A constant volume bomb for opposed piston two-stroke engine experiments

Abstract

The present invention belongs to the technical field of thermal engines and relates to a constant volume bomb for combustion experiments of an opposed piston two-stroke engine. It includes an injector, an injector block, a bomb body, six heating rods, two heating plates, two flange plates, four support seats, two combustion chamber modules, six ignition negative electrodes, an ignition positive electrode, three thermocouples and a cylinder pressure sensor. The constant volume bomb can highly reproduce the environmental parameters (combustion chamber shape, cylinder volume) in the cylinder of an opposed piston two-stroke engine, so as to simulate the actual combustion process in the cylinder of an opposed piston two-stroke engine. It can be used to study the influence of ignition parameters (ignition advance angle, ignition position) on the combustion process of an opposed piston two-stroke engine, and can be used for the parametric design of the combustion chamber of an opposed piston two-stroke engine to study the influence of different combustion chamber shapes on the actual combustion process.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal engines, and relates to a constant volume bomb for combustion experiments of an opposed piston two-stroke engine. Specifically, it is an experimental device that can highly simulate the in-cylinder environment (pressure, temperature, composition, combustion chamber shape, cylinder volume) of an opposed piston two-stroke engine, and can test and experiment on the effects of different combustion chamber parameters and ignition parameters on fuel spray, combustion process and various characteristics, providing data verification for the design of the combustion chamber shape and the determination of ignition parameters of an opposed piston two-stroke engine. Background Technique

[0002] Currently, four-stroke engines are commonly used in the field of vehicle and ship power. Four-stroke engines are relatively large in volume, complex in structure, have a low power-to-weight ratio, and poor compactness. The opposed piston two-stroke engine eliminates the cylinder head and valve structure, and the opposed pistons are arranged in the same cylinder, greatly improving the compactness and power-to-weight ratio. The opposed piston two-stroke engine eliminates the traditional cylinder head structure, and the combustion chamber is composed of the top surfaces of the opposed pistons. The fuel injector and the spark plug are both arranged on the cylinder wall. This arrangement form increases the flame propagation distance and is more demanding for the formation of the air-fuel mixture and the propagation of the flame. To further improve the compactness and power-to-weight ratio of the engine, the fuel injector and the spark plug can be arranged on the same side of the cylinder wall, resulting in most of the fuel sprayed by the fuel injector being on the opposite side of the spark plug. When igniting, the air-fuel mixture concentration near the spark plug is relatively lean, and the outer layer air-fuel mixture is relatively rich, which leads to problems such as unstable ignition and slow flame propagation speed. Therefore, when developing an opposed two-stroke engine, the most important part is the design of the combustion chamber shape and ignition parameters (ignition advance angle, ignition position). And to design the combustion chamber shape and determine the ignition parameters, a large number of spray and combustion experiments need to be carried out. Therefore, it is necessary to develop an experimental device that can simulate the in-cylinder spray and combustion of an opposed piston two-stroke engine.

[0003] A constant volume bomb is an experimental device for simulating engine combustion, which can efficiently simulate the temperature and pressure at each crankshaft angle of the engine and the combustion situation in the combustion chamber, and can accurately control various thermodynamic parameters to quantitatively study the influence of each parameter on the spray characteristics of the engine fuel injector. As the main device for studying the combustion characteristics of fuel spray, the constant volume bomb has obvious advantages.

[0004] The internal structure and volume of the constant volume bomb in the prior art are fixed, and it can only purely conduct experimental research on fuel spray and combustion, unable to reflect the real combustion process of fuel in the engine cylinder, let alone be used to simulate the real spray and combustion process in the cylinder of an opposed piston two-stroke engine, unable to study the influence of the combustion chamber parameters of the opposed piston two-stroke engine on the spray and combustion process, unable to provide guidance for the design and optimization of the combustion chamber structure of the opposed piston two-stroke engine, and unable to study the influence of the ignition parameters (ignition position, ignition advance angle) of the opposed piston two-stroke engine on the combustion process. Summary of the Invention

[0005] Aiming at the problems existing in the existing constant volume bomb, the present invention proposes a constant volume bomb for spray and combustion experiments of an opposed piston two-stroke engine. The constant volume bomb of the present invention can solve the problem that the constant volume bomb in the prior art can only conduct test measurements of fuel spray and combustion in a specific fixed volume, unable to highly reproduce the environmental parameters (combustion chamber shape, cylinder volume) in the cylinder of the opposed piston two-stroke engine, and thus unable to simulate the real combustion process in the cylinder of the opposed piston two-stroke engine.

