Lean vehicles

Abstract

The present invention provides a leaning vehicle in which an engine can be started up by a startup lithium-ion battery in a wide temperature range. The leaning vehicle comprises: vehicle wheels, which have a tread surface for grounding on the road surface and in which the cross-sectional shape of the tread surface is arcuate; an engine that has a crankshaft and outputs torque for driving the vehicle wheels from the crankshaft; a permanent-magnet-type startup motor that has a permanent magnet and that rotates the crankshaft and starts up the engine; a startup lithium-ion battery that supplies electric power to the permanent-magnet-type startup motor when the engine starts up; and an electric double layer capacitor, which is constantly connected in parallel to the startup lithium-ion battery supplying electric power to the permanent-magnet-type startup motor when the engine starts up, and which has a capacitance capable of charging the battery with an amount of power sufficient for the engine to be started up by the permanent-magnet-type startup motor at least once.

Description

[Technical Field]

[0001] The present invention relates to a lean vehicle. [Background Art]

[0002] Vehicles equipped with a lithium ion battery that drives a motor using electric power from the lithium ion battery are known. For example, Patent Document 1 discloses a hybrid vehicle including an engine, a motor generator, and a power storage device. The hybrid vehicle in Patent Document 1 is, for example, a four-wheeled vehicle, a two-wheeled vehicle, or a three-wheeled vehicle. A lithium ion battery for starting is used as the power storage device in Patent Document 1. When functioning as a generator, the motor generator of Patent Document 1 receives rotational force from the engine or wheels to generate electric power, and the generated electric power charges the battery. Furthermore, the motor generator of Patent Document 1 rotates using the battery as a power source. The hybrid vehicle performs EV traveling using the power of the motor generator. Also, during EV traveling, the power of the motor generator is transmitted to the output shaft of the engine. This enables the engine to be started.

[0003] Lithium ion batteries have, for example, higher energy density than lead batteries. Therefore, lithium ion batteries are capable of storing large amounts of electric power. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent No. 5753582 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Lean vehicles, which use the power of a lithium-ion battery to start the engine, are desirable to be able to start the engine over a wide temperature range while keeping the vehicle size down.

[0006] The objective of the present invention is to provide a lean vehicle that can start the engine using a lithium-ion battery over a wide temperature range while suppressing an increase in vehicle size. [Means for solving the problem]

[0007] The inventors investigated engine starting using a lithium-ion battery for starting. As a result, the inventors found the following:

[0008] Lithium-ion batteries used for starting vehicles have a high energy density by utilizing the movement of lithium ions. However, at low temperatures, lithium-ion batteries for starting vehicles tend to experience increased resistance to lithium ion movement in the electrolyte (diffusion resistance) and increased resistance in electrode reactions (charge transfer resistance). In particular, lithium ion mobility tends to decrease at low temperatures. Therefore, lithium-ion batteries for starting vehicles tend to have increased internal resistance at low temperatures compared to, for example, lead-acid batteries. Consequently, the current output from lithium-ion batteries for starting vehicles tends to decrease at low temperatures.

[0009] To prevent the time it takes for the starter motor to start the engine using battery power from becoming excessively long in low temperatures, it is conceivable to install a high-capacity lithium-ion battery for starting. For example, a four-wheeled vehicle designed as a hybrid vehicle can be equipped with a high-capacity lithium-ion battery for starting.

[0010] However, in lean vehicles, such as two-wheeled or three-wheeled vehicles, posture control is performed by the rider's weight shift during driving or turning. The wheels of a lean vehicle have a tread surface with an arc-shaped cross-section. When a lean vehicle turns, it leans toward the center of the turn. That is, a lean vehicle tilts to the left during a left turn and to the right during a right turn. The body of a lean vehicle is preferably made lighter and smaller so that posture control can be performed smoothly by the rider's weight shift. For this reason, the installation space for equipment within the body of a lean vehicle is generally severely limited. Since the battery is a relatively large and heavy item among the components of a lean vehicle, the installation space for the battery is severely limited. For example, if the battery is larger, the external dimensions of the body frame that accommodates the battery will increase. As a result, the body of the lean vehicle will become larger. For this reason, it is not easy to increase the capacity of the starting lithium-ion battery in a lean vehicle to a level where it can output sufficient power even at low temperatures.

[0011] Therefore, the inventors considered connecting an electric double-layer capacitor in parallel with the lithium-ion battery used for starting in a lean vehicle, rather than increasing the capacity of the lithium-ion battery used for starting. In this investigation, the inventors found the following:

[0012] At low temperatures, lithium-ion batteries can output a small amount of power (current) per unit time. Therefore, to output enough power to perform cold starts, which start the engine at ambient temperature, larger lithium-ion batteries are required. Increasing the size of lithium-ion batteries leads to larger lean vehicles.

[0013] However, if an electric double-layer capacitor is permanently connected in parallel to the lithium-ion battery used for starting, the electric double-layer capacitor can be charged by the power output from the lithium-ion battery before starting. During the engine's combustion operation, the starting lithium-ion battery and electric double-layer capacitor are charged. For example, if the engine's combustion operation is short, the charge in the electric double-layer capacitor at the time of combustion cessation may be insufficient to start the engine. Also, at low temperatures, the output current of the starting lithium-ion battery may decrease. However, even in such cases, the starting lithium-ion battery outputs a voltage due to the chemical reaction of the electrodes within the battery. Therefore, the starting lithium-ion battery can constantly charge the electric double-layer capacitor connected in parallel. As a result, the electric double-layer capacitor is charged with enough power to start the engine next time. An electric double-layer capacitor has a capacitance capable of storing enough power to start an engine at least once. In this case, the power stored in the electric double-layer capacitor can be used to start the engine when it is time to start it. Electric double-layer capacitors do not utilize chemical reactions between electrodes like batteries. Therefore, electric double-layer capacitors exhibit less internal resistance at low temperatures compared to, for example, batteries. Furthermore, the volume of an electric double-layer capacitor is sufficient if it has enough capacitance to charge enough power to start an engine at least once, making it more compact than, for example, a large-capacity lithium-ion battery used for starting a four-wheeled vehicle.

[0014] (1) A lean vehicle that tilts to the left during a left turn and to the right during a right turn, The lean vehicle is, A wheel having a tread surface for contacting the road surface, the cross-sectional shape of the tread surface being arc-shaped, An engine having a crankshaft and outputting torque from the crankshaft to drive the wheels, A permanent magnet type starter motor having a permanent magnet and rotating the crankshaft to start the engine, The system includes a starting lithium-ion battery and an electric double-layer capacitor that supply power to the permanent magnet starting motor when the engine is started, wherein the electric double-layer capacitor is always connected in parallel with the starting lithium-ion battery and has a capacitance that can be charged by the power output from the starting lithium-ion battery before the engine is started, to an amount of power sufficient to start the engine at least once. .

[0015] Furthermore, a configuration different from a constant parallel connection can be considered, for example, in the charging scenario. For instance, one configuration could be one in which the battery is first charged by the generator's current, and the capacitor is charged only when the battery voltage is above the full charge voltage. In other words, a configuration that prioritizes battery charging can be considered. However, in this configuration, for example, even if the engine starts, if the engine stops before the battery is fully charged, the capacitor will not be charged. In this case, the capacitor will not be utilized for the next start, and the engine will be started using battery power. In such a configuration, if the battery is a lithium-ion battery, a larger battery will be required to start the engine at low temperatures. In contrast, a constant parallel connection prevents situations where the capacitor is not charged. Therefore, it is possible to start the engine even at low temperatures while keeping the lithium-ion battery size down.

[0016] Another possibility is to set the capacitance of the electric double-layer capacitor to be less than the amount of power it can charge to start the engine once. For example, one could simply design the drive circuit that drives the starter motor to be powered by the power stored in the capacitor and / or battery. That is, the power of the capacitor is less than the power required to start the engine once, but the drive circuit can simply be configured to "utilize the power stored in the capacitor and / or battery for driving." However, if the battery that is always connected in parallel is a lithium-ion battery, and the current that can be output from the lithium-ion battery is limited at low temperatures, there is a possibility that the engine will not be able to start. Alternatively, a larger battery may be required. In contrast, by setting the capacitance of the electric double-layer capacitor to an amount sufficient to charge enough power to start the engine at least once, the engine can be started even if the current that can be output from the lithium-ion battery is limited at low temperatures. Therefore, the size of the lithium-ion battery can be kept down.

[0017] Furthermore, in addition to electric double-layer capacitors, lithium-ion capacitors can be considered as capacitors capable of charging enough power to start the engine. However, lithium-ion capacitors utilize a chemical reaction in a part of the electrode. For this reason, lithium-ion capacitors tend to have a decrease in output current at low temperatures due to the same principle as lithium-ion batteries. Consequently, lithium-ion capacitors cannot play a role in supplementing the low-temperature output current of lithium-ion batteries used for starting. In addition, lithium-ion capacitors have a lower limit voltage set above 0V as the lower limit of their usable voltage range. For example, a typical lithium-ion capacitor has a lower limit voltage of, for example, 2.5V. In lean vehicles, if the voltage of the lithium-ion capacitor falls below the lower limit voltage due to, for example, battery degradation or prolonged storage, the lithium-ion capacitor itself may degrade. While batteries are components intended to be replaced according to their lifespan, if the lithium-ion capacitor degrades, the degradation of the lithium-ion capacitor will not be resolved even if, for example, the battery is replaced. Even if voltage is applied to a lithium-ion capacitor in a degraded state, charging of the lithium-ion capacitor will be hindered. For this reason, lithium-ion capacitors cannot be said to be suitable for lean vehicles. In contrast, electric double-layer capacitors have a lower voltage limit of 0V. Therefore, even if the voltage of an electric double-layer capacitor drops to 0V due to, for example, a failure in the surrounding circuit or discharge due to battery degradation, the electric double-layer capacitor itself does not degrade. In other words, even after the voltage has dropped to 0V, electric double-layer capacitors can still be charged and discharged. Furthermore, as mentioned above, electric double-layer capacitors exhibit less increase in internal resistance at low temperatures compared to, for example, lithium-ion capacitors. Consequently, an electric double-layer capacitor that is always connected in parallel with a starting lithium-ion battery can charge enough power to start the engine and, based on the charged power, output a current sufficient to start the engine.

[0018] The present inventors have contemplated a configuration in which an electric double-layer capacitor having a capacitance capable of charging an amount of electric power sufficient to start an engine at least once is always connected in parallel with a starting lithium-ion battery. Since the volume of the electric double-layer capacitor is sufficient for a capacitance capable of charging an amount of electric power sufficient to start an engine of a leaning vehicle at least once, the electric double-layer capacitor can be reduced in size compared to, for example, a case where a large-capacity starting lithium-ion battery like that for a four-wheeled vehicle is mounted. Even when a starting lithium-ion battery, whose output current tends to decrease at low temperatures, is used to start an engine, an increase in size of the starting lithium-ion battery can be suppressed. With this configuration, the inventors of the present invention have found that by utilizing the high energy density characteristic of the starting lithium-ion battery for a leaning vehicle, the engine can be started in a wide temperature range while suppressing an increase in size of the vehicle in the leaning vehicle.

[0019] The leaning vehicle of the present invention, which has been made based on the above findings, comprises the following configuration.

[0020] (1) A leaning vehicle that leans toward the left side of the vehicle during a left turn and leans toward the right side of the vehicle during a right turn, The leaning vehicle comprises: a wheel having a tread surface for contacting a road surface, wherein a cross-sectional shape of the tread surface is arcuate; an engine having a crankshaft, the engine outputting torque for driving the wheel from the crankshaft; a permanent magnet type starter motor having a permanent magnet, the starter motor rotating the crankshaft to start the engine; a starting lithium-ion battery that supplies electric power to the permanent magnet type starter motor when the engine is started; an electric double-layer capacitor that is always connected in parallel with the starting lithium-ion battery which supplies electric power to the permanent magnet type starter motor when the engine is started, the electric double-layer capacitor having a capacitance capable of charging an amount of electric power sufficient to start the engine at least once by the permanent magnet type starter motor; and comprising the above.

