Power unit

Abstract

A power unit is provided that allows for easy access between the stator and rotor of an axial flux generator constituting the power unit. The engine (11) of the power unit (10) has an engine side shaft (15) that outputs driving force by rotating around a rotation axis (14). The axial flux generator (12) has: a stator (16); a first rotor (17) rotatably disposed on one side of the stator (16); a second rotor (18) rotatably disposed on the other side of the stator (16); and a generator side shaft (19) connected to the rotation center of the first rotor (17) and the second rotor (18) and continuous with the engine side shaft (15). The engine side shaft (15) abuts against the thrust fixing part (131) along the rotation axis (14).

Description

Technical Field

[0001] This invention relates to power units. Background Technology

[0002] Traditionally, there has been a power unit that integrates the engine and generator. The generator used in this power unit can be either radial or axial. Axial generators are called axial flux generators. Compared to radial generators, axial flux generators are easier to miniaturize and are therefore mostly used in smaller devices.

[0003] Patent Document 1 describes an example of an axial flux generator. In the generator described in Patent Document 1, a rotor that is approximately in the shape of a disc is arranged opposite the stator along the axial direction. Moreover, by rotating the rotor, an induced current is generated using electromagnetic induction, thereby generating electricity.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-125021 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, when using the invention described in the aforementioned Patent Document 1 to construct a power unit, improving the output efficiency of the generator assembled in the engine is not simple.

[0009] Specifically, in the power unit, to transmit the driving force from the engine side to the generator side, the engine's crankshaft is connected to the rotating shaft of the axial flux generator. Here, to improve the power generation efficiency of the axial flux generator, it is important to bring the stator and rotor as close as possible along the direction of the rotating shaft. On the other hand, the engine's crankshaft is assembled to the engine body with certain tolerances in the axial direction for the assembly of components. Therefore, when the engine's crankshaft is connected to the shaft of the axial flux generator, the position of the rotor of the axial flux generator is not fixed in the axial direction. Thus, bringing the stator and rotor of the axial flux generator close together presents a complex challenge.

[0010] The present invention was made in view of this problem, and the object of the present invention is to provide a power unit that can bring the stator and rotor of the axial flux generator constituting the power unit into close proximity with a simple configuration.

[0011] Technical solutions for solving technical problems

[0012] The power unit of the present invention is characterized by comprising an engine, an axial flux generator driven by the engine, and a thrust fixing part. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator comprises: a stator; a first rotor rotatably disposed on one side of the stator; a second rotor rotatably disposed on the other side of the stator; and a generator side shaft connected to the rotation center of the first rotor and the second rotor and continuous with the engine side shaft, the engine side shaft abutting against the thrust fixing part along the rotation axis. According to the power unit of the present invention, the engine side shaft abuts against the thrust fixing part.

[0013] Furthermore, the power unit of the present invention is characterized by comprising an engine, an axial flux generator driven by the engine, and a thrust fixing part. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator has a stator, a rotor disposed near the stator, and a generator side shaft connected to the rotation center of the rotor and continuous with the engine side shaft. The engine side shaft abuts against the thrust fixing part along the rotation axis. The engine side shaft is subjected to force by a force-applying part, thereby abutting against the thrust fixing part. The engine side shaft has: a first thrust abutting part disposed near the axial flux generator; and a second thrust abutting part disposed at a position further away from the axial flux generator than the first thrust abutting part. The force-applying part abuts against the first thrust abutting part and applies force, such that the second thrust abutting part abuts against the thrust fixing part.

[0014] Invention Effects

[0015] According to the power unit of the present invention, the engine side shaft abuts against the thrust fixing part. Therefore, via the generator side shaft continuous with the engine side shaft, the axial positions of the first rotor and the second rotor are also predetermined. Thus, the gaps between the first rotor and the second rotor and the stator can be made to a predetermined length, thereby improving the power generation efficiency of the axial flux generator. Attached Figure Description

[0016] Figure 1A This is a cross-sectional view showing the power unit according to an embodiment of the present invention.

[0017] Figure 1B This is a rear view showing the power unit according to an embodiment of the present invention.

[0018] Figure 2A This is a cross-sectional view showing the power unit according to an embodiment of the present invention.

[0019] Figure 2B This is a cross-sectional view showing the power unit according to an embodiment of the present invention.

