JP2006232162A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle capable of reducing certainly the vibration when an engine is in low speed operation and also suppressing deterioration of the fuel economy by making it possible for the device to be constructed light and small. <P>SOLUTION: The output power of a Diesel engine (DE) 11 is transmitted to the driving wheels 15 and a motor generator (MG) 13 as generator through a planetary gear unit 14 as a power dividing mechanism, while the output power of the MG 12 as an electric motor is transmitted to the driving wheels 15, and a flywheel 51 to absorb a change in rotation of the DE 11 is secured fast to the rotor 49 of the MG 13 through a coupling shaft 52. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hybrid vehicle that can run using an engine and an electric motor as a power source.

  In recent years, a hybrid vehicle has been proposed that is equipped with an engine that outputs torque by the combustion of fuel and an electric motor that outputs torque by supplying electric power, and can travel by transmitting the torque of the engine and the electric motor to wheels. Has been. In such a hybrid vehicle, driving and stopping of the engine and the electric motor are controlled according to the driving state, so that the wheel is driven only by the torque of the electric motor, or the wheel is driven by the torque of both the engine and the electric motor. The electric motor can be driven by the electric power stored in the battery. When the energy of the battery decreases, the engine is driven to charge the battery.

  That is, in the hybrid vehicle, an engine and an electric motor are provided as driving force sources, and a planetary gear that combines the power of the engine and the electric motor and transmits it to the wheels is provided. Specifically, the output shaft of the engine is connected to the planetary gear carrier, the output shaft of the electric motor is connected to the ring gear of the planetary gear, and power is transmitted from the sprocket connected to the ring gear to the wheels. It is configured. A generator is provided between the planetary gear and the engine, and the rotating shaft of the generator is connected to the sun gear of the planetary gear. Therefore, the engine power is divided into wheels and a generator by the planetary gear, and the engine rotation speed can be controlled by controlling the rotation speed of the generator. That is, the power split mechanism constituted by the planetary gears has a function of converting the rotational speed of the engine and a function of splitting the engine power into wheels and a generator.

  In the hybrid vehicle configured as described above, a flywheel is attached to the rear end portion of the crankshaft of the engine. That is, in a hybrid vehicle, since the moment of inertia of the engine is large, rotation fluctuation is likely to occur in a low rotation area immediately after starting, and the rotation fluctuation is absorbed by the flywheel.

  In addition, as a hybrid vehicle which makes such a structure, it describes in the following patent document 1, for example.

JP 2000-125413 A

  In the hybrid vehicle of Patent Document 1 described above, the flywheel absorbs rotational fluctuations that occur in the low-rotation region immediately after engine startup. However, in a hybrid vehicle, a large moment of inertia acts on the engine, so a large rotational fluctuation is likely to occur. In order to absorb this rotational fluctuation reliably, a certain amount of heavy flywheel is required, and the entire power plant This increases the weight of the vehicle and causes an increase in the weight of the vehicle, resulting in a deterioration in fuel consumption. In addition, if a heavy flywheel is mounted on the crankshaft of the engine, this flywheel becomes a starting resistance when starting the engine, which not only deteriorates startability but also causes engine vibration during starting. .

  The present invention is intended to solve such a problem, and provides a hybrid vehicle that can reduce the vibration at the time of low engine rotation while reducing the fuel consumption by reducing the size and weight of the device. The purpose is to do.

  In order to solve the above-described problems and achieve the object, a hybrid vehicle of the present invention includes an engine, a generator capable of generating power using at least a part of the output of the engine, and power supply from the generator. An electric motor capable of receiving and rotating, a power split mechanism for transmitting the output of the engine to the drive wheels and the generator, and transmitting the output of the electric motor to the drive wheels, and a drive shaft of the generator It is characterized by having a consolidated flywheel.

  In the hybrid vehicle of the present invention, the power split mechanism includes a sun gear, a plurality of planetary gears arranged around the sun gear, a gear carrier holding each planetary gear, and a ring gear arranged on the outer periphery of the planetary gear. A planetary gear unit configured, wherein the drive shaft of the generator is fixed to the sun gear, the drive shaft of the engine is fixed to the gear carrier, and the drive shaft of the electric motor is fixed to the ring gear. It is characterized by that.

