engine

Abstract

We provide an air-cooled engine with improved cooling efficiency. [Solution] The engine 10 includes an engine block 11, a valve mounting hole 21, a spark plug mounting hole 23, and a ventilation hole 30. The engine block 11 has a cylinder bore 12 inside. The valve mounting hole 21 is connected to the side of the cylinder bore 12, and a valve 25 is placed inside it. The spark plug mounting hole 23 is connected to the side of the cylinder bore 12, and a spark plug 22 is placed inside it. The ventilation hole 30 penetrates the engine block 11 near the valve mounting hole 21 or the spark plug mounting hole 23.

Description

Technical Field

[0001] The present invention relates to an engine, and more particularly to an air-cooled engine.

Background Art

[0002] Engines can be broadly classified into air-cooled engines and water-cooled engines. An air-cooled engine prevents overheating of the engine by transmitting the heat generated from the engine during operation to the outside through air. On the other hand, a water-cooled engine prevents overheating of the engine by absorbing the operating heat of the engine with water and radiating the water after heat absorption to the atmosphere by a radiator.

[0003] In recent years, water-cooled engines tend to be used more frequently because they can cool the engine more effectively than air-cooled engines.

[0004] On the other hand, in a flying device also called a drone, an air-cooled engine may be adopted as a drive source. A drone equipped with an air-cooled engine is described in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the engines described above, there is room for improvement from the viewpoints of the configuration of the entire engine and the application fields peculiar to it.

[0007] In air-cooled engines, the low specific heat of air, the heat transfer medium, posed a challenge in terms of engine heat dissipation. On the other hand, water-cooled engines require radiators, connecting pipes, pumps, and coolant, resulting in a larger overall size and heavier weight.

[0008] In particular, if the engine is used in flying devices such as drones, the strict weight restrictions of drones mean that adopting a water-cooled engine would likely present significant challenges such as increased size.

[0009] This invention was made in view of these problems, and the object of this invention is to provide an air-cooled engine that is compact and has improved cooling efficiency. [Means for solving the problem]

[0010] An engine according to an embodiment of the present invention is characterized by comprising: an engine block having a cylinder bore formed inside it; a valve mounting hole connected to the side surface of the cylinder bore and having a valve arranged inside it; a plug mounting hole connected to the side surface of the cylinder bore and having a spark plug arranged inside it; and a ventilation hole penetrating the engine block near the valve mounting hole or the plug mounting hole.

[0011] Furthermore, in the engine according to the embodiment of the present invention, the vent hole has a valve vent hole, and the valve vent hole is formed in the engine block near the valve mounting hole.

[0012] Furthermore, in the engine according to the embodiment of the present invention, the valve vent hole has a first valve vent hole, and the first valve vent hole is formed in the engine block between the valve mounting hole and the cylinder bore.

[0013] Furthermore, in the engine according to the embodiment of the present invention, the valve vent hole has a second valve vent hole, and the second valve vent hole is formed in the engine block between the valve mounting hole and the outer surface of the engine block.

[0014] Furthermore, in the engine according to the embodiment of the present invention, the vent hole has a plug vent hole, and the plug vent hole is formed in the engine block near the plug vent hole.

[0015] Furthermore, in the engine according to the embodiment of the present invention, the spark plug vent hole has an open intermediate vent hole portion in its middle section, the spark plug is disposed in the engine block in the portion where the intermediate vent hole portion is disposed, and the intermediate vent hole portion is covered by a vent hole protective portion.

[0016] Furthermore, the engine according to the embodiment of the present invention is characterized by having a protrusion formed inside the vent hole. [Effects of the Invention]

[0017] An engine according to an embodiment of the present invention is characterized by comprising: an engine block having a cylinder bore formed therein; a valve mounting hole connected to the side surface of the cylinder bore and having a valve arranged therein; a plug mounting hole connected to the side surface of the cylinder bore and having a spark plug arranged therein; and a ventilation hole penetrating the engine block near the valve mounting hole or the plug mounting hole. According to the engine of the present invention, the portion of the engine block in which the valve mounting hole or the plug mounting hole is formed can be actively cooled.

[0018] Furthermore, in the engine according to the embodiment of the present invention, the vent hole has a valve vent hole, and the valve vent hole is formed in the engine block near the valve mounting hole. According to the engine of the present invention, the portion of the engine block in which the valve mounting hole is formed can be actively cooled.

[0019] Furthermore, in the engine according to an embodiment of the present invention, the valve vent hole has a first valve vent hole, and the first valve vent hole is formed in the engine block between the valve mounting hole and the cylinder bore. According to the engine of the present invention, the space between the valve mounting hole and the cylinder bore can be effectively cooled.

[0020] Furthermore, in the engine according to an embodiment of the present invention, the valve vent hole has a second valve vent hole, and the second valve vent hole is formed in the engine block between the valve mounting hole and the outer surface of the engine block. According to the engine of the present invention, the space between the valve mounting hole and the outer surface of the engine block can be effectively cooled.

[0021] Furthermore, in the engine according to an embodiment of the present invention, the vent hole has a plug vent hole, and the plug vent hole is formed in the engine block near the plug vent hole. According to the engine of the present invention, the plug mounting hole and its vicinity can be effectively cooled.

[0022] Furthermore, in the engine according to an embodiment of the present invention, the plug vent hole has an open intermediate vent hole portion in its middle section, the spark plug is disposed in the engine block in the portion where the intermediate vent hole portion is located, and the intermediate vent hole portion is covered by a vent hole protection portion. According to the engine of the present invention, the spark plug can be disposed in the intermediate vent hole portion, which is the middle part of the plug vent hole. Also, by covering the intermediate vent hole portion with a vent hole protection portion, the plug vent hole functions as a closed pipe as a whole. As a result, when the engine is running, air can circulate well inside the plug vent hole, and the engine block near the spark plug can be effectively cooled.

