POWER GENERATION SYSTEM AND DRIVE DEVICE THAT INDICATES THIS

Abstract

Power generation system (2) comprising the following: an internal combustion engine (6) which is operated within a predetermined speed range; and at least one power generating motor (7) which generates electricity when its input shaft is rotated by the internal combustion engine, wherein the internal combustion engine (6) comprises the following: a piston (15) that can move back and forth in a cylinder (14); a valve actuation mechanism (26) that actuates an inlet valve (22) to open and close an inlet port (18) and that actuates an outlet valve (23) to open and close an outlet port (19); a supercharger (31) that compresses the intake air to be introduced into the cylinder; and a fuel supply device (44) that supplies fuel, wherein, as the piston moves back and forth, starting at top dead center, reaching bottom dead center and returning to top dead center, the valve actuation mechanism (26) actuates the inlet valve (26) and the exhaust valve (23) in the following manner to provide a valve overlap period in which both the exhaust valve and the inlet valve are open and which includes a time in which the piston (15) is at bottom dead center: - the exhaust valve (23), which was closed before a downward movement of the piston from top dead center to bottom dead center, is opened during the downward movement; - the inlet valve (22), which was closed before the downward movement of the piston, is opened after the opening of the exhaust valve (23) during the downward movement; - the exhaust valve (23) is closed after the downward movement has ended and during an upward movement of the piston from bottom dead center to top dead center; and - the inlet valve (22) is closed after the exhaust valve (23) closes during the upward movement of the piston, the fuel supply device (44) supplies the fuel to the cylinder after the exhaust valve has closed during the upward movement of the piston, and an air-fuel mixture is burned in the cylinder while both the exhaust valve and the intake valve are closed during the upward movement of the piston, and wherein the input shaft of the power generating motor (7) is connected to an output shaft of the internal combustion engine (6) in such a way as to rotate at the same speed as the output shaft of the internal combustion engine.

Description

BACKGROUND OF THE INVENTION 1. AREA OF THE INVENTION

[0001] The present disclosure relates to a power generation system in which an internal combustion engine is used and a drive device comprising the power generation system. 2. DESCRIPTION OF THE STATE OF THE ART

[0002] Power generation systems that generate electricity using a motor as a drive source to power a generator are already known (see, for example, Japanese patent publication JP 2010-173 390 A and Japanese patent publication JP H08-47 107 A).

[0003] There is a need to improve the power generation efficiency of power generation systems as described above, which use an internal combustion engine.

[0004] DE 10 2010 025 002 A1 discloses an energy conversion system comprising an internal combustion engine and a generator driven by the internal combustion engine, and with a rotary connection that couples a first shaft of the internal combustion engine with at least a second shaft of the energy conversion system, wherein the second shaft rotates in the opposite direction to the first shaft and the first shaft is arranged parallel to the second shaft, wherein products of moments of inertia and respective associated rotational speed ratios of individual rotating components coupled to each other rotationally by means of the rotary connection cancel each other out at least approximately.

[0005] Further state of the art is disclosed in DE 10 2008 014 249 A1, US 5 823 280 A and US 2015 / 0285161 A1, DE 10 2015 103 992 A1, US 2014 / 0297079 A1, DE 10 2017 110 410 A1 and JP 2004-352 042 A. BRIEF SUMMARY OF THE INVENTION

[0006] One object of the present invention is to provide a power generation system that can exhibit an improved power generation efficiency and a drive device comprising the power generation system.

[0007] To solve the above problem, a power generation system is proposed as defined in the claims.

[0008] The configuration described above uses an internal combustion engine in which the air-fuel mixture is burned once per piston stroke. Specifically, a two-stroke engine is used for power generation. In this two-stroke engine, the energy extracted per unit of rotation (heat energy generated by combustion and thus mechanical energy derived from the crankshaft's rotation) is higher than in a four-stroke engine, where the air-fuel mixture is burned once every two piston strokes. Therefore, the speed range over which the engine operates with high efficiency can be shifted to the lower end of the speed spectrum. By achieving high efficiency at low speeds and avoiding high speeds, mechanical and sliding friction losses can be reduced.In the power generation motor, a reduction in electromotive force can be achieved by avoiding operation in a high-speed range, and the power generation efficiency can be increased. This means that a low-speed range, over which both the combustion engine and the power generation motor operate efficiently, can be used as the predetermined speed range for the combustion engine, and the overall power generation efficiency of the system can be improved.

[0009] The integration of the supercharger allows for the supply of supercharged air to the cylinder and increases the air intake volume (compressibility), resulting in improved combustion efficiency. By ensuring sufficient valve overlap, enhanced scavenging is achieved through the use of supercharged air during this period. Supplying fuel to the cylinder after the exhaust valve closes prevents the escape of unburned fuel into the cylinder's environment, thus reducing the amount of unburned fuel in the exhaust gas.

[0010] In this power generation system, the intake and exhaust ports can be configured such that, viewed from the piston positioned at top dead center, they are axially opposite each other along the cylinder of a crankshaft coupled to the piston. This configuration allows air intake to continue even when the piston is near top dead center, unlike a configuration where the piston itself opens and closes an intake port as it moves between top dead center and bottom dead center (i.e., a configuration where the piston itself acts as an intake valve). This increases flexibility in adjusting the intake duration.

[0011] In this power generation system, the fuel supply device can be a direct injection valve that injects fuel into the cylinder after the intake valve closes. With this configuration, because the fuel is injected after the intake valve closes, the compression ratio in the cylinder can be further increased to improve fuel efficiency.

[0012] In this power generation system, the input shaft of the power generation motor can be connected to the output shaft of the internal combustion engine in such a way that it rotates at the same speed. Since the internal combustion engine is a two-stroke engine capable of operating at low speed and high torque, this configuration improves power generation efficiency without the need for a speed reduction mechanism between the input shaft of the power generation motor and the output shaft of the internal combustion engine, and simplifies the overall system structure.

[0013] The power generation system can consist of at least one or more power generation motors. With this configuration, if the power generation system is designed as a single unit, the points where the individual power generation motors are connected can be adjusted throughout the entire unit. This allows for a more precise adjustment of the unit's center of gravity than with a configuration using only one power generation motor.

[0014] In this power generation system, the generating engines can be aligned with each other in the axial direction of a crankshaft coupled to the piston. This configuration makes it easier to prevent a shift in the center of gravity of the entire power generation system in the axial direction of the crankshaft than a configuration with only one generating engine.

[0015] In this power generation system, the internal combustion engine can have a crankshaft coupled to the piston and a balance shaft that can be operated together with the crankshaft to rotate at the same speed and suppress first-order crankshaft coupling vibrations. The input shaft of the power generation engine can receive power transmitted from the crankshaft via the balance shaft. This configuration offers greater flexibility in choosing the mounting location of the power generation engine compared to a configuration where the power generation engine is directly connected to the crankshaft, thus providing increased design flexibility.For example, the power generating motor can be located axially inside both ends of the crankshaft in the axial direction of the crankshaft to prevent it from protruding and to avoid increasing the overall axial dimension of the power generating system, which is designed as a single unit. This allows for a compact design of the system as a whole.

[0016] According to the present invention, a drive device is further proposed as defined in the claims.

[0017] The drive device may further include a throttle valve that regulates the amount of intake air introduced into the cylinder and an actuator that actuates the throttle valve. In this case, the drive device may also include a controller that operates the actuator based on the amount of electricity stored in the energy storage device and / or a drive demand on the drive motor. With this configuration, the torque of the internal combustion engine is controlled via the actuator based on whether the amount of stored electricity is excess or insufficient and / or whether the drive demand is high or low, thus preventing the power output of the internal combustion engine from being excessive or insufficient.

[0018] The drive unit can be installed in a vehicle that moves on land or in a missile that flies in the air. The drive unit with the above configuration is suitable for use in machines where there is a significant need for weight reduction or vibration reduction.