[0021] The lean vehicle in the above configuration comprises wheels, an engine, a permanent magnet starter motor, a lithium-ion battery for starting, and an electric double-layer capacitor. The wheels have a tread surface with an arc-shaped cross-section. As a result, the lean vehicle can travel while tilting to the left during a left turn and to the right during a right turn. The lithium-ion battery used for starting supplies power to the permanent magnet starter motor when starting the engine. At low temperatures, the amount of power (current) that can be output per unit time from the lithium-ion battery used for starting is less than, for example, that of a lead-acid battery of the same capacity. Increasing the capacity of the lithium-ion battery used for starting is not easy in lean vehicles that travel at an angle when turning. The lithium-ion battery for starting in this lean vehicle configuration is always connected in parallel with an electric double-layer capacitor. Therefore, the electric double-layer capacitor can be charged by the power output from the lithium-ion battery before starting. The electric double-layer capacitor is also always connected in parallel with the lithium-ion battery for starting. Therefore, when the engine is started, the lithium-ion battery for starting supplies power to the motor, and at the same time, the pre-charged electric double-layer capacitor also supplies power to the motor. In other words, the power charged in the electric double-layer capacitor and the power from the lithium-ion battery for starting are supplied to the permanent magnet type starting motor. Furthermore, even when the charge level of the starting lithium-ion battery is less than that of a fully charged state, the starting lithium-ion battery outputs a voltage due to the reaction of its electrodes. Therefore, even when the charge level of the starting lithium-ion battery is low, it can charge the electric double-layer capacitor that is always connected in parallel, for example, before starting the engine. An electric double-layer capacitor connected in parallel with the starting lithium-ion battery has a capacitance capable of charging enough power to start the engine at least once. Unlike batteries, electric double-layer capacitors do not utilize chemical reactions between electrodes. Therefore, compared to batteries, for example, electric double-layer capacitors exhibit less increase in internal resistance at low temperatures. Consequently, the required volume of the electric double-layer capacitor for the output current is small. Furthermore, the volume of the electric double-layer capacitor corresponds to the capacitance capable of charging enough power to start the engine at least once. For this reason, electric double-layer capacitors can be miniaturized. Additionally, the volume of the starting lithium-ion battery can be reduced compared to, for example, maintaining the capacity of the starting electric double-layer capacitor to the point where the engine can be started at low temperatures without it. Therefore, the starting lithium-ion battery can be miniaturized compared to, for example, a lithium-ion battery without a constantly parallel-connected electric double-layer capacitor.

[0022] A configuration in which the capacitor is always connected in parallel with the battery is different from a configuration in which the capacitor is connected in series with the battery, for example, when the engine is started. In a series connection, the current flowing through the battery is limited, which in turn limits the current flowing through the capacitor. This means that the torque of the permanent magnet starter motor is limited. Therefore, in a configuration where the capacitor is connected in series with the battery when starting the engine, the lithium-ion battery must be larger to start the engine over a wide temperature range, including low temperatures. As a result, the body of the lean vehicle becomes larger.

[0023] According to (1), an electric double-layer capacitor having a capacitance capable of charging enough power to start the engine at least once is always connected in parallel. This allows the engine to be started by the lithium-ion battery over a wide temperature range, including low temperatures, without increasing the capacity of the lithium-ion battery used for starting. Therefore, it is possible to start the engine over a wide temperature range using the lithium-ion battery while suppressing an increase in the size of the vehicle.

[0024] According to one aspect of the present invention, a lean vehicle can employ the following configuration.

[0025] (2) A lean vehicle of (1), The electric double-layer capacitor has a capacitance of 30F or more.

[0026] With the above configuration, the crankshaft can be rotated for a period of time that allows the engine to be started over a wide temperature range, including low temperatures, without increasing the capacity of the lithium-ion battery used for starting, for example, as in the case of a four-wheeled vehicle.

[0027] According to one aspect of the present invention, a lean vehicle can employ the following configuration. (3) A lean vehicle of (1) or (2), Five to seven of the aforementioned electric double-layer capacitors are connected in series.

[0028] According to the above configuration, the series-connected electric double-layer capacitors can have an energy storage capacity that can start the engine even when the lithium-ion battery for starting the lean vehicle is not functioning.

[0029] According to one aspect of the present invention, a lean vehicle can employ the following configuration.

[0030] (4) A lean vehicle which is any one of (1) to (3) The electric double-layer capacitor is mounted on the vehicle body such that it remains mounted on the vehicle body when the starting lithium-ion battery is removed from the vehicle body of the lean vehicle.

[0031] With the above configuration, even if the starting lithium-ion battery is removed from the vehicle for replacement, the electric double-layer capacitor remains attached to the vehicle. Therefore, even if the starting lithium-ion battery reaches the end of its lifespan, in a lean vehicle, simply replacing the starting lithium-ion battery allows the engine to be started using the starting lithium-ion battery in a wide temperature range, including low temperatures.

[0032] According to one aspect of the present invention, a lean vehicle can employ the following configuration.

[0033] (5) A lean vehicle which is any one of (1) to (4) The permanent magnet type starting motor comprises a rotor having a plurality of magnetic pole portions made of permanent magnets, The permanent magnet type starter motor comprises a stator core having multiple slots formed at intervals in the circumferential direction of the permanent magnet type starter motor, and a stator having windings provided so as to pass through the slots, The number of the magnetic poles is greater than the number of the multiple teeth.

[0034] According to the above configuration, while suppressing losses when the permanent magnet starter motor generates electricity, windings with low electrical resistance can be used to increase the torque of the permanent magnet starter motor during starting. Furthermore, according to the above configuration, a large current that can be supplied to the permanent magnet starter motor is able to accept when starting the engine at low temperatures. Therefore, it is easier to start the engine with the lithium-ion battery for starting over a wide temperature range, including low temperatures.

[0035] According to one aspect of the present invention, a lean vehicle can employ the following configuration.

[0036] (6) A lean vehicle which is any one of (1) to (5) The aforementioned electric double-layer capacitor is of the leaded type, equipped with lead wires that function as terminals for connecting to the outside.

[0037] According to the above configuration, the electric double-layer capacitors can be soldered to a substrate, for example, allowing the array configuration to be manufactured in a shorter time compared to the case of bolt-type terminals.

[0038] According to one aspect of the present invention, a lean vehicle can employ the following configuration.

[0039] (7) A lean vehicle which is any one of (1) to (6) The lithium-ion battery for starting has a rectangular parallelepiped shape with length, width, and height, and a positive terminal and a negative terminal are provided on the upper surface including the length, which is the shortest of the length, width, and height. The electric double-layer capacitors are cylindrical in shape, consisting of 5 to 7 units connected in series with each other, and the relationship between the diameter φ and height Lc of the electric double-layer capacitors and the horizontal length Lb and vertical length W of the upper surface is given by the following equations (A) and (B). (Lb / 7)≦φ≦ (Lb / 5) (A) Lc ≤ W (B)

[0040] If the relationship between the diameter φ and height Lc of a cylindrical electric double-layer capacitor and the lateral length Lb and vertical length W of the top surface of a rectangular lithium-ion battery for starting is as shown in equations (A) and (B) above, it is possible to arrange 5 to 7 electric double-layer capacitors in a narrower area than the bottom surface of the lithium-ion battery for starting. By connecting 5 to 7 electric double-layer capacitors in series, the electric double-layer capacitors can have a maximum operating voltage that allows them to operate together with the lithium-ion battery for starting. Furthermore, if the electric double-layer capacitors have a height Lc as defined by the above equations, they can be charged with enough power to start the engine at least once.

[0041] In the design of lean vehicles, the placement of battery-related components is carried out while taking into account the dimensions of the lithium-ion battery used for starting. For example, if a cover is placed around the lithium-ion battery used for starting, a space is provided inside the cover that takes into account the dimensions of the lithium-ion battery used for starting.

[0042] Because the electric double-layer capacitor has the relationship shown in equations (A) and (B), it becomes possible to arrange the electric double-layer capacitor in the space provided considering the dimensions of the lithium-ion battery for starting. Therefore, the engine can be started by the lithium-ion battery over a wide temperature range while further suppressing the increase in vehicle size.

[0043] A lean vehicle is a type of saddle-type vehicle. A lean vehicle is a vehicle ridden in a riding style. The driver sits straddling the saddle of the lean vehicle. Examples of lean vehicles include scooters, mopeds, off-road vehicles, and on-road motorcycles. Lean vehicles are not limited to motorcycles; they may also include ATVs (All-Terrain Vehicles) or three-wheeled vehicles. Three-wheeled vehicles may have two front wheels and one rear wheel, or one front wheel and two rear wheels.

[0044] A "wheel having a tread surface for contacting the road surface, wherein the cross-sectional shape of the tread surface is arc-shaped" is, for example, configured such that the tread surface (the surface for contacting the road surface) extends to the side of the wheel. The cross-sectional shape of the tread surface in this wheel is an arc or a shape similar to an arc. Here, the cross-section of the tread surface is a cross-section that passes through the rotation axis of the wheel. The cross-sectional shape of the tread surface of the wheel may have a shape in which the central part in the vehicle width direction protrudes to form a ridge. The tread surface of the wheel may be configured such that the contact area with the road surface during turning is larger than the contact area with the road surface during straight driving. The wheel may be configured such that the contact area with the road surface changes continuously according to the inclination of the lean vehicle, for example. For example, the tread surface of the wheel does not include a cylindrical surface centered on the wheel's axis of rotation when not in contact with the road surface. For example, the outermost cross-sectional shape of the wheel is not composed of straight lines when not in contact with the road surface. The tread surface is formed, for example, on the tire of a wheel. If grooves are formed on the tread surface of the tire, the shape of the tread surface refers to a macroscopic shape that ignores the irregularities caused by the grooves. Such a wheel is, for example, a motorcycle wheel specified by ISO or JIS. In contrast, the wheels of vehicles other than lean vehicles (e.g., automobiles) have a relatively flat tread surface with a contact surface with the road surface, and can be clearly distinguished from the wheels described above.

[0045] A permanent magnet type starting motor has permanent magnets. For example, a configuration in which the rotor has coils instead of permanent magnets is different from the motor in this configuration. A magnetic starter motor is, for example, a magnetic starter generator. However, a magnetic starter motor may be a motor that is not used as a generator. The motors used in engine starting devices include, for example, outer rotor type motors, inner rotor type motors, and axial gap type motors. Other examples of motors used in engine starting devices include brushed motors and brushless motors with inverters. A permanent magnet starter motor starts an engine when the crankshaft is not rotating. In other words, a permanent magnet starter motor starts an engine when the lean vehicle is stationary. However, a permanent magnet starter motor may also start an engine when the crankshaft is rotating or when the lean vehicle is in motion.

[0046] A lithium-ion battery for starting an engine is a battery used as an energy source for starting an engine. A lithium-ion battery for starting an engine is a rechargeable and dischargeable battery. In other words, a battery is a storage battery. A battery is a secondary battery that charges and discharges through chemical reactions at its electrodes. A battery charges and discharges through oxidation and reduction reactions at its electrodes. A battery stores the electricity being charged as chemical energy. A battery converts the stored chemical energy into electrical energy. The terminal voltage of a battery is not proportional to the amount of electricity stored in the battery. A lithium-ion battery for starting an engine stores electricity as chemical energy. Therefore, it can retain the charged electricity for long periods of time, such as from when the engine is stopped until the next engine start. In this respect, a lithium-ion battery for starting an engine differs from a capacitor, including a lithium-ion capacitor. For example, the power stored in a capacitor is easily lost during relatively short periods of non-charging. For instance, a capacitor of the size used in lean vehicles will discharge the power needed to start the engine much faster than a lithium-ion battery used for starting. The maximum discharge rated current of a lithium-ion battery used for starting is less than the maximum charge rated current. However, some lithium-ion batteries used for starting may have a maximum discharge rated current that is greater than the maximum charge rated current. A lithium-ion battery for starting is a battery that stores the power needed to start the engine. The lithium-ion battery for starting is used at least to start the engine when the crankshaft is not rotating. In other words, the lithium-ion battery for starting is used at least to start the engine when the lean vehicle is stationary. However, the lithium-ion battery for starting may also be used to start the engine when the crankshaft is rotating or when the lean vehicle is in motion.

