engine

Abstract

To provide an air-cooled engine with improved cooling efficiency. [Solution] An engine 10 has an engine block 11, valve mounting holes 21, spark plug mounting holes 23, and an air hole 30. A cylinder bore 12 is defined inside the engine block 11. The valve mounting holes 21 are connected to a side surface of the cylinder bore 12, and a valve 25 is disposed therein. The spark plug mounting holes 23 are connected to a side surface of the cylinder bore 12, and a spark plug 22 is disposed therein. The air hole 30 passes through the engine block 11 near the valve mounting holes 21 or the spark plug mounting holes 23.

Description

[Technical field]

[0001] The present invention relates to engines, and more particularly to air-cooled engines. [Background technology]

[0002] Engines can be broadly classified into air-cooled and water-cooled engines. Air-cooled engines prevent overheating by transferring heat generated by the engine during operation to the outside via air. On the other hand, water-cooled engines prevent overheating by absorbing the heat generated by the engine's operation with water and releasing the absorbed heat into the atmosphere via a radiator.

[0003] In recent years, water-cooled engines have become more common because they can be cooled more effectively than air-cooled engines.

[0004] On the other hand, in flying devices also called drones, air-cooled engines are sometimes used as a driving 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] JP 2021-167198 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned engine has room for improvement in terms of the overall configuration of the engine and its specific field of application.

[0007] Air-cooled engines have a problem with heat dissipation from the engine because the specific heat of the heat medium, air, is small. On the other hand, water-cooled engines require a radiator, connecting pipes, pumps, cooling water, etc., so the entire water-cooled engine becomes large and heavy.

[0008] In particular, if the engine is used in a flying device such as a drone, drones have strict weight restrictions, so if a water-cooled engine is used, issues such as larger size are likely to become more pronounced.

[0009] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an air-cooled engine that is compact and has improved cooling efficiency. [Means for solving the problem]

[0010] The present invention The engine is The engine comprises an engine block having a cylinder bore therein, a valve mounting hole connected to a side surface of the cylinder bore and having a valve mounted therein, a plug mounting hole connected to a side surface of the cylinder bore and having a spark plug mounted therein, and an air hole penetrating the engine block in the vicinity of the valve mounting hole. The vent hole has a valve vent hole, and the valve vent hole has a first valve vent hole and a second valve vent hole that is a separate vent hole not communicating with the first valve vent hole, the first valve vent hole is formed so as to penetrate the engine block between the valve mounting hole and the cylinder bore, and the second valve vent hole is formed so as to penetrate the engine block between the valve mounting hole and an outer surface of the engine block. Effect of the Invention

[0017] According to the present invention, it is possible to provide an air-cooled engine that is compact and has improved cooling efficiency. [Brief description of the drawings]