  The hybrid vehicle of the present invention is characterized in that the flywheel is fixed to a drive shaft of the generator via a clutch mechanism.

According to the hybrid vehicle of the present invention, the output of the engine is transmitted to the drive wheels and the generator by the power split mechanism, the power of the electric motor can be transmitted to the drive wheels, and the flywheel is fixed to the drive shaft of the generator. As a result, the equivalent inertia mass = (speed increase ratio) ² × (flywheel inertia moment), and the generator speed at engine startup corresponds to the engine speed, and the generator speed is the engine speed. Since the speed is increased with respect to the rotational speed, an inertial mass equivalent to that of the flywheel attached to the end of the crankshaft can be obtained by adding an inertial moment of 1 / (speedup ratio) ^2. By eliminating the flywheel of the shaft and mounting the flywheel on the generator, the flywheel of this electric motor can be miniaturized and the engine low Vibration during rotation can be reliably reduced, and as a result, the device can be reduced in size and weight, and deterioration of fuel consumption can be suppressed.

  Embodiments of a hybrid vehicle according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  1 is a schematic diagram illustrating a power transmission structure of an engine, a generator, and an electric motor in a hybrid vehicle according to a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram of the hybrid vehicle according to the first embodiment, and FIG. FIG. 4 is a collinear diagram showing the driving force of the generator, the engine, and the electric motor when the hybrid vehicle transitions from steady running to accelerated running. FIG. 4 shows the generator and engine when the engine is started from a stopped state in the hybrid vehicle. FIG. 5 is a collinear diagram showing the driving force of the generator, the engine, and the electric motor when the engine is started from the motor running state in the hybrid vehicle.

  In the hybrid vehicle of the first embodiment, as shown in FIGS. 1 and 2, the vehicle is equipped with a diesel engine (DE) 11 as a power source and a motor generator (MG) 12 as an electric motor. The vehicle is also equipped with a motor generator (MG) 13 that receives the output of the DE 11 and generates electric power. These DE11, MG12, and MG13 are connected by a power split mechanism 14. The power split mechanism 14 distributes the output of the DE 11 to the MG 13 and the drive wheel 15 and transmits the output from the MG 12 to the drive wheel 15 or to the drive wheel 15 via the speed reducer 16 and the drive shaft 17. It functions as a transmission related to the driving force.

  MG12 is an AC synchronous motor and is driven by AC power. The inverter 18 converts the electric power stored in the battery 19 from DC to AC and supplies it to the MG 12, and converts the electric power generated by the MG 13 from AC to DC and stores it in the battery 19. The MG 13 has basically the same configuration as the MG 12 described above, and has a configuration as an AC synchronous motor. In this case, the MG 12 mainly outputs the driving force, whereas the MG 13 mainly receives the output of the DE 11 and generates power.

  The MG 12 mainly generates a driving force, but can also generate electric power (regenerative power generation) by using the rotation of the driving wheels 15 and can also function as a generator. At this time, a brake (regenerative brake) acts on the drive wheel 15, and the vehicle can be braked by using this together with the foot brake or the engine brake. On the other hand, the MG 13 mainly receives the output of the DE 11 and generates power, but can also function as an electric motor that receives and drives the power of the battery 19 via the inverter 18.

  The crankshaft 20 of DE11 is provided with a crank position sensor 21 that detects the piston position and the engine speed. The crank position sensor 21 is connected to the engine ECU 22 and outputs a detection result. The drive shafts 23 and 24 of the MG 12 and MG 13 are provided with rotation speed sensors 25 and 26 for detecting the respective rotation positions and rotation speeds. Each rotation speed sensor 25, 26 is connected to a motor ECU 27 and outputs a detection result.

  The power split mechanism 14 described above is constituted by a planetary gear unit. That is, the power split mechanism (planetary gear unit) 14 includes a sun gear 41, a plurality of planetary gears 42 arranged around the sun gear 41, a gear carrier 43 that holds the planetary gears 42, and a planetary gear 42 on the outer periphery. The ring gear 44 is arranged. The crankshaft 20 of the DE 11 is coupled to the gear carrier 43 via the central shaft 45, and the output of the DE 11 is input to the gear carrier 43 of the planetary gear unit 14. The MG 12 has a stator 46 and a rotor 47 inside. The rotor 47 is coupled to the ring gear 44 via the drive shaft 23, and the rotor 47 and the ring gear 44 are connected to the speed reducer 16 via a gear unit (not shown). Are combined. The speed reducer 16 transmits the output input from the MG 12 to the ring gear of the planetary gear unit 14 to the drive shaft 17, and the MG 12 is always connected to the drive shaft 17.

