Engine

Abstract

Provided is an engine capable of efficaciously cooling individual cylinder chambers.　An engine 10 comprises an engine block 11, a cylinder chamber 12, and a water jacket 20. The cylinder chamber 12 has a first cylinder chamber 121 and a second cylinder chamber 122. On the interior of the first cylinder chamber 121, mutually opposed pistons are disposed so as to move in a reciprocating manner. On the interior of the second cylinder chamber 122, other mutually opposed pistons are disposed so as to move in a reciprocating manner, and a part of the water jacket 20 is formed between the first cylinder chamber 121 and the second cylinder chamber 122.

Description

engine

[0001] The present invention relates to engines, and more particularly to opposed-piston engines.

[0002] Conventionally, opposed-piston engines have generally been structured so that pistons with opposing piston heads move linearly within a single horizontally arranged cylinder, as shown in Patent Documents 1 and 2. Within this cylinder, the area where the piston heads face each other functions as a combustion chamber, and a gas mixture of fuel and air ignites and explodes, moving the piston and supplying power to an external actuator such as a generator.

[0003] However, the engine described in the patent document has a small combustion chamber volume, making it difficult to achieve a high compression ratio, and there are also issues with insulating the combustion chamber. Also, the intake and exhaust valves of conventional opposed-piston engines open directly into the combustion chamber, which has the drawback of increasing the volume of the combustion chamber.

[0004] To solve this problem, the engine described in Patent Document 3 below was invented. In the engine described in Patent Document 3, independent left and right pistons are arranged facing each other inside a horizontal cylinder. In addition, a single combustion chamber is formed between the left and right piston heads and communicates with the outside of the horizontal cylinder.

[0005] JP 2007-46534 A JP 8-93498 A Patent No. 5508604

[0006] The opposed-piston engines described in the aforementioned patent documents have one combustion chamber, and generate kinetic energy by the reciprocating motion of two pistons inside the combustion chamber. However, if the combustion chamber is enlarged or multiple combustion chambers are added in order to improve the output of the opposed-piston engine, problems with heat dissipation during engine operation can arise.

[0007] Specifically, if multiple cylinder chambers are formed to improve the output of an opposed-piston engine, heat is generated from each cylinder chamber during engine operation, increasing the amount of thermal energy generated by the entire engine. In Patent Document 3, a water jacket is formed to surround the cylinder chamber for heat dissipation, but this was not designed to accommodate a situation where multiple cylinder chambers are formed. Furthermore, if the water jacket is formed to surround multiple cylinder chambers from the periphery, there may be a problem of insufficient heat dissipation between the cylinder chambers.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine in which each cylinder chamber can be cooled effectively.

[0009] An engine according to one embodiment of the present invention comprises an engine block, a cylinder chamber, and a water jacket, the cylinder chamber having a first cylinder chamber and a second cylinder chamber, wherein opposing pistons are arranged so as to reciprocate within the first cylinder chamber, and another opposing piston is arranged so as to reciprocate within the second cylinder chamber, and a portion of the water jacket is formed between the first cylinder chamber and the second cylinder chamber.

[0010] In addition, in an engine according to one embodiment of the present invention, the central axes of the first cylinder chamber and the second cylinder chamber are approximately parallel to a horizontal plane, the water jacket has an upper jacket portion, a lower jacket portion, and an intermediate communication portion, the upper jacket portion is configured to surround upper portions of the first cylinder chamber and the second cylinder chamber, the lower jacket portion is configured to surround lower portions of the first cylinder chamber and the second cylinder chamber, and the intermediate communication portion is configured to communicate the upper jacket portion and the lower jacket portion in the space sandwiched between the first cylinder chamber and the second cylinder chamber.

[0011] In addition, an engine according to one embodiment of the present invention further includes a gasket, wherein the engine block has a first engine block and a second engine block, the gasket is disposed between the first engine block and the second engine block, and has a communication opening formed therein, the first engine block has a first water jacket portion that partially forms the water jacket and a first intermediate communication portion that partially forms the intermediate communication portion, the second engine block has a second water jacket portion that partially forms the water jacket and a second intermediate communication portion that partially forms the intermediate communication portion, the first water jacket portion and the second water jacket portion communicate with each other via the communication opening of the gasket, and the gasket is present between the first intermediate communication portion and the second intermediate communication portion.

[0012] In addition, in an engine according to one embodiment of the present invention, the gasket located between the first intermediate communication portion and the second intermediate communication portion does not have the communication opening formed therein.

[0013] An engine according to one embodiment of the present invention includes an engine block, a cylinder chamber, and a water jacket. The cylinder chamber has a first cylinder chamber and a second cylinder chamber. Two opposing pistons are arranged to reciprocate within the first cylinder chamber, and another opposing piston is arranged to reciprocate within the second cylinder chamber. A portion of the water jacket is formed between the first and second cylinder chambers. According to the engine of the present invention, a portion of the water jacket is formed between the first and second cylinder chambers. This allows air contained in the cooling fluid to move to an upper portion of the water jacket through this portion. This prevents air from accumulating in the lower portion of the water jacket. Furthermore, this portion allows the cooling fluid to flow smoothly in the vertical direction, effectively cooling the cylinder chamber.

[0014] In an engine according to an embodiment of the present invention, the central axes of the first cylinder chamber and the second cylinder chamber are substantially parallel to a horizontal plane, the water jacket has an upper jacket section, a lower jacket section, and an intermediate communication section, the upper jacket section is configured to surround upper portions of the first cylinder chamber and the second cylinder chamber, the lower jacket section is configured to surround lower portions of the first cylinder chamber and the second cylinder chamber, and the intermediate communication section is configured to communicate the upper jacket section with the lower jacket section in a space sandwiched between the first cylinder chamber and the second cylinder chamber. According to the engine of the present invention, the intermediate communication section connects the upper jacket section with the lower jacket section, allowing air present in the lower jacket section to flow to the upper jacket section via the intermediate communication section. In addition, cooling fluid can be effectively circulated via the intermediate communication section.