[0024] [Figure 1] 1 is a perspective view showing an engine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing the engine according to the embodiment of the present invention from a different angle. [Diagram 3] 1 is an exploded perspective view showing an engine block of an engine according to an embodiment of the present invention; [Figure 4]FIG. 2 is an exploded perspective view showing the engine block of the engine according to the embodiment of the present invention, viewed from another angle. [Diagram 5] 1 is a cross-sectional view showing an internal configuration of an engine according to an embodiment of the present invention. [Figure 6A] 1 is a side view showing an internal configuration of an engine according to an embodiment of the present invention. FIG. [Figure 6B] 1 is a perspective view showing an internal configuration of an engine according to an embodiment of the present invention. FIG. [Figure 7A] FIG. 2 is a perspective view showing a second engine block of the engine according to the embodiment of the present invention. [Figure 7B] FIG. 4 is a side view showing a second engine block of the engine according to the embodiment of the present invention. [Figure 8] FIG. 2 is a cutaway perspective view showing a first valve vent of the engine according to the embodiment of the present invention. [Figure 9A] FIG. 2 is a perspective view showing a first engine block of the engine according to the embodiment of the present invention. [Figure 9B] FIG. 2 is an exploded perspective view showing a first engine block of the engine according to the embodiment of the present invention. [Figure 10] 1 is a perspective view showing an engine according to an embodiment of the present invention. [Figure 11] 1 is an exploded perspective view showing an engine according to an embodiment of the present invention. [Figure 12A] FIG. 2 is an exploded perspective view showing an air guidance section of the engine according to the embodiment of the present invention. [Figure 12B] FIG. 4 is an exploded perspective view showing the airflow guidance section of the engine according to the embodiment of the present invention, viewed from a different angle. [Figure 13] 1 is a perspective view showing a flying device equipped with an engine according to an embodiment of the present invention. FIG. [Figure 14] 1 is a plan view showing a flying device equipped with an engine according to an embodiment of the present invention. FIG. [Figure 15] 1 is a side view showing a flying device equipped with an engine according to an embodiment of the present invention. FIG. [Figure 16] FIG. 4 is a perspective view showing an engine according to another embodiment of the present invention. [Figure 17A]FIG. 4 is a perspective view partially showing an engine according to another embodiment of the present invention. [Figure 17B] FIG. 4 is a cutaway perspective view showing an engine according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the engine 10 according to the embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the front-rear direction is the direction in which a first crankshaft 143 and a second crankshaft 153, which will be described later, extend. The front-rear direction is also the direction in which air for cooling the engine 10 flows. The left-right direction is the direction perpendicular to the front-rear direction, and is the direction in which a first piston 141 and a second piston 151, which will be described later, reciprocate. In the following description, the same members are basically given the same reference numerals, and repeated description is omitted. Furthermore, in this embodiment, the configuration described in the claims will be mainly illustrated and described. Therefore, although parts other than the relevant configuration of the engine 10, such as a lubricating oil supply mechanism, a fuel supply mechanism, various electrical equipment, etc. are not illustrated, these are provided in the engine 10.

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

[0027] 1 and 2, engine 10 is an opposed-piston engine having a plurality of opposed pistons. The internal configuration and operation of engine 10 will be described later with reference to FIG. 3 and subsequent drawings.

[0028] The engine 10 is configured to be operated using gasoline, diesel, hydrogen, or the like as fuel. The engine 10 can be used as a drive source for various devices. The engine 10 is used as a drive source for vehicles, generators, water heaters, flying devices, drones, series hybrid drones, parallel hybrid drones, and the like. A series hybrid drone is a drone in which a generator is operated by the engine 10, a motor is rotated by the electric power generated by the generator, a rotor is rotated by the motor, and the aircraft is levitated in the air by the lift generated by the rotation of the rotor. A parallel hybrid drone is a drone in which a main rotor is mechanically rotated by the engine 10, and the aircraft is levitated by the lift generated by the rotation of the main rotor. In addition, the parallel hybrid drone also has a sub-rotor rotated by a motor to control the attitude of the aircraft, in addition to the main rotor mechanically driven by the engine 10. The engine 10 of this embodiment is an opposed piston type engine, and is lightweight and has low vibration, making it suitable as a drive source for a series hybrid drone, a parallel hybrid drone, and the like.

[0029] In this embodiment, the engine 10 mainly includes an engine block 11, a valve hole 21 (see FIG. 7A), a spark plug hole 23 (see FIG. 9B), and an air vent 30 (see FIG. 1). As shown in FIG. 5, the engine block 11 has a cylinder bore 12 formed therein. As shown in FIG. 7A, the valve hole 21 is connected to the side of the cylinder bore 12, and a valve 25 (FIG. 6A) is disposed therein. As shown in FIG. 9B, the spark plug hole 23 is connected to the side of the cylinder bore 12, and a spark plug 22 is disposed therein. As shown in FIG. 7A to FIG. 9A, the air vent 30 is an air tunnel that penetrates the engine block 11 near the valve hole 21 or the spark plug hole 23. According to the engine 10 of this embodiment, the part of the engine block 11 where the valve hole 21 or the spark plug hole 23 is formed can be actively cooled in particular.

[0030] Specifically, the engine 10 has an engine block 11 which is a 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 a number of engine parts. These parts are fastened to each other by fastening members such as bolts.