[0023] Furthermore, the engine according to the embodiment of the present invention is characterized by forming a protrusion inside the vent hole. According to the engine of the present invention, the effect of heat dissipation inside the vent hole can be significantly improved.

Brief Description of the Drawings

[0024] [Figure 1] It is a perspective view showing an engine according to an embodiment of the present invention. [Figure 2] It is a perspective view showing the engine according to the embodiment of the present invention from another angle. [Figure 3] It is an exploded perspective view showing the engine block of the engine according to the embodiment of the present invention. [Figure 4] It is an exploded perspective view showing the engine block of the engine according to the embodiment of the present invention from another angle. [Figure 5] It is a cross-sectional view showing the internal structure of the engine according to the embodiment of the present invention. [Figure 6A] It is a side view showing the internal structure of the engine according to the embodiment of the present invention. [Figure 6B] It is a perspective view showing the internal structure of the engine according to the embodiment of the present invention. [Figure 7A] It is a perspective view showing the second engine block of the engine according to the embodiment of the present invention. [Figure 7B] It is a side view showing the second engine block of the engine according to the embodiment of the present invention. [Figure 8] It is a cutaway perspective view showing the first valve vent hole of the engine according to the embodiment of the present invention. [Figure 9A] It is a perspective view showing the first engine block of the engine according to the embodiment of the present invention. [Figure 9B] It is an exploded perspective view showing the first engine block of the engine according to the embodiment of the present invention. [Figure 10] It is a perspective view showing the engine according to the embodiment of the present invention. [Figure 11] It is an exploded perspective view showing the engine according to the embodiment of the present invention. [Figure 12A] It is an exploded perspective view showing the air guiding part of the engine according to the embodiment of the present invention. [Figure 12B] It is an exploded perspective view showing the air guiding part of the engine according to the embodiment of the present invention from another angle. [Figure 13] This is a perspective view showing a flying device equipped with an engine according to an embodiment of the present invention. [Figure 14] This is a plan view showing a flying device equipped with an engine according to an embodiment of the present invention. [Figure 15] A side view showing a flight device equipped with an engine according to an embodiment of the present invention. [Figure 16] This is a perspective view showing an engine according to another embodiment of the present invention. [Figure 17A] This is a perspective view partially showing an engine according to another embodiment of the present invention. [Figure 17B] This is a cross-sectional perspective view showing an engine according to another embodiment of the present invention. [Modes for carrying out the invention]

[0025] Hereinafter, an engine 10 according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the front-rear direction refers to the direction in which the first crankshaft 143 and the second crankshaft 153, which will be described later, extend. The front-rear direction is also the direction in which air flows to cool the engine 10. The left-right direction is the direction perpendicular to the front-rear direction and is the direction in which the first piston 141 and the second piston 151, which will be described later, reciprocate. In the following description, the same reference numerals are used for the same components in principle, and repeated descriptions are omitted. Furthermore, in this embodiment, the configuration described in the claims will be mainly illustrated and described. Therefore, parts of the engine 10 other than the said configuration, such as the lubrication oil supply mechanism, fuel supply mechanism, and various electrical components, are not shown, but these are provided in the engine 10.

[0026] Figure 1 is a perspective view showing engine 10. Figure 2 is a perspective view showing engine 10 from a different angle.

[0027] Referring to Figures 1 and 2, engine 10 is an opposed-piston engine having multiple pistons arranged in opposition to each other. The internal configuration and operation of engine 10 will be described later with reference to Figures 3 and onward.

[0028] Engine 10 is configured to operate using gasoline, diesel fuel, hydrogen, etc. Engine 10 can be used as a power source for various devices. Engine 10 can be used as a power source for vehicles, generators, water heaters, flying devices, drones, series hybrid drones, parallel hybrid drones, etc. A series hybrid drone is a drone in which engine 10 drives a generator, the electricity generated from the generator rotates a motor, the motor rotates a rotor, and the lift generated by the rotation of the rotor makes the drone float in the air. A parallel hybrid drone is a drone in which engine 10 mechanically rotates a main rotor, and the lift generated by the rotation of the main rotor makes the drone float. In addition, a parallel hybrid drone has a sub-rotor that rotates with a motor to control the attitude of the drone, separate from the main rotor that is mechanically driven by engine 10. The engine 10 of this embodiment is an opposed-piston type engine, and because it is lightweight and has low vibration, it is suitable as a power source for series hybrid drones, parallel hybrid drones, etc.

[0029] In this embodiment, the engine 10 mainly comprises an engine block 11, a valve mounting hole 21 (see Figure 7A), a spark plug mounting hole 23 (see Figure 9B), and a ventilation hole 30 (see Figure 1). As shown in Figure 5, the engine block 11 has a cylinder bore 12 inside. As shown in Figure 7A, the valve mounting hole 21 is connected to the side of the cylinder bore 12, and a valve 25 (Figure 6A) is placed inside it. As shown in Figure 9B, the spark plug mounting hole 23 is connected to the side of the cylinder bore 12, and a spark plug 22 is placed inside it. As shown in Figures 7A to 9A, the ventilation hole 30 is an air tunnel that penetrates the engine block 11 near the valve mounting hole 21 or the spark plug mounting hole 23. According to the engine 10 of this embodiment, the portion of the engine block 11 where the valve mounting hole 21 or the spark plug mounting hole 23 is formed can be cooled particularly actively.

[0030] Specifically, the engine 10 has an engine block 11, which is the main body. The engine block 11 is made of, for example, a cast aluminum alloy. As will be described later, the engine block 11 is made up of multiple engine blocks. These parts are fastened together by fastening members, for example, bolts.