[0006] The technical solution of the present invention is:

[0007] A constant volume bomb for experiments of an opposed piston two-stroke engine, the constant volume bomb includes an injector, an injector chuck, a bomb body, six heating rods, two heating plates, two flange plates, four support seats, two combustion chamber modules, six ignition negative electrodes, an ignition positive electrode, three thermocouples, and a cylinder pressure sensor; the two heating plates are respectively heating plate a and heating plate b, the two flange plates are respectively flange plate a and flange plate b, and the two combustion chamber modules are respectively combustion chamber module a and combustion chamber module b;

[0008] The projectile body is a hollow cylinder. The wall thickness at both ends of the hollow cylinder is less than that of the middle part. That is, the hollow cylinder is divided into three parts: the left end part, the middle part, and the right end part. The wall thickness of the left end part is the same as that of the right end part, and the wall thickness of the middle part is greater than that of the left end part or the right end part. The combustion chamber module a is placed in the cavity of the left end part of the projectile body and extends to the middle part of the projectile body. The combustion chamber module b is placed in the cavity of the right end part of the projectile body and extends to the middle part of the projectile body. There is a gap between the inner surface (i.e., the surface facing the middle part of the projectile body) of the combustion chamber module a and the inner surface of the combustion chamber module b. The size of the gap is 2 - 4 mm, and this gap is the combustion chamber. A circular groove a is formed on the outer surface of the combustion chamber module a, and the heating plate a is placed in the circular groove a on the outer surface of the combustion chamber module a. A circular groove b is formed on the outer surface of the combustion chamber module b, and the heating plate b is placed in the circular groove b on the outer surface of the combustion chamber module b. The flange a is fixedly connected to the left end face of the projectile body by bolts, and the heating plate a does not contact the inner surface of the flange a. The flange b is fixedly connected to the right end face of the projectile body by bolts, and the heating plate b does not contact the inner surface of the flange b. That is, the combustion chamber module is fixed and sealed by being pressed against the projectile body by the flange. The heating plate a is used to heat the combustion chamber module a, and the heating plate b is used to heat the combustion chamber module b.

[0009] A cavity enclosed by the inner surface of the combustion chamber module a, the inner surface of the combustion chamber module b, and the inner surface of the middle part of the projectile body is the combustion chamber.

[0010] There is a notch on the side of the projectile body. A plane is formed at the notch, and this plane is perpendicular to the two circular surfaces of the projectile body. The fuel injector is fixedly connected to this plane through a fuel injector block. The fuel injector is used to inject fuel into the gap formed by the top surfaces of the two combustion chamber modules inside the projectile body, that is, into the combustion chamber.

[0011] The ignition negative electrode is a metal cylinder with a bottom diameter of 2 - 4 mm and a height of 6 - 10 mm. One ends of six ignition negative electrodes are installed on the inner wall of the central part of the projectile body through threads and are evenly distributed at 60 degrees. The other ends of the six ignition negative electrodes extend into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b. The ignition positive electrode is installed on the side of the projectile body through threads. One end extends into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b, and the other end is outside the projectile body.

[0012] One end of the ignition positive electrode that extends into the gap formed between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b is made of copper. Since the material of copper is relatively soft, it can be manually placed in any position. This end of the ignition positive electrode is placed near any one of the ignition negative electrodes to generate an electric spark to ignite the mixture.

[0013] The described support base is a cylinder with a bottom diameter of 14 - 24 mm and a height of 40 - 60 mm, and has an external thread. It is installed on the side of the projectile through the thread to support the projectile.

[0014] There is a through - hole penetrating the projectile on the circular surface of the projectile. This through - hole passes through the injector mounting hole and is perpendicular to it. Both ends of the through - hole have internal threads for installing cooling water pipes. Cooling water is introduced into the injector mounting hole to cool the injector, preventing it from operating unstably due to excessive temperature.

[0015] The side of the described projectile is provided with exhaust holes for exhaust gas emission and intake holes for filling fresh gas.

[0016] The six heating rods and the cylinder pressure sensor are installed on the side of the projectile to heat the projectile and measure the gas pressure in the combustion chamber.

[0017] Three thermocouples are also installed on the projectile. The three thermocouples are installed on the side of the projectile through NPT1 / 4 threads. One of the thermocouples extends into the gap formed by the inner surfaces of the combustion chamber module a and the combustion chamber module b to measure the gas temperature in the combustion chamber, and the other two thermocouples are used to measure the temperature of the projectile.

[0018] Two flange plates are respectively connected to the projectile using six bolts to compress and fix the combustion chamber module on the projectile. A graphite gasket is placed between the contact surfaces of the projectile and the combustion chamber module to achieve a sealing effect.