[0020] Figure 3A This is a cross-sectional view showing a power unit according to another embodiment of the present invention.

[0021] Figure 3B This is a perspective view showing the piston portion, etc., according to an embodiment of the present invention.

[0022] Figure 4 This is an enlarged cross-sectional view showing a power unit of another embodiment of the present invention. Detailed Implementation

[0023] Hereinafter, the power unit 10 according to an embodiment of the present invention will be described in detail based on the accompanying drawings. In the following description, the same reference numerals will be used to refer to the same parts in principle, and repeated descriptions will be omitted.

[0024] Figure 1A This is a cross-sectional view of the power unit 10. Figure 1B This is a diagram showing the rear of power unit 10.

[0025] The power unit 10 includes an engine 11, an axial flux generator 12 driven by the engine 11, and a thrust fixing part 132. When the power unit 10 is operated, the engine 11 rotates to drive the axial flux generator 12, which outputs alternating current (AC) power. The power unit 10 is used as a power source for aircraft, vehicles, etc. Compared with radial generators, the axial flux generator 12 can achieve a high degree of balance between miniaturization and high output. Therefore, by applying the axial flux generator 12 to aircraft such as drones, the aircraft can be made lighter, thereby extending the continuous flight range of the aircraft.

[0026] Engine 11, exemplified here, is a single-cylinder engine. Engine 11 mainly comprises a housing 25, a piston 26, an engine side shaft 15, and a connecting rod 27. When engine 11 is running, the piston 26 reciprocates through repeated high-speed compression, combustion, exhaust, and intake strokes. The engine side shaft 15, connected to the piston 26 by the connecting rod 27, converts the reciprocating motion into rotational motion. The engine side shaft 15 outputs driving force by rotating around a rotation axis 14. Furthermore, the engine side shaft 15 has a first thrust contact portion 23 and a second thrust contact portion 24. The specific configuration of the engine side shaft 15 will be described with reference to... Figure 2A To be described later.

[0027] Thrust fixing parts 131 and 132 are disposed inside the housing 25 and are used to axially fix the engine side shaft 15. The thrust fixing part 131 has a portion extending rearward toward the engine side shaft 15. A bearing (not shown) is clamped between the thrust fixing part 131 and the engine side shaft 15. The thrust fixing part 132 is inserted into a portion extending forward toward the engine side shaft 15. A bearing (not shown) is clamped between the thrust fixing part 132 and the engine side shaft 15.

[0028] The force-applying part 20 is disposed on the thrust fixing part 131. The force-applying part 20 is disposed on the front side of the thrust fixing part 131 and is the part that applies force to the first thrust abutment part 23 of the engine side shaft 15 in the forward direction. As the force-applying part 20, for example, the piston part 21 or the spring 22 described later can be used.

[0029] The piston section 21 is the part that applies force to the first thrust contact section 23 using the pressure of an auxiliary machine of the engine 11 (not shown here), namely an oil pump. The oil pump forms an oil supply path to supply oil to the main journal of the engine side shaft 15. The piston section 21 receives pressure from a branch path branching off from the oil supply path and applies force to the first thrust contact section 23. By using the piston section 21 as the force-applying part 20, a larger applied force can be obtained without the need for a dedicated device to generate the applied force. The force-applying part 20 will be referred to... Figure 3B To be described later.

[0030] Spring 22 is, for example, a helical spring having an axis in the front-rear direction. The restoring force of the helical spring applies force to the first thrust contact 23 in the forward direction. Spring 22 can be made of an elastic material other than a helical spring, such as a synthetic resin with elasticity like rubber. By using spring 22 as the force-applying part 20, applied force can be obtained with a simple configuration.

[0031] The axial flux generator 12 has a stator 16, a first rotor 17, a second rotor 18, and a generator side shaft 19. Here, the axial flux generator 12 is disposed adjacent to the rear side of the engine 11 and fixed to the housing 25 of the engine 11.

[0032] The stator 16 is connected to the housing 25 of the engine 11 via the stator fixing part 28, thereby fixing its position. The stator 16 has multiple coils arranged in a circumferential direction.

[0033] The first rotor 17 is configured to rotate on one side, i.e., the front side, of the stator 16. The first rotor 17 is equipped with multiple permanent magnets arranged along the circumferential direction.