[0031] The first crankshaft 143 and the second crankshaft 153 are routed out from the front side of the engine block 11. Rotational driving force can be extracted to the outside from the first crankshaft 143 and the second crankshaft 153. Also, as shown in Figure 2, the first crankshaft 143 and the second crankshaft 153 are routed out from the rear side of the engine block 11 toward the rear. The first crankshaft 143 and the second crankshaft 153 are equipped with a reversing synchronous mechanism consisting of gears and belts. This reversing synchronous mechanism reverses the rotation of the second crankshaft 153 relative to the first crankshaft 143 and equalizes the rotational speeds of the first crankshaft 143 and the second crankshaft 153. Furthermore, the rotational driving force of the first crankshaft 143 and the second crankshaft 153 controls the reciprocating motion of the valve 25, which will be described later.

[0032] Engine 10 is a so-called air-cooled engine that uses air for cooling during operation. Engine 10 has numerous ribs 115 to increase its surface area in order to promote cooling by air. The ribs 115 extend along the front-rear direction, which is parallel to the direction in which the cooling air flows. The ribs 115 are formed on the upper, lower, front, and rear surfaces of the engine block 11.

[0033] The engine 10 has vents 30 to further improve the cooling efficiency of air cooling. As shown in Figures 1 and 2, the vents 30 have valve vents 31 and plug vents 34. Furthermore, the valve vents 31 have a first valve vent 32 and a second valve vent 33. The valve vents 31 to the plug vents 34 are air passages that penetrate the engine block 11 along the front-rear direction. When the engine 10 is running, air passes through the valve vents 31 to the plug vents 34 at high speed, allowing the air to absorb the operating heat generated during the operation of the engine 10, thereby preventing the engine 10 from overheating. The individual parts constituting the vents 30 will be described later with reference to Figures 7A and later.

[0034] Figure 3 is an exploded perspective view showing the engine block 11 of engine 10. Figure 4 is an exploded perspective view showing the engine block 11 of engine 10 from a different angle.

[0035] Referring to Figures 3 and 4, the engine block 11 has, from right to left, a third engine block 113, a first engine block 111, a second engine block 112, and a fourth engine block 114. The first to fourth engine blocks 111 through 114 are fastened together by fastening members, such as bolts.

[0036] The first engine block 111 has a first cylinder bore 121 formed inside it, which is part of the cylinder bore 12. As shown in Figure 3, a first extension forming surface 171 is formed from the upper end of the first cylinder bore 121. The first extension forming surface 171 is a wall-like portion that constitutes the extension space 24, which will be described later. The plug vent hole 34 is configured to penetrate the first engine block 111 along the front-rear direction.

[0037] Referring to Figure 4, the second engine block 112 has a second cylinder bore 122 formed inside it, which is part of the cylinder bore 12. A second extension forming surface 172 is formed from the upper end of the second cylinder bore 122. The second extension forming surface 172 is a wall-like portion that constitutes the extension space 24, which will be described later. In addition, the first valve vent hole 32 and the second valve vent hole 33 are formed to penetrate the second engine block 112 along the front-rear direction.

[0038] The detailed configurations of the first engine block 111 and the second engine block 112 will be described later with reference to Figures 7A and later.

[0039] The third engine block 113 houses the first crankshaft 143, which will be described later. The first crankshaft 143 is held in a rotatable state by a semicircular crankshaft holder 164 formed on the left side of the third engine block 113 and a semicircular crankshaft holder 163 formed on the right side of the first engine block 111. A bearing is also provided between the two.

[0040] The fourth engine block 114 houses the second crankshaft 153, which will be described later. The second crankshaft 153 and other components are held in a rotatable state by a semicircular crankshaft holder 161 formed on the right side of the fourth engine block 114 and a semicircular crankshaft holder 162 formed on the left side of the second engine block 112. A bearing is also provided between the two.

[0041] Figure 5 is a cross-sectional view along the AA section line in Figure 1, showing the wall portion of the engine block 11 that forms the cylinder bore 12 and extension space 24. The AA section line is a cross-section that includes the vertical and horizontal directions.

[0042] The cylinder bore 12 is a space that is substantially cylindrical in shape. The cylinder bore 12 has a first cylinder bore 121 on the right side and a second cylinder bore 122 connected to the left end of the first cylinder bore 121. Approximately in the center of the cylinder bore 12 in the front-rear direction, an extension space 24 protrudes upward from the upper surface of the cylinder bore 12. The first cylinder bore 121, the second cylinder bore 122, and the extension space 24 are in communication. As will be described later, the extension space 24 is the space in which the tip of the valve 25 and the spark plug 22 are arranged. Therefore, intake, exhaust, and ignition are performed through the extension space 24.

[0043] The cylinder bore 12 and extension space 24 in this configuration are spaces surrounded by walls formed inside the engine block 11.

[0044] Specifically, the first cylinder bore 121 is a substantially cylindrical space surrounded by the first cylinder wall 181. The first cylinder wall 181 is a cylindrical wall formed inside the first engine block 111. The right and left ends of the first cylinder wall 181 are open.

[0045] The second cylinder bore 122 is a substantially cylindrical space surrounded by the second cylinder wall 191. The second cylinder wall 191 is a cylindrical wall formed inside the second engine block 112. The right and left ends of the second cylinder wall 191 are open.

[0046] The extension space 24 is the space enclosed by the first extension wall portion 182 and the second extension wall portion 192. The first extension wall portion 182 is a roughly tongue-shaped portion that extends upward from the upper end of the first cylinder wall portion 181 at the right end of the first cylinder wall portion 181. The second extension wall portion 192 is a roughly tongue-shaped portion that extends upward from the upper end of the second cylinder wall portion 191 at the left end of the second cylinder wall portion 191.

[0047] The cylinder bore 12 is a substantially cylindrical space having a central axis 20 extending along the left-right direction. The cylinder bore 12 has an inner surface 28. The inner surface 28 is a surface formed by the inner surfaces of the first cylinder wall portion 181 and the second cylinder wall portion 191. An extension space 24 extends from the inner surface 28. Specifically, the extension space 24 is a space that extends upward in a direction perpendicular to the central axis 20 of the cylinder bore 12. The extension space 24 communicates with the cylinder bore 12.