[0015] In an engine according to an embodiment of the present invention, the engine block further includes a gasket, the engine block having a first engine block and a second engine block, the gasket is disposed between the first engine block and the second engine block and has a communication opening, the first engine block has a first water jacket portion that partially defines the water jacket and a first intermediate communication portion that partially defines the intermediate communication portion, the second engine block has a second water jacket portion that partially defines the water jacket and a second intermediate communication portion that partially defines the intermediate communication portion, the first water jacket portion and the second water jacket portion communicate with each other via the communication opening in the gasket, and the gasket is located between the first intermediate communication portion and the second intermediate communication portion. According to the engine of the present invention, the first water jacket portion and the second water jacket portion communicate with each other via the communication opening in the gasket, thereby ensuring good circulation of cooling fluid between the first water jacket portion and the second water jacket portion. Furthermore, by providing the gasket between the first and second intermediate communication portions, the gasket can be cooled by the cooling fluid flowing through the first and second intermediate communication portions.

[0016] In addition, in an engine according to one embodiment of the present invention, the gasket between the first and second intermediate communication portions does not have the communication opening formed therein. According to the engine of the present invention, the cooling fluid flows along the main surface of the gasket, thereby effectively cooling the gasket.

[0017] 1 is a perspective view of an engine according to an embodiment of the present invention; FIG. 1 is a perspective view of an engine according to an embodiment of the present invention, showing a first engine block; FIG. 2 is a perspective view of an engine according to an embodiment of the present invention, showing a second engine block; FIG. 3 is a perspective view of an engine according to an embodiment of the present invention, showing an engine section; FIG. 4 is a view of an engine according to an embodiment of the present invention, showing an abutment surface of a first engine block; FIG. 5 is a view of an engine according to an embodiment of the present invention, showing an abutment surface of a second engine block; FIG. 6 is a perspective view of an engine according to an embodiment of the present invention, showing a cylinder chamber and each valve, etc.; FIG. 7 is a perspective view of an engine according to an embodiment of the present invention, showing a cylinder chamber and each valve, etc.; FIG. 8 is a cross-sectional view of an engine according to an embodiment of the present invention, showing a schematic configuration of a water jacket, etc.; FIG. 9 is a cross-sectional view of an engine according to an embodiment of the present invention, showing a wall portion of an engine block that forms a cylinder chamber and an extension space; FIG. 10 is a perspective view of an engine according to an embodiment of the present invention, showing an engine block and a gasket; FIG. 11 is a plan view of a gasket; FIG. 12 is a perspective view of an engine according to an embodiment of the present invention, showing a water jacket and a gasket; FIG. 13 is a perspective view of an engine according to an embodiment of the present invention, showing a water jacket and a gasket; FIG. 14 is a perspective view of an engine according to an embodiment of the present invention, showing a water jacket and a gasket from a different angle; FIG. 15 is an exploded perspective view of a water jacket and a gasket; FIG. 16 is a cutaway perspective view of an engine according to an embodiment of the present invention, showing a water jacket and a gasket. 1 is a diagram showing an engine according to an embodiment of the present invention, illustrating the effect of water flow in a water jacket. FIG.

[0018] An engine 10 according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, the longitudinal direction refers to the direction in which pistons, described below, reciprocate. The left-right direction refers to the direction in which cylinder spaces, described below, are arranged. In the following description, the same components are generally designated by the same reference numerals, and repeated description will be omitted. Furthermore, in this embodiment, the configuration recited in the claims will be mainly illustrated and described. Therefore, parts of the engine 10 other than the relevant components, such as a spark plug, a crankshaft rotation synchronization mechanism, a lubricating oil supply mechanism, a fuel supply mechanism, and electrical components, are not illustrated.

[0019] FIG. 1 is a perspective view showing an engine 10. As shown in FIG.

[0020] The engine 10 is an opposed-piston engine having multiple pistons arranged opposite each other. The internal configuration and operation of the engine 10 will be described later with reference to Figure 2A and subsequent figures. The engine 10 mainly comprises an engine block 11, a cylinder chamber 12, and a water jacket 20, as will be described later.

[0021] The engine 10 is configured to operate 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, flight devices, drones, series hybrid drones, parallel hybrid drones, and the like. A series hybrid drone is a drone in which a generator is driven by the engine 10, and the power generated by the generator drives a motor, which in turn drives a rotor, thereby generating lift to keep the drone afloat. A parallel hybrid drone is a drone in which a main rotor is mechanically rotated by the engine 10, and the lift generated by the rotation of the main rotor keeps the drone afloat. The engine 10 of this embodiment is an opposed-piston engine, and is lightweight and low-vibration, making it suitable as a drive source for series hybrid drones, parallel hybrid drones, and the like.

[0022] Specifically, the engine 10 has an engine block 11, which is a main body of the engine. The engine block 11 is made of, for example, a cast aluminum alloy. The engine block 11 is made up of a first engine block 111, a second engine block 112, a third engine block 113, and a fourth engine block 114. These components are fastened to one another by fastening members (not shown).

[0023] A third crankshaft 163 and a fourth crankshaft 173 extend from the right side of the engine 10. Rotational power can be extracted to the outside from the third crankshaft 163 and the fourth crankshaft 173. Shafts can also be extended from the left side of the engine 10 to extract power to the outside from these shafts.

[0024] FIG. 2A is a perspective view showing the first engine block 111.

[0025] 2A, the rearward facing surface of the first engine block 111 is defined as a first abutment surface 40. The first abutment surface 40 is a flat surface that abuts against a second abutment surface 41 of the second engine block 112, which will be described later.