[0034] The second rotor 18 is configured to rotate on the other side of the stator 16, i.e., the rear side. The second rotor 18 has multiple permanent magnets arranged along the circumferential direction.

[0035] Here, the gap between the first rotor 17 and the stator 16 is extremely short to improve the power generation efficiency of the axial flux generator 12. Similarly, the gap between the second rotor 18 and the stator 16 is also extremely short. In this embodiment, the engine side shaft 15 is positioned axially to stably shorten the length of these gaps. Related matters will be referred to... Figure 2A as well as Figure 2B Please provide an explanation.

[0036] The generator side shaft 19 is a generally rod-shaped component that is non-rotatably connected to the rotation center of the first rotor 17 and the second rotor 18. In addition, the generator side shaft 19 is continuous with the engine side shaft 15, forming an integral straight rod-shaped rotating component.

[0037] Figure 2A This is a cross-sectional view showing the state of the force-applying unit 20 before it applies force. Also, refer to... Figure 2A The composition of the engine side shaft 15 is described in detail.

[0038] The engine side shaft 15 has a pin 151, an arm 152, a front extension 153, and a rear extension 154. The pin 151 is rotatably connected to the lower portion of the connecting rod 27. The arm 152 is disposed on both sides of the pin 151, connecting the pin 151 to the front extension 153 and the rear extension 154. The front extension 153 extends forward through the thrust fixing part 132. The rear extension 154 passes through the thrust fixing part 131 and is connected to the generator side shaft 19.

[0039] The first thrust abutment portion 23 is a portion in which the rear extension portion 154 of the engine side shaft 15 is partially enlarged axially. The first thrust abutment portion 23 is formed by enlarging the rear extension portion 154, which is generally cylindrical, along its entire circumference. When the force-applying portion 20 is the piston portion 21 described later, the force-applying portion 20 does not apply force to the first thrust abutment portion 23 when the power unit 10 is not in operation.

[0040] The second thrust abutment portion 24 is a portion in which the front extension portion 153 of the housing 25 is partially enlarged axially. The second thrust abutment portion 24 is formed by enlarging the front extension portion 153, which is generally cylindrical, along its entire circumference. When the power unit 10 is not in operation, as described above, the force application portion 20 does not apply force to the first thrust abutment portion 23 forward, so the front of the second thrust abutment portion 24 does not abut against the rear of the thrust fixing portion 132.

[0041] Figure 2B This is a cross-sectional view showing the state in which the force-applying part 20 applies force.

[0042] By operating the engine 11, pressure from the hydraulic circuit acts on the force-applying part 20, which applies force to the rear of the first thrust abutment part 23 of the engine side shaft 15, moving it forward. As a result, the engine side shaft 15 and the generator side shaft 19 are displaced forward, and the front of the second thrust abutment part 24 abuts against the rear of the thrust fixing part 132. Thus, the generator side shaft 19, which is continuous with the engine side shaft 15, and consequently the first rotor 17 and the second rotor 18, are positioned according to predetermined lengths. Consequently, the gaps between the first rotor 17 and the stator 16, and between the second rotor 18 and the stator 16, are also set to predetermined lengths.

[0043] That is, the first rotor 17, stator 16, and second rotor 18 of the axial flux generator 12 are configured to become Figure 2B In the conditions shown, the gap between them becomes the design value.

[0044] Therefore, if the first rotor 17 and the second rotor 18 rotate in this state, alternating current can be generated efficiently through the electromagnetic interaction between the second rotor 18 and the stator 16.

[0045] Figure 3A This is a cross-sectional view showing another type of power unit 10. The engine 11 of the power unit 10 shown in this figure is a two-cylinder engine with two pistons. That is, two pistons 26 and connecting rods 27 are mounted on the engine side shaft 15. Other configurations are similar to... Figure 2A The power unit 10 shown is the same. Even with this structure, when the power unit 10 is operating, the force-applying part 20 also applies force to the first thrust-abutting part 23 forward, causing the second thrust-abutting part 24 to abut against the thrust-fixing part 132. Thus, in the axial flux generator 12, the gap between the first rotor 17 and the stator 16 and the gap between the second rotor 18 and the stator 16 become a predetermined distance. As a result, the axial flux generator 12 can generate electricity more efficiently.

