a long time for the engine to reach normal operating temperature, and the warm-up process is slow, affecting the sortie efficiency and response speed of the unmanned aerial vehicle.

[0004] Difficulty in starting at low temperature: Due to limitations in fuel supply system and carburetor design, the fuel atomization quality of the engine is poor under certain working conditions, leading to insufficient combustion and decreased efficiency. This problem is particularly pronounced in low-temperature environments, further exacerbating the difficulty in starting.

[0005] To improve the low-temperature starting performance, cylinder head preheating measures are commonly used at present, but such methods usually have high power consumption and long preheating time, increasing the overall system energy consumption and reducing the flight time and economy of the unmanned aerial vehicle, which is not conducive to long-term operation tasks in application scenarios. SUMMARY

[0006] Therefore, the utility model provides a reed valve for a two-stroke aero-piston engine, which improves the existing reed valve of the two-stroke aero-piston engine by setting an electric heating sheet on the elastic valve sheet to directly heat the oil-gas mixture entering the engine cylinder. When the mixture flows through the reed valve, it quickly absorbs heat based on direct contact, increasing the thermodynamic energy of the mixture and the evaporation rate of the fuel, further improving the atomization quality and facilitating the rapid ignition of the mixture near the top dead center of the engine compression, achieving rapid starting of the two-stroke aero-piston engine.

[0007] To achieve the above technical purposes, the utility model adopts the following specific technical solutions:

[0008] A reed valve for a two-stroke aero-piston engine, comprising:

[0009] A valve seat is installed at the intake port of the body of the aero-piston engine and is provided with a one-way intake portion;

[0010] A valve body is fixed on the valve seat and comprises at least one set of elastic valve sheets; the elastic valve sheets are attached to the one-way air inlet part and open the one-way air inlet part based on elasticity when the aviation piston engine inhales;

[0011] The reed valve further comprises a pressing plate and a pressing plate bolt; the pressing plate bolt is sequentially threaded through the pressing plate and the elastic valve sheet and then connected to the valve seat;

[0012] The elastic valve sheet is provided with an electric heating wire or an electric heating sheet; the electric heating wire or the electric heating sheet heats the mixed gas entering the air inlet during the start-up stage of the aviation piston engine.

[0013] Further, in order to ensure the performance of the elastic valve sheet under high-frequency vibration and avoid the breakage of the electric heating sheet due to metal fatigue, the elastic valve sheet comprises a glass fiber film sheet and an electric heating sheet embedded on the surface of the glass fiber film sheet.

[0014] Further, in order to ensure the air intake and increase the heating area, the valve seat is a V-shaped valve seat, two one-way air inlet parts are respectively arranged on the two sides of the valve seat, and two elastic valve sheets are respectively attached to the outer sides of the two one-way air inlet parts.

[0015] Further, in order to ensure the elastic performance of the elastic valve sheet under high-frequency vibration, the one-way air inlet part is divided into at least two air holes by at least one partition body, and the elastic valve sheet comprises a fixed part and a deformation part consistent with the number of air holes.

[0016] The pressing plate and the pressing plate bolt act on the fixed part, and in the closed state of the reed valve, each deformation part blocks each air hole.

[0017] Further, in order to maintain the compactness of the reed valve, both lead ends of the electric heating sheet are arranged on the fixed part, and the electric heating sheet is continuously distributed along the edges of each deformation part in a labyrinth shape.

[0018] Further, at least two through holes are arranged on the fixed part, and each through hole facilitates the passage of each pressing plate bolt.

[0019] Further, in order to maintain the compactness of the reed valve, the lead end is annular and arranged on the outer periphery of the through hole; the lead end is in conductive connection with the pressing plate bolt passing through the annular center of the lead end.

[0020] Further, in order to ensure the compactness of the aviation piston engine assembly, the pressing plate bolt is connected to a lead wire; the lead wire sequentially passes through the valve seat and an air inlet pipe pressing plate of an air inlet assembly of the aviation piston engine and then reaches outside the air inlet assembly; and one end of the lead wire away from the pressing plate bolt is connected to an electric plug.

[0021] Further, in order to realize that the electric heating sheet works automatically in the starting stage of the engine and is closed in the rest time, the reed valve further comprises a control circuit; the control circuit comprises a temperature sensor, a comparator and a metal-oxide-semiconductor field effect transistor;

[0022] The temperature sensor collects the temperature of the mixed gas at the outlet of the reed valve, and a signal output end is connected to the comparator.