[0019] The above and further tasks, features and advantages of the present invention will become clearer from the following detailed description of preferred embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a conceptual diagram of a drive device according to a first embodiment. Fig. 2 is a schematic diagram showing the interior of an internal combustion engine of the type in Fig. The drive device shown in Figure 1 is shown. Fig. Figure 3A shows a combustion chamber viewed from below. Fig. 3B is an enlarged view of the inlet and outlet openings and their immediate surroundings. Fig. Figure 4 is a side view of the internal combustion engine of the drive device according to the first embodiment. Fig. Figure 5 is a diagram showing the change in the stroke of the inlet and outlet valves. Fig. Figure 6 is a speed-power output curve of the internal combustion engine of the drive device according to the first embodiment. Fig. Figure 7 is a cross-sectional view of an internal combustion engine of a drive device according to a second embodiment. Fig. Figure 8 shows a combustion chamber according to the second embodiment when viewed from below. Fig. Figure 9 is a side view of an internal combustion engine of a drive device according to a third embodiment. Fig. 10 is a schematic diagram of the interior of the in Fig. 9 shown internal combustion engine of the drive device. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0020] The following describes, with reference to the drawings, power generation systems according to exemplary embodiments and drive devices incorporating one of the power generation systems. Throughout the drawings, the same or equivalent elements are identified by the same reference numerals and are not described in detail repeatedly. In the cylinder axis direction, the bottom dead center of a piston inserted into the cylinder in the cylinder axis direction is located in the lower part of the cylinder, while in the cylinder axis direction, the top dead center of the piston inserted into the cylinder in the cylinder axis direction is located in the upper part of the cylinder. <First embodiment>

[0021] Fig. Figure 1 is a conceptual diagram of a drive device 1A according to a first embodiment. Drive devices installed in ride-on vehicles are described as examples of the drive device 1A of the present embodiment and the drive devices in Figures 1B and 1C according to the second and third embodiments, which are described later. A ride-on vehicle refers to a vehicle with a seat or saddle on which a rider sits in a straddle position, regardless of whether the vehicle has wheels. Preferred examples of ride-on vehicles include two-wheeled motorcycles (including so-called scooters), three-wheeled motorcycles, buggies, and passenger watercraft.

[0022] The propulsion device 1A comprises: a power generation system 2; a power storage device 3 that stores the power generated by the power generation system 2; a drive motor 4 that acts as a propulsion source for the ride-on vehicle by absorbing power supplied by the power storage device 3; and a control unit 5.

[0023] The power generation system 2 comprises an internal combustion engine (hereinafter referred to as the "engine") 6 and at least one electric generating motor 7, which generates electricity when its input shaft is rotated by the engine 6 (in this example, two electric motors 7 are provided). The engine 6 is operated within a predetermined constant speed range, as will be described later.

[0024] Engine 6 is a multi-cylinder, two-stroke, downdraft Otto engine. In the present embodiment, the fuel for engine 6 is gasoline (the fuel can be a liquid alcohol, such as ethanol or methanol). Engine 6 is a supercharged engine. Fig. Figure 1 conceptually represents engine 6 as a four-cylinder in-line engine. However, the number and arrangement of the cylinders are not necessarily limited. Engine 6 can be a single-cylinder engine. If engine 6 is a multi-cylinder engine, the cylinders can be arranged in a V or boxer configuration.

[0025] The engine 6 has one cylinder 14 and an engine body 10, which defines a combustion chamber S1 and a crankcase S2. The dashed line A1 in Fig. Figure 1 represents the cylinder axis. The main engine body 10 comprises a cylinder head 11, a cylinder block 12, and a crankcase 13, and these main body components 11 to 13 are coupled sequentially in the cylinder axis direction. In the present patent specification, a cylinder head cover 11a (see Figure 1) is described. Fig. 4) considered as part of the cylinder head 11. The cylinder 14 is mainly formed by the cylinder block 12, and the crankcase S2 is mainly defined by the crankcase 13.

[0026] The engine 6 has a piston 15 and a crankshaft 16. The piston 15 is reciprocating within the cylinder 14 and is connected to the crankshaft 16 via a connecting rod 15a. The crankshaft 16 is rotatably supported by the crankcase 13 and is housed in the crank chamber S2. During a reciprocating movement of the piston 15, the crankshaft 16 rotates.

[0027] Fig. Figure 2 schematically shows the four cylinders 14 and the crankshaft 16 of the engine 6. The crankshaft 16 has several journal sections 16a, which are positioned on the axis of rotation of the crankshaft 16, and crankpin sections 17, which are arranged in a one-to-one correspondence with the cylinders 14 for the rotatable support of the connecting rods 15a. The journal sections 16a and the crankpin sections 17 are connected by crank webs 16b. In the present embodiment, the crank webs 16b also act as crankshaft weights to reduce the inertial force of the pistons 15 and the connecting rods 15a (see Figure 2). Fig. 1).

[0028] In the present embodiment, the four crankpin sections 17 are arranged as shown in the illustration in Fig. 2 such that they have a phase shift of 90° or 180° relative to each other. In particular, assuming that the four crankpin sections 17 are designated as a first crankpin section 17a, a second crankpin section 17b, a third crankpin section 17c and a fourth crankpin section 17d in succession along the axis of rotation of the crankshaft 16 and that the direction of rotation of the crankshaft 16 is the positive direction, the second crankpin section 17b is arranged according to the illustration in Fig. 2 is arranged in such a position that it has a phase shift of 180° to the first pin section 17a, the third pin section 17c is arranged in such a position that it has a phase shift of 90° to the first pin section 17a, and the fourth pin section 17d is arranged in such a position that it has a phase shift of 270° (i.e. 90° in the negative direction) to the first pin section 17a.

[0029] The arrangement of the four crankpin sections 17 is not limited to that described above. For example, the second crankpin section 17b can be arranged in such a position that it has a phase shift of 90° to the first crankpin section 17a, the third crankpin section 17c can be arranged in such a position that it has a phase shift of 270° (i.e., 90° in the negative direction) to the first crankpin section 17a, and the fourth crankpin section 17d can be arranged in such a position that it has a phase shift of 180° to the first crankpin section 17a.

[0030] According to the representation in Fig. The input shafts of the power-generating motors 7 are connected to each of the two ends of the crankshaft 16. The crankshaft 16 and the respective input shafts of the power-generating motors 7 are connected via components, such as shaft couplings, in such a way that they are coaxial with each other. This means that the two power-generating motors 7 are aligned with each other in the axial direction of the crankshaft 16. When the crankshaft 16, which serves as an output shaft of the motor 6, rotates, the respective input shafts of the power-generating motors 7 are driven at a speed corresponding to that of the crankshaft 16. (Combustion chamber and valve system)

[0031] With renewed reference to Fig. In the cylinder head 11, the combustion chamber S1 is located above the top of the piston 15 in the cylinder axis direction. The cylinder head 11 forms the top surface of the combustion chamber S1. At least one inlet port 18 and at least one outlet port 19 open into the combustion chamber S1, specifically into the cylinder head 11's top surface. The inlet port 18 communicates with an inlet channel 20 formed in the cylinder head 11 and forms a downstream end of the inlet channel 20 and thus of the inlet passage. The outlet port 19 communicates with an outlet channel 21 formed in the cylinder head 11 and forms an upstream end of the outlet channel 21 and thus of the outlet passage.

[0032] The inlet port 18 is opened and closed by an inlet valve 22, while the outlet port 19 is opened and closed by an outlet valve 23. The inlet valve 22 is a poppet valve in which a dome-shaped valve element is biased by a valve spring (not shown) to be in close contact with a valve seat (not shown) located near the inlet port 18. The outlet valve 23 is designed in the same way as the inlet valve 22. A spark plug 24 is mounted on the cylinder head 11 such that one electrode (a spark-generating element) of the spark plug 24 is positioned in the combustion chamber S1 and near the top surface of the combustion chamber S1. The timing at which the spark plug 24 is actuated, i.e., the timing of the ignition of an air-fuel mixture, is controlled by the control unit 5.

[0033] Fig. Figure 3A shows the combustion chamber S1 viewed from below, and the top surface of the combustion chamber S1 is visible. In the present embodiment, two inlet openings 18 and two outlet openings 19 are provided. The inlet channel 20 has an inlet for admitting air and is branched at an intermediate point into two parts, each of which is connected to the two inlet openings 18. The outlet channel 21 has two parts, each of which is connected to the two outlet openings 19. The two parts merge at an intermediate point, and the outlet channel 21 has an outlet for releasing the exhaust gas. The top surface of the combustion chamber S1 is approximately hemispherical. A spark plug hole 24a, which holds the spark plug 24 ( Fig. 1) is located in the center of the ceiling surface. The ceiling surface of the combustion chamber S1 has a stepped section 25a extending along the diameter of the ceiling surface, and the ceiling surface is divided by the stepped section 25a into a first area 25b and a second area 25c. The two inlet openings 18 open into the first area 25b, while the two outlet openings 19 open into the second area 25c. As shown in Fig. 3B is the second area 25c positioned below the first area 25b in the cylinder axis direction. Since both the intake ports 18 and the exhaust ports 19 open into the top surface of the combustion chamber S1, the openings are positioned above the top dead center of the cylinder 14 in the cylinder axis direction. In particular, both the intake ports 18 and the exhaust ports 19 are designed such that, when viewed from (or with respect to) the piston 15 positioned at top dead center, the openings are opposite the crankshaft 16 in the cylinder axis direction. The exhaust ports 19 open into the combustion chamber S1 at lower points in the cylinder axis direction than the intake ports 18.