[0031] A first crankshaft 143 and a second crankshaft 153 extend from the front side of the engine block 11. A rotational driving force can be output from the first crankshaft 143 and the second crankshaft 153 to the outside. As shown in FIG. 2, the first crankshaft 143 and the second crankshaft 153 also extend rearward from the rear side of the engine block 11. The first crankshaft 143 and the second crankshaft 153 are provided with a reverse synchronization mechanism consisting of gears and a belt. This reverse synchronization mechanism is a mechanism that rotates the second crankshaft 153 in the opposite direction relative to the first crankshaft 143 and equalizes the rotational speeds of the first crankshaft 143 and the second crankshaft 153. The rotational driving force of the first crankshaft 143 and the second crankshaft 153 controls the reciprocating motion of a valve 25, which will be described later.

[0032] The engine 10 is a so-called air-cooled engine that uses air to cool the engine during operation. The engine 10 has a large number of ribs 115 to increase the surface area and promote cooling by air. The ribs 115 extend in 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 a vent hole 30 to further improve the cooling efficiency by air cooling. As shown in FIG. 1 and FIG. 2, the vent hole 30 has a valve vent hole 31 and a plug vent hole 34. Furthermore, the valve vent hole 31 has a first valve vent hole 32 and a second valve vent hole 33. The valve vent hole 31 to the plug vent hole 34 are air passages that penetrate the engine block 11 along the front-rear direction. When the engine 10 is operated, air passes through the inside of the valve vent hole 31 to the plug vent hole 34 at a high speed, so that the air absorbs the operating heat generated during the operation of the engine 10, and the engine 10 can be prevented from overheating. The components that make up the vent hole 30 will be described later with reference to FIG. 7A and subsequent figures.

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

[0035] 3 and 4, engine block 11 has, from the right side, a third engine block 113, a first engine block 111, a second engine block 112, and a fourth engine block 114. The first engine block 111 to the fourth engine block 114 are fastened to each other by fastening members such as bolts.

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

[0037] 4, the second engine block 112 has a second cylinder bore 122 formed therein, which is a part of the cylinder bore 12. A second extension forming surface 172 is formed from an upper end of the second cylinder bore 122. The second extension forming surface 172 is a wall-like portion that constitutes an 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 in 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 FIG. 7A and subsequent figures.

[0039] The third engine block 113 houses a first crankshaft 143 (described later) and the like. The first crankshaft 143 is rotatably held by a semicircular crank holding portion 164 formed on the left side of the third engine block 113 and a semicircular crank holding portion 163 formed on the right side of the first engine block 111. A bearing is provided between the two.

[0040] The fourth engine block 114 houses a second crankshaft 153 (described later) and the like. The second crankshaft 153 and the like are rotatably held by a semicircular crank holding portion 161 formed on the right side of the fourth engine block 114 and a semicircular crank holding portion 162 formed on the left side of the second engine block 112. A bearing is provided between the two.

[0041] Fig. 5 is a cross-sectional view taken along the line AA in Fig. 1, and shows the wall of the engine block 11 that defines the cylinder bore 12 and the extension space 24. The line AA is a cross section that includes the top-bottom and left-right directions.

[0042] The cylinder bore 12 is a space having a substantially cylindrical 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. An extension space 24 protrudes upward from the upper surface of the cylinder bore 12 at substantially the center in the front-rear direction of the cylinder bore 12. The first cylinder bore 121, the second cylinder bore 122, and the extension space 24 are in communication with each other. As described later, the extension space 24 is a space in which a valve 25 and the tip of a spark plug 22 are disposed. Thus, intake, exhaust, and ignition are performed via the extension space 24.

[0043] The cylinder bore 12 and the extension space 24 configured as above 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 a first cylinder wall portion 181. The first cylinder wall portion 181 is a cylindrical wall formed inside the first engine block 111. The right and left ends of the first cylinder wall portion 181 are open.

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

[0046] The extension space 24 is a space surrounded by the first extension wall portion 182 and the second extension wall portion 192. The first extension wall portion 182 is a generally tongue-shaped portion that extends upward from the upper end portion 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 generally tongue-shaped portion that extends upward from the upper end portion 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 side surface 28. The inner side surface 28 is a surface formed by the inner surfaces of a first cylinder wall portion 181 and a second cylinder wall portion 191. An extension space 24 extends from the inner side 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 has a first engine section 14 and a second engine section 15.

[0049] The first engine section 14 has a first piston 141, a first connecting rod 142, and a first crankshaft 143. The first connecting rod 142 connects the first piston 141 and the first crankshaft 143 so as to be rotatable with each other.

