Abstract: There is provided a control scheme for restarting an internal combustion engine of a hybrid powertrain during ongoing vehicle operation. The method includes generating a torque output from an electrical machine to rotate the engine, and determining an engine crank torque. The torque output from the electrical machine is selectively controlled based upon the engine crank torque. The engine is fired when rotational speed of the engine exceeds a threshold. An engine torque simulation model accurately determines engine compression pressures in real-time to accommodate changes in engine operating conditions, based upon present engine operating conditions.

Abstract: A combined diesel gas-turbine system for optimizing operation and combustion processes of a diesel engine includes a catalytic sub-system, a turbo-generator sub-system and a hybrid sub-system. The catalytic sub-system is in communication with an exhaust port of the diesel engine and is operative for combusting and reducing all pollutants from diesel exhaust. The catalytic sub-system is a three-way catalytic converter and a first catalytic converter in series with a second catalytic converter. The turbo-generator sub-system is operative for the reclamation of secondary energy from the catalytic sub-system and includes a turbine in communication with the second catalytic converter for receiving a source of cleaned exhaust gas to drive the turbine. The hybrid sub-system is operative for the management of energy within the system. The system may incorporate a waste heat recovery system and convert it to mechanical power.

Abstract: A hybrid vehicle control system for cutting off fuel to an internal combustion engine of hybrid vehicle while providing smooth transitions from a hybrid drive mode to an electric drive mode is provided. The hybrid vehicle control system includes an integrated controller configured to receive inputs corresponding to vehicle speed and an indicated driving force, and to select an appropriate mode transition pattern from a group of mode transition patters according to the change in indicated driving force.

Abstract: A vehicle power supply apparatus has first and second engine-driven electrical generators and first and second storage batteries, the first generator supplying a stable voltage to the first battery and a first set of loads, and the second generator supplying the second battery and a second set of loads, which can tolerate supply voltage variations. Operation of the second generator and charging/discharging of the second battery are controlled to maintain the total engine torque applied to the generators at a level whereby fuel consumption is reduced, while the supply voltage of the variation-tolerant loads is allowed to vary substantially.

Abstract: A power unit (14) which has a spark-ignition engine unit (1) of the Wankel type including a three flanked rotary piston (R) mounted on an eccentric shaft (63) rotating eccentrically within a cavity within a two lobed epitroochoidal inner peripheral surface (14), the cavity including an inlet port (7) through which air at ambient pressure is induced into the working chambers, and an outlet port (45) through which exhaust gasses are exhausted from the working chambers, and the power unit also including a rotary expander unit (4) which has a two flanked rotor (24) mounted on an eccentric shaft (12) rotating eccentrically within a single lobed epitrochoidal chamber (25), both shafts (62, 63) being coupled to rotate together, and the exhaust port (45) of epitrochoidal cavity of the engine unit (1) being connected to an inlet port (26) of the expander unit (4) so that the exhaust gasses from the engine unit (1) are further expanded in the expander unit (4).

Abstract: A propulsion system for a fuel cell hybrid vehicle that includes a fuel cell system and an EESS, where the propulsion system employs an algorithm for increasing system efficiency. A power limit value is defined as the maximum system efficiency times the charge/discharge efficiency of the EESS. If the vehicle operator requests a power greater than the power limit value, then the fuel cell system will preferably provide the power, and if the power request from the vehicle operator is less than the power limit value, then the EESS will preferably provide the power. The algorithm also considers changing operation conditions and parameters that impact the fuel cell system efficiency and the electric energy storage system efficiency, such as the state of charge of the EESS and regenerative braking.

Abstract: The invention concerns a hybrid drive train comprising a heat engine (2), at least one first electrical machine (31) and at least a second electrical machine (32) each including a stator and a rotor, a battery (BAT) connected to the first and second electrical machines (31, 32), and a controlling member (5) for controlling the charge or discharge of the battery (BAT), the heat engine (2) and the first and second electrical machines (31, 32). The invention is characterized in that the first electrical machine (31) is arranged between the transmission member (4) and one (7D) of the driven wheels (7G, 7D), and in that the second electrical machine (32) is arranged inside the heat engine (2), the rotor of the second electrical machine (32) being fixed on a crank web and its stator (34) being fixed in the housing (36) of the heat engine (2).

