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Toyota’s patent US8141341 deals with vehicle and control method of vehicle – toyota jidosha kabushiki kaisha .

One proposed vehicle comprises an internal combustion engine having a purifying catalyst that purifies exhaust gas, an electronic control unit that executes a catalyst deterioration reducing control upon a satisfaction of a catalyst deterioration acceleration condition that accelerates deterioration of the purifying catalyst and executes a catalyst smell reducing control upon a satisfaction of a catalyst smelling condition that makes the purifying catalyst smell (see, for example, Patent Document 1). This vehicle is described as a vehicle, giving a high priority to executing the catalyst deterioration reducing control that prohibits a fuel cutoff when a vehicle speed is more than or equal to a preset vehicle speed, and giving a high priority to executing the catalyst smell reducing control that performs the fuel cutoff when the vehicle speed becomes less than the preset vehicle speed, in consideration that there are few cases to give the driver or passenger unpleasantness since the catalyst smell does not stay near the vehicle during its drive at a high or middle vehicle speed.Patent Document 1: Japanese Patent Laid-Open No. 2005-147082

The Toyota patent solves the following problem:

The catalyst smell reducing control in which the fuel cutoff is performed is not executed regardless of the catalyst smelling flag Fs1equal to 1 (step S140) when the vehicle speed V becomes less than the preset vehicle speed Vref (step S130) while the catalyst deterioration reducing control in which the fuel cutoff is prohibited is being executed (step S150). Such control prevents from executing the catalyst smell reducing control while the suspension of the catalyst deterioration reducing control and prevents performing the fuel cutoff after performing a fuel injection and performing the fuel injection again for a relatively short time in the internal combustion engine. Therefore, it is enabled to reduce an occurrence of a shock due to the temporal decline of the output torque from the internal combustion engine, and is thereby enabled to reduce a sense of incompatibility given to the driver or passenger by reducing the occurrence of the shock due to the execution of the catalyst deterioration reducing control and the catalyst smell reducing control.

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Toyota’s patent US8141352 deals with exhaust purification device of an internal combustion engine – toyota jidosha kabushiki kaisha .

Known in the art is an internal combustion engine arranging in the engine exhaust passage an NOXstorage catalyst which stores NOXcontained in the exhaust gas when the air fuel ratio of the inflowing exhaust gas is lean and releases the stored NOXwhen the air fuel ratio of the inflowing exhaust gas becomes a stoichiometric air fuel ratio or rich and arranging in the engine exhaust passage upstream of this NOXstorage catalyst a compact three-way catalyst (see for example Japanese Patent Publication (A) No. 2004-108176). In this internal combustion engine, if the NOXstorage ability of the NOXstorage catalyst approaches saturation, the air fuel ratio of the exhaust gas is temporarily made rich whereby NOXis released from the NOXstorage catalyst and reduced.

The Toyota patent solves the following problem:

In an internal combustion engine, an NOX selective reducing catalyst is arranged in the engine exhaust passage, and an NOX storage catalyst able to store NOX contained in the exhaust gas is arranged at the upstream of the NOX selective reducing catalyst. The NOX storage catalyst is fed with mist fuel, and the NOX stored in the NOX storage catalyst and the fed fuel are used to produce an intermediate product comprising bonded molecules comprised of NH2 and a hydrocarbon molecule more than an equivalent ratio with respect to one NOX molecule. These intermediate products are adsorbed at the NOX selective reducing catalyst, whereby the adsorbed intermediate product reduces the NOX in the exhaust gas.

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Toyota’s patent US7923170 deals with fuel cell separator with a vapor-phase grown carbon-based porous material of nanosize structure – hori, masaru .

A solid polymer fuel cell is comprised of a stack of single cells and two current collectors disposed on the outside of the stack. Each of the single cells consists of a solid polymer electrolyte membrane, two electrodes disposed on both sides of the solid polymer electrolyte membrane, and separators with gas-feeding grooves for feeding a fuel gas, such as hydrogen, and an oxidant gas, such as oxygen, to each of the electrodes.

The separators in the solid polymer fuel cell are required to have high levels of gas impermeability so as to allow the fuel gas and oxidant gas to be fed to the electrodes completely separately. In addition, the internal resistance of the battery is required to be minimized so as to achieve a high generation efficiency, and, for this reason, the separators are also required to be highly electrically conductive. Furthermore, in order to allow the heat accompanying the battery reaction to be efficiently dissipated and to obtain a uniform temperature distribution within the battery, the separators are required to have high thermal conductivity. To ensure long-term durability, the separators are also required to be highly corrosion-resistant. For these reasons, the separators in polymer electrolyte fuel cells are mainly made of stainless steel or carbon material.

The separators for fuel cells typically consist of a flat plate with a plurality of parallel grooves formed on one or both sides thereof. This configuration is adopted so as to ensure that the water produced in the grooves during electricity generation can be discharged, as well as to allow the electricity generated by a catalyst electrode in the fuel battery cell to be transmitted to the outside. The grooves are also used as channels for a reaction gas to flow into the fuel battery cell.

Normally, the fuel cell separator is made of a carbon or metal plate. To provide the plate with the gas channels, a carbon plate is generally mechanically machined, while a metal plate is generally press-molded. However, these techniques for providing gas channels have been problematic in that, for example: (1) the degree of freedom in the shape of the channel is small; (2) sufficient supply of gases below ribs cannot be ensured; (3) contact resistance is large; (4) flooding tends to occur under the ribs (namely, diffusion polarization is large); and (5) removal of the produced water is insufficient and cell performance is instable.