  Similarly to the MG 12 described above, the MG 13 has a stator 48 and a rotor 49 inside, and the rotor 49 is coupled to the sun gear 41 via the drive shaft 24 and a gear unit (not shown). That is, the output of the DE 11 is divided by the planetary gear unit 14 and input to the rotor 49 of the MG 13 via the sun gear 41. The output of the DE 11 is divided by the planetary gear unit 14 and can be transmitted to the drive shaft 17 via the ring gear 44 or the like.

  Then, by controlling the amount of power generated by the MG 13 to control the rotation of the sun gear 41, the entire planetary gear unit 14 can be used as a continuously variable transmission. That is, the output of DE 11 or MG 12 is output to the drive shaft 17 after being shifted by the planetary gear unit 14. Further, the rotational speed of the DE 11 can be controlled by controlling the power generation amount of the MG 13 (power consumption when it functions as an electric motor). Note that when the rotational speeds of the MG12 and MG13 are controlled, the motor ECU 27 controls the inverter 18 with reference to the outputs of the rotational sensors 25 and 26, whereby the rotational speed of the DE11 can also be controlled. is there.

  The various controls described above are controlled by a plurality of electronic control units (ECUs). The driving by DE11 and the driving by MG12 and MG13, which are characteristic as a hybrid vehicle, are comprehensively controlled by the main ECU. That is, the distribution of the output of DE 11 and the output of MG 12 and MG 13 is determined by main ECU 28, and control commands are output to engine ECU 22 and motor ECU 27 to control DE 11, MG 12, and MG 13.

  Further, the engine ECU 22 and the motor ECU 27 also output information on the DE 11, MG 12, and MG 13 to the main ECU 28. The main ECU 28 is also connected to a battery ECU 29 that controls the battery 19 and a brake ECU 30 that controls the brake. The battery ECU 29 monitors the state of charge of the battery 19 and outputs a charge request command to the main ECU 28 when the amount of charge is insufficient. Receiving the charge request, the main ECU 28 controls the MG 13 to generate power so that the battery 19 is charged. The brake ECU 30 controls the vehicle and controls the regenerative braking by the MG 12 together with the main ECU 28.

  Since the hybrid vehicle of the present embodiment is configured as described above, by distributing the necessary output required for the entire vehicle to DE11 and MG12 (MG13) while operating the hybrid vehicle, DE11 It is possible to satisfy the output required for the entire vehicle while controlling the driving state to a desired driving state.

  That is, in the steady running of this hybrid vehicle, as shown by the solid line in FIG. 3, the vehicle can run mainly at DE11, and the power generation by the MG 13 as a generator is minimized, that is, the rotational speed, in order to increase the efficiency. Is controlled so as to be reduced to zero. When the hybrid vehicle shifts from steady running to accelerated running, the main ECU 28 increases the rotational speed of the DE 11 and starts power generation by the MG 13 as a generator, as shown by a one-dot chain line in FIG. The MG 12 is driven by the power generated by the MG 13 and the power stored in the battery 19 so as to obtain a predetermined driving force.

  On the other hand, when starting DE11 from the stop state of the hybrid vehicle as shown by the solid line in FIG. 4, as shown by the alternate long and short dash line in FIG. 4, the main ECU 28 generates power by MG 13 as a generator to start DE11. And the control is performed so that the rotational speed of the DE 11 increases. Further, when starting DE11 from the motor running state of the hybrid vehicle as shown by the solid line in FIG. 5, as shown by the alternate long and short dash line in FIG. 5, the main ECU 28 uses the MG 13 as a generator to start DE11. Power generation is started and control is performed so that the rotational speed of the DE 11 increases.