[0023] An output end of the comparator is connected to a gate of the metal-oxide-semiconductor field effect transistor; a source of the metal-oxide-semiconductor field effect transistor is connected to a negative pole of a power supply of the aviation piston engine, and a drain is connected to the press plate bolt.

[0024] Further, in order to keep the compactness of the aviation piston engine, the temperature sensor is installed in a crankcase of the aviation piston engine.

[0025] By adopting the technical scheme, the aviation piston engine has the following beneficial effects:

[0026] The V-shaped valve seat is adopted, so that the air intake amount is increased and the heating area of the mixed gas is increased.

[0027] The elastic valve sheet adopts the combination mode of the glass fiber diaphragm and the electric heating sheet, and the electric heating sheet can still keep the elastic property of the reed sheet under the condition of high-frequency vibration of the engine for a long time; meanwhile, compared with other heating modes, the electric heating sheet has higher toughness under the condition of high-frequency vibration, so that fatigue fracture of the electric heating sheet caused by high-frequency bending of the elastic valve sheet base can be avoided.

[0028] The aviation piston engine has the following beneficial effects:

[0029] The control circuit is designed, the comparator determines whether a high level or a low level is output based on the voltage of the temperature sensor, the transistor controls the conduction and disconnection of the heating circuit after receiving the high level and the low level of the comparator, and then the electric heating sheet works in the starting stage and stops working when the temperature reaches the expected temperature after the starting is completed; the control circuit can control the automatic start and stop of the electric heating sheet, and has the advantages of simple structure and strong anti-interference capability. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only represent some of the embodiments of the present disclosure, and all of the embodiments of the present disclosure can be obtained without creative labor on the basis of these drawings.

[0031] Figure 1 A structure schematic view of the leaf valve for a two-stroke aviation piston engine in the specific embodiment of the present utility model;

[0032] Figure 2 A structure schematic view of the elastic valve sheet in the specific embodiment of the present utility model;

[0033] Figure 3 A top view of the two-stroke aviation piston engine on which the leaf valve is installed in the specific embodiment of the present utility model;

[0034] Figure 4 A schematic view of the distribution position of the lead wire and the temperature sensor in the specific embodiment of the present utility model;

[0035] Figure 5 A schematic view of the installation mode of the temperature sensor in the specific embodiment of the present utility model (a sectional view in A-A direction); Figure 3

[0036] Wherein: 1, the body; 2, the air intake assembly; 3, the leaf valve; 31, the valve seat; 32, the elastic valve sheet; 33, the electric heating sheet; 34, the pressing plate; 35, the pressing plate bolt; 36, the through hole; 4, the temperature sensor; 5, the lead wire. DETAILED DESCRIPTION

[0037] The embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0038] The embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0039] ​It is to be understood that the embodiments described hereinbelow within the scope of the appended claims. It will be apparent to one of ordinary skill in the art that aspects described herein can be implemented differently, and that any structure and / or function described herein is merely illustrative. Based on the disclosure provided herein, one skilled in the art should appreciate that an aspect described herein can be implemented in combination with any other aspect described herein and that two or more aspects described herein can be combined in various manners. For example, an apparatus can be implemented and / or a method can be practiced using any number of the aspects set forth herein. In addition, such an apparatus can be implemented and / or such a method can be practiced using other structure and / or functionality in addition to or other than one or more of the aspects set forth herein.

[0040] It is also important to note that the drawings provided in the following embodiments are only schematic and represent basic concepts of the present disclosure. In the drawings, the shape, the number and the size of components are not drawn in accordance with actual implementation, and the shape, the number and the size of each component in actual implementation can be changed arbitrarily, and the layout of components can be more complex.

[0041] In addition, in the following description, specific details are provided to facilitate a thorough understanding of examples. However, one skilled in the art will understand that the aspects described can be practiced without these specific details.

[0042] In an embodiment of the present application, a reed valve for a two-stroke aviation piston engine is provided, as shown in the drawings, comprising: Figures 1-3

[0043] A valve seat 31 is installed at the air inlet of the body 1 of the aviation piston engine, and is provided with a one-way air inlet portion;

[0044] A valve body is fixed on the valve seat 31, and comprises at least one set of elastic valve sheets 32; the elastic valve sheets 32 are attached to the one-way air inlet portion, and open the one-way air inlet portion based on elasticity;

[0045] Wherein: the reed valve 3 further comprises a pressing plate 34 and a pressing plate bolt 35; the pressing plate bolt 35 is threadedly connected to the valve seat 31 after passing through the pressing plate 34 and the elastic valve sheet 32 in sequence;

[0046] An electric heating sheet 33 or an electric heating wire is arranged on the elastic valve sheet 32; the electric heating sheet 33 or the electric heating wire heats the mixed gas entering the air inlet during the starting stage of the aviation piston engine.