[0019] The projectile and the combustion chamber module are the main heat - receiving components. The material is 316 stainless steel that can withstand a high temperature of 1500K. The materials of the flange plate, the injector clamp, and the support base are 45 - steel. The material of the heating plate 5 is brass, with a maximum power of 700W and a maximum heating temperature of 800K.

[0020] Beneficial effects

[0021] (1) The structural setting of the constant - volume bomb of the present invention matches the structure of the opposed - piston two - stroke engine, and can highly simulate the in - cylinder environmental parameters (combustion chamber shape, cylinder volume, temperature, pressure, composition) of the opposed - piston two - stroke engine, thus highly restoring the real combustion process in the engine cylinder.

[0022] (2) The constant - volume bomb of the present invention can be used to study the influence of ignition parameters (ignition advance angle, ignition position) on the combustion process of the opposed - piston two - stroke engine.

[0023] (3) The constant - volume bomb of the present invention changes the combustion chamber volume by adjusting the distance between the inner surfaces of the combustion chamber module a and the combustion chamber module b to simulate the cylinder volume of the opposed - piston two - stroke engine at different ignition advance angles.

[0024] (4) The constant volume bomb of the present invention simulates different ignition positions by adjusting the discharge between the ignition positive electrode and the ignition negative electrodes at different positions.

[0025] (5) The constant volume bomb of the present invention adopts a separated design of the combustion chamber module. The combustion chamber module can be replaced arbitrarily on the premise of meeting the basic dimensions of the bomb.

[0026] (6) The inner surfaces of the two combustion chamber modules of the constant volume bomb of the present invention can be processed into different shapes to form combustion chambers of different shapes. Moreover, the combustion chamber module can rotate relative to the bomb body to adjust the relative position with the fuel injector. Therefore, it can be used for the parametric design of the combustion chamber of an opposed piston two-stroke engine to study the influence of different combustion chamber shapes on the actual combustion process.

[0027] (7) The intake and exhaust pipes, thermocouples, heating rods, and cylinder pressure sensors of the constant volume bomb of the present invention are integrally installed on the bomb body, which has the advantages of compact structure and small volume. The two combustion chamber modules are placed opposite to each other, and the fuel injector and ignition electrodes are installed on the inner wall of the bomb body, highly restoring the actual structure of the opposed piston two-stroke engine. Description of the Drawings

[0028] Figure 1 is a schematic three-dimensional structure diagram of the constant volume bomb of the present invention;

[0029] Figure 2 is a vertical circular sectional view of the constant volume bomb of the present invention;

[0030] Figure 3 is a central circular sectional view of the bomb body of the constant volume bomb of the present invention. Detailed Embodiment

[0031] The present invention will be further described below with reference to the drawings and embodiments.

[0032] Embodiment

[0033] As Figures 1-3 shown, a constant volume bomb for experiments on an opposed piston two-stroke engine, the constant volume bomb includes a fuel injector 1, a fuel injector clamp 2, a bomb body 3, six heating rods 4, two heating plates 5, two flange plates 6, four support seats 7, two combustion chamber modules 8, six ignition negative electrodes 9, an ignition positive electrode 10, three thermocouples 11, and a cylinder pressure sensor 12; the two heating plates 5 are respectively a heating plate a and a heating plate b, the two flange plates 6 are respectively a flange plate a and a flange plate b, and the two combustion chamber modules 8 are respectively a combustion chamber module a and a combustion chamber module b;

[0034] The projectile 3 is a hollow cylinder. The wall thickness at both ends of the hollow cylinder is less than that of the middle part, that is, the hollow cylinder is divided into three parts: the left end part, the middle part, and the right end part. The wall thickness of the left end part is the same as that of the right end part, and the wall thickness of the middle part is greater than that of the left end part or the right end part; the combustion chamber module a is placed in the cavity of the left end part of the projectile 3 and extends to the middle part of the projectile 3, and the combustion chamber module b is placed in the cavity of the right end part of the projectile 3 and extends to the middle part of the projectile 3. There is a gap between the inner surface of the combustion chamber module a (i.e., the surface facing the middle part of the projectile 3) and the inner surface of the combustion chamber module b. The size of the gap is 3 mm, and this gap is the combustion chamber; a circular groove a is opened on the outer surface of the combustion chamber module a, and the heating plate a is placed in the circular groove a on the outer surface of the combustion chamber module a. A circular groove b is opened on the outer surface of the combustion chamber module b, and the heating plate b is placed in the circular groove b on the outer surface of the combustion chamber module b. The flange a is fixedly connected to the left end face of the projectile 3 by bolts, and the heating plate a does not contact the inner surface of the flange a. The flange b is fixedly connected to the right end face of the projectile 3 by bolts, and the heating plate b does not contact the inner surface of the flange b; that is, the combustion chamber module 8 is fixed and sealed by being pressed against the projectile 3 by the flange 6; the heating plate a is used to heat the combustion chamber module a, and the heating plate b is used to heat the combustion chamber module b;