[0047] An electric double-layer capacitor stores the power being charged as electric charge. Electric double-layer capacitors charge and discharge without chemical reactions at the electrodes. The terminal voltage of an electric double-layer capacitor is approximately proportional to the charged energy. An electric double-layer capacitor has the capacity to store the power that contributes to the rotation of the motor in an engine starting device. More specifically, an electric double-layer capacitor is an energy-storage electric double-layer capacitor. More specifically, an electric double-layer capacitor has a greater equivalent series resistance (ESR) than a smoothing electric double-layer capacitor. An electric double-layer capacitor has a greater series inductance (ESL) as parasitic inductance than a smoothing electric double-layer capacitor. Electric double-layer capacitors differ from, for example, lithium-ion capacitors. For instance, electric double-layer capacitors have a discharge lower voltage limit of 0V. The discharge lower voltage limit is the voltage below which, if the battery reaches a certain level during discharge, including natural discharge, will cause significant and irreversible degradation. The discharge voltage limit of a lithium-ion capacitor is greater than 0V. For example, the discharge voltage limit of a lithium-ion capacitor is 2.5V. Therefore, if a lean vehicle is equipped with a lithium-ion capacitor, for example, if the voltage of the lithium-ion capacitor connected to the battery falls below the discharge voltage limit due to battery failure or prolonged storage, the lithium-ion capacitor will degrade. This degradation of the lithium-ion capacitor is irreversible. Consequently, even if the battery is subsequently replaced, the performance achieved by connecting lithium-ion capacitors in parallel cannot be restored. In contrast, electric double-layer capacitors do not degrade even at a voltage of 0V. Therefore, replacing a faulty battery can restore the performance achieved through parallel connection. Furthermore, since electric double-layer capacitors do not degrade even at 0V, they can store the minimum amount of power necessary to start an engine, for example, when a faulty battery is removed and the engine is started by the rider's kick starter, or when power is supplied by electrically connecting to another vehicle.

[0048] The starting lithium-ion battery and the electric double-layer capacitor are always connected in parallel. For example, the starting lithium-ion battery and the electric double-layer capacitor are connected without a switching device made of transistors. Therefore, the device, including the connection structure, is simple and compact. However, the connection state is not limited to this, and the electric double-layer capacitor may be connected to the starting lithium-ion battery via a switch for temporarily switching the connection state, for example, during maintenance. Furthermore, for example, five to seven electric double-layer capacitors are connected in series. However, the number of capacitors connected in series is not particularly limited; for example, it may be four or fewer, or eight or more. Also, a second set different from the first set of electric double-layer capacitors connected in series may be connected in parallel to the first set. A third set may be connected in parallel to the second set. Each of the second and third sets consists of capacitors connected in series. In other words, a series-parallel configuration is also possible. However, in a series-parallel configuration, the unit (set) is a series connection, and multiple units are connected in parallel.

[0049] For example, when an electric double-layer capacitor is connected in parallel with the battery as viewed from the engine starter, it means that the currents from both the electric double-layer capacitor and the battery are electrically connected so that they merge and flow into the engine starter. Conversely, for example, when all the current from the electric double-layer capacitor flows into the battery, and this current then flows into the engine starter, this is different from the electric double-layer capacitor being connected in parallel with the battery as viewed from the engine starter. The state in which an electric double-layer capacitor is connected in parallel with the battery as viewed from the engine starter includes a state where the battery and the electric double-layer capacitor are connected only by wiring. It also includes a state in which a device other than wiring is inserted between the battery and the electric double-layer capacitor. For example, the state in which an electric double-layer capacitor is connected in parallel with the battery as viewed from the engine starter includes a state in which a connector (coupler) that electrically connects or disconnects depending on the operation is included between the battery and the electric double-layer capacitor. It also includes a state in which an electrical component other than a connector is inserted between the battery and the electric double-layer capacitor. Examples of such electrical components include switches, relays, resistors, connectors, and fuses. Wiring, on the other hand, is, for example, a lead wire. However, wiring is not limited to a single lead wire, but may also consist of multiple lead wires connected together. Furthermore, wiring includes devices whose primary function is conductivity. For example, wiring includes connectors, switches, relays, resistors, connectors, and fuses.

[0050] The technical terms used herein are intended to define only specific embodiments and are not intended to limit the invention. As used herein, the terms "and / or" include any or all combinations of one or more related enumerated components. As used herein, the use of the terms “including,” “comprising,” or “having,” and variations thereof, identifies the presence of the described features, processes, operations, elements, components, and / or equivalents thereof, but may include one or more of the steps, operations, elements, components, and / or groups thereof. As used herein, the terms “attached,” “combined,” and / or their equivalents are used broadly and, unless otherwise specified, encompass both direct and indirect attachment and combination. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology and this disclosure, and not as ideal or overly formal unless expressly defined herein. It is understood that numerous techniques and processes are disclosed in the description of this invention. Each of these has its own separate interests, and each may be used in conjunction with one or more, or possibly all, of the other disclosed technologies. Therefore, for clarity, this explanation will refrain from unnecessarily repeating all possible combinations of individual steps. Nevertheless, the specification and claims should be read with the understanding that all such combinations fall within the scope of the invention and claims. This specification describes a new type of lean vehicle. The following description includes numerous specific details to provide a complete understanding of the present invention for illustrative purposes. However, it will be clear to those skilled in the art that the present invention can be carried out without these specific details. This disclosure should be considered as illustrative of the present invention and is not intended to limit the present invention to any specific embodiment shown in the following drawings or description. [Effects of the Invention]

[0051] According to the present invention, a lean vehicle can be realized in which the engine can be started by a lithium-ion battery for starting over a wide temperature range. [Brief explanation of the drawing]

[0052] [Figure 1] This diagram schematically shows a lean vehicle according to one embodiment of the present invention. [Figure 2] This figure schematically shows a lean vehicle and electrical system, which are the first application example of the embodiment shown in Figure 1. [Figure 3] Figure 2 is an external view showing the lithium-ion battery and electric double-layer capacitor used for starting the engine. [Figure 4] Figure 2 is a schematic partial cross-sectional view showing the general configuration of the engine unit. [Figure 5] Figure 4 shows a cross-sectional view of a permanent magnet type starter motor, perpendicular to its axis of rotation. [Figure 6] Figure 2 is a circuit diagram showing the schematic electrical configuration of the lean vehicle. [Figure 7] Figure 2 shows a chart illustrating the change in current during engine startup in a lean vehicle. [Figure 8] This is a circuit diagram showing the schematic electrical configuration of a lean vehicle in the second application example. [Figure 9] This diagram illustrates an example of the arrangement of a starting lithium-ion battery and an electric double-layer capacitor in the third application example. [Modes for carrying out the invention]

[0053] The present invention will be described below with reference to the drawings, based on embodiments.

[0054] Figure 1 is a schematic diagram showing a lean vehicle according to one embodiment of the present invention. Part (a) of Figure 1 is a side view of the lean vehicle. Part (b) of Figure 1 is a partial cross-sectional view of the wheel shown in Part (a).

[0055] The lean vehicle 1 shown in Figure 1 comprises wheels 3a and 3b, an engine 10, a permanent magnet starter motor 20, a lithium-ion battery 4 for starting, and an electric double-layer capacitor 71. The lean vehicle 1 also comprises a body 2. The lean vehicle 1 is a saddle-type vehicle. Figure 1 shows a motorcycle as an example of the lean vehicle 1. Leaning vehicle 1 tilts to the left during a left turn and to the right during a right turn.

[0056] The wheels 3a and 3b on the lean vehicle 1 are the front wheel 3a and the rear wheel 3b. The rear wheel 3b is the drive wheel. As shown in part (b) of Figure 1, the wheel 3a has a tread surface TR for contact with the road surface. The tread surface TR is formed, for example, on a tire. The cross-sectional shape of the tread surface TR is arc-shaped. Note that part (b) of Figure 1 shows the macroscopic shape, ignoring the irregularities caused by grooves formed on the tread surface TR. The cross-sectional shape of the tread surface TR is the same for the rear wheel 3b. The tread surfaces TR of wheels 3a and 3b have an arc-shaped cross-section when not in contact with the road surface. Wheels 3a and 3b that are not in contact with the road surface do not include a cylindrical surface centered on the wheel's axis of rotation. When wheels 3a and 3b are in contact with the road surface, the parts of wheels 3a and 3b that are in contact with the road surface deform into a planar shape according to the road surface due to the weight of the vehicle. However, the shape of the parts of wheels 3a and 3b that are in contact with the road surface is not the same as the cross-sectional shape of the tread surface TR when not in contact with the road surface, as described above. The tread surfaces of wheels 3a and 3b have an arc-shaped cross-section when not in contact with the road surface. This shape of the tread surfaces of wheels 3a and 3b differs from that of, for example, a four-wheeled vehicle. From a macroscopic perspective, excluding grooves and scratches formed on the tread surface TR, the contact area between the wheels 3a, 3b and the road surface changes continuously as the lean vehicle 1 tilts.

[0057] The engine 10 is equipped with a crankshaft 15. The engine 10 outputs power via the crankshaft 15. The engine 10 outputs torque from the crankshaft 15 to drive the wheels 3b. The wheels 3b receive power from the crankshaft 15 and move the lean vehicle 1. The power output from the engine 10 can be transmitted to the wheels 3b, for example, via a transmission and clutch.

[0058] The permanent magnet type starter motor 20 has permanent magnets. More specifically, the permanent magnet type starter motor 20 includes a permanent magnet section 37 made of permanent magnets.

[0059] The starting lithium-ion battery 4 and electric double-layer capacitor 71 are energy storage devices that can be charged and discharged. The starting lithium-ion battery 4 and electric double-layer capacitor 71 output the stored power to the outside. The starting lithium-ion battery 4 and electric double-layer capacitor 71 supply power to the permanent magnet starting motor 20. The starting lithium-ion battery 4 and electric double-layer capacitor 71 supply power to the permanent magnet starting motor 20 when starting the engine 10. In addition, the starting lithium-ion battery 4 and electric double-layer capacitor 71 are charged by the power generated by the permanent magnet starting motor 20.

[0060] The lithium-ion battery 4 for starting supplies power to the permanent magnet starter motor 20 when starting the engine 10. Furthermore, after the engine has started, for example, the lithium-ion battery 4 is charged by the current supplied from the permanent magnet starter motor 20.

[0061] The electric double-layer capacitor 71 is always connected in parallel with the starting lithium-ion battery 4. The electric double-layer capacitor 71 supplies power to the permanent magnet starting motor 20 together with the starting lithium-ion battery 4 when starting the engine 10. The electric double-layer capacitor 71 has a capacitance that can charge enough power to start the engine 10 at least once using the permanent magnet starting motor 20. For example, the total weight of the electric double-layer capacitor 71 is less than the weight of the starting lithium-ion battery 4.

[0062] The electrical path from the electric double-layer capacitor 71 to the permanent magnet type starting motor 20 either does not have a fuse, or it has a fuse of 50A or more (not shown). For example, if a fuse of less than 50A is installed, and the starting lithium-ion battery 4 fails to function and the vehicle is started using current from the electric double-layer capacitor 71, the fuse may blow, making it impossible to start the vehicle. The electrical path from the electric double-layer capacitor 71 to the permanent magnet type starting motor 20 is configured without a fuse, or with a fuse of 50A or more (not shown), thereby suppressing the occurrence of starting failure due to a blown fuse during startup. The lean vehicle 1 has, for example, five or more electric double-layer capacitors 71. The lean vehicle 1 has, for example, five to seven electric double-layer capacitors 71. This is to minimize the volume in the lean vehicle 1 while maintaining a voltage rating suitable for the lean vehicle 1. The lean vehicle 1 may have, for example, five or six electric double-layer capacitors 71.

[0063] The electric double-layer capacitor 71 has a capacitance of, for example, 30F or more. This allows it to accommodate engines 10 of a wide range of sizes at low temperatures. For example, even if the lithium-ion battery 4 for starting is not functioning, that is, if it does not output power, the permanent magnet type starting motor 20 can be powered to start an engine 10 belonging to a wide range of sizes. The electric double-layer capacitor 71 can also start engines with displacement (stroke capacity) of 100 mL or more.