[0034] With renewed reference to Fig. In the present embodiment, the engine 6 has a valve actuation mechanism 26 that actuates the intake valve 22 and the exhaust valve 23. In this embodiment, the valve actuation mechanism 26 is of the overhead camshaft (OHC) type, specifically of the double overhead camshaft (DOHC) type. The valve actuation mechanism 26 comprises an intake camshaft 27, an intake cam 27a, an exhaust camshaft 28, an exhaust cam 28a, and a transmission mechanism 29. The intake camshaft 27 and the exhaust camshaft 28 are positioned in the cylinder axis direction above the intake valve 22 and the exhaust valve 23, respectively, and extend parallel to the crankshaft 16. The transmission mechanism 29 transmits the rotation of the crankshaft 16 to the intake camshaft 27 and the exhaust camshaft 28.The transmission mechanism 29 is, for example, a chain drive mechanism formed by a drive pinion 29a fixed to the crankshaft 16, an intake-side driven pinion 29b fixed to the intake camshaft 27, an exhaust-side driven pinion 29c fixed to the exhaust camshaft 28, and a chain 29d wound around the three pinions 29a to 29c. The transmission mechanism 29 can be a gear set. The intake cam 27a is fixed to the intake camshaft 27 and rotates with the intake camshaft 27 to make contact with the upper end of the intake valve 22. The exhaust cam 28a is fixed to the exhaust camshaft 28 and rotates with the exhaust camshaft 28 to make contact with the upper end of the exhaust valve 23. The inlet cam 27a and the outlet cam 28a each have a cam elevation.In other words, the cams are oval-shaped when viewed in the axial direction of the camshaft. Cams 27a and 28a cause the corresponding valves 22 and 23 to open once during one rotation of the respective camshafts 27 and 28.

[0035] The engine 6 is a two-stroke engine, and an engine cycle, which includes air intake, ignition-combustion, and exhaust gas discharge, is carried out during a reciprocating motion of the piston 15 and a rotation of the crankshaft 16. This feature will be described later with reference to Fig. 5 described. The intake camshaft 27 and the exhaust camshaft 28 rotate at the same speed as the crankshaft 16. In the present embodiment, the three pinions 29a to 29c have the same number of teeth or the same diameter. Thus, according to the setting, a valve opening period in which the intake valve 22 is open and a valve opening period in which the exhaust valve 23 is open occur once during one reciprocating motion of the piston 15 and one rotation of the crankshaft 16. (Intake system and fuel system)

[0036] The engine 6 comprises an air filter 39, a supercharger 31, an intake chamber housing 32, and a throttle device 33 as components forming the intake system. In this intake system, ambient air is drawn in as intake air and cleaned by the air filter 39. The cleaned intake air is compressed by the supercharger 31, and the compressed intake air flows into the intake chamber housing 32. The supercharger 31 is, for example, a mechanical supercharger that is driven by the crankshaft 16. Various types of mechanical superchargers are available, and in the present embodiment, the supercharger 31 is designed as a centrifugal pump. The intake chamber housing 32 absorbs intake air pressure fluctuations.

[0037] The throttle device 33 is arranged downstream of the supercharger 31 and the inlet chamber housing 32 in the direction of the intake air flow. A supercharger 31 and an inlet chamber housing 32 are provided, and the outlet of the supercharger is connected to the inlet of the chamber via a single inlet passage 30a. The inlet chamber housing 32 has chamber outlets, the number of which corresponds to the number of cylinders. The chamber outlets are each connected to the combustion chambers S1 via several independent inlet passages 30b.

[0038] The throttle device 33 comprises the following: four throttle valves 34, each adjusting the flow rate of air entering a corresponding combustion chamber S1 (the amount of air intake); and an actuator 36 that actuates the throttle valves 34. The four throttle valves 34 are in one-to-one correspondence with the four cylinders 14. Each throttle valve 34 is, for example, a rotary valve having a circular flap element. Rotation of the circular flap element changes the degree of opening of the inlet passage 30b leading to the combustion chamber S1. This means that the respective flap elements of the throttle valves 34 are positioned in the inlet passages 30b leading to the combustion chambers S1. These flap elements are fixed to or integrated into a flap shaft 35, and the actuator 36 rotatably drives the flap shaft 35.The throttle device 33 is an electronically controlled device controlled by the controller 5. This means that the actuator 36 is controlled by the controller 5 and is, for example, an electric motor. The details of the control of the throttle device 33 by the controller 5 will be described later.

[0039] The engine 6 comprises a fuel tank 41, a fuel pressurization mechanism 42, a fuel line 43, an upstream fuel supply device 44, a downstream fuel supply device 45, a primary fuel pump 46, and a reservoir 47 as components forming the fuel system. The fuel tank 41 stores the fuel for the engine 6.

[0040] The primary fuel pump 46 pressurizes the fuel stored in the fuel tank 41. For example, the fuel is pressurized to approximately 300 kPa. The fuel pressurization mechanism 42 further pressurizes the fuel pressurized by the primary fuel pump 46. The fuel pressurization mechanism 42 is, for example, a piston pump that pressurizes the fuel to approximately 2 MPa. In the present embodiment, the pressurization force source for the fuel pressurization mechanism 42 (reciprocating force source for the piston of the fuel pressurization mechanism 42) is the valve actuation mechanism 26 and thus the motor 6.This means that the valve actuation mechanism 26 has the function of actuating both the inlet and outlet valves 22 and 23 and the fuel pressurization mechanism 42. The fuel pressurization mechanism 42 is arranged in the cylinder axis direction above the inlet and outlet valves 22 and 23 and is attached to the cylinder head 11. As shown in Figure 1. Fig. 1. A pressure-applying cam 42a is fixed to the exhaust camshaft 28 in addition to the exhaust cam 28a. The pressure-applying cam 42a has a cam ridge. In other words, the pressure-applying cam 42a has an oval shape when viewed in the axial direction of the camshaft. The plunger of the fuel pressure-applying mechanism 42 comes into contact with the pressure-applying cam 42a. The fuel pressure-applying mechanism 42 is located opposite the exhaust valve 23 in the radial direction of the exhaust camshaft 28. The plunger of the fuel pressure-applying mechanism 42 is driven by the pressure-applying cam 42a, which rotates together with the exhaust camshaft 28.This pressurizes the fuel flowing from the primary fuel pump 46 into the housing of the fuel pressurization mechanism 42 and directs it to the outside environment of the housing.

[0041] The upstream fuel supply device 44 and the downstream fuel supply device 45 are provided for each cylinder. The upstream fuel supply device 44 is located upstream of the throttle device 33 in the direction of intake air flow, while the downstream fuel supply device 45 is located downstream of the throttle device 33 in the direction of intake air flow. Both the upstream fuel supply device 44 and the downstream fuel supply device 45 are normally closed solenoid-operated valves, and the valve opening timing, valve opening duration, and valve closing timing of the supply devices are controlled by the aforementioned control unit 5.The fuel line 43 carries the fuel pressurized by the primary fuel pump 46 to the upstream fuel supply device 44 and carries the fuel pressurized by the fuel pressurization mechanism 42 to the downstream fuel supply device 45. The accumulator 47 is connected to that part of the fuel line 43 which connects the fuel pressurization mechanism 42 to the downstream fuel supply device 45 and absorbs the fuel pressure fluctuations in this part.

[0042] The upstream fuel supply devices 44 are in one-to-one correspondence with the inlet passages 30b. For example, each upstream fuel supply device 44 injects the fuel from a point in the direction of inlet air flow upstream of the throttle device 33 into the corresponding inlet passage 30b. The upstream fuel supply device 44 can be configured as shown in Fig. 4 are housed in the inlet chamber housing 32.

[0043] The downstream fuel supply devices 45 are arranged downstream of the upstream fuel supply devices 44 in the direction of intake air flow. The downstream fuel supply devices 45 are mounted on the cylinder head 11 and are directly aligned with the cylinders 14. In the present embodiment, the injection port of each downstream fuel supply device 45 opens into the combustion chamber S1 of the corresponding cylinder 14. This means that each downstream fuel supply device 45 is a direct injection valve that injects the fuel directly into the corresponding cylinder 14. The timing of the fuel injection from the downstream fuel supply devices 45 is controlled by the control unit 5.