[0047] ​Due to the low speed during the cold start phase of the engine, the atomization effect of the fuel in the mixed gas is poor, and the temperature in the cylinder is low, the success rate of the spark plug ignition is low, and then the two-stroke aviation piston engine has a low start success rate. The valve seat 31 of the embodiment is made of metal material and is provided with a connecting lug. The valve seat 31 is fixed at the air inlet of the engine body 1 based on the connecting lug. The inlet is communicated with the output end of the engine air intake assembly 2 of the aviation piston engine, and the outlet is connected to the engine body 1. During the suction stroke of the aviation piston engine, the external airflow is mixed with the fuel in the engine air intake assembly 2 to form a mixed gas. The mixed gas reaches the inlet of the reed valve 3, and the temperature of the reed inlet is increased after being heated by the electric heating sheet 33, thereby improving the atomization effect. The elastic valve plate 32 is elastically deformed under the pressure of the mixed gas and opens the one-way air inlet part. The heated and further atomized mixed gas is more easily ignited in the cylinder. After the end of the suction stroke, the elastic valve plate 32 rebounds and closes the one-way air inlet part, waiting for the next suction stroke. Therefore, the reed valve of the two-stroke aviation piston engine of the embodiment can improve the start success rate of the aviation piston engine.

[0048] In the embodiment, in order to ensure the performance of the elastic valve plate 32 under high-frequency vibration state and avoid the fracture failure of the electric heating sheet 33 after metal fatigue, the elastic valve plate 32 includes a glass fiber film sheet and an electric heating sheet 33 embedded on the surface of the glass fiber film sheet. The glass fiber film sheet of the embodiment is externally provided with an inlay groove, and the electric heating sheet 33 is adhered in the inlay groove by high-temperature glue.

[0049] The base of the elastic valve plate 32 of the embodiment adopts a glass fiber film sheet which has excellent high-temperature resistance, high strength and good toughness. At the same time, the combination of the glass fiber film sheet and the electric heating sheet 33, the electric heating sheet 33 adopts rigidity or semi-rigidity (such as a thin film heater, a metal foil resistor or a conductive polymer heating layer), when the electric heating sheet 33 is attached to the glass fiber film sheet base with good mechanical properties, the main mechanical stress can be borne by the base to a certain extent, the bending stress of the heating layer is reduced, and the overall life is improved. Therefore, the elastic performance of the reed can still be maintained for a long time under the condition of high-frequency vibration of the engine; at the same time, compared with other heating methods, the electric heating sheet 33 has higher toughness under high-frequency vibration conditions, which can avoid fatigue fracture of the electric heating sheet 33 caused by high-frequency bending of the base of the glass fiber film sheet.

[0050] In the embodiment, as shown in Figure 1 In order to ensure the air intake and improve the heating area, the valve seat 31 is a V-shaped valve seat, and two one-way air inlet parts are formed on both sides. Two elastic valve plates 32 are respectively and oppositely attached to the outer sides of the two one-way air inlet parts. In the embodiment, in order to ensure the elastic performance of the elastic valve plate 32 under high-frequency vibration, the one-way air inlet part is divided into at least two air holes by at least one partition body; the elastic valve plate 32 includes a fixed part and a deformation part consistent with the number of air holes;

[0051] The pressing plate 34 and the pressing plate bolt 35 of the embodiment act on the fixed part; in the closed state of the reed valve 3, each deformation part blocks each air hole.

[0052] In the embodiment, as shown in the figure, in order to maintain the compactness of the structure of the reed valve 3, both lead ends of the electric heating sheet 33 are arranged on the fixed part, and are distributed in series along the edges of each deformation part in a labyrinth shape. Figure 2

[0053] In the embodiment, as shown in the figure, at least two through holes 36 are arranged on the glass fiber film, and each through hole 36 facilitates the passing of each pressing plate bolt 35. Figure 2

[0054] In the embodiment, in order to maintain the compactness of the structure of the reed valve 3, the lead end is annular, and is arranged at the outer periphery of the through hole 36 and is in conductive connection with the pressing plate bolt 35 passing through the through hole 36.