Abstract: A serial hybrid drivetrain enables “super-efficiency” (fuel efficiency exceeding 100 miles-per-gallon) in a lightweight transportation vehicle, utilizing only high power density storage media (for example ultracapacitor media), with the total energy of storage constrained to minimize storage mass, and the resulting low energy requiring a short-cycle of charge and discharge. A unique control system design enables a high extraction of the total energy from the medium, as well as full-rate recovery of regenerative braking energy.

Abstract: There is provided a hybrid outboard motor capable of transmitting motive power of a power source appropriately and efficiently in a limited space while achieving compactness, high performance, and the like. The hybrid outboard motor includes: a casing; a power unit housed in the casing; a screw disposed outside the casing, the screw being driven by the power unit; a power transmission system transmitting motive power of the power unit to the screw; an internal combustion engine and an electric motor serving also as a generator, the internal combustion engine and the electric motor being arranged in parallel in a beam direction in the casing; and a first clutch disposed between the internal combustion engine and the electric motor, wherein one or both of the internal combustion engine and the electric motor are connected to a propulsion unit including the screw so as to rotate it.

Abstract: A system and method for a propulsion system includes an electric motor and an energy storage unit configured to supply a primary power to the electric motor. The propulsion system also includes a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit. Each of the plurality of APUs includes a free-piston engine configured to generate a mechanical output, a linear generator configured to transform the mechanical output to an electrical power, and a controller. The controller receives a power command from the electric motor and/or the energy storage unit, determines an amount of secondary power needed to meet the power command, and selectively activates a number of the plurality of APUs to generate the needed amount of secondary power.

Abstract: When a start command of an engine is given in the presence of the driver's power demand, the start control sets the ignition timing of the engine to a power demand ignition timing, in order to enable quick output of a large power from the engine in response to the driver's power demand. When the start command of the engine is given in the absence of the driver's power demand in a vehicle drive state, there is little possibility of the occurrence of gear chattering noise because of application of a torque to a driveshaft. The start control accordingly sets the ignition timing of the engine to a vibration control ignition timing, in order to reduce the vibration of the vehicle body. When the start command of the engine is given in the absence of the driver's power demand in a vehicle stop state, on the other hand, application of a small torque may cause the occurrence of chattering noise.

Abstract: A power converter module and a battery-operated vehicle which is powered using the power converter module are disclosed. This power converter module may swappable with a battery module that is similarly sized, so that the battery-operated vehicle can selectively run from either the battery module or the power converter module. The power converter module converts fuel into an electrical power supply having a form similar to the power supplied by the battery module.

Abstract: A hybrid input differential engine system comprising a planetary gear set. Preferably, an ICE is connected to the planet gear carrier, the output shaft is connected to the ring gear, and the sun gear is connected to a supercharger/expander and an electric or hydraulic motor/generator. As engine torque increases, the supercharger speeds up, increasing torque still further, enabling a small displacement engine to have very high torque at low RPM. In cruise conditions, the sun gear direction is reversed by the motor/generator, causing the supercharger to act as an expander for efficiently throttling the engine. The motor/generator modulates the speed/torque relationships between the engine and the supercharger/expander. A second motor/generator may be used on the output shaft. The electric machines and electric storage may be downsized because less electrical power is needed for the operation of the system.

Abstract: A method for operating an oil control valve coupled to a cam phaser configured to adjust a position of at least one cam between hard stops, the oil control valve included in an internal combustion engine having an intake valve and/or an exhaust valve controlled via the cam phaser. The method including operating the oil control valve responsive to cam position feedback information, the oil control valve adjusted in a first relationship based on the feedback information and operating the oil control valve in a cleaning mode during select combustion conditions by abruptly switching the oil control valve between two states responsive to the cam position feedback information. The oil control valve adjusted in a second relationship based on the feedback information, the second relationship including more abrupt adjustment than the first relationship.

Abstract: A method of regulating a crankshaft position in a hybrid electric vehicle includes deactivating cylinders of an internal combustion engine, driving a crankshaft of the internal combustion engine using an electric machine, and determining a target crankshaft position when a rotational speed of the crankshaft crosses a first threshold. The crankshaft is driven towards the target crankshaft position at a nudge rotational speed, and rotation of the crankshaft is braked using the electric machine when a brake crankshaft position is achieved at the target rotational speed. Rotation of the crankshaft is arrested at the target position.

