An aero-piston engine
By controlling the intake, scavenging, and exhaust ports with pistons, the problems of incomplete fuel combustion and increased engine size and weight are solved, resulting in more efficient fuel combustion and improved engine performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHONGQING ZONGSHEN AERO ENGINE MFG CO LTD
- Filing Date
- 2025-06-27
- Publication Date
- 2026-07-10
Smart Images
Figure CN224478980U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to aircraft piston engines. Background Technology
[0002] An aircraft piston engine is an engine that uses the combustion of fuel in the cylinder to drive the piston, which in turn rotates the crankshaft via a connecting rod mechanism to output power. In existing aircraft piston engines, air is introduced into the intake port through an intake manifold connected to the outside environment. From there, air is introduced into the crankcase, where it enters the cylinder through a scavenging port to mix with fuel for combustion. As the piston moves towards the crankcase under the pressure of the combusted gases in the cylinder, it compresses the air in the crankcase, making it easier for air to escape through the intake port. This can lead to insufficient air entering the cylinder later, resulting in incomplete combustion. Therefore, current technology typically installs a reed valve on the intake manifold connected to the intake port to prevent air from escaping from the crankcase. Because reed valves have a certain weight and size, an installation interface for them is required on the engine. This results in a large and heavy engine. With the increasingly demanding requirements for aircraft piston engines, this design is no longer sufficient.
[0003] Chinese patent document CN113915037A discloses a two-stroke engine with a dual-injection system, including an engine control unit (ECU), cylinders, pistons, a combustion chamber, a crankcase, a crankshaft connecting rod mechanism, a marker device, an intake manifold, an intake port connected to an external intake manifold, a scavenging port, and an exhaust port, as well as a pressure fuel supply system, a fuel supply device, and a spark ignition device. The piston is installed inside the cylinder and engages with the cylinder wall. The piston is connected to the crankshaft connecting rod mechanism and reciprocates with it, thereby controlling the opening and closing of the intake port and the scavenging port. The exhaust port is controlled by a piston valve. The scavenging port is located inside the cylinder and is used to introduce crankcase gases into the combustion chamber for exhaust scavenging. The main working process of this engine is as follows: When the piston is at bottom dead center (B), the intake port is closed by the piston, and the exhaust port and scavenging port are open. Exhaust gases are discharged from the combustion chamber, and gases from the crankcase enter the cylinder through the scavenging port to remove residual exhaust gases. As the piston moves to top dead center (TDC) A, the crankcase volume increases. The piston continues to move, and its head closes the scavenging port, creating a vacuum in the crankcase. Some gas is still forced out of the combustion chamber, and the scavenging process ends as the exhaust port closes. The combustible mixture in the combustion chamber begins to be compressed. During the latter part of the piston's upward stroke, the intake port opens, and intake gas passes through the throttle body and enters the crankcase through the intake port. When the piston reaches top dead center (TDC) A, the compression process ends. The intake process continues until the intake port closes during the next piston stroke. At the end of the compression process, the exhaust port and scavenging port are closed, and the intake port is open. At this time, the spark ignition device generates an electric spark, igniting the combustible mixture in the combustion chamber, and the combustion gases expand to do work. As the piston moves downward, the piston skirt closes the intake port. As the piston continues to move to bottom dead center (B), the crankcase volume decreases, and the gas within is pre-compressed. Simultaneously, the exhaust port opens, and the expanded combustion gases, now waste gases, are discharged through the exhaust port, marking the end of the power stroke and the beginning of the exhaust process. Subsequently, the piston head opens the scavenging port, allowing pre-compressed gas to enter the combustion chamber from the crankcase through the scavenging port, removing any remaining waste gases. This process continues until the exhaust port is closed during the next piston stroke.