[0064] However, it is also possible to use an electric double-layer capacitor 71 with a capacitance of less than 30F. Furthermore, an engine 10 equipped in the lean vehicle 1 may have a displacement of less than 100mL.

[0065] The electric double-layer capacitor 71 is, for example, always connected in parallel with the starting lithium-ion battery 4. Multiple electric double-layer capacitors 71 are connected in series with each other. Multiple electric double-layer capacitors 71 are connected in series to increase the effective storage capacity. Storage capacity is the amount of energy that can be charged. The energy that an electric double-layer capacitor 71 can charge can be expressed, for example, as electric charge. Storage capacity is different from capacitance. Generally, the combined capacitance of multiple capacitors connected in series is equal to the capacitance of the individual capacitors.

[0066] However, the electric double-layer capacitor 71 of this embodiment has a maximum operating voltage lower than the operating voltage used in the lean vehicle 1. For example, if a lean vehicle 1 is equipped with only one electric double-layer capacitor 71, a configuration can be considered in which the operating voltage is stepped down using a step-down means such as a voltage converter or a voltage divider resistor, and then charged. In this case, the voltage discharged from the single electric double-layer capacitor 71 is stepped up by a step-up means and used. In this case, the energy, i.e., charge, stored in the single electric double-layer capacitor 71 is equal to the product of the capacitance and the voltage. Therefore, the energy stored is small because the voltage is low. In other words, the energy storage capacity is small. In this embodiment, by having five or more electric double-layer capacitors 71, the system is connected to the starting lithium-ion battery 4 without the need for a step-down means. Since the five or more electric double-layer capacitors 71 can be charged at a high voltage, they can store a larger charge compared to the case of a single electric double-layer capacitor. In other words, the energy storage capacity is large.

[0067] The starting lithium-ion battery 4 and the electric double-layer capacitor 71 are physically separate. The starting lithium-ion battery 4 and the electric double-layer capacitor 71 are located at different positions relative to the vehicle body 2. The starting lithium-ion battery 4 and the electric double-layer capacitor 71 can be located adjacent to each other. The arrangement is not limited to this, and the starting lithium-ion battery 4 and the electric double-layer capacitor 71 can also be located at positions spaced apart from each other in the lean vehicle 1. For example, the starting lithium-ion battery 4 is installed in the vehicle body 2 so that it can be replaced. The electric double-layer capacitor 71 is installed in the vehicle body 2 so that it is not removed from the vehicle body 2 along with the starting lithium-ion battery 4 when the starting lithium-ion battery 4 is replaced. In other words, the electric double-layer capacitor 71 is installed in the vehicle body 2 so that it remains installed in the vehicle body 2 when the starting lithium-ion battery 4 is removed from the vehicle body 2. More specifically, the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are installed in the vehicle body 2 by different components.

[0068] The permanent magnet starter motor 20 rotates the crankshaft 15 using power from the starting lithium-ion battery 4. This starts the engine 10. The electric double-layer capacitor 71 and the starting lithium-ion battery 4 are connected. Therefore, the permanent magnet starter motor 20 rotates the crankshaft 15 using both the power charged in the electric double-layer capacitor 71 and the power charged in the starting lithium-ion battery 4.

[0069] In the configuration shown in Figure 1, the lithium-ion battery 4 supplies power to the permanent magnet starter motor 20 when starting the engine 10. At low temperatures, the current that can be output per unit time from the lithium-ion battery 4 is smaller than, for example, that of a lead-acid battery of the same capacity. However, the lithium-ion battery 4 is connected to an electric double-layer capacitor 71. Therefore, the electric double-layer capacitor 71 can be charged by the power output from the lithium-ion battery 4 before starting. When the engine 10 is started, the lithium-ion battery 4 supplies power to the permanent magnet starter motor 20, and at the same time, the pre-charged electric double-layer capacitor 71 can also supply power to the permanent magnet starter motor 20. The electric double-layer capacitor 71 does not utilize the chemical reaction of electrodes like the lithium-ion battery 4. Therefore, the electric double-layer capacitor 71 exhibits less increase in internal resistance at low temperatures compared to, for example, the lithium-ion battery 4. Consequently, the electric double-layer capacitor 71 suppresses the decrease in output current at low temperatures compared to, for example, the lithium-ion battery 4. Furthermore, the volume of the electric double-layer capacitor 71 can be made compact, as its capacitance is sufficient to charge enough power to start the engine 10 at least once. Therefore, it can be mounted on a lean vehicle 1 that tilts when turning without compromising the freedom of vehicle design. In this way, by connecting an electric double-layer capacitor 71 having a capacitance capable of charging enough power to start the engine 10 at least once, the engine 10 can be started by the lithium-ion battery 4 over a wide temperature range, including low temperatures, without increasing the capacity of the lithium-ion battery 4.

[0070] [First application example] Next, we will describe an example of the application of the embodiment described above with reference to Figure 1.

[0071] Figure 2 is a schematic diagram showing a lean vehicle and electrical system, which is a first application example of the embodiment shown in Figure 1. Part (a) of Figure 2 is a plan view of the lean vehicle. Part (b) of Figure 2 is a partial cross-sectional view of the wheel shown in Part (a). Part (c) of Figure 2 is a side view of the lean vehicle. Part (d) of Figure 2 is a schematic wiring diagram showing the connections of the electrical system of the lean vehicle. In the application examples shown in Figure 2 and subsequent figures, elements corresponding to the embodiment shown in Figure 1 will be described using the same reference numerals as in Figure 1.

[0072] The lean vehicle 1 shown in Figure 2 has a body 2. The body 2 is equipped with a seat 2a for the driver to sit on. The driver sits by straddling the seat 2a. A motorcycle is shown in Figure 2 as an example of a lean vehicle 1.

[0073] Lean vehicle 1 is equipped with front wheels 3a and rear wheels 3b. Wheels 3a and 3b have tread surfaces TR for contact with the road surface. The tread surfaces of wheels 3a and 3b of lean vehicle 1 have an arc-shaped cross-section when not in contact with the road surface.

[0074] Engine 10 constitutes the engine unit EU. That is, lean vehicle 1 is equipped with the engine unit EU. The engine unit EU includes an engine 10 and a permanent magnet starter motor 20. The engine 10 outputs power via the crankshaft 15. The engine 10 outputs torque from the crankshaft 15 to drive the wheels 3b. The wheels 3b receive power from the crankshaft 15 and move the lean vehicle 1. The engine 10 has a displacement of, for example, 100 mL or more. The engine 10 has a displacement of, for example, less than 400 mL. Furthermore, the lean vehicle 1 is equipped with a CVT transmission and a clutch CL. Power output from the engine 10 is transmitted to the wheels 3b via the CVT transmission and clutch CL.

[0075] The permanent magnet type starting motor 20 is driven by the engine 10 to generate electricity. The permanent magnet type starting motor 20 shown in Figure 2 is a magnet type starting generator. The permanent magnet type starter motor 20 has a rotor 30 and a stator 40. The rotor 30 is equipped with a permanent magnet section 37 made of permanent magnets. The rotor 30 rotates with power output from the crankshaft 15. The stator 40 is positioned opposite the rotor 30.

[0076] The starting lithium-ion battery 4 and electric double-layer capacitor 71 are energy storage devices that can be charged and discharged. The starting lithium-ion battery 4 and electric double-layer capacitor 71 output the stored power to the outside. The starting lithium-ion battery 4 and electric double-layer capacitor 71 supply power to the permanent magnet starting motor 20 and the electrical device L. The starting lithium-ion battery 4 and electric double-layer capacitor 71 supply power to the permanent magnet starting motor 20 when the engine 10 is started. In addition, the starting lithium-ion battery 4 and electric double-layer capacitor 71 are charged by the power generated by the permanent magnet starting motor 20.

[0077] The lithium-ion battery 4 for starting supplies power to the permanent magnet starter motor 20 when starting the engine 10. Furthermore, after the engine 10 has started, for example, the lithium-ion battery 4 is charged by the current supplied from the permanent magnet starter motor 20. The lean vehicle 1 is equipped with an inverter 21. The inverter 21 includes a plurality of switching units 211 that control the current flowing between the permanent magnet type starting motor 20 and the starting lithium-ion battery 4.

[0078] The electric double-layer capacitor 71 is always connected in parallel with the starting lithium-ion battery 4. The lean vehicle 1 shown in Figure 2 is equipped with multiple electric double-layer capacitors 71. The electric double-layer capacitors 71 are connected in series with each other. The electric double-layer capacitors 71 connected in series with each other operate electrically as a single electric double-layer capacitor. The electric double-layer capacitor 71 shown in Figure 2 is always connected in parallel with the starting lithium-ion battery 4 as viewed from the inverter 21. The electric double-layer capacitor 71 supplies power to the permanent magnet starting motor 20 together with the starting lithium-ion battery 4 when starting the engine 10. The electric double-layer capacitor 71 has a capacitance that can charge enough power to start the engine at least once using the permanent magnet starting motor 20. The total weight of the electric double-layer capacitor 71 is less than the weight of the starting lithium-ion battery 4.

[0079] The starting lithium-ion battery 4 and the electric double-layer capacitor 71 are physically separate components. The starting lithium-ion battery 4 and the electric double-layer capacitor 71 are mounted separately on the vehicle body 2. The starting lithium-ion battery 4 is mounted on the vehicle body 2 so that it can be replaced. The electric double-layer capacitor 71 is mounted on the vehicle body 2 so that it does not come off the vehicle body 2 together with the starting lithium-ion battery 4 when the starting lithium-ion battery 4 is replaced. In other words, the electric double-layer capacitor 71 is mounted on the vehicle body 2 so that it can remain attached to the vehicle body 2 even when the starting lithium-ion battery 4 is removed from the vehicle body 2. More specifically, the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are mounted on the vehicle body 2 by different components. The electric double-layer capacitor 71 can be installed in such a way that it can be removed from the vehicle body 2 only after the starting lithium-ion battery 4 has been removed from the vehicle body 2. For example, the vehicle body 2 is provided with a storage recess for housing both the electric double-layer capacitor 71 and the starting lithium-ion battery 4, with the electric double-layer capacitor 71 positioned further back than the starting lithium-ion battery 4. Furthermore, the electric double-layer capacitor 71 can be provided in such a way that it can be removed from the vehicle body 2 while the starting lithium-ion battery 4 is attached to the vehicle body 2.

[0080] The electric double-layer capacitor 71 is positioned such that, based on the wiring distance, the distance between the electric double-layer capacitor 71 and the inverter 21 is shorter than the distance between the starting lithium-ion battery 4 and the inverter 21. In other words, based on the wiring distance, the electric double-layer capacitor 71 is positioned closer to the inverter 21 than the starting lithium-ion battery 4. In the example shown in part (d) of Figure 2, the wiring distance from the electric double-layer capacitor 71 through the inverter 21 to the permanent magnet starting motor 20 is shorter than the wiring distance from the starting lithium-ion battery 4 through the inverter 21 to the permanent magnet starting motor 20.

[0081] The permanent magnet starter motor 20 rotates the crankshaft 15 using power from the lithium-ion battery 4 for starting. This allows the permanent magnet starter motor 20 to start the engine 10. Since the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are always connected in parallel, the permanent magnet starting motor 20 rotates the crankshaft 15 using both the power charged in the electric double-layer capacitor 71 and the power charged in the starting lithium-ion battery 4.

[0082] The lean vehicle 1 is equipped with a main switch 5. The main switch 5 is a switch for supplying power to the electrical equipment L (see Figure 6) installed in the lean vehicle 1 in accordance with its operation. The electrical equipment L is a collective representation of devices that operate while consuming power, excluding the permanent magnet type starter motor 20. The electrical equipment L includes, for example, headlights 9, a fuel injector 18 (described later), and spark plugs 19. The lean vehicle 1 is equipped with a starter switch 6. The starter switch 6 is a switch for starting the engine 10 in response to operation. The lean vehicle 1 is equipped with a main relay 75. The main relay 75 opens and closes a circuit including an electrical device L in response to a signal from the main switch 5. The lean vehicle 1 is equipped with an acceleration instruction unit 8. The acceleration instruction unit 8 is an operator for instructing the lean vehicle 1 to accelerate in response to an operation. More specifically, the acceleration instruction unit 8 is an accelerator grip.