[0050] The second engine section 15 is disposed to face the first engine section 14. The second engine section 15 has 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 configured as described above operate as follows. First, in the intake stroke, the first piston 141 and the second piston 151 move from the center to the outside inside the cylinder bore 12, so that a mixture of fuel and air is introduced into the cylinder bore 12. The mixture is introduced via the extension space 24. Next, in the compression stroke, the first piston 141 and the second piston 151 are pushed toward the center by the inertia of the rotating first crankshaft 143 and the second crankshaft 153, and the mixture is compressed inside the cylinder bore 12. Next, in the combustion stroke, an ignition plug, which will be described later, ignites in the extension space 24, so that the mixture is burned inside the cylinder bore 12, and the first piston 141 and the second piston 151 are pushed to the outer end, which is the bottom dead center. Then, during the exhaust stroke, the first piston 141 and the second piston 151 are pushed inward due to the inertia of the rotating first crankshaft 143 and the second crankshaft 153, and the burnt gas present inside the cylinder bore 12 is discharged to the outside via the extension space 24.

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

[0053] As shown in FIGS. 6A and 6B, the valve 25 is provided so as to be movable toward and away from the extension space 24 from the left side.

[0054] Here, two valves 25 are provided, an intake valve 251 and an exhaust valve 252 .

[0055] The intake valve 251 is disposed in an intake valve mounting hole 211, which will be described later with reference to Figure 7A etc. The exhaust valve 252 is disposed in an 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 leftward by a spring (not shown).

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

[0057] The camshaft 27 is a steel rod extending in the front-rear direction. An intake cam 261 and an exhaust cam 262 are provided on the camshaft 27 so as to be non-rotatable relative to each other.

[0058] The intake cam 261 is disposed immediately adjacent to the left end of the intake valve 251 and configured to move the intake valve 251 forward and backward. When the intake cam 261 pushes the intake valve 251 rightward, a gap is formed between the intake valve mounting hole 211 shown in FIG. 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 disposed immediately adjacent to the left end of the exhaust valve 252 and configured to move the exhaust valve 252 forward and backward. The exhaust cam 262 is disposed around the axis of the camshaft 27 with a predetermined phase difference from the intake cam 261. When the exhaust cam 262 pushes the exhaust valve 252 rightward, a gap is formed between the exhaust valve mounting hole 212 and the exhaust cam 262 shown in Fig. 7A, and the burned gas is discharged to the outside from the extension space 24 and the cylinder bore 12 through this gap.

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

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

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

[0063] As described above, the second engine block 112 is formed with the intake valve hole 211 and the exhaust valve hole 212. The intake valve 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 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 is formed with the first valve vent 32 and the second valve vent 33. The first valve vent 32 and the second valve vent 33 are air passages that penetrate between the second cylinder bore 122 and the outer skin of the engine block 11, i.e., the thick portion, along the front-rear direction. With reference to FIG. 7A, the upper portion of the right end portion 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 to form a design surface. A part of the second valve vent 33 is formed between the inner wall portion 1121 and the outer wall portion 1122.

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

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

[0067] The second internal passage 332 is a cavity formed between the inner wall portion 1121 and the outer wall portion 1122 at the middle portion of the second valve vent hole 33. The second internal passage 332 is formed so as to enclose the inner wall portion 1121 forming 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 path for cooling the intake valve hole 211 and the exhaust valve hole 212 from the outside. In particular, the exhaust valve 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 hole 212, overheating of the exhaust valve 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, heat generated from the intake valve hole 211 and the exhaust valve 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 rearward in a substantially cylindrical shape from the outer wall portion 1122. 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 rearward from the second rear opening 333.

[0069] 7A and 7B, a protruding portion 41 protruding in a substantially cylindrical shape may be provided on the side surface of the second engine block 112 facing the second internal passage 332. A plurality of protruding portions 41 may be formed. Furthermore, the protruding portion 41 may be formed on the second engine block 112 in a portion facing the second internal passage 332, above the exhaust valve hole 212 and in its vicinity. In this manner, the surface area of ​​the second engine block 112 facing the second internal passage 332 in the vicinity of the exhaust valve hole 212 can be increased. Therefore, heat generated through the exhaust valve hole 212 during operation of the engine 10 can be dissipated well through the protruding portion 41 inside the second internal passage 332.