  By the way, in a hybrid vehicle, since a large moment of inertia acts on DE11, a large rotation fluctuation is likely to occur in a low rotation region, and a flywheel having a predetermined weight is required to absorb this rotation fluctuation. Conventionally, the flywheel is directly connected to the crankshaft 20 of DE11. In this case, however, the weight of the flywheel is increased, resulting in an increase in the weight of the vehicle and a deterioration in fuel consumption.

  Therefore, in the present embodiment, as shown in FIGS. 1 and 2, a flywheel 51 that absorbs the rotational fluctuation of the DE 11 is solidified to the MG 13 as a generator. That is, a connecting shaft (driving shaft) 52 is integrally connected to the rotor 49 of the MG 13 on the opposite side of the driving shaft 24, and the flywheel 51 is integrally fixed to the end of the connecting shaft 52. Has been. Further, a damper mechanism 53 that absorbs the rotational shock of DE11 is interposed between the crankshaft 20 of DE11 and the central shaft 45 of the planetary gear unit 14.

  Therefore, when DE11 is started using MG13 from the stop state of the hybrid vehicle as shown by the solid line in FIG. 4, the rotational speed of DE11 increases and the rotational speed of MG13 increases as shown by the one-dot chain line in FIG. By increasing, the rotational fluctuation of DE11 becomes large. At this time, the rotational force of the DE 11 is transmitted from the crankshaft 20 to the central shaft 45 via the damper mechanism 53, and further from the planetary gear 42, the gear carrier 43, and the sun gear 41 in the planetary gear unit 14 to the MG 13 via the drive shaft 24. However, since the flywheel 51 is connected to the MG 13 via the connecting shaft 52, the rotational fluctuation of the DE 11 is absorbed by the inertial force of the flywheel 51.

  Moreover, DE11 is started using MG13 from the motor running state of the hybrid vehicle as shown by a solid line in FIG. 5, and the rotational speed of DE11 and the rotational speed of MG13 are increased as shown by a one-dot chain line in FIG. Also when the rotational fluctuation of DE11 becomes large, as described above, the rotational fluctuation of DE11 is absorbed by the inertial force of flywheel 51 connected to MG13.

In this case, the following mathematical formula is established.
Equivalent inertia mass = (speed increase ratio) ² × (flywheel inertia moment)
That is, the rotational speed of the MG 13 as a generator at the start of the DE 11 corresponds to the rotational speed of the DE 11, and the rotational speed of the MG 13 is increased by the planetary gear unit 14 with respect to the rotational speed of the DE 11. Therefore, in order to obtain an inertial mass equivalent to that of the flywheel attached to the end of the conventional crankshaft 20, an inertia moment of 1 / (speed increase ratio) ² may be added to MG13. That is, when the flywheel of the crankshaft is eliminated and the flywheel 51 is mounted on the MG 13, the weight of the flywheel 51 may be 1 / (speed increase ratio) ² compared to the conventional one.

  Thus, in the hybrid vehicle of the first embodiment, the planetary gear unit 14 as the power split mechanism transmits the output of the DE 11 to the drive wheels 15 and the MG 13 as the generator, and the output of the MG 12 as the electric motor. Power can be transmitted to the drive wheel 15, and the flywheel 51 is firmly coupled to the rotor 49 of the MG 13 via the connecting shaft 52.

  Therefore, the flywheel 51 attached to the MG 13 can absorb the rotational fluctuation at the time of low rotation of the DE 11 to reliably reduce engine vibration, and the flywheel 51 attached to the MG 13 can be connected to the end of the crankshaft 20. It can be made smaller and lighter than the conventional flywheel mounted on the part, and as a result, the entire apparatus can be made smaller and lighter, and deterioration of fuel consumption can be suppressed.

  A damper mechanism 53 is interposed between the crankshaft 20 of the DE 11 and the central shaft 45 of the planetary gear unit 14. Therefore, the shock at the time of starting or stopping of the DE 11 or at the time of acceleration / deceleration can be reliably absorbed by the damper mechanism 53, and the engine vibration can be reduced.