[0083] In the configuration shown in Figure 2, the lithium-ion battery 4 supplies power to the permanent magnet starter motor 20 when starting the engine 10. At low temperatures, the current that can be output per unit time from the lithium-ion battery 4 is smaller than, for example, that of a lead-acid battery of the same capacity. However, the lithium-ion battery 4 is connected to an electric double-layer capacitor 71. Therefore, the electric double-layer capacitor 71 can be charged by the power output from the lithium-ion battery 4 before starting. When the engine 10 is started, the lithium-ion battery 4 supplies power to the permanent magnet starter motor 20, and at the same time, the pre-charged electric double-layer capacitor 71 can also supply power to the permanent magnet starter motor 20. The electric double-layer capacitor 71 does not utilize the chemical reaction of electrodes like the lithium-ion battery 4. Therefore, the electric double-layer capacitor 71 exhibits less increase in internal resistance at low temperatures compared to, for example, the lithium-ion battery 4. Consequently, the electric double-layer capacitor 71 suppresses the decrease in output current at low temperatures compared to, for example, the lithium-ion battery 4. Furthermore, the volume of the electric double-layer capacitor 71 is small enough to accommodate the capacitance required to charge the engine 10 at least once, making it compact. Therefore, it can be mounted on a lean vehicle 1 that tilts when turning, without compromising the design flexibility of the vehicle. In this way, by connecting an electric double-layer capacitor 71 having a capacitance capable of charging enough power to start the engine 10 at least once, the engine 10 can be started by the lithium-ion battery 4 over a wide temperature range, including low temperatures, without increasing the capacity of the lithium-ion battery 4.

[0084] Figure 3 is an external view showing the lithium-ion battery 4 and electric double-layer capacitor 71 for starting shown in Figure 2. Part (a) of Figure 3 is a plan view. Part (b) of Figure 3 is a side view. Part (b) of Figure 3 is a bottom view.

[0085] [Lithium-ion battery] The lithium-ion battery 4 for starting, shown in Figure 3, is rectangular in shape. The lithium-ion battery 4 for starting has a top surface 4a, a bottom surface 4b, and four sides 4c. The starting lithium-ion battery 4 and electric double-layer capacitor 71 shown in Figures 2 and 3 are positioned such that the upper surface 4a of the starting lithium-ion battery 4 (Figure 3) faces upward in the upright lean vehicle 1. However, the starting lithium-ion battery 4 and electric double-layer capacitor 71 can also be positioned at an angle relative to the position shown in Figure 2.

[0086] The starting lithium-ion battery 4 has a positive terminal 41 and a negative terminal 42. Terminals 41 and 42 are located in recesses provided on the upper surface of the starting lithium-ion battery 4.

[0087] The starting lithium-ion battery 4 has multiple battery cells 45. Each battery cell 45 has a positive electrode and a negative electrode (not shown). The positive electrode in the starting lithium-ion battery 4 is made of a material containing a lithium transition metal composite oxide. The starting lithium-ion battery 4 stores power supplied from an external source through a chemical reaction of the electrodes. The starting lithium-ion battery 4 outputs power to the outside through a chemical reaction of the electrodes. The starting lithium-ion battery 4 incorporates a battery control circuit (not shown) for controlling the charge level of each battery cell 45.

[0088] [capacitor] The lean vehicle 1 (see Figure 2) has, for example, multiple electric double layer capacitors 71 (EDLCs). Each electric double-layer capacitor 71 is an electrical component that can function independently. Each electric double-layer capacitor 71 is a leaded type, equipped with lead wires 71a and 71b that function as terminals. These electric double-layer capacitors 71 are connected to a circuit board 72. Multiple electric double-layer capacitors 71 and the circuit board 72 constitute an electric double-layer capacitor block 7. That is, the electric double-layer capacitor block 7 has multiple electric double-layer capacitors 71 and a circuit board 72 connected to each electric double-layer capacitor 71. The electric double-layer capacitor block 7 is installed in the lean vehicle 1. The circuit board 72 is soldered to the electric double-layer capacitors 71. The circuit board has a wiring pattern 72p that connects the electric double-layer capacitors 71 in series with each other. Multiple electric double-layer capacitors 71 are connected in series with each other via the circuit board 72. Lead-type electric double-layer capacitors 71 can be connected in series in a short time by soldering them to the circuit board 72 during the assembly process. Multiple electric double-layer capacitors 71 connected in series with each other function electrically as a single electric double-layer capacitor. Therefore, multiple electric double-layer capacitors 71 that function electrically as a single electric double-layer capacitor may hereafter be simply referred to as electric double-layer capacitors 71.

[0089] Figure 3 shows five or more electric double-layer capacitors 71 as an example applied to lean vehicle 1 (Figure 2). Lean vehicle 1 shown in Figure 2 has, for example, six electric double-layer capacitors 71.

[0090] The electric double-layer capacitor 71 has electrodes (not shown) and an electrolyte, and the electrodes include a final charge material (not shown) and activated carbon. The electric double-layer capacitor 71 stores power by forming an electric double layer consisting of an arrangement of ions and electrons or holes at the interface where the activated carbon and the electrolyte are in contact. The electric double-layer capacitor 71 stores power in the form of electric charge. The electric double-layer capacitor 71 stores power without chemical changes in the electrodes. For this reason, the electric double-layer capacitor 71 can be charged and discharged with a larger current than, for example, a starting lithium-ion battery 4 having the same capacity. In particular, the electric double-layer capacitor 71 has fewer limitations on the charging current at low temperatures compared to the lithium-ion battery 4 used for starting. Therefore, the electric double-layer capacitor 71 can store more power in a shorter time compared to the lithium-ion battery 4 used for starting, which has the same capacity. Furthermore, the electric double-layer capacitor 71 has fewer limitations on the discharge current at low temperatures compared to the lithium-ion battery 4 used for starting. Therefore, the electric double-layer capacitor 71 can discharge with a larger current compared to the lithium-ion battery 4 used for starting, which has the same capacity.

[0091] The electric double-layer capacitor 71 shown in Figure 3 has a capacitance on its own that is capable of charging enough power for the permanent magnet starter motor 20 to rotate the crankshaft 15 to start the engine 10 at least once. Therefore, even if the starting lithium-ion battery 4 cannot output enough power to start the engine 10, the engine 10 can be started with the current charged in the electric double-layer capacitor 71. Even if the starting lithium-ion battery 4 is not connected, the engine 10 can be started at least once with the current charged in the electric double-layer capacitor 71. Capacitor capacity is expressed in farads (F). However, to match, for example, a starting lithium-ion battery 4, the capacity can also be expressed as the integrated current (Ah or As) assuming the battery's standard operating voltage. The integrated current represents the charge stored in the capacitor. Therefore, the capacity can be expressed as the charge (C: coulomb) stored assuming the battery's standard operating voltage. The battery's standard operating voltage is, for example, 12V. The battery's standard operating voltage may be, for example, equal to or higher than 12V. The battery's standard operating voltage may be, for example, 24V. In this specification, the power stored in the series-connected electric double-layer capacitors 71 may also be expressed in terms of charge (C) assuming an operating voltage. 1C is equal to 1As.

[0092] [Capacitor shape and arrangement] The electric double-layer capacitors 71 are cylindrical in shape. Multiple cylindrical electric double-layer capacitors 71 are arranged substantially parallel to each other. For example, six electric double-layer capacitors 71 are arranged in six rows. A pair of lead wires 71a and 71b protrude from one of the two bottom surfaces (top and bottom) of the cylindrical electric double-layer capacitor 71. Each electric double-layer capacitor 71 is arranged with its bottom surface, from which the lead wires 71a and 71b protrude, facing the circuit board 72.

[0093] [Placement of capacitors and batteries] The electric double-layer capacitor 71 is positioned below the lower edge of the starting lithium-ion battery 4 in the vertical direction of the lean vehicle 1, for example, when viewing the lean vehicle 1 shown in Figure 2 from the left. For example, the electric double-layer capacitor 71 is aligned along the bottom surface of the starting lithium-ion battery 4. It is positioned below the bottom surface of the starting lithium-ion battery 4.

[0094] [Dimensional relationships] The relationship between the diameter φ and height Lc of the electric double-layer capacitor 71 and the lateral length Lb and vertical length W of the starting lithium-ion battery 4 is given by equations (A) and (B) below. (Lb / 7)≦φ≦ (Lb / 5) (A) Lc ≤ W (B)

[0095] As the electric double-layer capacitor 71, for example, a capacitor with a capacitance of 30F or more is used. Also, as the electric double-layer capacitor 71, an electric double-layer capacitor having a maximum operating voltage of 2.5V to 5V is used. As the electric double-layer capacitor 71, for example, an electric double-layer capacitor 71 having a maximum operating voltage of 2.7V to 3V is used. The maximum operating voltage of the electric double-layer capacitor 71 is, for example, 2.7V.

[0096] Preferably, the electric double-layer capacitor 71 has a capacity capable of charging the permanent magnet starter motor 20 with enough power to rotate the crankshaft 15 for at least 0.5 seconds to start the engine 10. This allows the engine 10 to operate for at least one cycle, including the compression stroke. This enables combustion. For example, if the current supplied to the permanent magnet starter motor 20 that rotates the crankshaft 15 is 100A or more, the power required to rotate the crankshaft 15 for 0.5 seconds is greater than 200J. Because the electric double-layer capacitor 71 has a capacity of 30F or more, when the standard operating voltage in the lean vehicle 1 is 12V, the total power stored by the multiple electric double-layer capacitors 71 is greater than 400J. If the charge of the multiple electric double-layer capacitors 71 is discharged to half of its full charge, it can supply more than 200J of energy. In this case, the permanent magnet starter motor 20 rotates the crankshaft 15 for at least 0.5 seconds to start the engine 10.

[0097] Furthermore, the electric double-layer capacitor 71 has a capacity that can be substantially fully charged within 20 seconds by the power generated by the permanent magnet starter motor 20 when the engine 10 is idling. If the engine 10 is left idling for 20 seconds, the engine 10 can be restarted using the power from the electric double-layer capacitor 71 after it has stopped. For example, if the average current supplied to the engine 10 by the permanent magnet starter motor 20 while idling is 20A, the power supplied to the electric double-layer capacitor 71 in 20 seconds will be greater than 400J. Because the electric double-layer capacitor 71 has a capacity of 30F or more, it can store more than 400J of power when the standard operating voltage in the lean vehicle 1 is 12V. In other words, the electric double-layer capacitor 71 is fully charged within 20 seconds by the power generated by the permanent magnet starter motor 20 while the engine 10 is idling. As a result, the permanent magnet starter motor 20 can rotate the crankshaft 15 for a maximum of 0.5 seconds to start the engine 10.

[0098] The electric double-layer capacitor 71 may have a capacity capable of charging the permanent magnet starter motor 20 with enough power to rotate the crankshaft 15 for at least one second to start the engine 10. This allows the engine 10 to be started at least once. If the current supplied to the permanent magnet starter motor 20 is 100A, the power required to rotate the crankshaft 15 for more than one second is greater than approximately 400J. By having an electric double-layer capacitor 71 with a capacity of 50F or more, the crankshaft 15 can be rotated for more than one second to start the engine 10. In this case, the engine 10 is started while the lean vehicle 1 is stopped and the crankshaft 15 is stopped rotating. Furthermore, the electric double-layer capacitor 71 reaches a standard operating voltage in the lean vehicle 1 within 20 seconds by the power generated by the permanent magnet starter motor 20 when the engine 10 is idling. The electric double-layer capacitor 71 has a capacitance of, for example, less than 400F.

[0099] Furthermore, the electric double-layer capacitor 71 can also be configured to have a capacity that can be fully charged in less than 10 seconds by the power generated by the permanent magnet starter motor 20 when the engine 10 is idling. In this case, the electric double-layer capacitor 71 has a capacity of, for example, less than 200F. If the engine 10 is left idling for 10 seconds, the engine 10 can be restarted using the power from the electric double-layer capacitor 71 after it has stopped.