[0048] The engine 10 includes a first engine section 14 and a second engine section 15.

[0049] The first engine section 14 includes a first piston 141, a first connecting rod 142, and a first crankshaft 143. The first connecting rod 142 rotatably connects the first piston 141 and the first crankshaft 143.

[0050] The second engine section 15 is positioned opposite the first engine section 14. The second engine section 15 includes a second piston 151, a second connecting rod 152, and a second crankshaft 153. The second connecting rod 152 rotatably connects the second piston 151 and the second crankshaft 153.

[0051] The first engine section 14 and the second engine section 15 of the engine section 13 with the above configuration operate as follows. First, in the intake stroke, the first piston 141 and the second piston 151 move from the center outward inside the cylinder bore 12, introducing a mixture of fuel and air into the cylinder bore 12. The mixture is introduced via the extension space 24. Next, in the compression stroke, the inertia of the rotating first crankshaft 143 and the second crankshaft 153 pushes the first piston 141 and the second piston 151 towards the center, compressing the mixture inside the cylinder bore 12. Next, in the combustion stroke, the spark plug, which will be described later, ignites in the extension space 24, causing the mixture to burn inside the cylinder bore 12, thereby pushing the first piston 141 and the second piston 151 to the outer end, which is the bottom dead center. Subsequently, during the exhaust stroke, the inertia of the rotating first crankshaft 143 and second crankshaft 153 pushes the first piston 141 and second piston 151 inward, and the post-combustion gases present inside the cylinder bore 12 are discharged to the outside via the extension space 24.

[0052] Figure 6A is a side view showing the internal configuration of engine 10. Figure 6B is a perspective view showing the internal configuration of engine 10.

[0053] As shown in Figures 6A and 6B, the valve 25 is provided so as to be able to move back and forth within the extension space 24 from the left side.

[0054] There are two valves 25 in this case, an intake valve 251 and an exhaust valve 252.

[0055] The intake valve 251 is installed in the intake valve mounting hole 211, which will be described later with reference to Figure 7A, etc. The exhaust valve 252 is installed in the exhaust valve mounting hole 212, which will be described later with reference to Figure 7A, etc. The intake valve 251 and the exhaust valve 252 are each biased to the left by a spring (not shown).

[0056] A camshaft 27, an intake cam 261, and an exhaust cam 262 are provided as mechanisms for moving each valve 25 forward and backward.

[0057] The camshaft 27 is a steel rod extending along the front-to-back direction. The intake cam 261 and exhaust cam 262 are mounted on the camshaft 27 so as not to rotate relative to each other.

[0058] The intake cam 261 is positioned immediately adjacent to the left end of the intake valve 251 and is configured to move the intake valve 251 forward and backward. When the intake cam 261 pushes the intake valve 251 to the right, a gap is formed between the intake valve mounting hole 211 shown in Figure 7A and the intake cam 261, and the air-fuel mixture is supplied to the extension space 24 and the cylinder bore 12 through this gap.

[0059] The exhaust cam 262 is positioned immediately adjacent to the left end of the exhaust valve 252 and is configured to move the exhaust valve 252 forward and backward. The exhaust cam 262 is positioned around the axis of the camshaft 27 with a predetermined phase difference relative to the intake cam 261. As the exhaust cam 262 pushes the exhaust valve 252 to the right, a gap is formed between the exhaust valve mounting hole 212 shown in Figure 7A and the exhaust cam 262, and the burnt gas is discharged to the outside from the extension space 24 and the cylinder bore 12 through this gap.

[0060] The intake valve 251 and exhaust valve 252 close the extension space 24 by a biasing force of a spring (not shown) when no pressing force is applied. That is, the intake valve 251 closes the extension space 24 by a biasing force of a spring (not shown) when it is not being pressed by the intake cam 261. The exhaust valve 252 closes the extension space 24 by a biasing force of a spring (not shown) when it is not being pressed by the exhaust cam 262.

[0061] The spark plug 22 is positioned on the right side of the extension space 24. The tip of the spark plug 22 is positioned inside the extension space 24. The tip of the spark plug 22 is inserted into the plug mounting hole 23, which will be described later with reference to Figure 9B.

[0062] Figure 7A is a perspective view showing the second engine block 112 of engine 10. Figure 7B is a side view showing the second engine block 112 of engine 10.

[0063] As described above, intake valve mounting holes 211 and exhaust valve mounting holes 212 are formed in the second engine block 112. The intake valve mounting hole 211 is a space that communicates from the front side of the upper surface of the second engine block 112 to the front side of the second extension forming surface 172. The exhaust valve mounting hole 212 is a space that communicates from the rear side of the upper surface of the second engine block 112 to the rear side of the second extension forming surface 172.

[0064] As described above, the second engine block 112 has a first valve vent 32 and a second valve vent 33. The first valve vent 32 and the second valve vent 33 are air passages that penetrate the space between the second cylinder bore 122 and the outer skin of the engine block 11, i.e., the thickened portion, along the front-rear direction. Referring to Figure 7A, the upper portion of the right end of the second engine block 112 has an inner wall portion 1121 and an outer wall portion 1122. The inner wall portion 1121 is a wall in which the second cylinder bore 122 and the second extension forming surface 172 are formed. The outer wall portion 1122 is a surface disposed outside the inner wall portion 1121 and forming a decorative surface. A part of the second valve vent 33 is formed between the inner wall portion 1121 and the outer wall portion 1122.

[0065] Referring to Figure 7B, the second valve vent 33 is formed in the engine block 11 between the valve mounting hole 21 and the outer surface of the engine block 11. In other words, the intake valve mounting hole 211 and the exhaust valve mounting hole 212 are separated by the inner wall portion 1121, and the second valve vent 33 is formed outside the inner wall portion 1121. Specifically, the second valve vent 33 has, from the front side, a second front opening 331, a second internal passage 332, and a second rear opening 333. When the engine 10 is running, air flows in the order of the second front opening 331, the second internal passage 332, and the second rear opening 333.