[0026] The first engine block 111 has a first cylinder chamber front portion 1211 and a second cylinder chamber front portion 1221 each formed in a generally cylindrical shape extending forward from the first abutment surface 40. The first cylinder chamber front portion 1211 and the second cylinder chamber front portion 1221 are adjacent to each other in the left-right direction. The first cylinder chamber front portion 1211 is a generally cylindrical space and forms the front portion of the first cylinder chamber 121 (described later). The second cylinder chamber front portion 1221 is a generally cylindrical space and forms the front portion of the second cylinder chamber 122 (described later).

[0027] The first extension space front portion 3311 is a portion of the first contact surface 40 recessed forward, and is continuous with the upper end of the first cylinder chamber front portion 1211. The first extension space front portion 3311 constitutes the front portion of the first extension space 331 described below.

[0028] The second extension space front portion 3321 is a portion of the first contact surface 40 recessed forward, and is continuous with the upper end of the second cylinder chamber front portion 1221. The second extension space front portion 3321 constitutes the front portion of the second extension space 332 described below.

[0029] 2B , the surface of the second engine block 112 facing forward is the second abutment surface 41. The second abutment surface 41 is a flat surface that abuts against the first abutment surface 40 of the first engine block 111 described above.

[0030] The second engine block 112 has a first cylinder chamber rear portion 1212 and a second cylinder chamber rear portion 1222 formed rearward from the second abutment surface 41. The first cylinder chamber rear portion 1212 and the second cylinder chamber rear portion 1222 are adjacent to each other in the left-right direction. The first cylinder chamber rear portion 1212 is a substantially cylindrical space and forms the rear portion of the first cylinder chamber 121, which will be described later. The second cylinder chamber rear portion 1222 is a substantially cylindrical space and forms the rear portion of the second cylinder chamber 122, which will be described later.

[0031] The first extension space rear portion 3312 is a portion of the second abutment surface 41 recessed rearward, and is continuous with the upper end of the first cylinder chamber rear portion 1212. The first extension space rear portion 3312, together with the first extension space front portion 3311 described above, constitutes the first extension space 331, which will be described later.

[0032] The second extension space rear portion 3322 is a portion where the second abutment surface 41 is recessed rearward, and is continuous with the upper end of the second cylinder chamber rear portion 1222. The second extension space rear portion 3322, together with the second extension space front portion 3321 described above, constitutes the second extension space 332, which will be described later.

[0033] FIG. 3 is a perspective view of the engine section 13 housed in the engine block 11 as seen from the front.

[0034] The engine section 13 has a first engine section 14, a second engine section 15, a third engine section 16, and a fourth engine section 17. The first engine section 14 and the second engine section 15 form one opposing engine section. The third engine section 16 and the fourth engine section 17 form one opposing engine section. By having multiple opposing engine sections in the engine 10, it is possible to increase the output while ensuring the lightweight and low vibration characteristics of the engine 10.

[0035] The cylinder chamber 12 includes a first cylinder chamber 121 and a second cylinder chamber 122 adjacent to the first cylinder chamber 121. The first cylinder chamber 121 and the second cylinder chamber 122 are adjacent to each other in the left-right direction. In FIG. 3 , the first cylinder chamber 121 and the second cylinder chamber 122 are indicated by dotted lines. A first piston 141 and a second piston 151 are disposed in the first cylinder chamber 121 so as to reciprocate, facing each other. A third piston 161 and a fourth piston 171 are disposed in the second cylinder chamber 122 so as to reciprocate, facing each other. The central axes of the first cylinder chamber 121 and the second cylinder chamber 122 are substantially parallel to a horizontal plane. A combustion chamber 24 is formed in the middle of the first cylinder chamber 121 and the second cylinder chamber 122 in the front-rear direction, respectively.

[0036] 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 rotatably connects the first piston 141 and the first crankshaft 143.

[0037] The second engine section 15 is disposed opposite 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.

[0038] The third engine section 16 has a third piston 161, a third connecting rod 162, and a third crankshaft 163. The third connecting rod 162 rotatably connects the third piston 161 and the third crankshaft 163.

[0039] The fourth engine section 17 is disposed to face the third engine section 16. The fourth engine section 17 has a fourth piston 171, a fourth connecting rod 172, and a fourth crankshaft 173. The fourth connecting rod 172 rotatably connects the fourth piston 171 and the fourth crankshaft 173.

[0040] The first crankshaft 143 of the first engine section 14 and the third crankshaft 163 of the third engine section 16 are integrally connected to each other. Therefore, the first piston 141 of the first engine section 14 and the third piston 161 of the third engine section 16 reciprocate simultaneously.

[0041] Similarly, the second crankshaft 153 of the second engine section 15 and the fourth crankshaft 173 of the fourth engine section 17 are integrally continuous. Therefore, the second piston 151 of the second crankshaft 153 and the fourth piston 171 of the fourth engine section 17 reciprocate simultaneously.

[0042] The engine section 13 is configured such that an opposed engine section consisting of a first engine section 14 and a second engine section 15 and an opposed engine section consisting of a third engine section 16 and a fourth engine section 17 are arranged side by side in the left-right direction. Furthermore, the first engine section 14 and the third engine section 16 rotate a first crankshaft 143 and a third crankshaft 163. Furthermore, the second engine section 15 and the fourth engine section 17 rotate a second crankshaft 153 and a fourth crankshaft 173. With this configuration, a large amount of power can be generated even in a compact configuration.