[0070] Fig. 8 is a cutaway perspective view showing the first valve vent 32 of the engine 10. Fig. 8 is a cross section taken along the line BB in Fig. 7A. The line BB is a cross section including the up-down direction and the front-rear direction.

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

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

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

[0074] 9A, the first engine block 111 is formed with a plug vent 34. 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 top 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 disposed in the intermediate portion of the plug vent hole 34 in the front-rear direction. The spark plug 22 is inserted from a notch 351 formed in the vent hole protection portion 35 toward the engine block 11.

[0076] 9B , the plug vent 34 has, from the front side, a vent front portion 341, a vent middle portion 342, and a vent rear portion 343. When the engine 10 is in operation, air flows through the vent front portion 341, the vent middle portion 342, and the vent rear portion 343 in that order. The plug vent 34 is an air passage formed in the vicinity of 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 vent hole front portion 341 is a duct disposed in the front. When viewed from the front, the vent hole front portion 341 has a generally rectangular shape with a longitudinal direction in the left-right direction.

[0078] The vent hole intermediate portion 342 is an intermediate portion of the plug vent hole 34, and is a portion that is in an open state. The vent hole intermediate portion 342 is also a portion in the first engine block 111 where the plug installation hole 23 is disposed.

[0079] The rear air vent portion 343 is a duct disposed at the rear. When viewed from the front, the rear air vent portion 343 has a generally rectangular shape having a longitudinal direction in the left-right direction.

[0080] The vent hole protection part 35 is disposed so as to cover the vent hole intermediate part 342. By covering the vent hole protection part 35, the vent hole intermediate part 342 acts like a closed conduit. Further, in the cutout part 351, a plug protection part 221 having a substantially cylindrical shape and made of resin that covers the spark plug 22 is disposed.

[0081] The plug mounting hole 23 is a through-hole that penetrates the thick portion of the engine block 11 and connects the extension space 24 shown in FIG. 5 with 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 disposed in the extension space 24 shown in FIG. 5.

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

[0083] The engine 10 has an engine block 11, and various devices are attached to the engine block 11 in order to achieve highly efficient cooling when the engine 10 is in operation.

[0084] Here, to the engine block 11, a first blower fan 361, a second blower fan 362, a first air guide section 371, a second air guide section 372, an upper cover 391 and a lower cover 392 are attached.

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

[0086] The first blower fan 361 is a blowing means rotated by the first crankshaft 143 shown in Fig. 1. As shown in Fig. 11, the first blower fan 361 has a plurality of rotary blades. When the second blower fan 362 rotates, an airflow is generated that flows counterclockwise when viewed from the front.

[0087] The second blower fan 362 is a blowing means rotated by the second crankshaft 153 shown in Fig. 1. As shown in Fig. 11, the second blower fan 362 has a plurality of rotary blades. When the second blower fan 362 rotates, an airflow is generated along a clockwise direction when viewed from the front.

[0088] The first airflow guide section 371 is a cover attached to the engine block 11 so as to cover the first blower fan 361. The first airflow guide section 371 is a member constituting an air tunnel that guides the airflow generated by the rotation of the first blower fan 361 to the plug air hole 34. A first connection section 381 is fitted into an end opening of the first airflow guide section 371. The first connection section 381 is a relay member that connects an opening disposed at the left end of the first airflow guide section 371 and the plug air 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 member constituting an air tunnel that guides the airflow generated by the rotation of the second blower fan 362 to the first valve air vent 32 and the second valve air vent 33. A second connection section 382 is fitted into an end opening of the second air guide section 372. The second connection section 382 is a relay member that connects an opening disposed at the right end of the second air guide section 372 to the first valve air vent 32 and the second valve air vent 33.