[0046] Figure 3B This is a perspective view of the piston section 21 of the power unit 10 in another configuration. Here, only the upper part of the thrust fixing section 131 is shown.

[0047] A through hole 31 and a piston receiving portion 29 are formed in the thrust fixing portion 131. The through hole 31 is a through hole through which the rear extension 154, which is part of the aforementioned engine side shaft 15, is inserted. The piston receiving portion 29 is a generally arched cavity formed by cutting the outer portion of the thrust fixing portion 131 of the through hole 31. The piston portion 21 is a generally arched component, similar to the piston receiving portion 29, and is housed in the piston receiving portion 29. On paper, the forward-facing surface of the piston portion 21 abuts against the aforementioned first thrust abutment portion 23 and applies force.

[0048] The piston section 21 is pressurized by the hydraulic circuit 30. The hydraulic circuit 30 is a circuit that supplies oil from the aforementioned oil pump to the engine side shaft 15. The piston section 21 is arched, thereby enabling more stable force to be applied to the aforementioned engine side shaft 15.

[0049] Figure 4 This is an enlarged cross-sectional view showing another power unit 10 in a different configuration. Figure 4 The basic structure of the power unit 10 shown is the same as that shown in Figure 1, but the structure of the engine 39 is different.

[0050] The engine 39 has a first engine section 40 and a second engine section 41. The first engine section 40 and the second engine section 41 are arranged opposite each other. In addition, axial flux generators 12 are respectively arranged corresponding to the first engine section 40 and the second engine section 41. With this configuration, the overall power generation of the power unit 10 can be increased.

[0051] The first engine section 40 has a first piston 43 that reciprocates, a first crankshaft 42 that converts the reciprocating motion of the first piston 43 into rotational motion, and a first connecting rod 44 that rotatably connects the first piston 43 and the first crankshaft 42.

[0052] The second engine section 41 has a reciprocating second piston 46, a second crankshaft 45 that converts the reciprocating motion of the second piston 46 into rotational motion, and a second connecting rod 47 that rotatably connects the second piston 46 and the second crankshaft 45.

[0053] The first piston 43 of the first engine section 40 and the second piston 46 of the second engine section 41 share a combustion chamber 48. In other words, the first piston 43 and the second piston 46 reciprocate within a connected cylinder block 49. Thus, by having the first engine section 40 and the first piston 43 move simultaneously toward the center, a high expansion ratio of the air-fuel mixture in the combustion chamber 48 can be obtained while reducing the stroke amount.

[0054] Although not shown here, the engine 39 has a volumetric space that communicates with the combustion chamber 48, and a spark plug is disposed in this volumetric space. In addition, the combustion chamber 48 has an air intake and an exhaust port (not shown here). A mixture of gas and fuel, including gasoline, is introduced into the combustion chamber 48 through the air intake, and the exhaust gas after combustion is discharged from the combustion chamber 48 to the outside through the exhaust port.

[0055] Here, the first crankshaft 42 of the first engine section 40 is integrally connected to the generator side shaft 19 of the axial flux generator 12. On the other hand, the second crankshaft 45 of the second engine section 41 is integrally connected to the generator side shaft 19 of the other axial flux generator 12.

[0056] The engine 39 configured as described above operates as follows: First, during the intake stroke, the first piston 43 and the second piston 46 move from the center outwards inside the cylinder 49, introducing a fuel-air mixture into the cylinder 49. Next, during the compression stroke, due to the inertia of the rotating first crankshaft 42 and the second crankshaft 45, the first piston 43 and the second piston 46 are pushed towards the center, compressing the fuel-air mixture inside the cylinder 49. Next, during the combustion stroke, a spark plug (not shown) ignites in the combustion chamber 48, causing the fuel-air mixture to burn inside the cylinder 49, thereby pushing the first piston 43 and the second piston 46 to their outer ends, which are the bottom dead center. Then, during the exhaust stroke, due to the inertia of the rotating first crankshaft 42 and the second crankshaft 45, the first piston 43 and the second piston 46 are pushed inwards, expelling the combusted gases inside the cylinder 49 to the outside.