[0043] The first engine section 14 and the second engine section 15 of the engine section 13 configured as described above operate as follows. First, during the intake stroke, the first piston 141 and the second piston 151 move from the center toward the outside inside the first cylinder chamber 121, introducing a mixture of fuel and air into the first cylinder chamber 121. Next, during 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 toward the center, compressing the mixture inside the first cylinder chamber 121. Next, during the combustion stroke, an ignition plug (not shown) ignites in the first cylinder chamber 121, burning the mixture inside the first cylinder chamber 121, thereby pushing the first piston 141 and the second piston 151 to the outer ends, which are at bottom dead center. Then, 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 burned gas present inside the first cylinder chamber 121 is expelled to the outside.

[0044] The same operation is performed for the third engine section 16 and the fourth engine section 17 .

[0045] In the engine section 13, the stroke can be divided between the two pistons, the first piston 141 and the second piston 151, which reciprocate within the single first cylinder chamber 121. This allows for a higher compression ratio of the mixed gas compared to conventional engines. Furthermore, because the first piston 141 and the second piston 151 face each other within the first cylinder chamber 121, the cylinder head required in conventional engines is unnecessary, resulting in a simple and lightweight configuration of the engine section 13. Furthermore, the components constituting the engine section 13, i.e., the first piston 141 and the second piston 151, the first crankshaft 143 and the second crankshaft 153, etc., are arranged opposite each other and operate in an opposing manner. This cancels out vibrations generated by the components of the engine section 13, thereby reducing external vibrations generated by the engine section 13 as a whole. Therefore, by incorporating an engine section 13 having such a structure into a flight device, the flight device can be made smaller, lighter, and with less vibration. In particular, the reduced vibration can prevent adverse effects on precision equipment such as attitude control, motor output control, and other arithmetic and control devices, GPS sensors, etc. It can also prevent damage to delivery packages transported by the flight device due to vibration.

[0046] The engine unit 13 is equipped with a reverse synchronization mechanism (not shown). The reverse synchronization mechanism reverses the rotational directions of the first crankshaft 143 and the second crankshaft 153. Furthermore, the reverse synchronization mechanism synchronizes the reciprocating motion of the first piston 141 and the second piston 151. Therefore, in the engine unit 13, the first crankshaft 143 and the second crankshaft 153 have opposite rotational directions.

[0047] 4A is a diagram showing the first contact surface 40 of the first engine block 111. The first contact surface 40 is formed with an intake valve mounting hole 35. The intake valve mounting hole 35 has a first intake valve mounting hole 351 and a second intake valve mounting hole 352.

[0048] Two first intake valve mounting holes 351 are formed inside the first extension space front portion 3311. The first intake valve mounting holes 351 are circular through-holes that penetrate the wall portion of the first engine block 111 in the front-to-rear direction. A first intake valve 181 (described later) is disposed in each of the first intake valve mounting holes 351.

[0049] Two second intake valve mounting holes 352 are formed inside the second extension space front portion 3321. The second intake valve mounting holes 352 are circular through-holes that penetrate a wall formed inside the first engine block 111. A second intake valve 182, which will be described later, is disposed in each of the second intake valve mounting holes 352.

[0050] 4B is a diagram showing the second contact surface 41 of the second engine block 112. The second contact surface 41 is formed with an exhaust valve mounting hole 36 and a plug mounting hole 37. The exhaust valve mounting hole 36 has a first exhaust valve mounting hole 361 and a second exhaust valve mounting hole 362. The plug mounting hole 37 has a first plug mounting hole 371 and a second plug mounting hole 372.

[0051] The first exhaust valve installation hole 361 is a hole formed in the first extension space rear portion 3312. The first exhaust valve installation hole 361 passes through a circular wall formed inside the second engine block 112. A first exhaust valve 191, which will be described later, is disposed in the first exhaust valve installation hole 361.

[0052] The first plug installation hole 371 is a through-hole formed inside the first extension space rear portion 3312. The first plug installation hole 371 is a through-hole that penetrates the left side surface portion of the second engine block 112.

[0053] The second exhaust valve installation hole 362 is a hole formed in the second extension space rear portion 3322. The second exhaust valve installation hole 362 passes through a circular wall formed inside the second engine block 112. A second exhaust valve 192, which will be described later, is disposed in the second exhaust valve installation hole 362.

[0054] The second plug installation hole 372 is a through-hole formed inside the second extension space rear portion 3322. The second plug installation hole 372 is a through-hole that penetrates the right side surface portion of the second engine block 112.

[0055] Fig. 5A is a perspective view showing the cylinder chamber 12, the valves, etc. from above on the rear right side. Fig. 5B is a perspective view showing the cylinder chamber 12, the valves, etc. from above on the front left side.

[0056] The extension space 33 is connected to the cylinder chamber 12 and is a space that serves as the starting point of combustion in the combustion stroke described below. Specifically, the extension space 33 is a space that extends continuously upward from the center in the front-to-rear direction of the cylinder chamber 12. As the extension space 33, a first extension space 331 is formed in the first cylinder chamber 121, and a second extension space 332 is formed in the second cylinder chamber 122.

[0057] The first extension space 331 is a generally tongue-shaped portion having its largest surface facing the front-to-rear direction. The first extension space 331 has a first side surface 3313 and a second side surface 3314. The first side surface 3313 faces forward. The second side surface 3314 faces backward.

[0058] The second extension space 332 is a generally tongue-shaped portion having its largest surface facing the front-to-rear direction. The second extension space 332 has a first side surface 3323 and a second side surface 3324. The first side surface 3323 faces forward. The second side surface 3324 faces backward.

[0059] The intake valve 18 includes a first intake valve 181 and a second intake valve 182 .

[0060] The first intake valve 181 is provided so as to be movable forward and backward relative to the first side surface 3313 of the first extension space 331 from the front side. Two first intake valves 181 are provided here. Each first intake valve 181 is attached to a first intake valve installation hole 351 shown in FIG. 4A . The first intake valve 181 is used to draw an air-fuel mixture into the first cylinder chamber 121. When the first intake valve 181 enters the first extension space 331, it opens the first intake valve installation hole 351 shown in FIG. 4A , allowing air to be drawn into the first extension space 331 and the first cylinder chamber 121. When the first intake valve 181 retreats from the first extension space 331, it closes the first intake valve installation hole 351 shown in FIG. 4A .