[0090] The upper cover 391 is a member that covers the upper surface of the engine block 11, specifically, the upper surface of the portion where the above-mentioned first engine block 111 and second engine block 112 are arranged. As described later, when the engine 10 is mounted on the flight device 50, the flight device 50 flies forward, generating a flight wind that flows from the front to the rear of the engine 10. A part of the flight wind passes between the upper cover 391 and the lower surface of the engine block 11. A large number of ribs 115 extending along the front-rear direction are formed on the upper surface of the first engine block 111. Therefore, a part of the flight wind passes between the upper cover 391 and the engine block 11, thereby 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 above-mentioned first engine block 111 and second engine block 112 are arranged. As described above, part of the flying wind generated when the flight device 50 flies passes between the lower cover 392 and the lower surface of the engine block 11. A large number of ribs 115 extending along the front-rear direction are formed on the lower surface of the first engine block 111. Therefore, part of the flying wind 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] Fig. 12A is an exploded perspective view showing the second air guide section 372. Fig. 12B is an exploded perspective view showing the second air guide section 372 from a different angle.

[0093] 12A, second air guide section 372 has front air guide section 3721, rear air guide section 3722, and connection port 3723. Second air guide section 372 is an air passage component that guides the airflow generated by the rotation of second blower fan 362 described above to first valve air hole 32. Second air guide section 372 has an opening in the center that takes in air from the front. In addition, an air passage is formed around second air guide section 372 to direct the airflow generated by the rotation of second blower fan 362 described above in a predetermined direction.

[0094] The front air guide section 3721 is a member that constitutes the front portion of the second air guide section 372. As shown in FIG. 12B, the peripheral edge of the outer circumferential concave section 3724 is recessed toward the front to form the outer circumferential concave section 3724. When viewed from the rear, the outer circumferential concave section 3724 is a concave groove that gradually becomes deeper in the clockwise direction. By having the outer circumferential concave section 3724 have this shape, the airflow generated by the rotation of the second blower fan 362 can be made to flow toward the connection port 3723 more effectively.

[0095] The configuration of the first airflow guiding section 371 is similar to that of the second airflow guiding section 372 described above.

[0096] The second connection part 382 is a member having a substantially cylindrical shape. As shown in FIG. 12A, a front end of the second connection part 382 is connected by being inserted into a connection port 3723 formed at an end of the air passage of the rear air guide part 3722. Meanwhile, a rear end of the second connection part 382 is connected to the first valve air hole 32 and the second valve air hole 33 of the engine block 11 shown in FIG. 11. Therefore, the airflow generated by the rotation of the second blower fan 362 is blown to the first valve air hole 32 and the second valve air hole 33 via the second air guide part 372 and the second connection part 382, ​​thereby cooling the engine block 11.

[0097] Similarly, referring to FIG. 11, the airflow generated by the rotation of the first blower fan 361 is sent to the plug air hole 34 via the first air guide section 371 and the first connection section 381, and cools the engine block 11.

[0098] With the above-described configuration, the exterior and interior of the engine block 11 are effectively cooled, and therefore overheating of the engine 10 during operation can be effectively prevented. Specifically, referring to Fig. 3, the first engine block 111 and the second engine block 112 become particularly hot during operation because an explosion stroke takes place therein. Therefore, in order to prevent overheating of the engine 10, it is essential to cool the first engine block 111 and the second engine block 112.

[0099] Therefore, in this embodiment, as shown in Fig. 7A etc., the first valve vent 32 and the second valve vent 33 are formed in the second engine block 112. Also, as shown in Fig. 8 etc., the 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, it is possible to actively cool the vicinity of the valve arrangement hole 21 and the vicinity of the plug arrangement hole 23, which generate a large amount of heat when the engine 10 is in operation. Here, the air may be a flight wind generated by the flight of the flying device 50 described later, or may be a blown wind generated by the rotation of the first blower fan 361 described above or the like.

[0100] Referring to FIG. 11, the first blower fan 361 and the first air guide section 371 are provided to actively blow air to the valve vent 31 and the plug vent 34. The airflow generated by the rotation of the first blower fan 361 is blown to the plug vent 34 via the first air guide section 371. The airflow generated by the rotation of the second blower fan 362 is passed through the second air guide section 372 to the first valve vent 32 and the second valve vent 33. In this way, a large amount of air can be blown to the first valve vent 32, the second valve vent 33, and the plug vent 34, and the first engine block 111 and the second engine block 112 can be more actively cooled. Furthermore, the first air guide section 371 and the second air guide section 372 have a substantially circular opening in the center thereof that takes in air from the front. When the flying device 50, which will be described later, is flying, the flying air is sent to the opening. This also makes it possible to increase the speed of the air blown to the spark plug 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, lower and upper surfaces) of the first engine block 111 and the second engine block 112 so as to extend along the front-rear direction. The upper surfaces of the first engine block 111 and the second engine block 112 are covered with an upper cover 391. When the flight device 50 described later flies, flight wind flows between the upper surfaces of the first engine block 111 and the second engine block 112 and the upper cover 391. The lower surfaces of the first engine block 111 and the second engine block 112 are covered with a lower cover 392. When the flight device 50 described later flies, flight wind flows between the lower 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 also cooled from the outside.