[0004] Although the aforementioned prior art eliminates the need for a reed valve to prevent air from the crankcase from being discharged through the intake port, thus solving the problem of large size and weight in aircraft piston engines caused by the use of reed valves, it has been found in actual use that this prior art solution is still prone to incomplete fuel combustion. Utility Model Content
[0005] The purpose of this invention is to provide an aviation piston engine to solve the problem of incomplete fuel combustion that is common in existing aviation piston engines.
[0006] To achieve the above objectives, the basic solution of this utility model provides an aircraft piston engine, including a cylinder block, a piston, and a crankcase. The cylinder block is provided with a cylinder bore that mates with the piston. One end of the cylinder block is connected to the crankcase, and one end of the cylinder bore is connected to the crankcase. An intake port, a scavenging port, and an exhaust port are arranged circumferentially on the cylinder block around the cylinder bore. The scavenging port is connected to the crankcase through an air passage located outside the cylinder bore. The piston controls the opening and closing of the intake port, the scavenging port, and the exhaust port by moving along the cylinder bore. The stroke segment of the piston corresponding to the intake port is located on the side of the stroke segment of the piston corresponding to the exhaust port, close to the bottom dead center of the piston. The lower part of the stroke segment of the piston corresponding to the scavenging port coincides with the lower part of the stroke segment of the piston corresponding to the exhaust port. Furthermore, the distance from the upper edge of the exhaust port to the lower edge of the intake port is not greater than the length of the piston.
[0007] The beneficial effects of this basic scheme are as follows: By using the movement of the piston to control the opening and closing of the intake port, scavenging port, and exhaust port, there is no need to set up a separate reed valve to prevent a large amount of air in the crankcase from being discharged from the intake port, thus avoiding the problem of increased size and weight of the aero piston engine; at the same time, during the process of the piston moving from top dead center to bottom dead center, the piston first closes the intake port and then gradually opens the exhaust port. After opening the exhaust port partially, it gradually opens the scavenging port at the same time, so that the opening degree of the exhaust port and the scavenging port increases synchronously, causing the pressure in the cylinder bore at the exhaust port to continuously decrease. This allows the air entering the cylinder bore at the scavenging port to smoothly compress the exhaust gas in the cylinder bore toward the exhaust port, thereby reducing the amount of residual exhaust gas in the cylinder bore. Compared with the existing technology CN113915037A, which uses the method of fully opening the exhaust port first and then opening the scavenging port, which easily leads to increased pressure at the exhaust port and exhaust obstruction, this reduces the problem of turbulence of exhaust gas in the cylinder bore, resulting in a large amount of residual exhaust gas in the cylinder bore and affecting fuel combustion.
[0008] Preferably, the intake port and exhaust port are located on opposite sides of the cylinder bore. This arrangement reduces the mutual restriction between the intake and exhaust ports, thereby improving the smoothness of air intake and exhaust in the cylinder block and further enhancing fuel combustion efficiency.
[0009] Preferably, four air exchange ports are provided, and two of them are symmetrically arranged with respect to the plane formed by the center lines of the intake and exhaust ports. This arrangement ensures that the intake, exhaust, and air exchange ports are located at different positions within the cylinder bore, reducing mutual interference during installation and facilitating cylinder block machining. Simultaneously, the multiple air exchange ports allow air to quickly fill the cylinder bore space upon entering, compressing the exhaust gases and facilitating their discharge, thus further improving fuel combustion efficiency.
[0010] Preferably, all four air scavenging ports face the side of the cylinder bore closest to the intake port. This arrangement ensures that the air entering the cylinder bore from the air scavenging ports first occupies the space on the side closest to the intake port, thus better compressing the exhaust gas towards the exhaust port. This helps to further reduce the amount of residual exhaust gas in the cylinder bore, thereby further improving fuel combustion efficiency.
[0011] Preferably, the exhaust port extends downward at an angle, and the orientation of the exhaust port forms an angle of 60°-70° with the axis of the cylinder bore. This arrangement facilitates smoother exhaust gas flow, thereby further improving fuel combustion efficiency.