[0061] The second intake valve 182 is provided so as to be movable forward and backward relative to the first side surface 3323 of the second extension space 332 from the front side. Two second intake valves 182 are provided here. Each second intake valve 182 is attached to a second intake valve installation hole 352 shown in FIG. 4A . The second intake valve 182 is used to draw an air-fuel mixture into the second cylinder chamber 122. When the second intake valve 182 enters the second extension space 332, it opens the second intake valve installation hole 352 shown in FIG. 4A , allowing air to be drawn into the second extension space 332 and the second cylinder chamber 122. When the second intake valve 182 retreats from the second extension space 332, it closes the second intake valve installation hole 352 shown in FIG. 4A .

[0062] The exhaust valve 19 includes a first exhaust valve 191 and a second exhaust valve 192 .

[0063] The first exhaust valve 191 is provided so as to be movable forward and backward from the rear side relative to the second side surface 3314 of the first extension space 331. Here, one first exhaust valve 191 is provided. The first exhaust valve 191 is attached to the first exhaust valve installation hole 361 shown in FIG. 4B . The first exhaust valve 191 is used to exhaust post-combustion gas from the first cylinder chamber 121. When the first exhaust valve 191 enters the first extension space 331, it opens the first exhaust valve installation hole 361 shown in FIG. 4B , allowing exhaust from the inside of the first cylinder chamber 121 through the first exhaust valve installation hole 361. On the other hand, when the first exhaust valve 191 retreats from the first extension space 331, it closes the first exhaust valve installation hole 361 shown in FIG. 4B .

[0064] The second exhaust valve 192 is provided so as to be movable from the rear side toward and away from the second side surface 3324 of the second extension space 332. Here, one second exhaust valve 192 is provided. The second exhaust valve 192 is attached to the second exhaust valve installation hole 362 shown in FIG. 4B . The second exhaust valve 192 is used to exhaust post-combustion gas from the second cylinder chamber 122. When the second exhaust valve 192 enters the second extension space 332, it opens the second exhaust valve installation hole 362 shown in FIG. 4B , allowing exhaust from the interior of the second cylinder chamber 122 through the second exhaust valve installation hole 362. On the other hand, when the second exhaust valve 192 retreats from the second extension space 332, it closes the second exhaust valve installation hole 362 shown in FIG. 4B .

[0065] The spark plug 26 has an electrode formed at its tip disposed inside the extension space 33. The spark plug 26 has a first spark plug 261 and a second spark plug 262.

[0066] The first spark plug 261 is a component disposed on the left side of the first exhaust valve 191. The front end of the first spark plug 261 is disposed inside the first extension space 331.

[0067] The second spark plug 262 is a component disposed on the right side of the second exhaust valve 192. The front end of the second spark plug 262 is disposed inside the second extension space 332.

[0068] Figure 6 is a cross-sectional view schematically showing the configuration of the water jacket 20, etc. Figure 6 is a cross-section corresponding to the A-A cross section in Figure 1. In Figure 6, the boundary between the first engine block 111 and the second engine block 112 is indicated by a dotted line.

[0069] As described above, the engine block 11 includes a first engine block 111 , a second engine block 112 , a third engine block 113 , and a fourth engine block 114 .

[0070] The first cylinder chamber 121 is a space formed by joining the first engine block 111 and the second engine block 112. As described above, while the engine 10 is operating, the first piston 141 and the second piston 151 reciprocate within the first cylinder chamber 121.

[0071] The water jacket 20 is a space formed near the cylinder chamber 12 and through which a cooling fluid 25 flows. The water jacket 20 is configured to cool the first cylinder chamber 121 and the second cylinder chamber 122. Here, a configuration in which the water jacket 20 surrounds the first cylinder chamber 121 is illustrated. Similarly, the second cylinder chamber 122 described above is also surrounded by the water jacket 20.

[0072] The water jacket 20 has a first water jacket portion 206 , a second water jacket portion 207 , and a communication portion 208 .

[0073] The first water jacket portion 206 is a cavity formed in a thick portion of the first engine block 111. The first water jacket portion 206 is formed to surround the front portion of the first cylinder chamber 121. The first water jacket portion 206 communicates with the outside via the discharge portion 23.

[0074] The second water jacket portion 207 is a cavity formed in a thick portion of the second engine block 112. The second water jacket portion 207 is formed to surround the rear portion of the first cylinder chamber 121. The second water jacket portion 207 communicates with the outside via the introduction portion 22.

[0075] The communication portion 208 is a space that communicates with the first water jacket portion 206 and the second water jacket portion 207 at the boundary indicated by the dotted line, i.e., the boundary between the first engine block 111 and the second engine block 112.

[0076] When the engine 10 is operating, the cooling fluid 25 is introduced through the inlet 22, flows through the second water jacket 207, the communication section 208, and the first water jacket 206, receives heat from the first cylinder chamber 121, and is discharged to the outside through the outlet 23. As the cooling fluid 25, a fluid with a high specific heat capacity, such as water, can be used.

[0077] Here, with respect to the second cylinder chamber 122 described above, the water jacket 20 is formed so as to surround the second cylinder chamber 122 described above in the same manner as above.

[0078] FIG. 7 is a cross-sectional view taken along the line BB in FIG. 3, showing the wall portion of the engine block 11 that defines the first cylinder chamber 121 and the first extension space 331. As shown in FIG.