[0100] The inverter 21 shown in Figure 2 includes a switching unit 211 (see Figure 6). The inverter 21 rotates the permanent magnet starter motor 20 by supplying power to it. The inverter 21 controls the current by controlling the on / off state of the current flowing through the windings of the permanent magnet starter motor 20. In addition, when the engine 10 is in combustion operation, the inverter 21 supplies the power generated by the permanent magnet starter motor 20 to the starting lithium-ion battery 4 and the electric double-layer capacitor 71. In this case, the inverter 21 rectifies the current generated by the permanent magnet starter motor 20.

[0101] The lean vehicle 1 is equipped with a control device 60. The control device 60 is physically integrated with the inverter 21. In detail, the control device 60 and the inverter 21 in this application have a common housing. The control device 60 controls the current flowing between the permanent magnet starter motor 20, the starting lithium-ion battery 4, and the electric double-layer capacitor 71 by controlling the operation of the switching unit 211 of the inverter 21. In this way, the control device 60 controls the operation of the permanent magnet starter motor 20. For example, the control device 60, in response to a signal from the starter switch 6, causes the inverter 21 to supply current from the starting lithium-ion battery 4 to the permanent magnet starting motor 20. This supplies power from the starting lithium-ion battery 4 to the permanent magnet starting motor 20, and the engine 10 starts. After the engine starts, i.e., after combustion begins, the control device 60 controls the inverter 21 to supply current from the permanent magnet starting motor 20 to the starting lithium-ion battery 4. This charges the starting lithium-ion battery 4 with the power generated by the permanent magnet starting motor 20. Furthermore, even after the engine 10 has started, i.e., after the combustion operation has begun, the control device 60 causes the inverter 21 to supply power from the starting lithium-ion battery 4 to the permanent magnet starting motor 20 in response to the operation of the acceleration instruction unit 8. As a result, the permanent magnet starting motor 20 assists the engine 10 in driving the lean vehicle 1.

[0102] Furthermore, the control device 60 in this application also has the function of an engine control unit that controls the supply of fuel to the engine 10. The control device 60 controls the supply of fuel to the engine by controlling the operation of the fuel injection device 18, which will be described later. The control device 60 includes a central processing unit (not shown) and memory. It controls the supply of fuel to the engine 10 by executing a program stored in the memory. The control device 60 also includes a smoothing capacitor 61. The smoothing capacitor 61 smooths the voltage at the power terminals of the control device 60.

[0103] As shown in part (d) of Figure 2, the permanent magnet starter motor 20, the lithium-ion battery 4 for starting, the electric double-layer capacitor 71, the control device 60 including the main relay 75 and inverter 21, and the electrical device L are electrically connected by wiring J. For clarity of the symbols, the symbols (J) of the wiring are attached to a portion of the wiring shown in part (b) of Figure 2. Wiring J is composed of, for example, lead wires. Wiring J may also consist of multiple lead wires that are connected together. Wiring J may also include connectors, fuses, and connection terminals that relay the lead wires. Illustrations of connectors, fuses, and connection terminals are omitted. Furthermore, the physical wiring diagram in part (d) of Figure 2 shows the connections in the positive region. The negative region, i.e., the ground region, is electrically connected via the vehicle body 2. More specifically, the negative region is electrically connected via a metal frame of the vehicle body 2 (not shown). The distance of the electrical connections of each device via the vehicle body 2 is usually equivalent to or shorter than the connections in the positive region by lead wires, etc. Therefore, in part (d) of Figure 2, the illustration of the connections in the negative region by the vehicle body 2 is omitted, and the wiring of the positive region will be described mainly. The wiring J shown in Figure 2, when combined with other wiring installed in the vehicle, forms a wire harness not shown. Part (d) of Figure 2 shows only the wiring J that electrically connects the devices shown in the figure. Part (d) of Figure 2 schematically shows the connection relationships of the wiring J between each device, and the distance of the wiring J.

[0104] [Engine Unit] Figure 4 is a schematic partial cross-sectional view showing the general configuration of the engine unit EU shown in Figure 2.

[0105] The engine unit EU comprises an engine 10. The engine 10 includes a crankcase 11, a cylinder 12, a piston 13, a connecting rod 14, and a crankshaft 15. The piston 13 is reciprocally mounted within the cylinder 12. The crankshaft 15 is rotatably mounted within the crankcase 11. The crankshaft 15 is connected to the piston 13 via a connecting rod 14. A cylinder head 16 is mounted on top of the cylinder 12. The cylinder 12, cylinder head 16, and piston 13 form a combustion chamber. The crankshaft 15 is supported in the crankcase 11 in a rotatable manner. A permanent magnet starter motor 20 is mounted on one end 15a of the crankshaft 15. A continuously variable transmission (CVT) is mounted on the other end 15b of the crankshaft 15. The CVT can change the gear ratio, which is the ratio of the output rotational speed to the input rotational speed. The CVT can change the gear ratio corresponding to the rotational speed of the wheels relative to the rotational speed of the crankshaft 15.

[0106] The engine unit EU is equipped with a fuel injector 18. The fuel injector 18 supplies fuel to the combustion chamber by injecting fuel. The fuel injector 18 injects fuel into the air flowing through the intake passage Ip. The mixture of air and fuel is supplied to the combustion chamber of the engine 10. Furthermore, the engine 10 is equipped with a spark plug 19.

[0107] Engine 10 is an internal combustion engine. Engine 10 receives a supply of fuel. Engine 10 outputs power through the combustion operation of burning a fuel-air mixture. That is, the piston 13 reciprocates due to the combustion of the fuel-air mixture supplied to the combustion chamber. The crankshaft 15 rotates in conjunction with the reciprocating motion of the piston 13. The power is output to the outside of engine 10 via the crankshaft 15. The fuel injector 18 adjusts the power output from the engine 10 by adjusting the amount of fuel supplied. The fuel injector 18 is controlled by the control device 60. The fuel injector 18 is controlled to supply an amount of fuel based on the amount of air supplied to the engine 10. The engine 10 outputs power via the crankshaft 15. The power from the crankshaft 15 is transmitted to the wheels 3b via the CVT transmission and clutch CL (see Figure 2).

[0108] Figure 5 is a cross-sectional view showing a section perpendicular to the rotation axis of the permanent magnet type starter motor 20 shown in Figure 4. The permanent magnet type starting motor 20 will be explained with reference to Figures 4 and 5.

[0109] The permanent magnet type starting motor 20 has a rotor 30 and a stator 40. The permanent magnet type starting motor 20 in this application example is a radial gap type. The permanent magnet type starting motor 20 is an outer rotor type. That is, the rotor 30 is an outer rotor. The stator 40 is an inner stator. The rotor 30 has a rotor body 31. The rotor body 31 is made of, for example, a ferromagnetic material. The rotor body 31 has a bottomed cylindrical shape. The rotor body 31 has a cylindrical boss portion 32, a disc-shaped bottom wall portion 33, and a cylindrical back yoke portion 34. The bottom wall portion 33 and the back yoke portion 34 are integrally formed. However, the bottom wall portion 33 and the back yoke portion 34 may be constructed as separate parts. The bottom wall portion 33 and the back yoke portion 34 are fixed to the crankshaft 15 via the cylindrical boss portion 32. The rotor 30 is not provided with windings to which current is supplied.

[0110] The rotor 30 has a permanent magnet section 37. The rotor 30 has a plurality of magnetic pole sections 37a. The plurality of magnetic pole sections 37a are formed by the permanent magnet section 37. The plurality of magnetic pole sections 37a are provided on the inner circumferential surface of the back yoke section 34. In this application example, the permanent magnet section 37 has a plurality of permanent magnets. That is, the rotor 30 has a plurality of permanent magnets. The plurality of magnetic pole sections 37a are provided on each of the plurality of permanent magnets. Furthermore, the permanent magnet portion 37 can also be formed by a single annular permanent magnet. In this case, the single permanent magnet is magnetized such that multiple magnetic pole portions 37a are arranged on its inner surface.

[0111] Multiple magnetic pole sections 37a are arranged such that north poles and south poles are alternately positioned in the circumferential direction of the permanent magnet type starting motor 20. In this application example, the rotor 30 facing the stator 40 has 24 magnetic poles. The number of magnetic poles of the rotor 30 refers to the number of magnetic poles facing the stator 40. No magnetic material is provided between the magnetic pole sections 37a and the stator 40. The magnetic pole portion 37a is located radially outward from the stator 40 of the permanent magnet type starter motor 20. The back yoke portion 34 is located radially outward from the magnetic pole portion 37a. The permanent magnet type starter motor 20 has more magnetic pole portions 37a than the number of teeth 43. The rotor 30 may be an embedded magnet type (IPM type) in which the magnetic pole portion 37a is embedded in the magnetic material, but it is preferable that it be a surface magnet type (SPM type) in which the magnetic pole portion 37a is exposed from the magnetic material, as in this application example.

[0112] The stator 40 has a stator core ST and a plurality of windings W. The stator core ST has a plurality of teeth 43 that are spaced apart in the circumferential direction. The plurality of teeth 43 extend integrally from the stator core ST radially outward. In this application example, a total of 18 teeth 43 are spaced apart in the circumferential direction. In other words, the stator core ST has a total of 18 slots SL that are spaced apart in the circumferential direction. The teeth 43 are arranged at equal intervals in the circumferential direction.

[0113] The rotor 30 has more magnetic pole portions 37a than the number of teeth portions 43. The number of magnetic pole portions is 4 / 3 of the number of slots.

[0114] A winding W is wound around each tooth portion 43. In other words, the multi-phase winding W is arranged to pass through the slot SL. Figure 5 shows the state in which the winding W is inside the slot SL.

[0115] The permanent magnet starting motor 20 is a three-phase generator. Each of the windings W belongs to either the U phase, V phase, or W phase. The windings W are arranged, for example, in the order of U phase, V phase, and W phase.

[0116] When the engine 10 is running while the lean vehicle 1 is in motion, the electricity generated by the permanent magnet starter motor 20 charges the starting lithium-ion battery 4 and the electric double-layer capacitor 71. When the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are fully charged, the electricity generated by the permanent magnet starter motor 20 is not used for charging but is instead consumed as heat, for example, by a short circuit in the windings. For example, if thick windings with low electrical resistance are used in the permanent magnet starter motor 20 to increase the torque at startup, the amount of electricity consumed as heat when fully charged will also increase. In other words, the losses will increase. When a motor generates electricity, the current flowing through the winding W is affected by the impedance present in the winding W itself. Impedance is a factor that hinders the current flowing through the winding W. Impedance includes the product of rotational speed ω and inductance. Here, rotational speed ω actually corresponds to the number of magnetic poles passing near the teeth per unit time. That is, rotational speed ω is proportional to the ratio of the number of magnetic poles to the number of teeth in the motor and the rotational speed of the rotor. The permanent magnet type starter motor 20 shown in Figure 5 has more magnetic poles 37a than the number of teeth 43. That is, the permanent magnet type starter motor 20 has more magnetic poles 37a than the number of slots SL. Therefore, the winding W has a large impedance. Consequently, less power is consumed as heat when the starting lithium-ion battery 4 and electric double-layer capacitor 71 are fully charged. For this reason, in order to increase the torque during starting in the permanent magnet type starter motor 20, a thick winding with low electrical resistance can be used. The lean vehicle 1 is equipped with an electric double-layer capacitor 71 that is always connected in parallel to the lithium-ion battery 4 for starting. Therefore, when a permanent magnet type starting motor 20 that accepts a large current and increases torque during starting is employed, it is possible to supply a large current that can accommodate this acceptance even at low temperatures.

[0117] The rotor 30 of the permanent magnet type starting motor 20 is connected to the crankshaft 15 so as to rotate in accordance with the rotation of the crankshaft 15.

[0118] Figure 6 is a circuit diagram showing the schematic electrical configuration of the lean vehicle 1 shown in Figure 2. The circuit diagram in Figure 6 shows the electrical connections in an application example of the lean vehicle 1 shown in Figure 2.