[0012] Preferably, when the piston is at bottom dead center, the top edge of the piston is flush with the lower edge of the exhaust port. This arrangement guides the exhaust gas towards the exhaust port using the top of the piston, facilitating its discharge and further improving fuel combustion efficiency.
[0013] This utility model has the following beneficial effects:
[0014] By adopting the solution of this utility model, the aircraft piston engine can achieve more thorough exhaust gas discharge in the cylinder without increasing its size and weight, reducing the amount of residual exhaust gas, thereby improving the combustion efficiency of fuel and thus improving the performance of the engine. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of an embodiment of an aircraft piston engine according to the present invention;
[0016] Figure 2 for Figure 1 A schematic diagram of the cylinder block. Detailed Implementation
[0017] As those skilled in the art know, the top dead center (TDC) of a piston refers to the position where the piston crown is at its maximum distance from the crankshaft center. The bottom dead center (BDC) of a piston refers to the position where the piston crown is at its minimum distance from the crankshaft center.
[0018] In this invention, the piston stroke segment refers to the cylindrical space segment traversed by the piston as it moves within the cylinder bore. The piston stroke segment corresponding to the intake port refers to the space segment traversed by the piston between the upper and lower edges of the intake port and the corresponding cross-sections of the cylinder bore. Similarly, the piston stroke segment corresponding to the exhaust port refers to the space segment traversed by the piston between the upper and lower edges of the exhaust port and the corresponding cross-sections of the cylinder bore. The piston stroke segment corresponding to the scavenging port refers to the space segment traversed by the piston between the upper and lower edges of the scavenging port and the corresponding cross-sections of the cylinder bore.
[0019] The angle α between the direction of the exhaust port and the axis of the cylinder bore can be 60°, 61°, 62°, 63°, 64°, 66°, 67°, 69°, 70°, etc.
[0020] The following detailed description illustrates the specific implementation method:
[0021] The reference numerals in the accompanying drawings include: cylinder block 1, cylinder bore 2, exhaust port 3, air intake port 4, piston 5, intake port 6, connecting rod 7, and crankcase 8.
[0022] The basic implementation examples are as follows: Figure 1 and Figure 2 As shown: An aircraft piston engine includes a cylinder block 1, a piston 5 and a crankcase 8. One end of the cylinder block 1 is connected to the crankcase 8. The cylinder block 1 is provided with a cylinder bore 2 that mates with the piston 5. One end of the cylinder bore 2 is connected to the crankcase 8. A crankshaft (not shown) is provided inside the crankcase 8. The crankshaft is connected to the piston 5 through a connecting rod 7. The crankshaft is driven to rotate by the reciprocating motion of the piston 5 in the cylinder bore 2.
[0023] The cylinder block 1 has an intake port 6, a scavenging port 4, and an exhaust port 3 arranged circumferentially around the cylinder bore 2. The scavenging port 4 is connected to the crankcase 8 through an air passage located outside the cylinder bore 2. The piston 5 controls the opening and closing of the intake port 6, the scavenging port 4, and the exhaust port 3 by moving along the cylinder bore 2. The stroke segment of the piston 5 corresponding to the intake port 6 is located on the side of the stroke segment of the piston 5 corresponding to the exhaust port 3, which is close to the bottom dead center of the piston 5. The stroke segment of the piston 5 corresponding to the scavenging port 4 coincides with the lower part of the stroke segment of the piston 5 corresponding to the exhaust port 3. Furthermore, the distance from the upper edge of the exhaust port 3 to the lower edge of the intake port 6 is not greater than the length of the piston 5.
[0024] In this embodiment, the intake port 6 and the exhaust port 3 are located on opposite sides of the cylinder bore 2. The exhaust port 3 extends downward at an angle, and the angle α between the orientation of the exhaust port 3 and the axis of the cylinder bore 2 is 65°. When the piston 5 is at bottom dead center (e.g. Figure 1 (As shown in the diagram), the top edge of piston 5 is flush with the lower edge of exhaust port 3. Four air intake ports 4 are provided, and two of them are symmetrically arranged with respect to the plane formed by the center lines of intake port 6 and exhaust port 3. All four air intake ports 4 face the side of cylinder bore 2 closest to intake port 6.