[0079] As described above, the first cylinder chamber 121 is a substantially cylindrical space. The first cylinder chamber 121 has a first cylinder chamber front portion 1211 on the front side and a first cylinder chamber rear portion 1212 connected to the rear end of the first cylinder chamber front portion 1211. A first extension space 331 protrudes upward from the top surface of the first cylinder chamber 121 at approximately the center of the first cylinder chamber 121 in the front-to-rear direction. The first cylinder chamber front portion 1211, the first cylinder chamber rear portion 1212, and the first extension space 331 are in communication with each other.

[0080] The first cylinder chamber 121 and the first extension space 331 configured as described above are spaces surrounded by walls formed inside the engine block 11 .

[0081] Specifically, first cylinder chamber front portion 1211 is a substantially cylindrical space surrounded by first cylinder wall portion 1281. First cylinder wall portion 1281 is a cylindrical wall formed inside first engine block 111. The front and rear ends of first cylinder wall portion 1281 are open.

[0082] First cylinder chamber rear portion 1212 is a substantially cylindrical space surrounded by second cylinder wall portion 2282. Second cylinder wall portion 2282 is a cylindrical wall formed inside second engine block 112. The front and rear ends of second cylinder wall portion 2282 are open.

[0083] The first extension space 331 is a space surrounded by the first extension wall portion 1291 and the second extension wall portion 2292. The first extension wall portion 1291 is a generally tongue-shaped portion that extends upward from the upper end portion of the first cylinder wall portion 1281 at the rear end of the first cylinder wall portion 1281. The second extension wall portion 2292 is a generally tongue-shaped portion that extends upward from the upper end portion of the second cylinder wall portion 2282 at the front end of the second cylinder wall portion 2282.

[0084] The first cylinder chamber 121 is a substantially cylindrical space having a first central axis 1213 extending along the front-rear direction. The first cylinder chamber 121 has a first side surface 1214. The first side surface 1214 is a surface formed by the inner surfaces of the first cylinder wall portion 1281 and the second cylinder wall portion 2282. A first extension space 331 extends from the first side surface 1214. Specifically, the first extension space 331 is a space that extends upward in a direction perpendicular to the first central axis 1213 of the first cylinder chamber 121. The first extension space 331 communicates with the first cylinder chamber 121.

[0085] The same applies to the second cylinder chamber 122 described above.

[0086] FIG. 8 is a perspective view showing the engine block 11 and the gasket 21.

[0087] As described above, the engine block 11 has the first engine block 111 and the second engine block 112. The first contact surface 40 of the first engine block 111 and the second contact surface 41 of the second engine block 112 face each other in the front-rear direction.

[0088] The gasket 21 is a generally plate-shaped member having a shape corresponding to the first and second contact surfaces 40 and 41. The gasket 21 is made of a metal plate and a resin layer covering the surface of the metal plate. The gasket 21 is disposed so as to be sandwiched between the first contact surface 40 of the first engine block 111 and the second contact surface 41 of the second engine block 112. The gasket 21 fills the gap between the first and second engine blocks 111 and prevents liquids and gases from leaking between them. The gasket 21 has multiple openings. These openings are used for the passage of the cooling fluid 25, the insertion of fastening members such as stud bolts, and the formation of the extension space 33 and the cylinder chamber 12.

[0089] FIG. 9 is a plan view showing the gasket 21. As shown in FIG.

[0090] As described above, the outer edge shape of the gasket 21 conforms to the first contact surface 40 and the second contact surface 41 shown in FIG.

[0091] A plurality of through openings are formed in the gasket 21. Specifically, the gasket 21 is formed with a communication opening 211, a first cylinder opening 212, a second cylinder opening 213, and an insertion opening 214. In addition, a part of the gasket 21 is a separation portion 215 that functions as a partial wall.

[0092] The communication openings 211 are openings for allowing the cooling fluid 25 to flow. A plurality of communication openings 211 are formed along the periphery of the gasket 21. The position and shape of the communication openings 211 are similar to those of the communication openings 208 shown in FIG. 4A and the communication openings 209 shown in FIG. 4B . The communication openings 211 communicate with each other.

[0093] The first cylinder opening 212 is a large opening formed on the left side of the gasket 21. The outer edge shape of the first cylinder opening 212 is similar to the outer edge shapes of the first cylinder chamber 121 and the first extension space rear portion 3312 shown in FIG.

[0094] The second cylinder opening 213 is a large opening formed on the right side of the gasket 21. The outer edge shape of the second cylinder opening 213 is similar to the outer edge shapes of the second cylinder chamber 122 and the second extension space rear portion 3322 shown in FIG.

[0095] The insertion opening 214 is a substantially circular opening formed in the gasket 21 between the first cylinder chamber 121 and the second cylinder opening 213. A stud bolt (not shown here) is inserted through the insertion opening 214. The stud bolt is used to fasten the first engine block 111 to the fourth engine block 114 shown in FIG. 1 together.

[0096] The separating portion 215 is a portion where no opening is formed in the gasket 21 between the first cylinder opening 212 and the second cylinder opening 213. The separating portion 215 has a function of separating the first intermediate communication portion 204 and the second intermediate communication portion 205, which will be described later. The specific function of the separating portion 215 will be described later with reference to FIG. 12 .

[0097] Fig. 10A is a perspective view showing the water jacket 20 and the gasket 21. Fig. 10B is a perspective view showing the water jacket 20 and the gasket 21 from a different angle. Fig. 11 is an exploded perspective view showing the water jacket 20 and the gasket 21.

[0098] 10A and 10B, the water jacket 20 has an upper jacket portion 201, a lower jacket portion 202, and an intermediate communication portion 203. Here, referring to FIGS. 2A and 2B, the water jacket 20 is a cavity formed in a thick-wall portion surrounding the cylinder chamber 12 in the first engine block 111 and the second engine block 112. As will be described later, a cooling fluid 25, such as water, flows through the water jacket 20 to effectively cool the cylinder chamber 12, which repeats the explosion cycle.