Abstract: A method of controlling an engine stop position in a hybrid electric vehicle having a motor capable of controlling engine speed is provided. The method includes: a) reducing the engine speed according to an first engine speed reduction rate using the motor in a state where fuel supplied to the engine is cut off; b) after the engine speed is reduced to first reference speed, adjusting an actual engine speed reduction rate according to second engine speed reduction rate using the motor, and monitoring a current crank position to count the number of times when the current crank position coincides with a given target engine stop position; and c) if the number of times is more than a predetermined number and if the actual engine speed is equal to or below second reference speed, stopping the engine using the motor when the current crank position coincides with the target engine stop position.

Abstract: The invention relates to an apparatus for generating electricity, and also to a motor vehicle with an electric drive, and an apparatus of this type. The apparatus for generating electricity has a heating device, in particular an internal combustion engine for providing kinetic energy, with the additional output of thermal energy, which internal combustion engine is firstly coupled to a generator for converting the kinetic energy into electrical energy and secondly is coupled to a device for converting the thermal energy into electrical energy, wherein the internal combustion engine is designed in such a way that it is constantly operated with maximum efficiency. The motor vehicle with an electric drive has a storage device for electrical energy which is charged by the above-described apparatus for generating electricity.

Abstract: A method for detecting sustained combustion in the engine of a hybrid electric powertrain that includes a starter/generator driveably connected to the engine, a transmission for driving a load, and an input clutch for opening and closing a drive connection between the electric machine and the transmission, includes the steps of using the starter/generator to produce torque and crank the engine, preparing the engine to produce combustion, producing torque capacity across the input clutch while slipping the clutch, and continuing use of the starter/generator until a sum of the crankshaft torque applied by the starter/generator and the crankshaft torque applied by the transmission is less than some torque threshold for a predetermined period length.

Abstract: Engine exhaust is sent to a reformer, which produces hydrogen from fuel remaining in the exhaust. The hydrogen may be stored in a hydrogen tank, and may be used by a fuel cell to produce electricity to recharge a vehicle battery and/or to supply propulsion current to an electric propulsion system.

Abstract: A drive unit for a hybrid electric motor vehicle includes an engine, an electric machine including a rotor, a layshaft gearset including an input driveably connected to the engine and an output, for transmitting power between the input and the output and producing a first speed differential that causes a speed of the input to exceed a speed of the output, first and second driveshafts, a differential mechanism driveably connected to said output, for transmitting power between said output and the driveshafts, and a planetary gear unit driveably connected to the output and the rotor, for transmitting power between said rotor and said output and producing a second speed differential that causes a speed of the rotor to exceed the speed of the output.

Abstract: A drive unit for a hybrid electric motor vehicle includes a bevel pinion driveably connected to a power source, a bevel gear meshing with the bevel pinion and aligned with an axis, first and second drive shafts, a differential mechanism including an input secured to the bevel gear for transmitting power between the input and the first and the second drive shafts, an electric motor/generator including a rotor, and a planetary gear set driveably connected to the input and the rotor for transmitting power between the rotor and the input such that a speed of the rotor is greater than a speed of the input.

Abstract: A hybrid electric vehicle (HEV) employing a hybrid system using both an internal combustion engine and a second motor/generator as a propelling power source for vehicle propulsion, and also employing a first generator driven by the engine for power generation, an integrated HEV control system is provided to control the engine, and the first and second motor/generators. The integrated HEV control system is also operable for detecting the presence of system failures and thereafter selecting at least one remedial action responsive to the system failures such that the system failures are corrected or minimized. The selected remedial action is also verified as being appropriate, monitored and thereafter executed.

Abstract: A vehicle hybrid power system is provided according to the present invention. The hybrid power system is characterized by applying the concept of minimum equivalent fuel consumption, and then simulating equivalent fuel consumptions based on respective energy consumption or increase of motor and generator of a motor vehicle, and also defining simulated equivalent fuel consumption formula and making a list of system state parameters, system control parameters, and system negative load parameters, thereby obtaining simulated equivalent fuel consumption multidimensional data by entering the system parameters derived from a discretization/transformation process in the defined simulated equivalent fuel consumption formula; wherein, the simulated equivalent fuel consumption multidimensional data are revised to comprise subsystems, such as system engine, motor, generator, and others to determine a system control strategy of holistic optimization, thereby achieving the objective of saving energy.