[0035] A cavity surrounded by the inner surface of the combustion chamber module a, the inner surface of the combustion chamber module b, and the inner surface of the middle part of the projectile 3 is the combustion chamber;

[0036] A notch is provided on the side surface of the projectile 3, and a plane is formed at the notch. This plane is perpendicular to the two circular surfaces of the projectile. The fuel injector 1 is fixedly connected to this plane through the fuel injector chuck 2. The fuel injector 1 is used to inject fuel into the gap formed by the top surfaces of the two combustion chamber modules 8 inside the projectile 3, that is, into the combustion chamber;

[0037] The ignition negative electrode 9 is a metal cylinder with a bottom diameter of 3 mm and a height of 8 mm. One ends of the six ignition negative electrodes 9 are installed on the inner wall of the central part of the projectile 3 by threads and are evenly distributed at 60 degrees. The other ends of the six ignition negative electrodes 9 extend into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b. The ignition positive electrode 10 is installed on the side surface of the projectile 3 by threads. One end extends into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b, and the other end is outside the projectile;

[0038] One end of the ignition positive electrode 10 that extends into the gap formed between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b is made of copper. Since the material of copper is relatively soft, it can be manually placed in any position. Place this end of the ignition positive electrode 10 near any one of the ignition negative electrodes 9 to generate an electric spark to ignite the mixture;

[0039] The described support base 7 is a cylinder with a bottom diameter of 20 mm and a height of 50 mm and has an external thread, and is installed on the side of the projectile body 3 through the thread for supporting the projectile body.

[0040] There is a through hole penetrating the projectile body on the circular surface of the projectile body 3. This through hole passes through the fuel injector mounting hole and is perpendicular to it. There are internal threads at both ends of the through hole for installing the cooling water pipe. Cooling water is introduced into the mounting hole of the fuel injector 1 to cool the fuel injector 1 by water cooling to prevent it from working unstably due to excessive temperature.

[0041] The side of the described projectile body 3 is provided with exhaust holes for exhaust gas emission and intake holes for filling fresh gas.

[0042] The six heating rods 4 and the cylinder pressure sensor 12 are installed on the side of the projectile body 3 to heat the projectile body 3 and measure the gas pressure in the combustion chamber.

[0043] Three thermocouples 11 are also installed on the projectile body 3. The three thermocouples are installed on the side of the projectile body 3 through NPT1 / 4 threads. One of the thermocouples extends into the gap formed by the inner surfaces of the combustion chamber module a and the combustion chamber module b to measure the gas temperature in the combustion chamber, and the other two thermocouples are used to measure the temperature of the projectile body 3.

[0044] Two flange plates 6 are respectively connected to the projectile body 3 using six bolts to press and fix the combustion chamber module 8 on the projectile body 3. A graphite gasket is placed between the contact surfaces of the projectile body 3 and the combustion chamber module 8 to achieve a sealing effect.

[0045] The projectile body 3 and the combustion chamber module 8 are the main heat-receiving components, and the material is 316 stainless steel resistant to a high temperature of 1500K. The materials of the flange plate 6, the fuel injector block 2 and the support base 7 are 45 steel, and the material of the heating plate 5 is brass. The maximum power is 700W and the maximum heating temperature is 800K.

[0046] As described above, only the preferred embodiments of the present invention are given, and are not used to limit the implementation manner and protection scope of the present invention. Those skilled in the art should be able to realize that all equivalent replacements and obvious changes made by using the description and illustration content of the present invention should be included within the protection scope of the present invention.