[0044] According to the representation in Fig. 1 The downstream fuel supply device 45 is arranged in the cylinder axis direction below the intake port 20. As shown in Fig. 3A the inlet channel 20 is branched into two parts on the downstream side, and the downstream fuel supply device 45 is positioned below the branching point between the two parts of the inlet channel 20.

[0045] Fig. Figure 4 is a side view of the internal combustion engine when mounted in a ride-on vehicle. The directions upward, downward, forward, backward, left, and right are defined here with respect to the direction in which the rider of the ride-on vehicle is facing. The crankshaft 16 and the camshafts 27 and 28 are arranged to extend in the left / right direction. The engine 6 is mounted in the ride-on vehicle such that the exhaust port 21 is positioned in front of the intake port 20. The fuel pressurization mechanism 42 is attached to the cylinder head 11 (the cylinder head cover 11a) and is positioned at an upper front end of the main engine body 10.

[0046] The engine 6 is of the downdraft type, and the chamber outlet is positioned on an extension A2 of the centerline of the intake port 20. This extension A2 coincides with the centerline of the intake passage 30b. The components forming the intake system extend rearward and upward from the rear face of the cylinder head 11. The downstream fuel supply device 45 is in the form of a stepped tube, and the centerline A3, and thus the fuel injection device of the downstream fuel supply device 45, extends approximately parallel to the centerline of the intake port 30b.

[0047] The intake chamber housing 32, which is a relatively large component, is located behind and above the main engine body 10. The crankcase 13 is formed from an upper housing section 13a and a lower housing section 13b and is divided by a cross-section along the axis about which the crankshaft 16 rotates (i.e., an extension of the crankpin section 16a). The cylinder block 12 is located above the front of the upper housing section 13a. The supercharger 31 is located in a space above the upper housing section 13a and behind the cylinder head 11.

[0048] In the present embodiment, the two power-generating motors 7, which are connected to the crankshaft 16, are also housed in the crankcase 13 together with the crankshaft 16. This means that the power-generating system 2 is designed as a single unit.

[0049] With renewed reference to Fig. 1. The electricity generated by the two power-generating motors 7 is stored in the energy storage device 3. The power-generating motors 7 are, for example, three-phase asynchronous motors. The power-generating motors 7 are electrically connected via converter devices 8a, which are arranged in a one-to-one configuration with the motors 7. Each converter device 8a converts the alternating current generated by the corresponding power-generating motor 7 into direct current, which is used to charge the energy storage device 3. The energy storage device 3 is, for example, a battery or a capacitor.

[0050] The energy storage device 3 is electrically connected to the drive motor 4 via an inverter device 8b. The drive motor 4 is, for example, a three-phase asynchronous motor. The inverter device 8b converts the direct current stored in the energy storage device 3 into alternating current, which is supplied to the drive motor 4. The inverter device 8b controls the speed of the output shaft of the drive motor 4 according to a control command sent by the controller 5.

[0051] The controller 5 regulates the amount of current supplied to the drive motor 4 to propel the ride-on vehicle according to the driver's input. The controller 5 is, for example, a computer comprising a processor, such as a CPU, and memory devices, such as ROM and RAM (not all processor and memory devices are shown). The memory devices store programs for execution by the processor and various fixed data. The processor exchanges data with external devices. The processor receives detection signals input from various instruments and outputs control signals to various control targets. The controller 5 can perform various processes through centralized control using a single computer or through decentralized control using several interacting computers.

[0052] The controller 5 is communicatively connected to a drive request sensor 5a, the energy storage device 3, the actuator 36, and the inverter device 8b. The drive request sensor 5a is a sensor installed in the ride-on vehicle for detecting a drive request made to the drive motor 4 by the rider. In an example where the ride-on vehicle is a motorcycle, the drive request sensor 5a corresponds to an accelerator actuator sensor that detects the degree of actuation of an accelerator actuator (throttle grip) operated by the rider. The drive request sensor 5a transmits the detected drive request to the controller 5.Based on the drive request made to the drive motor 4, the control unit 5 controls the inverter device 8b to supply the drive motor 4 with current from the energy storage device 3 that fulfills the drive request.

[0053] The controller 5 regulates the supply of current to the drive motor 4, adjusting the amount of current generated by the power generation system 2 and the amount of current stored in the energy storage device 3 accordingly. A signal indicating the amount of current stored in the energy storage device 3 is sent from the energy storage device 3 to the controller 5.

[0054] In the present embodiment, the motor 6 is controlled by the controller 5 to maintain a (constant) speed within a predetermined motor speed range during the period of operation of the motor 6, in particular during the transition period without start-up and shutdown phases. The predetermined motor speed range (hereinafter referred to as the "constant speed range") is preferably set within the motor's power band. The power band refers to a speed range over which the motor can deliver its power with maximum efficiency and is generally a range between the speed at which the motor's torque is highest and the speed at which the motor's power is highest. Thus, during the transition period, the motor 6 is essentially operated in the constant speed range, enabling it to deliver its power with maximum efficiency.

[0055] The constant speed range predetermined for the motor 6 in the present embodiment will now be described in more detail. Since the motor 6 is a two-stroke engine, the speeds at which the motor 6 operates with high efficiency are lower than the speeds at which four-stroke engines operate with high efficiency (this feature will be described in more detail later). When the motor 6 is operated in a high-speed range, mechanical losses occur, including pumping losses and sliding friction losses. Furthermore, when the motor 6 is operated in a high-speed range, a high electromotive force is generated in the power-generating motor 7. Thus, operating the motor 6 at a speed above a certain speed (e.g., 6500 rpm) is disadvantageous in terms of efficiency for both the motor 6 and the power-generating motor 7.However, since the supercharger 31 is driven by the crankshaft 16 in the present embodiment, operating the engine 6 at a very low speed (e.g., below 2000 rpm) allows the supercharger 31 to generate the torque required to introduce intake air into the combustion chambers S1. Therefore, in the present embodiment, the range between 2000 rpm and 6500 rpm (inclusive) is defined as the constant speed range for the engine 6, and the engine 6 is operated at a constant speed (e.g., 3000 rpm) within this constant speed range.

[0056] In the present embodiment, the controller 5 controls the actuator 36 of the throttle device 33 based on the amount of current stored in the energy storage device 3 and the drive demand made to the drive motor 4. For example, to prevent overloading of the energy storage device 3, the controller 5 can cause the actuator 36 to stop the operation of the motor 6, even if the drive motor 4 is running, when the amount of current stored in the energy storage device 3 exceeds a predetermined level.

[0057] During the transition-free period, the controller 5 essentially controls the actuator 36 of the throttle device 33 such that the motor 6 operates in the predetermined constant speed range as described above. However, it is taken into consideration that the amount of current stored in the energy storage device 3 becomes insufficient if the amount of current consumed by the drive motor 4 is considerably greater than the amount of current generated by the operation of the motor 6 in the constant speed range. Thus, in the exceptional case where the amount of current stored in the energy storage device 3 falls below a predetermined level or the drive request sent by the drive request sensor 5a exceeds a predetermined level, the controller 5 can control the actuator 36 to increase the motor speed (motor torque) in favor of increasing current generation rather than efficiency.to cause the motor 6 to operate at a speed above the constant speed range.

[0058] During the start-up and shutdown periods, operation that takes engine efficiency into account cannot be performed. For example, the engine torque may be set higher during the start-up period than during the idle period to allow inertial components, such as the piston 15 and the power-generating motor 7, to move or rotate smoothly. During the start-up and shutdown periods, to prevent abrupt changes in engine speed, the controller 5 can control the actuator 36 of the throttle device 33 to gradually change the throttle opening and thus gradually change the engine speed over time. (Combustion stroke in each cylinder)

[0059] Fig. Figure 5 is a diagram showing the change in the lift dimension of the intake and exhaust valves for a cylinder and indicating the fuel injection timing and ignition timing for that cylinder. For clarity, the crankshaft angle for piston 15 at top dead center is defined as 0° or 360°, and the crankshaft angle for piston 15 at bottom dead center is defined as 180°. Engine 6 is a two-stroke engine, and one combustion stroke is carried out in the cylinder while piston 15 moves back and forth once, starting at top dead center and returning to top dead center.

[0060] When the piston 15 is at bottom dead center, the exhaust valve 23 is closed and the intake valve 22 is open. Thus, the intake air compressed by the supercharger 31 is fed into the combustion chamber S1 through the intake ports 18.