  FIG. 6 is a schematic diagram illustrating a power transmission structure of an engine, a generator, and an electric motor in a hybrid vehicle according to a second embodiment of the present invention. FIG. 7 is a flowchart illustrating engine control in the hybrid vehicle according to the second embodiment. . In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the hybrid vehicle of the second embodiment, as shown in FIG. 6, the vehicle includes a diesel engine (DE) 11, a motor generator (MG) 12 as an electric motor, and a motor generator (MG) 13 as a generator. While being mounted, these DE 11, MG 12, and MG 13 are connected by a power split mechanism 14. The output of the DE 11 is distributed to the MG 13 and the driving wheel 15, the output from the MG 12 is transmitted to the driving wheel 15, and the transmission is related to the driving force transmitted to the driving wheel 15 via the speed reducer 16 and the driving shaft 17. The power split mechanism 14 that functions as is mounted.

  In this embodiment, the flywheel 51 that absorbs the rotational fluctuation of the DE 11 is solidified to the MG 13 as the generator via the clutch mechanism 61. That is, the first connecting shaft (driving shaft) 62 is integrally connected to the rotor 49 of the MG 13 on the opposite side of the driving shaft 24, and the second connecting shaft (driving shaft) 63 is integrally connected to the flywheel 51. The clutch mechanism 61 is mounted between the connecting shafts 62 and 63. The clutch mechanism 61 connects the MG 13 and the flywheel 51 so that they can rotate integrally, and releases the connection between the MG 13 and the flywheel 51 so that the MG 13 can rotate independently.

  That is, by connecting the flywheel 51 to the MG 13 as in the first embodiment described above, rotational fluctuations of the DE 11 can be absorbed, but when the engine is started, the flywheel 51 becomes a starting resistance and starts performance. Deteriorates and engine vibration occurs. Therefore, in the present embodiment, the flywheel 51 is connected to the MG 13 only when the engine 11 is in a low rotation region such as idle rotation in which the rotational fluctuation of the DE 11 is likely to occur.

  Therefore, when DE11 is started using MG13 from the stop state of the hybrid vehicle, the rotational speed of DE11 increases as the rotational speed of DE11 increases and the rotational speed of MG13 increases. At this time, the rotational force of the DE 11 is transmitted from the crankshaft 20 to the central shaft 45 via the damper mechanism 53, and further from the planetary gear 42, the gear carrier 43, and the sun gear 41 in the planetary gear unit 14 to the MG 13 via the drive shaft 24. Although the flywheel 51 is connected to the MG 13 via the clutch mechanism 61 in the low rotation region where the rotation fluctuation of the DE11 is likely to occur, the rotation fluctuation of the DE11 is absorbed by the inertial force of the flywheel 51. The

  Here, engine start control in the hybrid vehicle of the present embodiment will be described. As shown in FIG. 7, whether or not there is a start request of DE11 (for example, turning on the ignition key switch, increasing the accelerator opening, lowering the battery charge, etc.) when the vehicle is stopped or the motor is running in step S11. If there is no request to start DE11, the process proceeds to step S20, where it is determined whether DE11 is stopped, and if DE11 is stopped, the process ends without doing anything.

  On the other hand, if it is determined in step S11 that there is a start request for DE11, the process proceeds to step S12, where the clutch mechanism (flywheel clutch) 61 is turned off and the connection between the MG 13 and the flywheel 51 is released. In step S13, cranking of DE11 is started by MG13, and fuel injection by the injector is started in step S14.

  In step S15, the rotational speed of the DE 11 is calculated, and in step S16, it is determined whether the engine start is completed when the rotational speed of the DE 11 reaches a predetermined first rotational speed (for example, 600 rpm). . If it is not determined in step S16 that the engine has been started, the process returns to step S11 and the process is repeated. On the other hand, if it is determined that the engine start has been completed, in step S17, the rotational speed of the DE 11 becomes equal to or lower than a predetermined second rotational speed (for example, 2000 rpm), so that the engine is in the low engine speed region (idle state). Judging whether or not. If the DE 11 is in the idle state at this step S17, the clutch mechanism (flywheel clutch) 61 is turned ON to connect the MG 13 and the flywheel 51 at step S18.

  Then, after starting DE11, when the rotational speed of DE11 further increases and enters the middle / high engine speed region, the process proceeds from step S11 to step S20, where it is determined that DE11 has not stopped. The process proceeds to step S17. Then, in this step S17, since it is determined that the DE 11 is not similar to the idle state, the clutch mechanism (flywheel clutch) 61 is turned off in step S19, and the connection between the MG 13 and the flywheel 51 is released.