[0066] The second front opening 331 is the front end of the second valve vent hole 33 and is a substantially circular opening formed on the front surface of the outer wall portion 1122.

[0067] The second internal passage 332 is located in the middle of the second valve vent 33 and is a cavity formed between the inner wall portion 1121 and the outer wall portion 1122. The second internal passage 332 is formed to enclose the inner wall portion 1121, which forms the second extension forming surface 172, from the outside. The second internal passage 332 is formed continuously from the front end to the rear end of the second engine block 112. In other words, the second internal passage 332 is a cooling passage for cooling the intake valve mounting hole 211 and the exhaust valve mounting hole 212 from the outside. In particular, the exhaust valve mounting hole 212 is a path through which high-temperature exhaust gas after combustion flows. Therefore, by forming the second internal passage 332 near the exhaust valve mounting hole 212, overheating of the exhaust valve mounting hole 212 and its vicinity can be suppressed. In the second internal passage 332, the air flowing through the second internal passage 332 receives heat via the inner wall portion 1121. Here, the heat generated from the intake valve mounting hole 211 and the exhaust valve mounting hole 212 is conducted to the air flowing through the second internal passage 332.

[0068] The second rear opening 333 is a portion that protrudes from the outer wall portion 1122 in a roughly cylindrical shape toward the rear. The inside of the second rear opening 333 is connected to the second internal passage 332. The air that has cooled the second engine block 112 is discharged toward the rear through the second rear opening 333.

[0069] Referring to Figures 7A and 7B, a substantially cylindrical projection 41 can also be provided on the side surface of the second engine block 112 facing the second internal passage 332. Multiple projections 41 can also be formed. Furthermore, the projection 41 can be formed on the portion of the second engine block 112 facing the second internal passage 332, above and near the exhaust valve mounting hole 212. This increases the surface area of ​​the second engine block 112 facing the second internal passage 332 in the vicinity of the exhaust valve mounting hole 212. Therefore, during engine 10 operation, the heat generated through the exhaust valve mounting hole 212 can be efficiently dissipated within the second internal passage 332 via the projection 41.

[0070] Figure 8 is a cutaway perspective view showing the first valve vent hole 32 of the engine 10. Figure 8 is a cross-section along the BB cross-section line of Figure 7A. The BB cross-section line is a cross-section that includes the vertical and longitudinal directions.

[0071] The first valve vent 32 is an air passage formed continuously from the front side to the rear side of the second engine block 112. The first valve vent 32 is formed between the valve mounting hole 21 and the second cylinder bore 122. Specifically, the first valve vent 32 is formed immediately above the second cylinder bore 122. Furthermore, the first valve vent 32 is formed below the intake valve mounting hole 211 and the exhaust valve mounting hole 212. In this way, the air passing through the first valve vent 32 receives heat from the second cylinder bore 122 side. In addition, the air passing through the first valve vent 32 receives heat from the plug protection part 221 and the exhaust valve mounting hole 212. In particular, since the exhaust valve mounting hole 212 is through which the air after combustion passes, the heat generated from the exhaust valve mounting hole 212 is absorbed by the air passing through the first valve vent hole 32, thereby preventing the exhaust valve mounting hole 212 from overheating.

[0072] Referring to Figure 7A, in this embodiment, the intake valve mounting hole 211 and the exhaust valve mounting hole 212 are sandwiched between the first valve vent hole 32 and the second valve vent hole 33. That is, the first valve vent hole 32 is located to the left of the intake valve mounting hole 211 and the exhaust valve mounting hole 212. The second valve vent hole 33 is located to the left of the intake valve mounting hole 211 and the exhaust valve mounting hole 212. With this configuration, the intake valve mounting hole 211 and the exhaust valve mounting hole 212 can be effectively cooled by the air flowing inside the first valve vent hole 32 and the second valve vent hole 33.

[0073] Figure 9A is a perspective view showing the first engine block 111 of engine 10. Figure 9B is an exploded perspective view showing the first engine block 111 of engine 10.

[0074] Referring to Figure 9A, a plug vent 34 is formed in the first engine block 111. The plug vent 34 is an air passage formed to penetrate the first engine block 111 along the front-rear direction. The plug vent 34 is formed near the upper surface of the first engine block 111. The plug vent 34 opens to the front and rear surfaces of the first engine block 111.

[0075] The intermediate portion of the plug vent hole 34 in the front-rear direction is covered by a vent hole protection portion 35 made of a metal plate or the like. The spark plug 22 is positioned in the intermediate portion of the plug vent hole 34 in the front-rear direction. The spark plug 22 is inserted toward the engine block 11 through a notch 351 formed in the vent hole protection portion 35.

[0076] Referring to Figure 9B, the plug vent 34 has, from the front, a front vent portion 341, a middle vent portion 342, and a rear vent portion 343. When the engine 10 is running, air flows in the order of front vent portion 341, middle vent portion 342, and rear vent portion 343. The plug vent 34 is an air passage formed near the spark plug 22. The air flowing through the plug vent 34 effectively cools the vicinity of the plug mounting hole 23 and the spark plug 22.

[0077] The front part 341 of the ventilation opening is a conduit located at the front. When viewed from the front, the front part 341 of the ventilation opening has a roughly rectangular shape with its longitudinal direction in the left-right direction.

[0078] The intermediate vent portion 342 is the intermediate part of the plug vent 34 and is an open portion. Furthermore, the intermediate vent portion 342 is the portion in the first engine block 111 where the plug mounting hole 23 is located.

[0079] The rear vent section 343 is a conduit located at the rear. When viewed from the front, the rear vent section 343 has a roughly rectangular shape with its longitudinal direction in the left-right direction.