[0061] While the piston 15 moves after a valve closing time t ICAs the intake valve 22 is closed, the downstream fuel supply device 45 moves upwards, injecting fuel into the combustion chamber S1, where the air-fuel mixture is generated. In the present embodiment, the downstream fuel supply device 45 injects fuel in separate periods (e.g., two separate periods). In other words, an injection-free period occurs between the fuel injection periods, during which fuel is not directly injected. All fuel injection periods are set to occur after the intake valve 22 closes. To reduce the amount of pollutants in the exhaust gas treated by a three-way catalytic converter, the amount of fuel injected by the downstream fuel supply device 45 can be set to achieve the ideal air-fuel ratio within the constant speed range defined for the transition-free period.

[0062] After the fuel has been supplied to the combustion chamber S1 from the downstream fuel supply device 45, the spark plug 24 acts to ignite and burn the compressed air-fuel mixture in the combustion chamber S1. The ignition point is set to occur around the moment when the piston 15 is at top dead center. Upon receiving the energy from the combustion of the air-fuel mixture, the piston 15 moves downwards and rotates the crankshaft 16.

[0063] During the downward movement of the piston 15, the exhaust valve 23 is open and the exhaust gas is released into the exhaust port 21 and thus into the outside air through the exhaust openings 19. A valve closing point t ECThe point at which the exhaust valve 23 is closed is fixed after the valve opening time of the intake valve 22. Thus, in engine 6, there is a period during which both the intake valve 22 and the exhaust valve 23 are open around the moment when the piston 15 is at bottom dead center. This period can be called the valve overlap period, which is referred to below as the "VOL period" (see hatched area in Figure 6). Fig. 5) The VOL period can be determined depending on the design of the profiles of the inlet cam 27a and the outlet cam 28a.

[0064] In the present embodiment, the four crankpin sections 17 of the crankshaft 16 are arranged such that they have a phase shift of 90° or 180° relative to each other. Thus, the combustion strokes of the four cylinders described above have a phase shift of 90° or 180° relative to each other. In particular, the second crankpin section 17b, the third crankpin section 17c, and the fourth crankpin section 17d are each arranged in positions such that they have phase shifts of 180°, 90°, and 270° relative to the first crankpin section 17a, respectively. Thus, the ignition of the air-fuel mixture occurs first in the cylinder corresponding to the first crankpin section 17a, then in the cylinder corresponding to the third crankpin section 17c, then in the cylinder corresponding to the second crankpin section 17b, and finally in the cylinder corresponding to the fourth crankpin section 17d.This means that the ignition timing in the four cylinders is offset from each other by the arrangement of the four crankpin sections 17 of the crankshaft 16 such that they have a phase shift of 90° or 180° to each other.

[0065] In the drive unit 1A of the present embodiment, the engine 6 is a two-stroke engine in which the air-fuel mixture is combusted once in the cylinder 14 with each reciprocating stroke of the piston 15; that is, the engine 6 is a two-stroke engine. In the two-stroke engine, the energy extracted per unit of rotation (heat energy generated by combustion and thus mechanical energy derived from the rotation of the crankshaft) is higher than in a four-stroke engine, in which the air-fuel mixture is combusted once in the cylinder every two reciprocating strokes of the piston 15. For this reason, the speed range over which the engine 6 operates with high efficiency can be shifted to the lower end of the speed range.

[0066] This feature is now referred to Fig. 6 described. Fig. Figure 6 shows the speed-power output curve of the engine 6 according to the present embodiment by a thick solid line, while the speed-power output curve of an engine according to a comparative example is shown by a two-dot dashed line. The engine according to the comparative example is a four-stroke engine and has a peak power output Wp that corresponds to that of the engine 6 according to the present embodiment. In the present embodiment, as can be seen from the figure, the engine speed (speed Np at peak power output) required to achieve the peak power output Wp, which corresponds to that in the comparative example, can be reduced to approximately half the speed Np' at peak power output in the comparative example. Thus, the speed range over which the engine 6 operates with high efficiency can be shifted to the lower speed range.

[0067] Fig. Figure 6 also shows the absolute value of mechanical losses with respect to engine speed (see the thin solid line and the hatched area shown below the thin solid line). In reciprocating engines, mechanical losses (including pumping and friction losses) are approximately proportional to the square of the engine speed. If the speed Np' at peak power output is in a high-speed range, as in the comparison example, the mechanical losses occurring at Np' are large. Thus, the net peak power output obtained when the engine speed is at Np' is significantly smaller than the peak power output Wp.The rotational speed Np at peak power output of motor 6 according to the present embodiment is lower than the rotational speed Np' at peak power output in the comparison example, and thus the mechanical losses occurring at the rotational speed at peak power output are lower for motor 6 than for the motor in the comparison example. The net peak power output Wpn in the present embodiment is accordingly higher than the net peak power output in the comparison example. By thus achieving high-efficiency operation in a low-speed range and avoiding operation in a high-speed range, the mechanical losses, including pumping losses and sliding friction losses, can be reduced.

[0068] In the power-generating motor 7, a reduction in electromotive force can be achieved by avoiding operation in a high-speed range, and the power-generating efficiency can be increased. This means that a low-speed range, over which both motor 6 and the power-generating motor 7 can be operated efficiently, can be used as the constant-speed range for motor 6, and the overall power-generating efficiency of the system can be improved. For these reasons, an efficient drive device can be provided.

[0069] In the present embodiment, since the speed of the motor 6 is mainly in the constant speed range during operation of the motor 6, vibrations and vibration noise can be readily suppressed by supporting the motor 6 and its associated components in such a way that the natural frequency is reduced in the constant speed range.

[0070] In the present embodiment, the engine speed is set to a lower value than in four-stroke engines. This allows the start-up and shutdown periods to be shortened, and the overall length of the transition periods to be reduced. This leads to a reduction in the vibrations occurring during the transition periods.

[0071] In the present embodiment, since the engine 6 can be operated in a low-speed range, it is possible to lengthen the valve opening periods of the inlet valve 22 and the exhaust valve 23 or to reduce the stroke speeds of the inlet valve 22 and the exhaust valve 23. Lengthening the valve opening periods of the inlet valve 22 and the exhaust valve 23 can lead to an increase in charging efficiency and an improvement in scavenging. Reducing the stroke speeds of the inlet valve 22 and the exhaust valve 23 can lead to a reduction in damage to the inlet valve 22 and the exhaust valve 23 due to their sliding motion.

[0072] The integration of the supercharger 31 enables the supply of supercharged air to cylinder 14 and the increase in air intake volume (compressibility), resulting in increased combustion efficiency. By ensuring the VOL period, enhanced scavenging is facilitated through the use of supercharged air during this time. The supply of fuel to cylinder 14 after the closing of the exhaust valve 23 prevents the escape of unburned fuel into the external environment of cylinder 14, thus reducing the amount of unburned fuel in the exhaust gas.

[0073] In the present embodiment, since the downstream fuel supply device 45 injects the fuel after the inlet valve 22 has closed, the compression ratio in the cylinder 14 can be further increased to further improve fuel efficiency.

[0074] In the present embodiment, the input shaft of the power-generating motor 7 can be connected to the output shaft of the motor 6 in such a way that it rotates at the same speed as the output shaft of the motor 6, and the motor 6 is a two-stroke engine capable of operating at low speed and high torque. Thus, the power-generating efficiency can be improved without providing a speed reduction mechanism between the input shaft of the power-generating motor 7 and the output shaft of the motor 6, and the overall structure of the system can be simplified.

[0075] In the present embodiment, the input shafts of the two power-generating motors 7 are connected to each of the two ends of the crankshaft 16 of the motor 6. The two power-generating motors 7 are housed together with the crankshaft 16 in the crankcase 13, and the power-generating system 2 is designed as a single unit. This allows the center of gravity of the unit to be adjusted more precisely than if only one power-generating motor were provided at one end of the crankshaft 16.

[0076] Since the two power generating motors 7 are aligned with each other in the axial direction of the crankshaft 16, a shift in the center of gravity of the entire power generating system in the axial direction of the crankshaft 16 can be more easily prevented than in a configuration where only one power generating motor is provided.

[0077] The controller 5 controls the actuator 36 of the throttle device 33 based on the amount of current stored in the energy storage device 3 and the drive demand placed on the drive motor 4. The torque of the motor 6 is controlled via the actuator 36 based on whether the amount of stored current is excessive or insufficient, and / or whether the drive demand is high or low, thus preventing the power output of the motor 6 from being excessive or insufficient.

[0078] The supercharger 31 is driven by the crankshaft 16 and is configured as a mechanical supercharger. As described above, the engine 6, according to the present embodiment, operates within a predetermined constant speed range, such as a low-speed range between 2000 rpm and 6500 rpm inclusive. Mechanical superchargers can readily deliver their full performance in a low- to medium-speed range, even with low exhaust emissions. Thus, when using a mechanical supercharger, the supercharger 31 can deliver its full performance over a large portion of the speed range in which the engine 6 operates, ensuring high air intake efficiency and high scavenging efficiency.