[0102] As described above, in the engine 10, the first engine block 111 and the second engine block 112 are effectively cooled from both the inside and the outside, so that overheating during operation of the engine 10 can be effectively prevented.

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

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

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

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

[0107] The main body 53 is formed by assembling rod-shaped members into a substantially rectangular parallelepiped, and houses the various components that make up the flight device 50. The main body 53 houses, for example, the engine 10, various electrical devices, a fuel tank, etc.

[0108] The arms 51 are generally rod-shaped members extending outward from the corners of the main body 53. Here, four arms 51 extend outward from the corners of the main body 53.

[0109] The motor 55 is provided at the outer end of the arm 51. The motor 55 is supplied with power from a generator driven by the engine 10. The motor 55 generates a driving force for rotating the rotor 54.

[0110] The rotor 54 is disposed on the outer end of the arm 51, and is rotated by a motor 55. By rotating the rotor 54, the entire flight device 50 floats, and the position and attitude can 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 comes into contact with the landing surface. As a result, during landing, the main body 53 and the like are supported at a position above and away from the landing surface.

[0112] The flight device 50 moves forward in the air, generating a flight wind, which can effectively cool the engine 10.

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

[0114] FIG. 16 is a perspective view showing an engine 10 according to another embodiment.

[0115] 16, the engine block 11 of the engine 10 is formed with vent holes 30. As described above, the vent holes 30 are through-holes through which air passes for cooling the engine block 11. The vent holes 30 include a valve vent hole 31, a first valve vent hole 32, a second valve vent hole 33 and a plug vent hole 34.

[0116] The plug vent hole 34 shown in the other embodiments has a different shape from the one described above. Specifically, the shape of the plug vent hole 34 in a front view is a substantially rectangular shape having a longitudinal direction along the up-down direction. Also, the plug vent hole 34 is a through hole that penetrates the first engine block 111 continuously from the front surface to the rear surface.

[0117] Fig. 17A is a perspective view partially showing an engine 10 according to another embodiment. Fig. 17B is a cutaway perspective view showing an engine 10 according to another embodiment. Fig. 17B is a cross section taken along the line CC in Fig. 17A. The CC cut surface is a cross section including the up-down direction and the front-rear direction.

[0118] 17A, the plug hole 23 is configured to penetrate the lower end of the plug vent hole 34. The plug hole 23 is a hole into which the portion of the spark plug 22 in the vicinity of its tip end is inserted.

[0119] A fastening hole 40 is formed in the plug vent hole 34. The fastening hole 40 is a through hole that penetrates the plug vent hole 34 in the left-right direction. The fastening hole 40 has a substantially cylindrical shape. The fastening hole 40 is a through hole through which a bolt passes to fasten the first engine block 111 to the fourth engine block 114 that configure the engine block 11 to each other, as described above. A plurality of fastening holes 40 are formed for each plug vent hole 34.