Abstract: A control apparatus and method are provided for operating a hybrid drive system that can optimize the storage of energy during different operating modes, such as during collection modes and transportation modes of a garbage collection vehicle. Initially, a hybrid drive system is provided for use with a drive train system and/or vehicle that is operable in first and second operating modes. An operating mode parameter of the drive train system and/or vehicle is sensed. Then, the operation of the hybrid drive system is adjusted in response to the operating mode parameter of the drive train system and/or vehicle.

Abstract: In a hybrid vehicle, first, an engine is locked by an engine shaft locking mechanism. A first motor is operated by torque control and a second motor is operated by number-of-revolutions control. Torque for controlling the second motor in this state is obtained. Based on the obtained control torque, whether the first motor is normal is checked. Successively, the second motor is operated by the torque control and the first motor is operated by the number-of-revolutions control to check whether the second motor is normal in a similar manner.

Abstract: A hybrid powertrain having an engine, multi-speed transmission connected to a final drive and not continuously connected to the engine, a single motor/generator connected to an energy storage device and a controller and not continuously connected to the engine or transmission, and three clutches. The first clutch is connected to the engine, the second clutch is connected to the transmission and first clutch, and the third clutch is connected to the motor/generator and first and second clutches. The first and second clutches are operable for selectively interconnecting the engine and transmission; the first and third clutches are operable for selectively interconnecting the engine and motor/generator; the second and third clutches are operable for selectively interconnecting the transmission and motor/generator; and the three clutches are operable for selectively interconnecting the engine, transmission and motor/generator to transmit power therebetween.

Abstract: A hybrid electric vehicle having an array of batteries that recharge with a generator connected to a Stirling engine, steam engine and/or steam turbine powered by combusting a solid fuel product. The battery array for this vehicle, which is a series hybrid, can be recharged using residential electrical current. A preferred solid fuel product for burning in the generator-charging engine of this vehicle is selected from cellulose, lignin and combinations thereof, most preferably in the form of pellets or small logs.

Abstract: In a powertrain that includes wheels for driving a vehicle, an engine including a crankshaft, a machine driveably connected to the crankshaft and able to operate alternately as an electric motor and electric generator, a transmission including an input clutch driveably connected to the crankshaft and an output driveably connected to at least two of the wheels, and an electric storage battery having a variable state of charge and electrically connected to the machine, a method for controlling vehicle creep including adjusting a torque capacity of the input clutch to a desired magnitude of input clutch torque transmitted to the wheels, determining a desired change in torque produced by the machine such that a speed of the crankshaft is controlled to a desired idle speed, using the magnitude of input clutch torque capacity and the desired change in torque produced by the machine to determine a desired magnitude machine torque, and using the machine to produce said desired magnitude of machine torque.

Abstract: A method is provided for determining when to allow a vehicle engine to be placed in an engine standby mode. Various conditions, such as driver-controlled conditions, vehicle conditions, and energy management conditions, are compared to corresponding predetermined conditions. If at least some of the conditions match their corresponding predetermined conditions, the vehicle engine is allowed to be placed in a standby mode.

Abstract: Converters are connected in parallel to each other. The converter boosts a voltage from a power storage devices based on a signal from an ECU and outputs the boosted voltage to a capacitor. The converter boosts a voltage from a power storage device based on a signal from the ECU and outputs the boosted voltage to the capacitor. The ECU generates the signals by using carrier signals having phases desynchronized with each other and identical frequencies, and outputs the generated signals to the converters, respectively.

Abstract: A system is provided for the coordination of at least one switchable vehicle function of a motor vehicle, at least one battery charge condition threshold value of the energy accumulator unit being assigned to the at least one vehicle function such that, when there is an exceeding of or falling below the battery charge condition threshold value, the assigned vehicle function can be activated. Different battery charge condition threshold values can be assigned to the at least one vehicle function as a function of the operating condition of the drive unit, the temperature of the energy accumulator, the temperature outside the vehicle, and/or the age condition of the energy accumulator unit.

Abstract: A control system comprises a cam position calculation module that determines intake and exhaust cam positions during operation of an engine. The engine includes a regeneration and fuel cut-off (FCO) mode. A cam position adjustment module generates alternate intake and exhaust cam positions during the regeneration and FCO mode. A cam positioning module positions the intake and exhaust cams based on lower values of the intake and exhaust cam positions and the alternate intake and exhaust cam positions, respectively, during the regeneration and FCO mode.