[0025] The specific implementation process is as follows: When piston 5 is at top dead center, it closes exhaust port 3 and scavenging port 4 while opening intake port 6. At this time, air from outside the cylinder can enter the crankcase 8 through intake port 6. As the gas mixture above piston 5 in the cylinder is ignited, piston 5 moves downwards under the force of the gas. During this downward movement, intake port 6 gradually closes. Once intake port 6 is completely closed, the continued downward movement of piston 5 gradually opens exhaust port 3, allowing exhaust gas above piston 5 to exit. As piston 5 continues to move downwards, scavenging port 4 gradually opens, allowing air from the crankcase 8 to enter the cylinder bore 2 above piston 5 through scavenging port 4, until piston 5 reaches bottom dead center. From the moment piston 5 closes intake port 6 until it reaches bottom dead center, intake port 6 remains closed, thus preventing a large amount of air from overflowing from the crankcase 8 to the outside during piston 5's movement to bottom dead center. Air entering the cylinder bore 2 from the four air inlets 4 will flow toward the side of the cylinder bore 2 where the air inlet 6 is located, so that the air first fills the area of the cylinder bore 2 above the piston 5 that is opposite to the exhaust port 3, thereby squeezing the exhaust gas in the cylinder bore 2 toward the area where the exhaust port 3 is located, which is conducive to the discharge of exhaust gas.
[0026] By adopting the solution of this utility model, the aviation piston 5 engine can achieve more thorough exhaust gas discharge in the cylinder block 1 without increasing the size and weight, thereby reducing the amount of residual exhaust gas, which is conducive to improving the combustion effect of fuel and thus improving the performance of the engine.
[0027] The above description is merely an embodiment of this utility model, and common knowledge such as specific structures and characteristics of the solution is not described in detail here. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of this utility model, and these should also be considered within the protection scope of this utility model. These modifications and improvements will not affect the effectiveness of the implementation of this utility model or the practicality of the patent.
Claims
1. An aircraft piston engine, comprising a cylinder block, a piston, and a crankcase, wherein the cylinder block has a cylinder bore that mates with the piston, one end of the cylinder block is connected to the crankcase, one end of the cylinder bore communicates with the crankcase, and an intake port, a scavenging port, and an exhaust port are circumferentially arranged on the cylinder block around the cylinder bore, the scavenging port communicating with the crankcase through an air passage located outside the cylinder bore, characterized in that: The piston controls the opening and closing of the intake port, scavenging port, and exhaust port by moving along the cylinder bore. The stroke segment of the piston corresponding to the intake port is located on the side of the stroke segment of the piston corresponding to the exhaust port, which is close to the bottom dead center of the piston. The stroke segment of the piston corresponding to the scavenging port coincides with the lower part of the stroke segment of the piston corresponding to the exhaust port. Furthermore, the distance from the upper edge of the exhaust port to the lower edge of the intake port is not greater than the length of the piston.
2. An aircraft piston engine according to claim 1, characterized in that: The air intake and exhaust ports are located on opposite sides of the cylinder bore.
3. An aircraft piston engine according to claim 2, characterized in that: The ventilation ports are provided in four ways, and two of the ventilation ports are arranged symmetrically with respect to the plane formed by the other two ventilation ports with respect to the center lines of the air inlet and the air outlet.
4. An aircraft piston engine according to claim 3, characterized in that: All four air inlets face the side of the cylinder bore closest to the air inlet.
5. An aircraft piston engine according to claim 4, characterized in that: The exhaust port is inclined downward and the orientation of the exhaust port forms an angle of 60°-70° with the axis of the cylinder bore.
6. An aircraft piston engine according to claim 5, characterized in that: When the piston is at bottom dead center, the top edge of the piston is flush with the lower edge of the exhaust port.