[0055] In the embodiment, the pressing plate 34 is made of insulating material, and the two ends of the electric heating sheet 33 are respectively connected to the two pressing plate bolts 35; the two pressing plate bolts 35 are respectively connected to the lead wire 5, as shown in the figure, the lead wire 5 passes through the valve seat 31 and the air inlet pipe pressing plate of the air inlet assembly 2 to reach the outside of the air inlet assembly 2, and then is connected to the power supply plug-in. Figure 4

[0056] The valve seat 31 is provided with a hole-equipped heat insulation pad block, and the lead wire 5 is fixed in the heat insulation pad block. The embodiment realizes reliable power supply of the electric heating sheet 33 without changing the overall structure of the two-stroke aviation piston engine and the installation mode of the reed valve 3.

[0057] Further, in order to realize the automatic working of the electric heating sheet 33 in the starting stage of the engine and the closing of the reed valve 3 at other times, the reed valve 3 further comprises a control circuit; the control circuit comprises a temperature sensor 4, a comparator, and a metal-oxide-semiconductor field effect transistor (MOSFET);

[0058] The temperature sensor 4 collects the temperature of the mixed gas at the outlet of the reed valve 3, and the signal output end is connected to the comparator;

[0059] The output end of the comparator is connected to the gate of the metal-oxide-semiconductor field effect transistor; the source of the metal-oxide-semiconductor field effect transistor is connected to the negative power supply (or ground power supply) of the aviation piston engine, and the drain is connected to the pressing plate bolt 35. The source of the MOSFET of the embodiment is electrically connected to the airborne power supply, and the drain is electrically connected to one end of the electric heating sheet 33.

[0060] ​​​The comparator of the embodiment determines whether to output a high level or a low level based on the voltage of the temperature sensor 4. The transistor controls the on and off of the heating circuit after receiving the high and low levels of the comparator, thereby realizing that the electric heating sheet 33 works in the starting stage and stops working when the temperature reaches the expected temperature after the starting is completed. Specifically,

[0061] The embodiment adopts LM35 as the temperature sensor 4. The output voltage of LM35 has a linear relationship with the temperature. The higher the temperature is, the higher the output voltage is. The embodiment presets 80℃ as the threshold temperature of the electric heating sheet 33. Therefore, the threshold voltage can be calculated based on the specific characteristics of LM35 (the typical output of LM35 is 10mV / ℃, so 80℃ corresponds to about 800mV).

[0062] The embodiment adopts LM393 chip as the comparator. The comparator has the function of outputting a high level or a low level based on the comparison of the reference voltage. In the initial stage, the threshold voltage is converted into a specific reference voltage value and input into the LM393 chip connected to the non-inverting input terminal of the LM393 chip. The output terminal of the LM35 is connected to the inverting input terminal of the LM393 chip.

[0063] In the embodiment, two pressure plate bolts 35 are electrically connected to two poles of the electric heating sheet 33 respectively. One of the two pressure plate bolts 35 is connected to the positive pole of the on-board power supply, and the other is connected to the drain of the MOSFET. In the starting stage of the engine, the temperature measured by the LM35 is lower than the threshold temperature, and the output voltage is lower than the threshold voltage. At this time, the voltage of the non-inverting input terminal (threshold voltage) of the LM393 is higher than the voltage of the inverting input terminal (the output of the LM35), the LM393 outputs a high level to the gate of the MOSFET, and the MOSFET turns on the source and the drain. At this time, the electric heating sheet 33 starts to work and improves the atomization effect of the fuel entering the cylinder of the aero-piston engine.

[0064] After the engine is started for a period of time, the temperature measured by the LM35 is higher than the threshold temperature, and the output voltage is higher than the threshold voltage. At this time, the voltage of the non-inverting input terminal (threshold voltage) of the LM393 is lower than the voltage of the inverting input terminal (the output of the LM35), the LM393 outputs a low level to the gate of the MOSFET, and the MOSFET turns off the source and the drain. At this time, the engine has been successfully started, the air intake assembly 2 has sufficient power to improve the atomization effect of the fuel, and further atomization is not needed. Therefore, the electric heating sheet 33 of the embodiment stops working at this time.