Claims

1. A constant volume bomb for the experiment of an opposed piston two-stroke engine, characterized in that: The constant volume bomb includes an injector (1), an injector block (2), a bomb body (3), two heating plates (5), two combustion chamber modules (8), six ignition negative electrodes (9), and an ignition positive electrode (10); the two heating plates (5) are respectively a heating plate a and a heating plate b, and the two combustion chamber modules (8) are respectively a combustion chamber module a and a combustion chamber module b; The bomb body (3) is a hollow cylinder, and the wall thickness at both ends of the hollow cylinder is smaller than the wall thickness of the middle part, that is, the hollow cylinder is divided into three parts, a left end part, a middle part, and a right end part. The wall thickness of the left end part is the same as that of the right end part, and the wall thickness of the middle part is greater than that of the left end part or the right end part; The combustion chamber module a is placed in the cavity of the left end part of the bomb body (3) and extends to the middle part of the bomb body (3). The combustion chamber module b is placed in the cavity of the right end part of the bomb body (3) and extends to the middle part of the bomb body (3). There is a gap between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b. A circular groove a is opened on the outer surface of the combustion chamber module a, and the heating plate a is placed in the circular groove a on the outer surface of the combustion chamber module a. A circular groove b is opened on the outer surface of the combustion chamber module b, and the heating plate b is placed in the circular groove b on the outer surface of the combustion chamber module b; A notch is provided on the side surface of the bomb body (3), and a plane is formed at the notch, and this plane is perpendicular to the two circular surfaces of the bomb body. The injector (1) is fixedly connected to this plane through the injector block (2), and the injector (1) is used to inject fuel into the combustion chamber inside the bomb body (3); The six ignition negative electrodes (9) and the ignition positive electrode (10) are installed on the bomb body (3).

2. The constant volume bomb for the experiment of an opposed piston two-stroke engine according to claim 1, characterized in that: The size of the gap between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b is 2-4 mm; A cavity surrounded by the inner surface of the combustion chamber module a, the inner surface of the combustion chamber module b, and the inner surface of the middle part of the bomb body (3) is the combustion chamber.

3. The constant volume bomb for the experiment of an opposed piston two-stroke engine according to claim 1 or 2, characterized in that: The ignition negative electrode (9) is a metal cylinder, the diameter of the metal cylinder is 2-4 mm, and the height is 6-10 mm. One end of the six ignition negative electrodes (9) is installed on the inner wall of the central part of the bomb body (3) by threads and is evenly distributed at 60 degrees. The other ends of the six ignition negative electrodes (9) extend into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b; The ignition positive electrode (10) is installed on the side surface of the bomb body (3) by threads. One end of the ignition positive electrode (10) extends into the gap formed by the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b, and the other end is outside the bomb body; One end of the ignition positive electrode (10) extending into the gap formed between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b is made of copper. This copper end of the ignition positive electrode (10) is placed near any ignition negative electrode (9) to generate an electric spark to ignite the air-fuel mixture.

4. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 1, characterized in that: The constant volume bomb further includes a support seat (7). The support seat (7) is a cylinder with an external thread. The bottom diameter of the cylinder is 14 - 24 mm, and the height is 40 - 60 mm. The support seat (7) is installed on the side of the bomb body (3) through the thread to support the bomb body.

5. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 4, characterized in that: There is a through hole penetrating the bomb body on the circular surface of the bomb body (3). This through hole passes through the injector mounting hole and is perpendicular to it. Both ends of the through hole have internal threads for installing cooling water pipes, and cooling water is introduced into the mounting hole of the injector (1) to perform water cooling on the injector (1); The side of the bomb body (3) is provided with an exhaust hole for exhaust gas emission and an intake hole for filling fresh gas.

6. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 5, characterized in that: The constant volume bomb further includes six heating rods (4) and a cylinder pressure sensor (12). The six heating rods (4) and the cylinder pressure sensor (12) are installed on the side of the bomb body (3) to heat the bomb body (3) and measure the gas pressure in the combustion chamber.

7. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 5 or 6, characterized in that: The constant volume bomb further includes three thermocouples. The three thermocouples are installed on the side of the bomb body (3) through NPT1 / 4 threads. One of the thermocouples extends into the gap formed between the inner surface of the combustion chamber module a and the inner surface of the combustion chamber module b to measure the gas temperature in the combustion chamber, and the other two thermocouples are used to measure the temperature of the bomb body (3).

8. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 7, characterized in that: The constant volume bomb further includes two flange plates (6). The two flange plates (6) are respectively connected to the bomb body (3) using six bolts to tightly fix the combustion chamber module (8) on the bomb body (3). A graphite gasket is placed between the contact surfaces of the bomb body (3) and the combustion chamber module (8).

9. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 8, characterized in that: The materials of the bomb body (3) and the combustion chamber module (8) are 316 stainless steel resistant to a high temperature of 1500K.

10. A constant volume bomb for an opposed-piston two-stroke engine experiment according to claim 8, characterized in that: The materials of the flange plate (6), the injector clamp (2) and the support seat (7) are 45 steel, and the material of the heating plate (5) is brass. The maximum power is 700W and the maximum heating temperature is 800K.

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