[0080] The ventilation hole protection part 35 is positioned to cover the intermediate portion 342 of the ventilation hole. By covering the intermediate portion 342 of the ventilation hole with the ventilation hole protection part 35, the intermediate portion 342 of the ventilation hole acts like a closed pipe. In addition, a roughly cylindrical plug protection part 221 made of resin, which covers the spark plug 22, is positioned in the notch 351.

[0081] The plug mounting hole 23 is a through-hole that penetrates the thick portion of the engine block 11, and is a through-hole that connects the extension space 24 shown in Figure 5 to the outside of the first engine block 111. The tip of the spark plug 22 is inserted into the plug mounting hole 23. The tip of the spark plug 22 is positioned in the extension space 24 shown in Figure 5.

[0082] Figure 10 is a perspective view showing engine 10. Figure 11 is an exploded perspective view showing engine 10.

[0083] The engine 10 has an engine block 11, and various devices are attached to the engine block 11 to improve the efficiency of cooling the engine 10 during operation.

[0084] In this configuration, the engine block 11 is fitted with a first blower fan 361, a second blower fan 362, a first air guide 371, a second air guide 372, an upper cover 391, and a lower cover 392.

[0085] Referring to Figure 11, a generator (not shown) that generates electricity using the rotational driving force of the first crankshaft 143 shown in Figure 1 may be installed between the first blower fan 361 and the engine block 11. Similarly, a generator (not shown) that generates electricity using the rotational driving force of the second crankshaft 153 shown in Figure 1 may be installed between the second blower fan 362 and the engine block 11.

[0086] The first blower fan 361 is a blower that is rotated by the first crankshaft 143 shown in Figure 1. As shown in Figure 11, the first blower fan 361 has multiple rotating blades. As the second blower fan 362 rotates, an airflow is generated that follows a counterclockwise direction when viewed from the front.

[0087] The second blower fan 362 is a blower that is rotated by the second crankshaft 153 shown in Figure 1. As shown in Figure 11, the second blower fan 362 is equipped with multiple rotating blades. When the second blower fan 362 rotates, an airflow is generated that follows a clockwise direction when viewed from the front.

[0088] The first air guide section 371 is a cover attached to the engine block 11 so as to cover the first blower fan 361. The first air guide section 371 is a component that constitutes an air tunnel that guides the airflow generated by the rotation of the first blower fan 361 towards the plug vent hole 34. The first connecting section 381 is fitted into the end opening of the first air guide section 371. The first connecting section 381 is a relay member that connects the opening located at the left end of the first air guide section 371 to the plug vent hole 34.

[0089] The second air guide section 372 is a cover attached to the engine block 11 so as to cover the second blower fan 362. The second air guide section 372 is a component that constitutes an air tunnel that guides the airflow generated by the rotation of the second blower fan 362 to the first valve vent 32 and the second valve vent 33. The second connecting section 382 is fitted into the end opening of the second air guide section 372. The second connecting section 382 is a relay member that connects the opening located at the right end of the second air guide section 372 to the first valve vent 32 and the second valve vent 33.

[0090] The upper cover 391 is a member that covers the upper surface of the engine block 11, specifically the portion where the aforementioned first engine block 111 and second engine block 112 are located. As will be described later, when the engine 10 is mounted on the aircraft 50, the aircraft 50 flies forward, generating a flight airflow that flows from front to rear relative to the engine 10. A portion of this flight airflow passes between the upper cover 391 and the lower surface of the engine block 11. Numerous ribs 115 extending in the front-to-back direction are formed on the upper surface of the first engine block 111. Therefore, a portion of the flight airflow passes between the upper cover 391 and the engine block 11, effectively cooling the upper portion of the engine block 11.

[0091] The lower cover 392 is a member that covers the lower surface of the engine block 11, specifically the lower surface of the portion where the first engine block 111 and the second engine block 112 described above are arranged. As described above, a portion of the airflow generated when the aircraft 50 is in flight passes between the lower cover 392 and the lower surface of the engine block 11. Numerous ribs 115 extending in the front-rear direction are formed on the lower surface of the first engine block 111. Therefore, a portion of the airflow passes between the lower cover 392 and the lower surface of the engine block 11, thereby effectively cooling the lower portion of the engine block 11.

[0092] Figure 12A is an exploded perspective view showing the second air guide section 372. Figure 12B is an exploded perspective view showing the second air guide section 372 from a different angle.

[0093] Referring to Figure 12A, the second air guide section 372 has a front air guide section 3721, a rear air guide section 3722, and a connection port 3723. The second air guide section 372 is an air passage component that guides the airflow generated by the rotation of the second blower fan 362 to the first valve vent hole 32. The second air guide section 372 has an opening in its center for taking in air from the front. In addition, an air passage is formed around the periphery of the second air guide section 372 that directs the airflow generated by the rotation of the second blower fan 362 in a predetermined direction.

[0094] The forward air guide portion 3721 is a component that constitutes the front part of the second air guide portion 372. As shown in Figure 12B, the outer peripheral recess portion 3724 is formed by recessing the peripheral edge of the outer peripheral recess portion 3724 toward the front. When viewed from the rear, the outer peripheral recess portion 3724 is a concave groove that gradually deepens in a clockwise direction. The shape of the outer peripheral recess portion 3724 allows the airflow generated by the rotation of the second blower fan 362 to flow more effectively toward the connection port 3723.

[0095] The configuration of the first air guide section 371 is the same as that of the second air guide section 372 described above.

[0096] The second connecting portion 382 is a substantially cylindrical member. As shown in Figure 12A, the front end of the second connecting portion 382 is connected by being inserted into a connection port 3723 formed at the air passage end of the rear air guide portion 3722. On the other hand, the rear end of the second connecting portion 382 is connected to the first valve vent 32 and the second valve vent 33 of the engine block 11, as shown in Figure 11. Therefore, the airflow generated by the rotation of the second blower fan 362 is blown through the second air guide portion 372 and the second connecting portion 382 to the first valve vent 32 and the second valve vent 33, cooling the engine block 11.