[0057] In engine 39, two pistons, first 43 and second 46, reciprocating within a cylinder block 49, divide the stroke. This increases the compression ratio of the air-fuel mixture compared to a conventional gasoline engine. Furthermore, since the first piston 43 and second piston 46 are opposed to each other within the cylinder block 49, a cylinder head, a feature typically found in engines, is unnecessary, resulting in a simpler and lighter engine structure. Moreover, the components of engine 39—namely, the first piston 43 and second piston 46, the first crankshaft 42, and the second crankshaft 45—are arranged and operate in opposition. This counteracts vibrations generated from the components of engine 39, reducing overall vibrations from the engine 39 to the outside. Therefore, by mounting this type of engine 39 onto an aircraft, miniaturization, weight reduction, and low vibration reduction of the aircraft are achieved. In particular, low vibration reduces adverse effects on precision equipment such as attitude control, motor output control, and GPS sensors. Additionally, it prevents damage to cargo transported by the aircraft due to vibration.

[0058] Hereinafter, the invention, which can be understood from the foregoing embodiments, will be described in conjunction with its effects.

[0059] The power unit of the present invention is characterized by comprising an engine, an axial flux generator driven by the engine, and a thrust fixing part. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator comprises: a stator; a first rotor rotatably disposed on one side of the stator; a second rotor rotatably disposed on the other side of the stator; and a generator side shaft connected to the rotation center of the first rotor and the second rotor and continuous with the engine side shaft, the engine side shaft abutting against the thrust fixing part along the rotation axis. According to the power unit of the present invention, the engine side shaft abuts against the thrust fixing part. Thus, via the generator side shaft continuous with the engine side shaft, the axial positions of the first rotor and the second rotor are also predetermined. Therefore, the gap between the first rotor and the second rotor and the stator can be made to a predetermined length, and the power generation efficiency of the axial flux generator can be improved.

[0060] Furthermore, in the power unit of the present invention, the engine side shaft is characterized by being forceped by a force-applying part, thereby abutting against the thrust fixing part. According to the power unit of the present invention, by using the force applied by the force-applying part to position the engine side shaft at a predetermined position, the first rotor and the second rotor can be positioned axially at predetermined positions during the operation of the power unit.

[0061] Furthermore, in the power unit of the present invention, the force-applying part is characterized by being a piston part utilizing the hydraulic circuit of the engine. According to the power unit of the present invention, since the force-applying part is a piston part utilizing the hydraulic circuit of the engine, the first rotor and the second rotor can be positioned at a predetermined location using the driving force of the engine.

[0062] Furthermore, in the power unit of the present invention, the piston portion is characterized by having a generally arched shape. According to the power unit of the present invention, the arched shape of the piston portion allows for more stable application of force to the rotating engine side shaft.

[0063] Furthermore, in the power unit of the present invention, the force-applying part is characterized by being a spring. According to the power unit of the present invention, since the force-applying part is a spring, the first rotor and the second rotor can be easily positioned in a predetermined location.

[0064] Furthermore, in the power unit of the present invention, the engine side shaft is characterized by having: a first thrust abutment portion disposed near the axial flux generator; and a second thrust abutment portion disposed further away from the axial flux generator than the first thrust abutment portion, wherein the force-applying portion applies force to the first thrust abutment portion, causing the second thrust abutment portion to abut against the thrust fixing portion. According to the power unit of the present invention, the second thrust abutment portion of the engine side shaft abuts against the thrust fixing portion, thereby enabling the engine side shaft to be fixed in a predetermined position during engine operation. Thus, the first rotor and the second rotor connected to the engine side shaft can be positioned in a predetermined axial direction.

[0065] Furthermore, in the power unit of the present invention, the first thrust contact portion and the second thrust contact portion are portions that partially enlarge the diameter of the engine side shaft. According to the power unit of the present invention, the first thrust contact portion and the second thrust contact portion are enlarged diameter portions, thereby enabling the rotating engine side shaft to be effectively pressed axially during operation of the power unit.

[0066] Furthermore, the power unit of the present invention is characterized by comprising an engine, an axial flux generator driven by the engine, and a thrust fixing part. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator has a stator, a rotor disposed near the stator, and a generator side shaft connected to the rotation center of the rotor and continuous with the engine side shaft. The engine side shaft abuts against the thrust fixing part along the rotation axis. The engine side shaft is subjected to force by a force-applying part, thereby abutting against the thrust fixing part. The engine side shaft has: a first thrust abutting part disposed near the axial flux generator; and a second thrust abutting part disposed further away from the axial flux generator than the first thrust abutting part. The force-applying part abuts against the first thrust abutting part and applies force, such that the second thrust abutting part abuts against the thrust fixing part. According to the power unit of the present invention, the engine side shaft abuts against the thrust fixing part. Therefore, via the generator side shaft which is continuous with the engine side shaft, the axial positions of the first and second rotors are also defined. Thus, the gaps between the first and second rotors and the stator can be made to a defined length, thereby improving the power generation efficiency of the axial flux generator.