[0065] On this basis, the LM393 of the embodiment is an open collector output, and a pull-up resistor is connected to pull the output to the required high level to drive the gate. At the same time, the output level of the comparator matches the threshold voltage (Vgs) of the gate-source voltage of the low-side switch of the N-channel MOSFET, so as to ensure that the high level can turn on the MOSFET, and the low level (or open circuit) can turn off the MOSFET.

[0066] The control circuit of the embodiment abandons the single-chip microcomputer needing programming, uses the classical comparator circuit, has simple structure, low cost, strong anti-interference ability and is very stable in the harsh environment (such as engine vibration, temperature change).

[0067] In the embodiment, in order to keep the compactness of the aviation piston engine, the temperature sensor 4 is installed in the crankcase of the aviation piston engine, as shown in the figure. Figure 5 The crankcase of the embodiment does not contact the high-temperature gas, only contacts the mixed gas, the temperature range is in the working range of the LM35, and damage to the LM35 is avoided.

[0068] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A reed valve for a two-stroke aero-piston engine, characterized in that The application relates to an aviation piston engine valve seat and valve body. The valve seat is arranged at an air inlet of a body of the aviation piston engine and is provided with a one-way air inlet part. The valve body is fixed on the valve seat and comprises at least one set of elastic valve sheets; the elastic valve sheets are attached to the one-way air inlet part and open the one-way air inlet part based on elasticity when the aviation piston engine inhales air. The spring valve further comprises a pressing plate and a pressing plate bolt; the pressing plate bolt is sequentially threaded through the pressing plate and the elastic valve sheet and is connected to the valve seat; an electric heating wire or an electric heating sheet is arranged on the elastic valve sheet; the electric heating wire or the electric heating sheet is used for heating mixed gas entering the air inlet during a starting stage of the aviation piston engine.

2. The reed valve for a two-stroke aero-piston engine according to claim 1, characterised in that, The elastic valve sheet comprises a glass fiber film sheet and an electric heating sheet embedded on a surface of the glass fiber film sheet.

3. The reed valve of a two-stroke aero-piston engine according to claim 2, characterized in that, The valve seat is a V-shaped valve seat, two sides of which are respectively provided with two one-way air inlet parts; two elastic valve sheets are respectively attached to the outer sides of the two one-way air inlet parts.

4. The reed valve of a two-stroke aero-piston engine according to claim 3, characterized in that, The one-way air inlet part is divided into at least two air holes by at least one partition body; the elastic valve sheet comprises a fixed part and a deformation part consistent with the number of the air holes; The pressing plate and the pressing plate bolt act on the fixed part; in a closed state of the spring valve, each deformation part blocks each air hole.

5. The reed valve of a two-stroke aero-piston engine according to claim 4, characterized in that, Both lead ends of the electric heating sheet are arranged on the fixed part; the electric heating sheet is continuously distributed along edges of each deformation part in a labyrinth shape.

6. The reed valve of a two-stroke aero-piston engine according to claim 5, characterized in that, At least two through holes are arranged on the fixed part; each through hole is convenient for each pressing plate bolt to pass through.

7. The reed valve of a two-stroke aero-piston engine according to claim 6, characterized in that The lead end is annular and is arranged at an outer periphery of the through hole; the lead end is in conductive connection with the pressing plate bolt passing through a center of the annular lead end.

8. The reed valve of a two-stroke aero-piston engine according to claim 7, characterized in that The pressing plate bolt is electrically connected with a lead wire; the lead wire sequentially passes through the valve seat and an air inlet pipe pressing plate of an air inlet assembly of the aviation piston engine and reaches outside the air inlet assembly; one end of the lead wire away from the pressing plate bolt is connected with an electric plug.

9. The reed valve of a two-stroke aero-piston engine according to claim 8, characterized in that, The spring valve further comprises a control circuit; the control circuit comprises a temperature sensor, a comparator and a metal-oxide-semiconductor field effect transistor; The temperature sensor collects a mixed gas temperature at an outlet of the spring valve and is electrically connected with a signal output end of the comparator; An output end of the comparator is connected with a gate of the metal-oxide-semiconductor field effect transistor; a source of the metal-oxide-semiconductor field effect transistor is connected with a negative electrode of a power supply of the aviation piston engine and a drain is connected with the pressing plate bolt.

10. A reed valve for a two-stroke aero-piston engine according to claim 9, characterized in that The temperature sensor is arranged in a crankcase of the aviation piston engine.

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