[0119] As shown in Figure 6, the permanent magnet starter motor 20 is electrically connected to the electric double-layer capacitor 71 via the inverter 21. The permanent magnet starter motor 20 is electrically connected to the starting lithium-ion battery 4 via the inverter 21 and the main relay 75. The inverter 21 includes a switching unit 211. The switching unit 211 constitutes a three-phase bridge inverter as the inverter 21. The switching unit 211 is connected to each phase of the multi-phase winding W and switches the application / non-application of voltage between the multi-phase winding W and the starting lithium-ion battery 4. Multiple switching units 211 thereby switch the flow / interruption of current between the multi-phase winding W and the starting lithium-ion battery 4. In other words, multiple switching units 211 control the current flowing between the starting lithium-ion battery 4 and the permanent magnet starting motor 20. More specifically, when the permanent magnet starting motor 20 functions as a starter motor, the on / off operation of the switching unit 211 switches the energization and de-energization of each of the multi-phase windings W. Also, when the permanent magnet starting motor 20 functions as a generator, the on / off operation of the switching unit 211 switches the flow / interruption of current between each of the windings W and the starting lithium-ion battery 4. The switching unit 211 is sequentially switched on and off, thereby controlling the rectification and voltage of the three-phase AC output from the permanent magnet type starting motor 20.

[0120] The control device 60 controls the current flowing between the permanent magnet starter motor 20, the starting lithium-ion battery 4, and the electric double-layer capacitor 71 by controlling the operation of the switching unit 211. For example, the control device 60 rotates the permanent magnet starter motor 20 by controlling the switching unit 211 using a vector control method. The control device 60 also supplies the power generated by the permanent magnet starter motor 20 to the starting lithium-ion battery 4, the electric double-layer capacitor 71, and the electrical device L by controlling the switching unit 211 using a vector control method. The method by which the control device 60 controls the switching unit 211 is not limited to this, and for example, a 120-degree energization method and a phase control method may also be used.

[0121] Both the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are electrically connected to the inverter 21 of the permanent magnet starting motor 20 via the main relay 75. Both the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are electrically connected to the electrical device L via the main relay 75. Both the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are electrically connected to the permanent magnet starting motor 20 via the main relay 75. Both the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are electrically connected to the control device 60. The electric double-layer capacitor 71 is a separate capacitor from the smoothing capacitor 61. The electric double-layer capacitor 71 is connected in parallel with the smoothing capacitor 61. The electric double-layer capacitor 71 stores power to drive the permanent magnet type starter motor 20. In contrast, the smoothing capacitor 61 smooths the power supply voltage. The capacitance of the electric double-layer capacitor 71 is greater than the capacitance of the smoothing capacitor 61. The parasitic inductance is greater than the parasitic inductance of the smoothing capacitor 61. The electric double-layer capacitor 71 is composed of an electric double-layer capacitor. The smoothing capacitor 61 is composed of an electrolytic capacitor.

[0122] The devices shown in Figure 6 actually include connectors (couplers), fuses, terminals, and current-regulating resistors. In this application example, since components such as connectors, fuses, terminals, and current-regulating resistors can be considered to be electrically included in the wiring, their illustration and explanation are omitted. Fuses may not be included in the devices shown in Figure 6.

[0123] All of the electric double-layer capacitors 71 shown in Figure 6 are connected in series. In other words, almost all of the current flowing through one electric double-layer capacitor 71 flows through the remaining electric double-layer capacitors 71. The state in which the main relay 75 in Figure 6 is activated, thereby closing the circuit including the starting lithium-ion battery 4, is referred to as the ON state of the main relay 75. Main switch 5 is turned ON by operation. When main switch 5 is ON, main relay 75 is turned ON. As shown in the circuit diagram in Figure 6, the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are connected in parallel from the perspective of the inverter 21. The circuit including the inverter 21, the electric double-layer capacitor 71 and the starting lithium-ion battery 4 includes a main relay 75. As the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are always connected in parallel from the perspective of the inverter 21, when the main relay 75 is ON and the starter switch 6 is ON during engine starting, the current output from the starting lithium-ion battery 4 and the current output from the electric double-layer capacitor 71 merge and flow to the inverter 21.

[0124] Furthermore, from the perspective of the inverter 21, the electric double-layer capacitor 71 and the starting lithium-ion battery 4 are always connected in parallel. The circuit including the inverter 21 and the starting lithium-ion battery 4 includes the main relay 75 and the inverter 21. When the main relay 75 is ON and the engine 10 is in combustion operation, the current output from the permanent magnet starting motor 20 passes through the inverter 21 and is then divided and supplied to the electric double-layer capacitor 71 and the starting lithium-ion battery 4. From the perspective of the inverter 21, the electric double-layer capacitor 71, the starting lithium-ion battery 4, and the electrical device L are connected in parallel. The electrical device L is, as mentioned above, for example, the headlight 9. Therefore, in more detail, when the main relay 75 is ON, the current output from the permanent magnet type starting motor 20 passes through the inverter 21 and is then divided and supplied to the electric double-layer capacitor 71, the starting lithium-ion battery 4, and the electrical device L. When the permanent magnet starter motor 20 is not generating power, the current from the starting lithium-ion battery 4 is supplied to the electrical device L. Furthermore, when the voltage of the electric double-layer capacitor 71 is lower than the voltage of the starting lithium-ion battery 4, a portion of the current output from the starting lithium-ion battery 4 flows to the electric double-layer capacitor 71. In other words, the starting lithium-ion battery 4 charges the electric double-layer capacitor 71. For example, when the engine 10 is not operating, the power of the electric double-layer capacitor 71 is consumed by the electrical device L. As a result, the voltage of the electric double-layer capacitor 71 becomes lower than the voltage of the starting lithium-ion battery 4. In this state, when the main relay 75 is turned on, the electric double-layer capacitor 71 is charged with the power of the starting lithium-ion battery 4. In this case, the electric double-layer capacitor 71 is charged until its voltage becomes equal to the voltage of the starting lithium-ion battery 4.

[0125] The circuit diagram in Figure 6 and the physical wiring diagram in part (d) of Figure 2 show the same connection configuration. However, the physical wiring diagram in part (d) of Figure 2 differs from Figure 6 in that it shows the actual connection relationships of the wiring J between each device, as well as the distance of the wiring J.

[0126] A circuit diagram typically shows the electrical connections of a device. More specifically, a circuit diagram shows the circuit topology of a device. That is, a circuit diagram shows, for example, whether devices are connected in series or in parallel. A circuit diagram also shows whether two devices are connected only by wiring or through other devices. A circuit diagram does not represent the actual wiring length. Nor does a circuit diagram represent the spatial position of each device. For example, the arrangement of three devices in a circuit diagram does not mean that the three devices are actually located in that order. Nor does the arrangement in a circuit diagram mean that the three devices are actually located in a line. In contrast, the physical wiring diagram shown in part (b) of Figure 2 shows the approximate actual wiring lengths between devices in the lean vehicle 1.

[0127] As shown in part (b) of Figure 2, the electric double-layer capacitor 71 is arranged such that the distance between the electric double-layer capacitor 71 and the inverter 21 is shorter than the distance between the starting lithium-ion battery 4 and the inverter 21, based on the wiring distance. The wiring distance from the electric double-layer capacitor 71 through the inverter 21 to the permanent magnet starter motor 20 is shorter than the wiring distance from the starting lithium-ion battery 4 through the inverter 21 to the permanent magnet starter motor 20. Furthermore, the electric double-layer capacitor 71 is positioned such that, based on the wiring distance, the distance between the electric double-layer capacitor 71 and the inverter 21 is longer than the distance between the electric double-layer capacitor 71 and the starting lithium-ion battery 4. As a result, the wiring distance from the electric double-layer capacitor 71 through the inverter 21 to the permanent magnet starting motor 20 is longer than the wiring distance from the starting lithium-ion battery 4 through the inverter 21 to the permanent magnet starting motor 20.

[0128] Next, with reference to Figure 7, the starting performance of the engine 10 in the lean vehicle 1 will be described.

[0129] Figure 7 is a chart showing the change in current during engine 10 startup in the lean vehicle 1 shown in Figure 2.

[0130] In Figure 7, the thick solid line represents the current Im flowing through the inverter 21. The thin solid line represents the current Ic flowing through the electric double-layer capacitor 71. The dashed line represents the current Ib flowing through the starting lithium-ion battery 4. Above 0A on the vertical axis, the charging current of the starting lithium-ion battery 4 and the electric double-layer capacitor 71 is shown, and below 0A, the discharge current is shown. Note that in Figure 7, for ease of understanding, the currents Im, Ic, and Ib are shown when no current is supplied to the electrical equipment.

[0131] The chart in Figure 7 shows the current when the crankshaft 15 rotates forward to start the engine 10 without any combustion operations such as fuel supply to the engine 10. Specifically, the starter switch 6 is operated to be ON for a predetermined period of time. During this period, the inverter 21 is controlled by the control device 60 to supply current to the windings of each phase of the permanent magnet starter motor 20 so that the permanent magnet starter motor 20 rotates. In other words, a predetermined starting period (for example, 0.5 seconds) is obtained. As a result, the permanent magnet starter motor 20 rotates the crankshaft 15 for the above starting period. During this period, no combustion operations of the engine 10 occur. Next, a predetermined stopping period (for example, 3 seconds) is obtained, and then the starter switch 6 is operated again to be ON for the above starting period. In this way, the starting period and stopping period are repeated alternately. The initial portion of the above-mentioned starting period (for example, 0.05 seconds) corresponds to the rotation start period. Until the stationary permanent magnet starting motor 20 begins to rotate, the impedance of the windings of the permanent magnet starting motor 20 is small. In other words, during the rotation start period of the starting period, a larger inrush current flows through the permanent magnet starting motor 20 than when it starts rotating after the rotation start period. This current corresponds to the torque required for the permanent magnet starter motor 20 to begin rotating the crankshaft 15 of the engine 10.

[0132] The electric double-layer capacitor 71 is connected to the starting lithium-ion battery 4. The current Im flowing through the inverter 21 is the sum of the current Ib discharged from the starting lithium-ion battery 4 and the current Ic discharged from the electric double-layer capacitor 71. As shown in Figure 7, during the rotation start period of the starting period, the current Im, which is the sum of the current Ib discharged from the starting lithium-ion battery 4 and the current Ic discharged from the electric double-layer capacitor 71, flows through the inverter 21. During the rotation start-up period, a large current Ic is discharged from the electric double-layer capacitor 71, resulting in a large current Im for the inverter 21. In other words, a current Im sufficient for starting the engine 10 is obtained as the current Im for the inverter 21. Consequently, the rotational speed of the crankshaft 15 increases rapidly, and the engine 10 starts up smoothly. Even if the lithium-ion battery 4 does not output enough current to start the engine 10 at low temperatures, the engine 10 can still be started.

[0133] After the rotation start period has elapsed, as the crankshaft 15 begins to rotate, the impedance of the windings of the permanent magnet starter motor 20 increases. As a result, both the current Ib discharged from the starting lithium-ion battery 4 and the current Ic discharged from the electric double-layer capacitor 71 decrease. The current Ic discharged from the electric double-layer capacitor 71 is smaller than the current Ib discharged from the starting lithium-ion battery 4. This is thought to be because, as the impedance of the windings of the permanent magnet starting motor 20 increases, the voltage drop across the windings of the permanent magnet starting motor 20 increases, and the difference between the terminal voltage of the permanent magnet starting motor 20 and the terminal voltage of the electric double-layer capacitor 71 after discharge decreases. In other words, since the fluctuation in terminal voltage due to the discharge of the starting lithium-ion battery 4 is smaller than the fluctuation in terminal voltage due to the discharge of the electric double-layer capacitor 71, it is thought that the change in discharge current after the above rotation start period has elapsed is small in the starting lithium-ion battery 4.