[0079] In the present embodiment, a low-speed range below 6500 rpm is used, thus reducing the excitation force generated in the motor 6. This makes it possible, for example, to reduce the stiffness of the bearings or the cylinders 14 in the motor 6, or to reduce the need to integrate a component to prevent vibrations. The use of a low-speed range below 6500 rpm can reduce the thermal impact on the motor 6. < Second embodiment>

[0080] Next, with reference to Fig. 7 and Fig. 8 a second embodiment is described.

[0081] Fig. Figure 7 is a cross-sectional view of the motor 6 of the drive device 1B according to the present embodiment, and Fig. Figure 8 shows the combustion chamber S1 viewed from below. In the first embodiment, the injection port of the downstream fuel supply device 45 opens into cylinder 14 for "injecting the fuel into the cylinder", whereas in the present embodiment, an injection port of a downstream fuel supply device 145 is located as shown in Figure 8. Fig. 7 and Fig. 8 flows into inlet channel 20.

[0082] This means that the downstream fuel supply device 145 is attached to the cylinder head 11 such that the injection port of the downstream fuel supply device 145 opens into the intake port 20. In the present embodiment, the downstream fuel supply device 145 injects the fuel during the valve opening period of the intake valve 22 (see Fig. 7) After the intake valve 22 closes, the spark plug 24 acts to ignite and burn the compressed air-fuel mixture in the combustion chamber S1. If the two intake ports 18 are provided and the intake port 20 has an inlet, the injection port of the downstream fuel supply device 145 is positioned closer to the inlet of the intake port 20 than to a bifurcation point where the intake port 20 splits into two parts (see Fig. 8).

[0083] According to the representation in Fig. 7. The downstream fuel supply device 145 injects the fuel such that the fuel spreads in an almost circular cylindrical profile. Hereinafter, the centerline of the circular cylindrical profile formed by the spreading fuel is referred to as the "centerline of injected fuel." The downstream fuel supply device 145 injects the fuel such that the centerline of injected fuel passes through a gap between the valve element and the valve seat of the intake valve 22. Thus, the fuel injected into the intake port 20 can reach the interior of the cylinder 14. The valve opening period of the downstream fuel supply device 145 is set with respect to the lift of the intake valve 22 to allow the fuel to flow through the aforementioned gap.In the present embodiment, the fuel is injected after the VOL period, as in . Fig. 5 is shown, in particular after the closing of the exhaust valve 23 and before the closing of the inlet valve 22. At the valve closing time t EC The increasing stroke of the inlet valve 22 of the exhaust valve 23 has reached approximately 90% of its maximum stroke. Therefore, if the valve closing time of the downstream fuel supply device 145 is set such that the downstream fuel supply device 145 begins injecting fuel immediately after the exhaust valve 23 closes, the centerline of injected fuel can easily pass through the aforementioned gap. The gap is formed in an annular shape along the entire circumference of the inlet opening 18. As shown in Fig. 7 A hole for mounting the downstream fuel supply device 145 in the cylinder axis direction below the intake port 20 can be formed to allow the fuel to flow through the gap near the spark plug 24. This easily secures the space for arranging the downstream fuel supply device 145, which injects the fuel into the intake port 20.

[0084] According to the representation in Fig. 8 The injection port of the downstream fuel supply device 145 is designed to inject the fuel in two directions. One of the center lines of injected fuel is directed towards one of the inlet ports 18, while the other center line of injected fuel is directed towards the other inlet port 18. Since the fuel is directed to both inlet ports 18, the distribution of the air-fuel mixture in the combustion chamber S1 can be uniform. Furthermore, because the fuel injection takes place in a charged atmosphere, backflow of fuel from cylinder 14 can be reliably prevented. Additionally, soot deposits on the downstream fuel supply device 45 are unlikely.

[0085] The present embodiment can provide the same effects as the first embodiment. In the present embodiment, the fuel can be injected even at a reduced fuel pressure, thus eliminating the need for the fuel pressurization mechanism 42 and the reservoir 47. This simplifies the structure of the fuel system. The downstream fuel supply device 145 does not need to have high pressure resistance, and a universal injector can be used. The fuel discharged from the primary fuel pump 46 is directed to the downstream fuel supply device 145.

[0086] In the present embodiment, there is a certain time delay between the issuance of a fuel injection command (valve opening command) to the downstream fuel supply device 145 and the arrival of the fuel inside the cylinder 14. The fuel injection command can be issued early with respect to this time delay. For example, the fuel injection command can be issued to the downstream fuel supply device 145 at a time corresponding to the time delay, before the valve closing time of the exhaust valve 23. Thus, "fuel injection after the exhaust valve closes" refers to the case in which the exhaust valve 23 closes before the fuel injected by the downstream fuel supply device 145 reaches the cylinder 14.

[0087] The components and their arrangement according to the representation in Fig. 7 and Fig. Figure 8 is merely an example of a case where intake port injection is used as described above, and modifications can be made as needed. The gap through which the fuel flows is not to be the section shown in Figure 8. Fig. 7, which is located in a direction orthogonal to the cylinder axis near the spark plug 24, and the fuel can flow through any section of the gap, which is formed in an annular shape around the inlet opening 18. It is not necessary to provide a downstream fuel supply device 145 for each cylinder 14. Several downstream fuel supply devices 145 can be provided for each cylinder 14 in a one-to-one correspondence with the multiple inlet openings 18. < Third embodiment>

[0088] Next, a drive device 1C according to a third embodiment is described with reference to Fig. 9 and Fig. 10 described.

[0089] Fig. Figure 9 is a side view of the motor 6 of the drive unit 1C. Fig. Figure 10 is a schematic diagram of the interior of the motor 6 of the drive device 1C. In the present embodiment, the motor 6 has a balance shaft 51 arranged parallel to the crankshaft 16. The input shafts of the two power-generating motors 7 are connected to both ends of the balance shaft 51, instead of to one of the two ends of the crankshaft 16. The present embodiment is essentially the same as the first embodiment, except for the locations where the power-generating motors 7 are mounted, and identical features are not described again.

[0090] The balance shaft 51 serves to suppress first-order coupling vibrations of the crankshaft 16. In the present embodiment, the four crankpin sections 17 of the crankshaft 16 have a phase shift of 90° or 180° relative to each other, so that the ignition timings in the four cylinders can be offset from one another. This intensifies the occurrence of the first-order coupling vibrations of the crankshaft 16. Thus, in the present embodiment, the balance shaft 51, which rotates at the same speed as the crankshaft 16, is designed to suppress the first-order coupling vibrations.

[0091] According to the representation in Fig. 10 is the balance shaft 51 with balance weights 53 (in Fig. (9 not shown) provided. According to the illustration in Fig. 9 A gear 16c is attached to the crankshaft 16, and the gear 16c rotates together with the crankshaft 16. A gear 52 is attached to the balance shaft 51 (in Fig. 10 (not shown) is attached, which meshes with the gear 16c. The gear 52 of the balance shaft 51 has the same number of teeth as the gear 16c, and the balance shaft 51 is operable together with the crankshaft 16, which is coupled to the piston 15, and rotates at the same speed as the crankshaft 16.

[0092] According to the representation in Fig. The input shafts of the generating motors 7 are connected to one of the two ends of the balance shaft 51. The balance shaft 51 and the respective input shafts of the generating motors 7 are connected, for example, via shaft couplings, such that they are coaxial with each other. This means that the two generating motors are aligned with each other in the axial direction of the balance shaft 51 and thus in the axial direction of the crankshaft 16, which is parallel to the balance shaft 51. The input shafts of the generating motors 7 receive power transmitted from the crankshaft 16 via the balance shaft 51.This means that when the crankshaft 16, which serves as the output shaft of the motor 6, rotates, the balance shaft 51 is driven at the same speed as the crankshaft 16, and accordingly the input shafts of the power generating motors 7, which have received power transmitted by the balance shaft 51, are driven at the same speed as the crankshaft 16.

[0093] According to the representation in Fig. 9 and Fig. In the present embodiment, the balance shaft 51 is arranged parallel to the crankshaft 16. The balance shaft 51 is shorter than the crankshaft 16. The two power-generating motors 7 superimpose on the crankshaft 16 when viewed in a direction orthogonal to both the crankshaft 16 and the balance shaft 51. The balance shaft 51, together with the two power-generating motors 7 connected to the balance shaft 51, is housed in the crankcase 13. As shown in the illustration in Fig. 9 the crankshaft 16 and the balance shaft 51 are positioned in the same plane, which divides the crankcase 13 into the upper housing section 13a and the lower housing section 13b.