[0099] The water jacket 20 also has a first water jacket portion 206, a second water jacket portion 207, and a communication portion 208. The first water jacket portion 206 is made up of a cavity formed in the first engine block 111 described above. The second water jacket portion 207 is made up of a cavity formed in the second engine block 112 described above. The communication portion 208 is made up of a cavity that connects to the communication portion 208 shown in FIG. 4A and the communication portion 209 shown in FIG. 4B. The communication portion 208 is a portion that connects the first water jacket portion 206 and the second water jacket portion 207, and is formed to pass through the communication opening 211 described above.

[0100] The jacket upper part 201 is configured to surround the upper parts of the first cylinder chamber 121 and the second cylinder chamber 122. The upper part of the jacket upper part 201 also has a complex shape in order to avoid the above-mentioned valves.

[0101] The jacket lower portion 202 is configured to surround the lower portions of the first cylinder chamber 121 and the second cylinder chamber 122. The jacket upper portion 201 and the jacket lower portion 202 are continuous at both left and right end portions.

[0102] The intermediate communication part 203 is part of the water jacket 20 and is disposed in the space sandwiched between the first cylinder chamber 121 and the second cylinder chamber 122 in the left-right direction. The intermediate communication part 203 is configured to communicate between the upper jacket part 201 and the lower jacket part 202. This allows air present in the part of the lower jacket part 202 surrounded by the first cylinder chamber 121 and the second cylinder chamber 122 to flow to the upper jacket part 201 via the intermediate communication part 203. In addition, the cooling fluid 25 can be effectively circulated via the intermediate communication part 203.

[0103] The intermediate communication portion 203 is shorter than the upper jacket portion 201 and the lower jacket portion 202 in the front-to-rear direction. The intermediate communication portion 203 has a first intermediate communication portion 204 and a second intermediate communication portion 205. Referring to FIG. 11 , the first intermediate communication portion 204 is the intermediate communication portion 203 in a portion forward of the gasket 21. The second intermediate communication portion 205 is the intermediate communication portion 203 in a portion rearward of the gasket 21. The first intermediate communication portion 204 communicates the lower jacket portion 202 and the upper jacket portion 201 in the first water jacket portion 206. Meanwhile, the second intermediate communication portion 205 communicates the lower jacket portion 202 and the upper jacket portion 201 in the second water jacket portion 207. As a result, the first intermediate communication part 204 and the second intermediate communication part 205 allow communication between the lower jacket part 202 and the upper jacket part 201 in both the first water jacket part 206 and the second water jacket part 207. This makes it possible to prevent air from accumulating in both the first water jacket part 206 and the second water jacket part 207, and further promotes the flow of cooling fluid 25, allowing the cylinder chamber 12 to be cooled effectively.

[0104] 12 is a cutaway perspective view showing the water jacket 20 and the gasket 21. Here, the water jacket 20 is cut along a plane extending in the front-rear direction and the up-down direction. The flow of the cooling fluid 25 is indicated by dashed arrows.

[0105] As described above, the gasket 21 is disposed between the first water jacket portion 206 and the second water jacket portion 207. Here, the portion of the gasket 21 existing between the first intermediate communication portion 204 and the second intermediate communication portion 205 corresponds to the separating portion 215 shown in Fig. 9. In other words, no opening is formed in this portion of the gasket 21.

[0106] In this way, the cooling fluid 25 flows along the main surface of the gasket 21, and the gasket 21 can be cooled effectively.

[0107] In the first water jacket portion 206, the cooling fluid 25 introduced into the jacket lower portion 202 is supplied to the jacket upper portion 201 via the first intermediate communication portion 204. When the cooling fluid 25 passes through the first intermediate communication portion 204, the cooling fluid 25 comes into contact with the front surface of the isolation portion 215 of the gasket 21, thereby cooling the gasket 21.

[0108] In the second water jacket portion 207, the cooling fluid 25 introduced into the jacket lower portion 202 is supplied to the jacket upper portion 201 via the second intermediate communication portion 205. When the cooling fluid 25 passes through the second intermediate communication portion 205, the cooling fluid 25 comes into contact with the rear surface of the isolation portion 215 of the gasket 21, thereby cooling the gasket 21.

[0109] Here, the flow path area of ​​the intermediate communication portion 203 with respect to the flow of the cooling fluid 25 is smaller than the flow path area of ​​the lower jacket portion 202 and the upper jacket portion 201. Therefore, the flow velocity of the cooling fluid 25 is faster in the intermediate communication portion 203 than in the upper jacket portion 201 and the lower jacket portion 202. This also makes it possible to increase the effect of cooling the separating portion 215 of the gasket 21 by the cooling fluid 25 flowing at high speed.

[0110] Furthermore, the separating portion 215 is the center of the gasket 21 and is also the portion sandwiched between the first cylinder chamber 121 and the second cylinder chamber 122. Therefore, the separating portion 215 of the gasket 21 is in an environment that is prone to high temperatures. Here, the cooling fluid 25 flowing vertically through the first intermediate communicating portion 204 and the second intermediate communicating portion 205 effectively cools the separating portion 215 of the gasket 21, thereby preventing the portion from overheating.

[0111] Here, a note will be added regarding the intermediate communication portion 203. The intermediate communication portion 203 is a cavity that connects the jacket lower portion 202 and the jacket upper portion 201, and is divided in the front-to-rear direction by the gasket 21. Therefore, the intermediate communication portion 203 has the function of allowing the cooling fluid 25 to flow in the up-down direction, but not allowing the cooling fluid 25 to flow in the front-to-rear direction.