[0134] During the shutdown period following the startup period, the starter switch 6 is in the off state. During this period, the control device 60 stops the inverter 21 from supplying current to the permanent magnet type starter motor 20. Therefore, the current Im flowing through the inverter 21 is 0. During this shutdown period, the current Ic of the electric double-layer capacitor 71 indicates charging, and the current Ib of the starting lithium-ion battery 4 indicates discharge. This indicates that the electric double-layer capacitor 71, whose terminal voltage dropped due to discharge during the startup period, is being charged by the power of the starting lithium-ion battery 4. Charging of the electric double-layer capacitor 71 by the power of the starting lithium-ion battery 4 continues until the terminal voltage of the electric double-layer capacitor 71 becomes equal to the terminal voltage of the starting lithium-ion battery 4. In the example in Figure 7, the next startup period begins before the terminal voltage of the electric double-layer capacitor 71 becomes equal to the terminal voltage of the starting lithium-ion battery 4.

[0135] Prior to the start-up period, for example at time 0, both the current Ib of the starting lithium-ion battery 4 and the current Ic of the electric double-layer capacitor 71 are 0A. The state of the engine 10 before starting at time 0 means that the electric double-layer capacitor 71 is charged by the starting lithium-ion battery 4. This is the result of the electric double-layer capacitor 71 being charged by the power of the starting lithium-ion battery 4 before the engine 10 was started. Thus, the power (current) that can be output per unit time from the starting lithium-ion battery 4 is small. However, the starting lithium-ion battery 4 equipped in the lean vehicle 1 is connected to an electric double-layer capacitor 71. Therefore, the electric double-layer capacitor 71 can be charged by the power output from the starting lithium-ion battery 4 before the rotation start period. During the rotation start period, the permanent magnet starting motor 20 is driven by the current Im, which is the sum of the current Ib discharged from the starting lithium-ion battery 4 and the current Ic discharged from the electric double-layer capacitor 71.

[0136] The lithium-ion battery 4 for starting supplies power to the permanent magnet starter motor 20 when starting the engine 10. Especially at low temperatures, the power (current) that can be output per unit time from the lithium-ion battery 4 is less than, for example, that of a lead-acid battery of the same capacity. However, the lithium-ion battery 4 for starting the lean vehicle 1 is connected to an electric double-layer capacitor 71. Therefore, the electric double-layer capacitor 71 can be charged by the power output from the lithium-ion battery 4 before starting the vehicle. When the engine 10 is started, the lithium-ion battery 4 supplies power to the permanent magnet starter motor 20, and at the same time, the pre-charged electric double-layer capacitor 71 can also supply power to the permanent magnet starter motor 20. The electric double-layer capacitor 71 does not utilize the chemical reaction of electrodes like a battery. Therefore, the electric double-layer capacitor 71 exhibits less increase in internal resistance at low temperatures compared to, for example, the lithium-ion battery 4. Furthermore, the volume of the electric double-layer capacitor 71 is sufficient to charge enough power to start the engine 10 at least once, so it can be made more compact compared to, for example, a four-wheeled vehicle equipped with a large-capacity lithium-ion battery for starting. Consequently, it can be installed in the lean vehicle 1 without compromising design flexibility. In this way, by connecting an electric double-layer capacitor 71 having a capacitance capable of charging enough power to start the engine 10 at least once, the engine can be started by the lithium-ion battery 4 over a wide temperature range, including low temperatures, without increasing the capacity of the lithium-ion battery 4, for example, as in the case of a four-wheeled vehicle.

[0137] [Second application example] Next, I will explain the second application example.

[0138] Figure 8 is a circuit diagram showing the schematic electrical configuration of lean vehicle 1 in the second application example.

[0139] In the application example shown in Figure 8, connection switches Sw1 and Sw2 are provided between the starting lithium-ion battery 4 and the electric double-layer capacitor 71. Connection switches Sw1 and Sw2 are operated, for example, by the control of the control device 60. Connection switches Sw1 and Sw2 are always in the ON state. Connection switches Sw1 and Sw2 may be turned OFF, for example, during maintenance.

[0140] The control device 60 normally maintains a parallel connection between the starting lithium-ion battery 4 and the electric double-layer capacitor 71. The parallel connection is released, for example, during maintenance. In other words, the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are virtually always connected. This ensures that even if sufficient current cannot be expected from the starting lithium-ion battery 4 in a low-temperature environment, current can be obtained from both the starting lithium-ion battery 4 and the electric double-layer capacitor 71. This current allows the engine 10 to be started. This is the same as the application example described with reference to Figure 6, etc. Furthermore, as shown in Figure 8, the lean vehicle 1 may be equipped with a circuit that allows the starting lithium-ion battery 4 and the electric double-layer capacitor 71 to be connected in series by switching connection switches Sw1 and Sw2.

[0141] [Third application example] Next, I will explain the third application example.

[0142] Figure 9 illustrates an example of the arrangement of a starting lithium-ion battery and electric double-layer capacitor in a third application example. Part (a) of Figure 9 is a side view showing the starting lithium-ion battery 4 and electric double-layer capacitor 71 together with a portion of the vehicle body 2. Part (b) of Figure 9 is a bottom view showing the starting lithium-ion battery 4 and electric double-layer capacitor 71 together with a portion of the vehicle body 2. The starting lithium-ion battery 4 and electric double-layer capacitor 71 shown in Figure 9 are, for example, the starting lithium-ion battery 4 and electric double-layer capacitor 71 shown in Figure 1, Figure 2, or Figure 8.

[0143] The starting lithium-ion battery 4 and the electric double-layer capacitor 71 are mounted on the vehicle body 2. The electric double-layer capacitor 71 is positioned below the lower edge of the starting lithium-ion battery 4 in the vertical direction of the lean vehicle 1, for example, when viewing the lean vehicle 1 shown in Figure 2 from the left. For example, the electric double-layer capacitor 71 is aligned along the bottom surface of the starting lithium-ion battery 4. It is positioned below the bottom surface of the starting lithium-ion battery 4.

[0144] For example, the starting lithium-ion battery 4 and the electric double-layer capacitor 71 are located in a housing 2b provided in the vehicle body 2. For example, the housing 2b is a recess with an opening. For example, the housing 2b is located below the sheet 2a (see, for example, Figure 2). The sheet 2a functions as a cover for the opening. However, the position of the storage section 2b is not limited to below the seat 2a. For example, the storage section 2b can be provided in front of the seat. In this case, a separate lid from the seat 2a is provided. At least a portion of the storage section 2b is made up of a battery cover. Part of the storage section 2b can also be made up of, for example, the vehicle frame. Furthermore, at least a portion of the storage section 2b can also be made up of, for example, a vehicle cover that covers the vehicle frame.

[0145] The electric double-layer capacitor 71 is positioned below the lower edge of the starting lithium-ion battery 4 in the vertical direction. The lower edge of the starting lithium-ion battery 4 is the line formed by the bottom surface 4b of the starting lithium-ion battery 4 when viewed in the left-right direction. Therefore, in part (a) of Figure 9, the lower edge is the part indicated by the same symbol 4b as the bottom surface. More specifically, the electric double-layer capacitor 71 is positioned below the bottom surface 4b of the starting lithium-ion battery 4 in the vertical direction. The housing section 2b has a space below the starting lithium-ion battery 4 in which the electric double-layer capacitor 71 is positioned. More specifically, the housing section 2b extends downward below the starting lithium-ion battery 4 while maintaining the size of the opening. The electric double-layer capacitor 71 is positioned in this extended space. The electric double-layer capacitor 71 is positioned between it and the starting lithium-ion battery 4 without any electrical components interposed between them. However, components other than electrical components may be positioned between the electric double-layer capacitor 71 and the starting lithium-ion battery 4. For example, a partition member may be positioned between the electric double-layer capacitor 71 and the starting lithium-ion battery 4. The relationship between the diameter φ and height Lc of the electric double-layer capacitor 71 and the lateral length Lb and vertical length W of the starting lithium-ion battery 4 is given by equations (A) and (B) above. The electric double-layer capacitor 71 can be placed in the extended space of the housing section 2b. In the design of the body 2 of the lean vehicle 1, extending the housing for the starting lithium-ion battery 4 is easier than providing a separate housing for the electric double-layer capacitor 71, which is separate from the starting lithium-ion battery 4. For example, the housing section 2b may be designed to accommodate another battery having the same lateral length Lb and vertical length W as the starting lithium-ion battery 4 shown in Figure 9, and having a height greater than the height Hb of the starting lithium-ion battery 4 shown in Figure 9. The housing section 2b may also accommodate a battery with a larger capacity than the starting lithium-ion battery 4 shown in Figure 9. Thus, the relationship between the diameter φ and height Lc of the electric double-layer capacitor 71 and the lateral length Lb and vertical length W of the starting lithium-ion battery 4 is as shown in equations (A) and (B) above. Therefore, by extending the housing portion of the starting lithium-ion battery 4, space for the electric double-layer capacitor 71 can be provided. For example, if an electric double-layer capacitor is to be installed in a space away from the lithium-ion battery used for starting, the available locations for the electric double-layer capacitor in the lean vehicle 1 become limited. For example, the placement space for the electric double-layer capacitor 71 shown in Figure 9 is easier than, for example, providing a space away from the starting lithium-ion battery 4. This offers greater flexibility in selecting the placement location of the electric double-layer capacitor 71 in the lean vehicle 1.

[0146] The relationship between the height Lc of the electric double-layer capacitor 71 and the vertical length W of the starting lithium-ion battery 4 is as shown in equations (B) and (C) above.

[0147] In the embodiments and application examples described above, the electric double-layer capacitors 71 were arranged along the bottom surface of the starting lithium-ion battery 4. However, the position of the electric double-layer capacitors 71 is not limited to this. For example, the electric double-layer capacitors 71 may be arranged along the side surface of the starting lithium-ion battery 4. [Explanation of Symbols]

[0148] 1. Lean vehicle 3a,3b wheels 4. Lithium-ion battery for starting 10 Engines 15 Crank Axle 20 Permanent magnet type starter motor 71 Electric double-layer capacitor

Claims

1. A lean vehicle that tilts to the left during a left turn and to the right during a right turn, The lean vehicle is, A wheel having a tread surface for contacting the road surface, the cross-sectional shape of the tread surface being arc-shaped, An engine having a crankshaft and outputting torque from the crankshaft to drive the wheels, A permanent magnet type starter motor having a permanent magnet and rotating the crankshaft to start the engine, The system comprises a starting lithium-ion battery and an electric double-layer capacitor that supply power to the permanent magnet starting motor when the engine is started, wherein the electric double-layer capacitor is always connected in parallel with the starting lithium-ion battery and has a capacitance that can be charged by the power output from the starting lithium-ion battery before the engine is started, to an amount of power sufficient to start the engine at least once.

2. A lean vehicle according to claim 1, The electric double-layer capacitor has a capacitance of 30 F or more.

3. A lean vehicle according to claim 1 or 2, Five to seven of the aforementioned electric double-layer capacitors are connected in series.

4. A lean vehicle according to any one of claims 1 to 3, The electric double-layer capacitor is mounted on the vehicle body such that it remains mounted on the vehicle body when the starting lithium-ion battery is removed from the vehicle body of the lean vehicle.

5. A lean vehicle according to any one of claims 1 to 4, The permanent magnet type starting motor comprises a rotor having a plurality of magnetic pole portions made of permanent magnets, The permanent magnet type starter motor comprises a stator core having multiple teeth formed with multiple slots spaced apart in the circumferential direction of the permanent magnet type starter motor, and a stator having windings provided so as to pass through the slots, The number of the magnetic poles is greater than the number of the multiple teeth.

6. A lean vehicle according to any one of claims 1 to 5, The aforementioned electric double-layer capacitor is of the leaded type, equipped with lead wires that function as terminals for connecting to the outside.

7. A lean vehicle according to any one of claims 1 to 6, wherein the starting lithium-ion battery is shaped like a rectangular parallelepiped having length, width and height, and a positive terminal and a negative terminal are provided on the upper surface including the length, which is the shortest of the length, width and height. The electric double-layer capacitors are cylindrical in shape, consisting of five to seven units connected in series with each other, and the relationship between the diameter φ and height Lc of the electric double-layer capacitors and the horizontal length Lb and vertical length W of the upper surface is given by the following equations (A) and (B). (Lb / 7)≦φ≦ (Lb / 5) (A) Lc ≤ W (B)

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