[0094] The present embodiment can provide the same effects as the first embodiment. Furthermore, the present embodiment offers greater flexibility in selecting the locations where the power-generating motors 7 are attached than when the power-generating motors 7 are directly connected to the crankshaft 16. This provides greater design flexibility. For example, the power-generating motors 7 can be positioned axially inside both ends of the crankshaft 16 in the axial direction of the crankshaft 16 to prevent them from protruding and to avoid increasing the overall axial dimension of the power-generating system, which is designed as a single unit. This allows for a compact design of the system as a whole.

[0095] In the present embodiment, the balance shaft 51 is shorter than the crankshaft 16, and the power-generating motors 7 are connected to the ends of the balance shaft 51. This allows for effective use of the space located on the side of the balance shaft 51 relative to the crankshaft 16 and in the axial direction of the balance shaft 51. < Other embodiments>

[0096] Although some embodiments have been described above, a feature may be modified, added or omitted without leaving the scope of protection of the present invention.

[0097] For example, the features described above for the first to third embodiments can be combined as needed.

[0098] In the embodiments described above, the fuel for engine 6 is gasoline. However, the fuel for engine 6 is not limited to gasoline and can be, for example, light oil, natural gas, or hydrogen. A fuel such as gasoline, which can be injected in liquid form from the downstream fuel supply device 45 or 145 and then combusted in gaseous form in the cylinder, is preferred for engine 6. When the fuel vaporizes in the cylinder, heat can be dissipated from the interior of the cylinder through the effect of the heat of vaporization. This heat dissipation can lead to increased compressibility and thus a significantly improved combustion efficiency.

[0099] The design of the motor included in the power generation system of the present invention is not limited to those described in the embodiments above. For example, an existing motor having inlet and outlet valves can be used. For example, the number of inlet and outlet ports is not limited to those described in the embodiments above. For example, the throttle device 33 need not be electronically controlled, and the throttle valve 34 need not be provided for each cylinder. To achieve weight reduction, one throttle valve 34 can be provided for several cylinders. The motor 6 does not need to be driven with a high response rate, since the purpose of driving the motor 6 is to electrically charge the power storage device 3.Thus, a throttle valve of the regulator type, whose throttle extent is adjusted according to the engine speed, can be used.

[0100] Although the engine 6 described in the above embodiments is of the downdraft type, the engine 6 can also be of the cross-flow type. The orientation of the engine 6 is not limited to that described in the above embodiments. For example, the crankshaft 16 and the camshafts 27 and 28 can extend in a forward / backward direction or an up / downward direction with respect to the direction in which the driver of the vehicle is facing, although in the above embodiments the crankshaft 16 and the camshafts 27 and 28 extend in a left / right direction with respect to the direction in which the driver of the vehicle is facing.Furthermore, the cylinder block 12 can be arranged below the crankcase 13 with respect to the direction in which the driver of the vehicle is pointing, although in the above embodiments the cylinder block 12 is arranged above the crankcase 13 with respect to the direction in which the driver of the vehicle is pointing.

[0101] In the embodiments described above, the output camshaft 28 is provided with the pressure-applying cam 42a in addition to the output cam 28a. However, the pressure-applying cam 42a can be located on a shaft other than the output camshaft 28, which can be operated together with the output camshaft 28. The pressure-applying cam 42a does not need to rotate at the same speed as the output cam 28a and can have multiple cam lobes.

[0102] The output cam 28a can be configured to perform the function of the pressure-actuating cam 42a for actuating the plunger of the fuel pressure-actuating mechanism 42. This means that the plunger of the fuel pressure-actuating mechanism 42 can be brought into contact with the output cam 28a. In this case, the output camshaft 28 does not need to be additionally equipped with the pressure-actuating cam 42a besides the output cam 28a.

[0103] In the above embodiments, a turbocharger driven by the exhaust gas of the engine 6 can be used as the turbocharger 31 instead of the mechanical turbocharger. A turbocharger driven by an electric motor instead of the engine 6 can also be used.

[0104] In the embodiments described above, a speed range over which both the motor 6 and the power-generating motor 7 operate efficiently (in the examples above, the speed range between 2000 rpm and 6500 rpm inclusive) is defined as the constant speed range for the motor 6. If the speed range over which the motor 6 operates efficiently and the speed range over which the power-generating motor 7 operates efficiently differ, a speed-adjusting device can be provided between the motor 6 and the power-generating motor 7 to convert between a speed at which the motor 6 operates efficiently and a speed at which the power-generating motor 7 operates efficiently.For example, if the speed at which the high-efficiency generating motor 7 operates is lower than the speed at which the high-efficiency motor 6 operates, a speed reduction device may be provided between the motor 6 and the generating motor 7. If the speed at which the high-efficiency generating motor 7 operates is higher than the speed at which the motor 6 operates, a speed increaser may be provided between the motor 6 and the generating motor 7.

[0105] In the embodiments described above, both the inlet port 18 and the outlet port 19 are configured such that, in the cylinder axis direction, the openings are opposite each other when viewed from the crankshaft 16 with the piston 15 positioned at top dead center. However, the present invention is not limited to this arrangement. For example, the inlet port 18 can be located below the top dead center of the cylinder 14 in the cylinder axis direction. In particular, the inlet port 18 can be positioned in the cylinder block 12 such that it opens into a space located between the piston's top dead center and the piston's bottom dead center in the cylinder 14. In this case, the inlet port 18 is opened and closed by the reciprocating motion of the piston 15 in the cylinder 14 instead of by the inlet valve 22. This means that the piston 15 performs the function of the inlet valve to open and close the inlet port 18.In this case, the stroke of the inlet valve 23, which is located in . Fig. 5 is shown, replaced by the degree of opening of the inlet opening 18, which varies according to the position of the piston 15.

[0106] In the third embodiment, the drive device 1C, which includes the balance shaft 51 as a component for suppressing the first-order coupling vibrations of the crankshaft 16, was described. However, the drive device of the present invention need not include a balance shaft. For example, the drive device can be configured such that the crankshaft 16 is likely to be subject to first-order coupling vibrations. For example, the four crankpin sections 17 of the crankshaft 16 can be arranged such that the second pin section 17b, the third pin section 17c, and the fourth pin section 17d each have a phase shift of 180°, 180°, and 0°, respectively, with respect to the first pin section 17a. With this configuration, the ignition timings in the adjacent cylinders corresponding to the second pin section 17b and the third pin section 17c coincide.Thus, the stiffness of the crankshaft 16 can be increased so that the crankshaft 16 can withstand a load caused by simultaneous explosion in these cylinders.

[0107] In the first and second embodiments, the input shaft of the power-generating motor 7 receives power transmitted directly from the crankshaft 16, whereas in the third embodiment, the input shaft of the power-generating motor 7 receives power transmitted from the crankshaft 16 via the balance shaft 51. However, the present invention is not limited to this configuration. The input shaft of the power-generating motor 7 can receive power transmitted via a component other than the balance shaft 51, which can be operated in conjunction with the crankshaft 16.For example, in the third embodiment, a shaft link that can be operated together with the input shaft of the power generating motor 7 can be used instead of the balance shaft 51, and a gear that meshes with the gear 16c of the crankshaft 16 can be provided in the shaft link, so that power is transmitted from the crankshaft 16 to the power generating motor 7 via the shaft link.

[0108] In the embodiments described above, the constant speed range of the engine 6 is set between 2000 rpm and 6500 rpm inclusive. However, the present invention is not limited to this constant speed range. An extremely low speed range can be included in the "constant speed range," for example, by using an electrically driven turbocharger as the turbocharger 313 or 131 instead of the turbocharger that is driven by the crankshaft 16 of the engine 6.

[0109] The input shaft of the power generating motor 7 does not need to rotate at the same speed as the output shaft of the motor 6. For example, a speed reduction mechanism can be provided between the output shaft of the motor 6 and the input shaft of the power generating motor 7 to drive the input shaft of the power generating motor 7 at a speed lower than the speed of the output shaft of the motor 6.