[0097] Similarly, referring to Figure 11, the airflow generated by the rotation of the first blower fan 361 is blown to the plug vent 34 via the first air guide 371 and the first connection 381, cooling the engine block 11.

[0098] As described above, the exterior and interior of the engine block 11 are effectively cooled, thereby effectively preventing overheating of the engine 10 during operation. Specifically, referring to Figure 3, the first engine block 111 and the second engine block 112 become particularly hot during operation because the explosion stroke takes place inside them. Therefore, cooling the first engine block 111 and the second engine block 112 is essential to prevent overheating of the engine 10.

[0099] Therefore, in this embodiment, as shown in Figure 7A, a first valve vent 32 and a second valve vent 33 are formed in the second engine block 112. Also, as shown in Figure 8, a plug vent 34 is formed in the first engine block 111. By blowing air into the first valve vent 32, the second valve vent 33, and the plug vent 34, the vicinity of the valve mounting hole 21 and the vicinity of the plug mounting hole 23, which generate a lot of heat when the engine 10 is in operation, can be actively cooled. Here, the air may be the airflow generated by the flight of the aircraft 50, which will be described later, or the airflow generated by the rotation of the first blower fan 361, etc.

[0100] Referring to Figure 11, the system includes a first blower fan 361 and a first air guide 371 to actively supply air to the valve vents 31 and plug vents 34. The airflow generated by the rotation of the first blower fan 361 is supplied to the plug vents 34 via the first air guide 371. The airflow generated by the rotation of the second blower fan 362 is supplied to the first valve vents 32 and second valve vents 33 via the second air guide 372. In this way, a large flow rate of air can be supplied to the first valve vents 32, second valve vents 33 and plug vents 34, allowing for more active cooling of the first engine block 111 and second engine block 112. Furthermore, the first air guide 371 and second air guide 372 have a substantially circular opening in their center that takes in air from the front. During the flight of the aircraft 50, which will be described later, airflow from the aircraft is supplied to this opening. This also allows for an increase in the air velocity of the air blown into the plug mounting hole 23, the second valve vent hole 33, and the plug vent hole 34, thereby improving the cooling efficiency of the engine block 11.

[0101] Furthermore, ribs 115 are formed on the surfaces (front, rear, bottom, and top) of the first engine block 111 and the second engine block 112, extending along the front-to-back direction. The top surfaces of the first engine block 111 and the second engine block 112 are covered by an upper cover 391. During flight of the aircraft 50, which will be described later, airflow flows between the top surfaces of the first engine block 111 and the second engine block 112 and the upper cover 391. The bottom surfaces of the first engine block 111 and the second engine block 112 are covered by a lower cover 392. During flight of the aircraft 50, which will be described later, airflow flows between the bottom surfaces of the first engine block 111 and the second engine block 112 and the lower cover 392. In this way, the first engine block 111 and the second engine block 112 are cooled from the outside as well.

[0102] Based on the above, the engine 10 effectively prevents overheating during operation by effectively cooling the first engine block 111 and the second engine block 112 from both the inside and the outside.

[0103] Figure 13 is a perspective view showing the flying device 50 equipped with the engine 10. Figure 14 is a plan view showing the flying device 50 equipped with the engine 10. Figure 15 is a side view showing the flying device 50 equipped with the engine 10. Here, the up, down, front, back, left, and right directions shown in Figure 1, etc., correspond to the up, down, front, back, left, and right directions in the figures from rib 115 onwards.

[0104] The flight device 50 is equipped with the aforementioned engine 10. More specifically, the flight device 50 is a series hybrid drone that flies by rotating a rotor 54 using electricity generated by the engine 10.

[0105] Specifically, the engine 10 comprises the engine 10, a main body 53, an arm 51, a motor 55, a rotor 54, and a skid 52.

[0106] Engine 10 is a power source that generates the driving force necessary for the flight device 50 to fly. The configuration of engine 10 is as described above.

[0107] The main body 53 is made up of rod-shaped members assembled into a roughly rectangular parallelepiped, and houses the various components that make up the flight device 50. For example, the engine 10, various electrical equipment, fuel tanks, etc., are housed in the main body 53.

[0108] The arms 51 are roughly rod-shaped members that extend outward from the corners of the main body 53. In this case, four arms 51 extend outward from the corners of the main body 53.

[0109] The motor 55 is located at the outer end of the arm 51. The motor 55 is powered by a generator driven by the engine 10. The motor 55 generates the driving force necessary for the rotor 54 to rotate.

[0110] The rotor 54 is positioned at the outer end of the arm 51 and is rotated by the motor 55. As the rotor 54 rotates, the entire flight device 50 floats, allowing its position and attitude to be controlled in the air.

[0111] The skid 52 is a member that extends downward from the lower end of the main body 53. When the flying device 50 lands, the skid 52 makes contact with the landing surface. As a result, when landing, the main body 53 and the like are supported at a position above the landing surface.

[0112] As the flying device 50 moves forward in the air, a flight airflow is generated. This flight airflow can effectively cool the engine 10.

[0113] The configuration of the engine 10 in other configurations will be described with reference to Figures 16 to 17B. The configuration and operation of the engine 10 in other configurations are, in principle, the same as the engine 10 described above with reference to Figure 1, etc. In the engine 10 described below, the configuration of the plug vent hole 34 and its surrounding area formed in the first engine block 111 differs from the configuration shown in Figure 1, etc. The following will focus on explaining these differences.

[0114] Figure 16 is a perspective view showing an engine 10 in a different configuration.