Abstract: A secondary electric power source (19) for a motor vehicle having one or more electric motors (12) for driving respective wheels (10a) of the motor vehicle and having a main electric power source (14) for providing power to electric motors (12) driving the wheels (10a), and a selector (17) for selecting power from either the main electric power source (14) or the secondary electric power source (19) or both.

Abstract: A method for operating a powertrain in a vehicle is provided. The powertrain includes an electric drive and an internal combustion engine. The method comprises providing torque to drive the vehicle from both the electric drive and the engine, where engine torque is varied within an allowable range; and when operating the engine at an edge of the range, adjusting the range based on whether a selected operating condition can be provided by the engine.

Abstract: This invention is for a hybrid vehicle operated by fuel with a high-ethanol content, which synergistically combines independent sources of ethanol power to move toward renewable and environmental-friendly fuel to replace gasoline. The vehicle combines one or more electric motors powered by Direct-Ethanol Fuel-Cells (DEFCs) using either HYPERMEC™ or a similar-type catalyst, with 2 of the 4 Preferred Embodiments provided for the ethanol hybrid also including a flexible-fuel engine. The electric motors powered by DEFCs in all the Preferred Embodiments are coupled with energy-storage systems which can independently operate the motors. For 4-wheel vehicles, all of these embodiments can be operated either in 2 or 4-wheel mode for engagement of the transmission, for either the electric motor or for the engine in Preferred-Embodiments 1 and 2, and for either of the electric motors in Preferred-Embodiments 3 and 4.

Abstract: A control scheme is provided for stopping an internal combustion engine of a hybrid powertrain during ongoing vehicle operation. The method, executed as program code in an article of manufacture comprises the following steps in the sequence set forth. First, engine operation is controlled to stop firing the engine. A damper clutch is controlled to lock rotation of the engine and the electro-mechanical transmission. Torque outputs from the first and second electrical machines are then selectively controlled to reduce engine speed. Torque outputs from the first and second electrical machines are then selectively controlled to stop rotation of the engine substantially near a predetermined crank position.

Abstract: There is provided a control scheme for restarting an internal combustion engine of a hybrid powertrain during ongoing vehicle operation. The method comprises generating a torque output from an electrical machine to rotate the engine, and determining an engine crank torque. The torque output from the electrical machine is selectively controlled based upon the engine crank torque. The engine is fired when rotational speed of the engine exceeds a threshold. An engine torque simulation model accurately determines engine compression pressures in real-time to accommodate changes in engine operating conditions, based upon present engine operating conditions.

Abstract: A hybrid electric vehicle is provided. The hybrid electric vehicle includes an internal combustion engine, a mechanical torque transmission device for transmitting engine torque to at least one wheel, the mechanical torque transmission device having a lash region, an electric energy conversion device connected downstream of the mechanical torque transmission device, and a control system. The control system, adjusts the electric energy conversion device to meet a desired vehicle response, adjusts the internal combustion engine torque to transition through the lash region, and then adjusts the electric energy conversion device torque and the internal combustion engine torque to meet the desired vehicle response.

Abstract: Renewable Energy Advanced Device Solution is at least wind powered and comprises at least a motor, a battery cell, a clutch means, and a generator armature, a communication means configured with a capacitance means and operatively connected to an accelerator pedal. The communication means is configured for directing the flow of energy from the capacitance means to the battery cell means and from the battery cell means to the motor. The motor of the vehicle is configured with harnesses communicatively connecting the generator armature with the capacitance means, the capacitance means with the communication means, and the communication means with the battery cell means responsive for supplying electrical energy to the motor and other electrical appliances for the vehicle. The communication means transfers electrical energy to kinetic energy that propels the vehicle and comprises means to connect the motor to enable the flow of electricity.

Abstract: The invention relates to a drive system for a motor vehicle comprising an internal combustion engine and at least one electric machine, said vehicle also being provided with at least one vehicle electric system for electric power supply. In addition, the drive system is provided with at least one energy accumulator with several energy accumulator cells and a control assembly for controlling different operating modes of the motor vehicle.

Abstract: This invention pertains to an economical method of easy conversion of any internal combustion fueled vehicle into a fuel saving hybrid electric vehicle (HEV) by an add-on kit, without replacing the engine and with a minimal modification of the vehicle body. The converted vehicle has a substantially longer driving range on the same amount of fuel than the vehicle before this conversion.