[0112] As shown in FIG. 10A and other figures, in this embodiment, the first cylinder chamber 121 and the second cylinder chamber 122 are provided, resulting in an upwardly recessed portion at the bottom between the two. Therefore, unless some countermeasure is taken, there is a concern that air may stagnate in this portion. Furthermore, in order to reduce the size of the engine 10, it is not possible to ensure a large gap between the first cylinder chamber 121 and the second cylinder chamber 122, making it difficult to cool the gap between the two. In this embodiment, an intermediate communication portion 203 is formed between the first cylinder chamber 121 and the second cylinder chamber 122 to prevent air from stagnating in this portion. Furthermore, a cooling fluid 25 is circulated between the first cylinder chamber 121 and the second cylinder chamber 122 to effectively cool the portion.

[0113] 13 is a diagram showing the effect of water flow in the water jacket 20. The comparative example on the left is a comparative example that does not have the intermediate communication portion 203 described above. The example on the right has the intermediate communication portion 203 described above. Here, the flow rate distribution is shown by hatching, with the hatched areas having low flow rates.

[0114] In the comparative example shown on the left, the intermediate communication portion 203 described above is not formed. Therefore, hatched areas exist in the area corresponding to the area between the first cylinder chamber 121 and the second cylinder chamber 122. Therefore, in the water jacket 20 of the comparative example, there are parts where the cooling fluid 25 does not flow or where the cooling fluid 25 stagnates. Therefore, there is a risk that these parts will not be sufficiently cooled by the cooling fluid 25 and will become heated.

[0115] On the other hand, in the embodiment shown on the right, there are fewer hatched areas. This indicates that the cooling fluid 25 flows smoothly through the intermediate communication portion 203, and there is little accumulation of the cooling fluid 25 throughout the water jacket 20. Therefore, in this embodiment, the engine 10 can be effectively cooled by flowing the cooling fluid 25 through the water jacket 20.

[0116] Although the embodiments of the present invention have been described above, the present invention is not limited to these and can be modified within the scope of the present invention. In addition, the above-described embodiments can be combined with each other.

[0117] 10 Engine 11 Engine block 111 First engine block 112 Second engine block 113 Third engine block 114 Fourth engine block 12 Cylinder chamber 121 First cylinder chamber 1211 First cylinder chamber front portion 1212 First cylinder chamber rear portion 1213 First central axis 1214 First side surface 122 Second cylinder chamber 1221 Second cylinder chamber front portion 1222 Second cylinder chamber rear portion 1291 First extension wall portion 1281 First cylinder wall portion 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 16 Third engine section 161 Third piston 162 Third connecting rod 163 Third crankshaft 17 Fourth engine section 171 Fourth piston 172 Fourth connecting rod 173 Fourth crankshaft 18 Intake valve 181 First intake valve 182 Second intake valve 19 Exhaust valve 191 First exhaust valve 192 Second exhaust valve 20 Water jacket 201 Jacket upper section 202 Jacket lower section 203 Intermediate communicating section 204 First intermediate communicating section 205 Second intermediate communicating section 206 First water jacket section 207 Second water jacket section 208 Communicating section 209 Communicating section 21 Gasket 211 Communicating opening 212 First cylinder opening 213 Second cylinder opening 214 Insertion opening 215 Isolation section 22 Introduction section 2282 Second cylinder wall section 2292 Second extension wall section 23 Exhaust portion 24 Combustion chamber 25 Cooling fluid 26 Spark plug 261 First spark plug 262 Second spark plug 33 Extension space 331 First extension space 3311 Front portion of first extension space3312 Rear portion of first extension space 3313 First side surface 3314 Second side surface 332 Second extension space 3321 Front portion of second extension space 3322 Rear portion of second extension space 3323 First side surface 3324 Second side surface 35 Intake valve installation hole 351 First intake valve installation hole 352 Second intake valve installation hole 36 Exhaust valve installation hole 361 First exhaust valve installation hole 362 Second exhaust valve installation hole 37 Plug installation hole 371 First plug installation hole 372 Second plug installation hole 40 First contact surface 41 Second contact surface

Claims

1. An engine comprising an engine block, a cylinder chamber, and a water jacket, wherein the cylinder chamber has a first cylinder chamber and a second cylinder chamber, wherein a piston arranged opposite to the first cylinder chamber is arranged so as to reciprocate inside the first cylinder chamber, and wherein another piston arranged opposite to the first cylinder chamber is arranged so as to reciprocate inside the second cylinder chamber, and wherein a portion of the water jacket is formed between the first cylinder chamber and the second cylinder chamber.

2. The engine described in claim 1, characterized in that the central axes of the first cylinder chamber and the second cylinder chamber are approximately parallel to a horizontal plane, the water jacket has an upper jacket section, a lower jacket section, and an intermediate connecting section, the upper jacket section is configured to surround upper portions of the first cylinder chamber and the second cylinder chamber, the lower jacket section is configured to surround lower portions of the first cylinder chamber and the second cylinder chamber, and the intermediate connecting section is configured to connect the upper jacket section and the lower jacket section in the space sandwiched between the first cylinder chamber and the second cylinder chamber.

3. An engine as described in claim 2, further comprising a gasket, wherein the engine block has a first engine block and a second engine block, the gasket is disposed between the first engine block and the second engine block and has a communication opening, the first engine block has a first water jacket portion that partially forms the water jacket and a first intermediate communication portion that partially forms the intermediate communication portion, the second engine block has a second water jacket portion that partially forms the water jacket and a second intermediate communication portion that partially forms the intermediate communication portion, the first water jacket portion and the second water jacket portion communicate with each other via the communication opening of the gasket, and the gasket is present between the first intermediate communication portion and the second intermediate communication portion.

4. An engine according to claim 3, characterized in that the gasket present between the first intermediate communication portion and the second intermediate communication portion does not have the communication opening formed therein.

Images