  Therefore, when the DE 11 is started, and during middle and high rotations, the clutch mechanism 61 releases the connection between the MG 13 and the flywheel 51 to prevent the flywheel 51 from becoming a starting resistance or a high-rotation resistance. Sometimes, the clutch mechanism 61 connects the MG 13 and the flywheel 51 to absorb the rotational fluctuation of the DE 11.

  As described above, in the hybrid vehicle of the second embodiment, the planetary gear unit 14 as the power split mechanism transmits the output of the DE 11 to the drive wheels 15 and the MG 13 as the generator, and the output of the MG 12 as the electric motor. Power can be transmitted to the drive wheel 15, and the flywheel 51 is firmly coupled to the MG 13 via the clutch mechanism 61.

  Therefore, by connecting the MG 13 and the flywheel 51 by the clutch mechanism 61 in the low rotation region of the DE11, the flywheel 51 can absorb the rotational fluctuation of the DE11 and reliably reduce the engine vibration. On the other hand, when the DE 11 is started, the clutch mechanism 61 releases the connection between the MG 13 and the flywheel 51, so that the flywheel 51 does not become a starting resistance at the time of starting the engine, and deterioration of startability is suppressed. Generation of engine vibration can be prevented. In addition, even in the middle / high rotation range of DE 11, the clutch mechanism 61 releases the connection between the MG 13 and the flywheel 51, so that the flywheel 51 does not become a resistance at the time of high engine rotation (acceleration), and the running performance. Can be prevented.

  As described above, the hybrid vehicle according to the present invention has a flywheel that absorbs engine rotation fluctuations mounted on the drive shaft of the generator to reduce the size and weight, and the engine and the electric motor are used as a power source. It is useful when applied to a hybrid vehicle that can travel as

It is the schematic showing the power transmission structure of the engine in the hybrid vehicle which concerns on Example 1 of this invention, a generator, and an electric motor. 1 is a schematic configuration diagram of a hybrid vehicle of Example 1. FIG. It is a collinear diagram showing the driving force of a generator, an engine, and an electric motor when shifting from steady running to accelerated running in a hybrid vehicle. It is a collinear diagram showing the drive force of a generator, an engine, and an electric motor when starting an engine from the stop state in a hybrid vehicle. It is a collinear diagram showing the drive force of a generator, an engine, and an electric motor when an engine is started from a motor running state in a hybrid vehicle. It is the schematic showing the power transmission structure of the engine, the generator, and the electric motor in the hybrid vehicle which concerns on Example 2 of this invention. 6 is a flowchart illustrating engine control in a hybrid vehicle according to a second embodiment.

Explanation of symbols

11 Diesel engine, DE
12 Motor generator, MG (electric motor)
13 Motor generator, MG (generator)
14 Power split mechanism (planetary gear unit)
18 Inverter 19 Battery 22 Engine ECU
27 Motor ECU
28 Main ECU
29 Battery ECU
41 Sun gear 42 Planetary gear 43 Gear carrier 44 Ring gear 49 Rotor 51 Flywheel 52, 62, 63 Connecting shaft (drive shaft)
53 Damper mechanism 61 Clutch mechanism

Claims (3)

  An engine, a generator capable of generating electricity using at least a part of the output of the engine, an electric motor capable of rotating upon receipt of electric power supplied from the generator, and the output of the engine to drive wheels and the generator A hybrid vehicle comprising: a power split mechanism for transmitting power and transmitting power from the electric motor to the drive wheels; and a flywheel fixed to a drive shaft of the generator.   2. The hybrid vehicle according to claim 1, wherein the power split mechanism is disposed on a sun gear, a plurality of planetary gears disposed around the sun gear, a gear carrier that holds the planetary gears, and an outer periphery of the planetary gear. A planetary gear unit comprising a ring gear, the drive shaft of the generator is fixed to the sun gear, the drive shaft of the engine is fixed to the gear carrier, and the drive shaft of the electric motor is fixed to the ring gear. A hybrid vehicle characterized by being connected. 2. The hybrid vehicle according to claim 1, wherein the flywheel is fixed to a drive shaft of the generator via a clutch mechanism.

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