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

[0121] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and modifications can be made without departing from the scope of the present invention. In addition, the above-described embodiments can be combined with each other. The invention that can be understood from the above-described embodiment will be described below together with its effects. An engine according to an embodiment of the present invention is characterized in that it comprises an engine block having a cylinder bore therein, a valve hole connected to a side surface of the cylinder bore and having a valve disposed therein, a plug hole connected to a side surface of the cylinder bore and having a spark plug disposed therein, and an air hole penetrating the engine block near the valve hole or the plug hole. According to the engine of the present invention, the portion of the engine block where the valve hole or the plug hole is formed can be actively cooled. In the engine according to the embodiment of the present invention, the vent hole includes a valve vent hole formed in the engine block near the valve mounting hole. According to the engine of the present invention, the portion of the engine block where the valve mounting hole is formed can be actively cooled. In the engine according to the embodiment of the present invention, the valve vent hole includes a first valve vent hole, and the first valve vent hole is formed in the engine block between the valve hole and the cylinder bore. According to the engine of the present invention, the area between the valve hole and the cylinder bore can be effectively cooled. In the engine according to the embodiment of the present invention, the valve vent hole includes a second valve vent hole formed in the engine block between the valve hole and an outer surface of the engine block. According to the engine of the present invention, it is possible to effectively cool the area between the valve hole and the outer surface of the engine block. In the engine according to the embodiment of the present invention, the vent hole includes a plug vent hole that is formed in the engine block near the plug vent hole. According to the engine of the present invention, the plug hole and its vicinity can be effectively cooled. In the engine according to the embodiment of the present invention, the plug vent has an open vent hole intermediate portion at its intermediate portion, the spark plug is disposed in the engine block at the portion where the vent hole intermediate portion is disposed, and the vent hole intermediate 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 vent hole intermediate portion, which is the middle portion of the plug vent hole. Furthermore, by covering the vent hole intermediate portion with the vent hole protection portion, the plug vent hole functions as a closed pipe as a whole. As a result, air flows smoothly through the inside of the plug vent hole during engine operation, and the engine block in the vicinity of the spark plug can be effectively cooled. In the engine according to the embodiment of the present invention, a protrusion is formed inside the air vent. According to the engine of the present invention, the heat dissipation effect inside the air vent can be made significant. [Explanation of symbols]

[0122] 10 Engine 11 Engine block 111 No. 1 engine block 112 No. 2 engine block 113 3rd engine block 114 4th engine block 115 Ribs 1121 Inner wall 1122 Outer wall 12 Cylinder bore 121 First cylinder bore 122 Second cylinder bore 13 Engine section 14 No. 1 Engine Section 141 First piston 142 First connecting rod 143 No. 1 crankshaft 15 No. 2 Engine Section 151 Second piston 152 Second connecting rod 153 No. 2 crankshaft 161 Crank holder 162 Crank holder 163 Crank holder 164 Crank holder 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 installation hole 211 Intake valve mounting hole 212 Exhaust valve mounting hole 22 Spark plug 221 Plug protection part 23 Plug installation hole 24 Extension space 25 Valve 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 Vent 341 Front vent 342 Ventilation hole middle part 343 Rear vent 35 Vent protection part 351 Notch 361 First blower fan 362 Second blower fan 371 First Air Guidance Section 372 Second Air Guidance Section 3721 Front air guide section 3722 Rear wind guide section 3723 Connection port 3724 Concave outer periphery 381 First Connection 382 Second Connection 391 Upper cover 392 Lower cover 40 Fastening hole 41 Protrusion 50 Flight equipment 51 Arm 52 Skid 53 Main body 54 Rotor 55 Motor

Claims

1. An engine block having a cylinder bore formed therein; a valve mounting hole connected to a side surface of the cylinder bore and having a valve mounted therein; a spark plug hole connected to a side surface of the cylinder bore and having a spark plug disposed therein; a vent hole passing through the engine block in the vicinity of the valve mounting hole, the vent comprises a valve vent; The valve vent hole includes a first valve vent hole and a second valve vent hole that is a separate vent hole not communicating with the first valve vent hole, The first valve vent hole is formed between the valve mounting hole and the cylinder bore so as to penetrate the engine block, The engine according to claim 1, wherein the second valve vent hole is formed between the valve mounting hole and an outer surface of the engine block so as to penetrate the engine block.

2. An engine as described in claim 1, characterized in that a protrusion is formed inside the valve vent.

3. An inner wall portion surrounding the valve arrangement hole from the outside, and an outer wall portion formed on the outside of the inner wall portion, 2. The engine of claim 1, wherein said second valve vent is formed between said inner wall and said outer wall.

4. A direction along the central axis of the cylinder bore is a first direction, When a direction perpendicular to the first direction is defined as a second direction, The cylinder bore further includes an extension space extending continuously along the second direction from a substantially central portion of the cylinder bore in the first direction, The engine according to claim 1 , wherein the valve mounting hole is configured to connect to a side surface of the extension space.

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