[0115] Referring to Figure 16, a ventilation hole 30 is formed in the engine block 11 of the engine 10. As previously mentioned, the ventilation hole 30 is a through-hole through which air passes to cool the engine block 11. The ventilation hole 30 includes a valve ventilation hole 31, a first valve ventilation hole 32, a second valve ventilation hole 33, and a plug ventilation hole 34.

[0116] The plug vents 34 shown in other configurations have a different shape from those described above. Specifically, the plug vents 34 in a front view have a roughly rectangular shape with a longitudinal direction along the vertical direction. Furthermore, the plug vents 34 are through-holes that continuously penetrate the first engine block 111 from the front to the rear.

[0117] Figure 17A is a perspective view partially showing the engine 10 according to another embodiment. Figure 17B is a cut perspective view showing the engine 10 according to another embodiment. Figure 17B is a cross-section along the CC cutting plane line of Figure 17A. The CC cutting plane is a cross-section that includes the vertical and horizontal directions.

[0118] Referring to Figure 17A, the plug mounting hole 23 is configured to penetrate the lower end of the plug ventilation hole 34. The plug mounting hole 23 is the hole into which the portion near the tip of the spark plug 22 described above is inserted.

[0119] Fastening holes 40 are formed in the plug vent hole 34. The fastening holes 40 are through holes that penetrate the plug vent hole 34 in the left-right direction. The fastening holes 40 have a substantially cylindrical shape. The fastening holes 40 are through holes through which bolts pass for fastening the first engine block 111 to the fourth engine block 114, which constitute the engine block 11, to each other, as described above. Multiple fastening holes 40 are formed in the plug vent hole 34.

[0120] Referring to Figure 17B, a protrusion 41 is formed inside the plug vent hole 34. The protrusion 41 is a portion that protrudes to the right in a roughly cylindrical shape from the left side surface of the plug vent hole 34. The protrusion 41 is formed collectively by casting together with the main body of the first engine block 111. Multiple protrusions 41 are arranged to surround the plug mounting hole 23. By forming the protrusion 41, the surface area of ​​the heat dissipation area around the plug mounting hole 23 can be increased. Therefore, the air passing inside the plug vent hole 34 actively exchanges heat with the protrusion 41, thereby effectively cooling the area around the plug mounting hole 23. In addition, a fastening hole 40 is also exposed inside the plug vent hole 34. Since the fastening hole 40 is also part of the first engine block 111, the fastening hole 40 is exposed inside the plug vent hole 34, and the air flowing through the plug vent hole 34 from front to rear absorbs heat from the fastening hole 40, thereby effectively cooling the first engine block 111.

[0121] Although embodiments of the present invention have been described above, the present invention is not limited thereto, and modifications are possible without departing from the spirit of the invention. Furthermore, the above-described embodiments can be combined with each other. [Explanation of symbols]

[0122] 10 Engines 11 Engine Block 111 First engine block 112 Second engine block 113 Third engine block 114. Fourth engine block 115 Rib 1121 Inner wall 1122 Outer wall 12 Cylinder bore 121 First cylinder bore 122 Second cylinder bore 13 Engine section 14. First Engine Section 141 First Piston 142 First Connecting Rod 143 First Crankshaft 15. Second Engine Section 151 Second piston 152 Second Connecting Rod 153 Second crankshaft 161 Crank retainer 162 Crank retaining part 163 Crank retaining part 164 Crank retaining part 171 First extension forming surface 172 Second extension forming surface 181 First cylinder wall 182 1st extension wall section 191 Second cylinder wall 192 Second extension wall section 20 center axis 21 Valve mounting hole 211 Intake valve mounting hole 212 Exhaust valve mounting hole 22 Spark plugs 221 Plug protection part 23 Plug mounting holes 24 Extension space 25 valves 251 Intake valve 252 Exhaust valve 261 Intake Cam 262 Exhaust Cam 27 Camshaft 28 Inner surface 30 ventilation holes 31 Valve vent 32 First valve vent 33 Second valve vent 331 2nd front opening 332 2nd internal passage 333 2nd rear opening 34 Plug vents 341 Front of the ventilation hole 342 Ventilation hole intermediate section 343 Rear of the ventilation opening 35 Vent protection part 351 Notch 361 First blower fan 362 Second blower fan 371 First air guide section 372 Second wind guide section 3721 Forward air guide 3722 Rear wind guide section 3723 Connection Port 3724 Outer circumference concave part 381 First connection section 382 Second connection section 391 Upper cover 392 Lower cover 40 Fastening hole 41 Protrusion 50 Flight equipment 51 Arm 52 Skid 53 Main body 54 rotors 55 Motor

Claims

1. The engine block, which has a cylinder bore formed inside, A valve mounting hole connected to the side of the cylinder bore, in which a valve is positioned, A plug mounting hole is connected to the side surface of the cylinder bore, and a spark plug is disposed inside it. An engine characterized by comprising a vent hole that penetrates the engine block near the valve mounting hole or the plug mounting hole.

2. The aforementioned vent hole has a valve vent hole, The engine according to claim 1, characterized in that the valve vent hole is formed in the engine block near the valve mounting hole.

3. The valve vent hole has a first valve vent hole, The engine according to claim 2, characterized in that the first valve vent hole is formed in the engine block between the valve mounting hole and the cylinder bore.

4. The valve vent hole has a second valve vent hole, The engine according to claim 2, characterized in that the second valve vent hole is formed in the engine block between the valve mounting hole and the outer surface of the engine block.

5. The ventilation hole has a plug ventilation hole, The engine according to claim 1, characterized in that the plug vent hole is formed in the engine block near the plug vent hole.

6. The plug vent hole has an open vent hole intermediate portion in its middle section, The spark plug is installed in the engine block in the portion where the intermediate part of the ventilation hole is located. The engine according to claim 5, characterized in that the intermediate portion of the ventilation hole is covered by a ventilation hole protective portion.

7. The engine according to claim 1, characterized in that a protrusion is formed inside the vent hole.

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