Abstract: A hybrid driving unit in which a first electric motor (20), a second electric motor (23), a transmission (22) and a power splitting planetary gear (21) are disposed in order from the front side (the side of an internal combustion engine) on an axis within a casing member (14). Since the first electric motor (20) and the second electric motor (23) are disposed adjacently to each other, partial cases for storing these first and second electric motors (20) and (23) may be combined, thus facilitating the accommodation for producing the unit in series.

Abstract: The invention relates to a method of transmitting power between a shaft (10) of a heat engine (2) and a wheel (6) axle shaft (12) of a hybrid vehicle. The inventive method involves the use of: a power transmission device (1) comprising an electric machine (4) which is connected to (i) the heat engine by means of a clutch (3) and (ii) a wheel (6) axle shaft (12); and a starting system (31) which is mechanically independent of the electric machine (4) and which is connected to the heat engine (2). According to the invention, the heat engine (2) is started by applying a torque to the shaft (10) simultaneously using the starting system (31) and the clutch (3).

Abstract: A control device is provided for a power train including: a differential mechanism having a first rotating element linked to a first rotary electric machine, a second rotating element linked to a second rotary electric machine and a third rotating element linked to an internal combustion engine; a switching mechanism that switches between a first state that permits relative rotation of the first, second and third rotating elements, and a second state that prohibits relative rotation thereof; and a transmission mechanism connected to the differential mechanism which transmits torque from the differential mechanism to a wheel. The control device includes: a first control portion that controls the switching mechanism so as to switch between the first and second states; and a second control portion that compensates for an amount of change in the torque transmitted to the wheel when the switching between the two states is performed.

Abstract: An engine's power may be gradually reduced during a torque phase of a clutch-to-clutch up-shift within an automatic transmission and then reduced fully during a subsequent inertia phase.

Abstract: A serial hybrid drivetrain enables “super-efficiency” (fuel efficiency exceeding 100 miles-per-gallon) in a lightweight transportation vehicle, utilizing only high power density storage media (for example ultracapacitor media), with the total energy of storage constrained to minimize storage mass, and the resulting low energy requiring a short-cycle of charge and discharge. A unique control system design enables a high extraction of the total energy from the medium, as well as full-rate recovery of regenerative braking energy.

Abstract: A method for determining a diffusion voltage in an electrochemical cell (e.g., a battery used in connection with an automotive vehicle) includes estimating a previous diffusion voltage, calculating a new diffusion voltage using an equation based on a diffusion circuit model and the previous diffusion voltage, and setting the previous diffusion voltage equal to the new diffusion voltage. The step of calculating the new diffusion voltage may then be repeated.

Abstract: In setting of an oil temperature increasing process mode, the drive control technique of the invention starts an engine to actuate a mechanical oil pump that pressure feeds a flow of lubricating oil for lubricating the mechanical parts of a transmission and other relevant parts, actuates an electric oil pump that pressure feeds the flow of lubricating oil, and makes a brake B1 included in the transmission in a semi-engagement state. A motor arranged adjacent to the transmission is then driven with lowered output efficiency. This arrangement effectively accelerates heat generation by the motor and ensures a quick temperature rise of the lubricating oil.

Abstract: A first aspect of the present invention is concerned with a series hybrid drive train for a vehicle comprising a traction motor, an electric generator, a three-position clutch (20) and a controller. The three-position clutch allows the generator to be connected to an internal combustion engine (12) of the vehicle, to the traction motor or to remain freewheeling. In a second aspect of the present invention, a four-position clutch is used to further allow the internal combustion engine to be connected directly to the wheels to thereby yield a series/parallel drive train. A third aspect of the present invention is concerned with a method of operating such a hybrid drive train.

Abstract: A sealed nickel-metal hydride storage cell includes a positive electrode containing nickel as a positive electrode active material, a negative electrode containing a hydrogen-absorbing alloy as a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and an electrolyte immersing therein the positive electrode and the negative electrode. The negative electrode has a theoretical capacity larger than a theoretical capacity of the positive electrode so as to provide a charge reserve capacity when the positive electrode is in a fully charged state and to provide a discharge reserve capacity when the positive electrode is in a fully discharged state. A ratio of the charge reserve capacity to the discharge reserve capacity ranges from 1:0 to 1:0.5.