[0110] In the embodiments described above, the power generation system 2 comprises two power generation motors 7. However, the number of power generation motors included in the power generation system of the present invention is not limited to two, and the power generation system may have one power generation motor or three or more power generation motors. For example, if the power generation system has one power generation motor 7, the power generation motor may be located at one end of the crankshaft 16 or the balance shaft 51. If multiple power generation motors 7 are provided, the power generation motors 7 need not be aligned with one another in the axial direction of the crankshaft 16. In the embodiments described above, the power generation system 2 has one drive motor 4. However, the power generation system of the present invention may have multiple drive motors 4.The downstream fuel supply devices in 45 and 145 need not be injectors and may be other types of devices. The upstream fuel supply device 44 may be omitted. Omitting the upstream fuel supply device 44 may reduce the occurrence of a phenomenon known as "blowing through".

[0111] The two power-generating motors 7 need not be housed within the crankcase 13. For example, end sections of the crankshaft 16 may protrude from the crank chamber S2, and the power-generating motors 7 may be provided on these protruding sections of the crankshaft 16. In this case, the power-generating motors 7 may be enclosed by a cover attached to the side wall of the crankcase 13.

[0112] The controller 5 controls the actuator 36 of the throttle device 33 based on the amount of current stored in the energy storage device 3 and the drive request made to the drive motor 4. The present invention is not limited to such a controller. For example, the controller 5 can control the actuator 36 based on the amount of current stored in the energy storage device or on the drive request made to the drive motor.

[0113] The control unit 5 can stop the operation of the motor 6 and simultaneously allow the drive motor 4 to continue operating (i.e., power consumption by the drive motor 4) when a request from the driver or operator is fulfilled, or under a predetermined condition (such as when the amount of electricity stored in the energy storage device 3 exceeds a predetermined level). If the drive is located indoors where exhaust fumes have a significant impact, or where noise reduction is desired, it is desirable to minimize the operating time of the motor 6. In such locations, a drive device that separately controls the operation of the drive motor 4 and the operation of the motor 6 for power generation is particularly useful.

[0114] The embodiments described above represent examples where the drive device is installed in a ride-on vehicle. However, the drive device is not limited to installation in ride-on vehicles and is also suitable for use in machines where there is a significant need for weight or vibration reduction. For example, the drive device of the present invention can also be used as a drive device for land-based vehicles that are not ride-on vehicles. For instance, the drive device of the present invention can be installed in a vehicle where the occupants sit side by side (e.g., a four-wheeled motor vehicle).The propulsion device of the present invention is not necessarily installed in a vehicle that moves on land and can, for example, be installed in an aircraft that flies in the air. For example, the propulsion device of the present invention can be installed in an unmanned multi-decker aircraft, such as a so-called "drone". The propulsion device of the present invention is applicable as a propulsion device for vehicles or aircraft that are not manned vehicles. This means that the propulsion device of the present invention can be installed in an unmanned vehicle.

[0115] The feature that the motor 6 can be operated at low speeds allows, for example, a reduction in the stiffness of the bearing components and the fuel system components, thereby reducing the overall weight of the drive unit. Thus, the drive unit of the present invention is suitable for use in recreational vehicles, such as ride-on vehicles, which require acceleration performance, and in aircraft, whose own weight has a slight impact on it. Alternatively, the drive unit of the present invention can be used, for example, in a series-production hybrid vehicle. The speed of the drive wheel can be adjusted by the drive motor, thereby eliminating the need for a speed control mechanism to adapt the motor speed to the vehicle's movement.

[0116] The power generation system of the present invention is not necessarily used in a drive device and can be used as a power generation system for supplying power to machines that are not moving machines.

[0117] The configuration described in the third embodiment, in which the input shaft of the power generating motor 7 is connected to the balance shaft 51, is effective for a power generating system in which a four-stroke engine is integrated.

[0118] In particular, a power generation system according to an embodiment other than those above comprises an internal combustion engine and a power generation engine that generates electricity when its input shaft is rotated by the internal combustion engine, wherein the internal combustion engine has a piston that can move back and forth in a cylinder, a crankshaft coupled to the piston, and a balance shaft that can be operated together with the crankshaft to rotate at the same speed as the crankshaft and to suppress first-order coupling vibrations of the crankshaft, wherein the input shaft of the power generation engine is connected to the balance shaft so that it rotates at the same speed as the balance shaft, and wherein the power generation engine generates electricity when the input shaft is rotated together with the balance shaft as a result of a rotation of the crankshaft.This configuration allows for the effective use of spaces located in the axial direction of the balance shaft, and the system as a whole can be designed to be compact.

Claims

[1] Power generation system (2) comprising: an internal combustion engine (6) which is operated within a predetermined speed range; and at least one power generating motor (7) which generates electricity when its input shaft is rotated by the internal combustion engine, wherein the internal combustion engine (6) comprises the following: a piston (15) that can move back and forth in a cylinder (14); a valve actuation mechanism (26) that actuates an inlet valve (22) to open and close an inlet port (18) and that actuates an outlet valve (23) to open and close an outlet port (19); a supercharger (31) that compresses the intake air to be introduced into the cylinder; and a fuel supply device (44) that supplies fuel, wherein, as the piston moves back and forth, starting at top dead center, reaching bottom dead center and returning to top dead center, the valve actuation mechanism (26) actuates the inlet valve (26) and the exhaust valve (23) in the following manner to provide a valve overlap period in which both the exhaust valve and the inlet valve are open and which includes a time in which the piston (15) is at bottom dead center: - the exhaust valve (23), which was closed before a downward movement of the piston from top dead center to bottom dead center, is opened during the downward movement; - the inlet valve (22), which was closed before the downward movement of the piston, is opened after the opening of the exhaust valve (23) during the downward movement; - the exhaust valve (23) is closed after the downward movement has ended and during an upward movement of the piston from bottom dead center to top dead center; and - the inlet valve (22) is closed after the exhaust valve (23) closes during the upward movement of the piston, the fuel supply device (44) supplies the fuel to the cylinder after the exhaust valve has closed during the upward movement of the piston, and an air-fuel mixture is burned in the cylinder while both the exhaust valve and the intake valve are closed during the upward movement of the piston, and wherein the input shaft of the power generating motor (7) is connected to an output shaft of the internal combustion engine (6) in such a way as to rotate at the same speed as the output shaft of the internal combustion engine. [2] Power generation system according to claim 1, wherein the inlet opening (18) and the outlet opening (19) are designed such that the inlet opening and the outlet opening are opposite each other in an axial direction of the cylinder of a crankshaft (16) coupled to the piston when viewed from the piston (15) positioned at top dead center. [3] Power generation system according to claim 1 or 2, wherein the fuel supply device (44) is a direct injection valve which injects the fuel into the cylinder (14) after the inlet valve (22) has been closed. [4] Power generation system according to one of claims 1-3, where the predetermined speed range is between 2000 and 6500 rpm inclusive and wherein the internal combustion engine (6) is operated at a constant speed within the predetermined speed range. [5] Power generation system according to one of claims 1-4, wherein the output shaft of the internal combustion engine is a crankshaft (16) coupled to the piston, and wherein the supercharger (31) is driven by the crankshaft (16) in a rotating manner. [6] Power generation system according to any one of claims 1-5, wherein the output shaft of the internal combustion engine is a crankshaft (16) coupled to the piston, and wherein the at least one power generating engine (7) comprises two power generating engines, each of which is connected to both ends of the crankshaft (16) and / or to both ends of a balance shaft (51) arranged parallel to the crankshaft. [7] Power generation system according to any one of claims 1-5, further comprising: a crankshaft (16) coupled to the piston, which is the output shaft of the internal combustion engine; a balance shaft (51) arranged parallel to the crankshaft; a crankcase (13) in which the crankshaft is housed, where the crankshaft and the balance shaft are connected in order to rotate in conjunction with each other, wherein the at least one power generating engine (7) is two power generating engines, wherein the two power generating motors are aligned to each other in the axial direction of the crankshaft (16), wherein the balance shaft (51) together with the two power generating motors which are connected to one of the two ends of the balance shaft is housed in the crankcase, and wherein the crankshaft and the balance shaft are arranged in the same plane, which divides the crankcase (13) into an upper case section (13a) and a lower case section (13b). [8] Drive device comprising the following: the power generation system (2) according to any one of claims 1-7; an electricity storage device (3) that stores electricity generated by the electricity generation system; and a drive motor (4) which acts as a drive source by absorbing current supplied by the energy storage device. [9] Drive device according to claim 8, wherein the internal combustion engine (6) further comprises a throttle valve (33) that adjusts the amount of intake air to be introduced into the cylinder, and an actuator (36) that actuates the throttle valve, and wherein the drive device further comprises a control (5) which controls the actuator based on the amount of current stored in the energy storage device and / or a drive request to the drive motor. [10] Propulsion device according to claim 8 or 9, installed in a propulsion body that moves on land or a flying body that flies in the air.

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