[0067] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and modifications can be made without departing from the spirit of the present invention. In addition, the foregoing embodiments can be combined with each other.

[0068] The power unit 10 can be applied to a flight device. Specifically, the motor is driven by electricity generated from the power unit 10, and the thrust generated by rotating the rotor through the rotational force of the motor causes the aircraft to float. This type of flight device is also called a series hybrid unmanned aerial vehicle (UAV).

[0069] Explanation of reference numerals in the attached figures

[0070] 10 Power Units

[0071] 11 Engine

[0072] 12-axis flux generator

[0073] 131 Thrust fixing part

[0074] 132 Thrust fixing part

[0075] 14 Rotation axis

[0076] 15 Engine side shaft

[0077] Sales Department 151

[0078] 152 Arm

[0079] 153 Forward Extension

[0080] 154 Rear Extension

[0081] 16 stators

[0082] 17 First Rotor

[0083] 18 Second Rotor

[0084] 19 Generator side shaft

[0085] 20. Force application unit

[0086] 21 Piston section

[0087] 22 Springs

[0088] 23 First thrust contact section

[0089] 24 Second Thrust Contact Section

[0090] 25. Housing

[0091] 26 Pistons

[0092] 27 Connecting rod

[0093] 28 Stator fixing part

[0094] 29 Piston Storage Section

[0095] 30 Hydraulic circuit

[0096] 31 Through-hole

[0097] 39 Engine

[0098] 40 First Engine Section

[0099] 41 Second Engine Section

[0100] 42 First crankshaft

[0101] 43 First Piston

[0102] 44 First connecting rod

[0103] 45 Second crankshaft

[0104] 46 Second Piston

[0105] 47 Second connecting rod

[0106] 48 Combustion Chamber

[0107] 49 cylinder block

Claims

1. A power unit, It includes an engine, an axial flux generator driven by the engine, and a thrust fixing unit. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator comprises: a stator; a first rotor rotatably disposed on one side of the stator; a second rotor rotatably disposed on the other side of the stator; and a generator side shaft connected to the rotation centers of the first rotor and the second rotor and continuous with the generator side shaft. The power unit is characterized in that... The engine side shaft abuts against the thrust fixing part along the rotation axis. The engine side shaft is subjected to force by the force-applying part, thereby abutting against the thrust fixing part. The engine side shaft has: a first thrust abutment portion disposed near the axial flux generator; and a second thrust abutment portion disposed further away from the axial flux generator than the first thrust abutment portion. The force-applying part applies force to the first thrust-abutting part, causing the second thrust-abutting part to abut against the thrust-fixing part.

2. The power unit according to claim 1, characterized in that, The force-applying part is the piston part that uses the hydraulic circuit of the engine.

3. The power unit according to claim 2, characterized in that, The piston section has a generally arched shape.

4. The power unit according to claim 1, characterized in that, The force-applying component is a spring.

5. The power unit according to claim 1, characterized in that, The first thrust contact portion and the second thrust contact portion are the parts where the diameter of the engine side shaft is partially expanded.

6. A power unit, It includes an engine, an axial flux generator driven by the engine, and a thrust fixing unit. The engine has an engine side shaft that outputs driving force by rotating about a rotation axis. The axial flux generator has a stator, a rotor disposed near the stator, and a generator side shaft connected to the rotation center of the rotor and continuous with the engine side shaft. The power unit is characterized in that... The engine side shaft abuts against the thrust fixing part along the rotation axis. The engine side shaft is subjected to force by the force-applying part, thereby abutting against the thrust fixing part. The engine side shaft has: a first thrust abutment portion disposed near the axial flux generator; and a second thrust abutment portion disposed further away from the axial flux generator than the first thrust abutment portion. The force-applying part abuts against the first thrust abutting part and applies force, causing the second thrust abutting part to abut against the thrust fixing part.

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