These problems are caused for the following reasons, for example. (1) When a carbon plate or a metal plate is used, as in the prior art, the shape of the channel is limited by machining or molding accuracies. As a result, fine shapes that would be resistant to flooding or drying-up cannot be realized. (2) In the exiting structures where the ribs are bulky, the issue of how to smoothly feed gases below the ribs, where the greatest amount of gas supplies are required, cannot be solved. (3) In the existing methods, the diffusion layer and the separator can only be formed as separate components, and the problem of contact resistance between the diffusion layer and the rib portion arises. (4) With the existing machining methods, it is difficult to selectively make only the portion below the ribs, where the amount of water produced is greatest, water repellent, thereby preventing improvements in drainage and cell performance. (5) In the existing methods, the separator is only partially provided with water-repellency or hydrophilic property, so that drainage cannot be performed in a detailed manner, resulting in a decrease in cell performance.

The Toyota patent solves the following problem:

The degree of freedom in the shape of channels in a separator is increased, enabling an optimum gas channel to be designed, enabling a sufficient supply of gas below gas channel ribs, and improving cell performance through the reduction in diffusion polarization. Drainage property is also improved and flooding is prevented, thereby reducing diffusion polarization and improving cell performance. Cell performance is also improved through the reduction of contact resistance. A fuel cell separator comprises a separator substrate on which gas channel ribs are formed through vapor-phase growth of a carbon-based porous material with a nanosize structure. An electrode structure for a fuel cell, methods of manufacturing the separator and the fuel cell, and a solid polymer fuel cell comprising the electrode structure.

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Toyota’s patent US7923858 deals with electric power source system and method for the same – toyota jidosha kabushiki kaisha .

1. Field of the Invention

The invention relates to an electric power source system that has a plurality of electric power sources, and a method that controls an electric power source system.

2. Description of the Related Art

An electric power source control device that employs batteries of two different voltage systems is described in Japanese Patent Application Publication No. JP-A-2002-176704. In some cases, electric power source control devices that employ a plurality of electricity storage devices, including the electric power source control device described in JP-A-2002-176704, convert the voltage of a first electricity storage device to the voltage of a second electricity storage device via voltage converter, such as a DC/DC converter or the like and thereby charge the second electricity storage device or supply electric power to an electrical load whose direct power source is the second electricity storage device.

In the foregoing related-art technology that enables the bidirectional exchange of current between different voltage systems, however, when the voltage converter switches the direction of voltage conversion to the opposite direction, the supply of current is momentarily interrupted due to the time lag caused by the switching operation. Therefore, a system in which the interruption is avoided needs an effective measure to prevent the interruption.

In relation to this respect, JP-A-2002-176704 describes a condition for switching the voltage conversion direction, but does not disclose or indicate a measure as mentioned above.

The Toyota patent solves the following problem:

An electric power source system in which a momentary interruption of the electric power supply does not occur when the direction of voltage conversion is switched by a voltage conversion device that is capable of bidirectional voltage conversion. The electric power source system includes a bidirectional switching regulator that selectively switches between the voltage conversion in the step-up direction from a low-voltage system to a high-voltage system and the voltage conversion in the step-down direction from the high-voltage system to the low-voltage system, and a linear regulator, connected in parallel to the bidirectional switching regulator, that converts voltage in the step-down direction. The direction of current that flows via the bidirectional switching regulator switches from the step-up direction to the step-down direction after current flows in the step-down direction via the linear regulator.
The invention provides an electric power source system that prevents the momentary interruption in the supply of electric power when the direction of voltage conversion is switched by a voltage conversion device, and a method for an electric power source.
A first aspect of the electric power source system according to the invention includes a first voltage conversion device that selectively switches between voltage conversion in a first direction from a first voltage system to a second voltage system, and voltage conversion in a second direction from the second voltage system to the first voltage system; and
a second voltage conversion device, connected in parallel to the first voltage conversion device, that converts the voltage in the second direction. In particular, the direction of current flowing via the first voltage conversion device switches from the first direction to the second direction after current starts to flow in the second direction via the second voltage conversion device.
That is, in the above aspect of the electric power source system, when the current flow direction of the first voltage conversion device is switched, the direction of the current switches from the first direction to the second direction only after current has begun to flow in the second direction via the second voltage conversion device. Therefore, when the direction of transfer of electric power switches from the first direction to the second direction in the first voltage conversion device, the current has already begun to flow in the second direction via the second voltage conversion device. Thus, the electric power source system of the invention prevents the interruption in the supply of electric power via the first voltage conversion device.
In addition, the electric power source system of the first aspect of invention may further include a malfunction detector that detects malfunctions of the first voltage system; and a switching controller that outputs a command signal to switch the direction of current that flows via the first voltage conversion device from the first direction to the second direction if a malfunction in the first voltage system is detected by the malfunction detector. In particular, the first voltage conversion device begins to cause current to flow in the second direction after the direction of current has been switched from the first direction to the second direction based on the command signal output by the switching controller, and the second voltage conversion device begins to cause current to flow in the second direction when the voltage of the first voltage system becomes equal to or lower than a predetermined output voltage.
To cause current to flow in the second direction via the first voltage conversion device, it is necessary to switch the direction of current after a malfunction is detected. However, to cause current to flow in the second direction via the second voltage conversion device, it is not necessary to switch the direction of current. Therefore, if current is caused to flow in the second direction via the second voltage conversion device, there is no time lag associated with the switching of the direction of current. That is, current can be caused to begin to flow in the second direction more quickly by causing current to flow in the second direction via the second voltage conversion device than by causing current to flow in the second direction via the first voltage conversion device.
The electric power source system may further include a current detector that detects the current flowing in the second direction via the second voltage conversion device, wherein the malfunction detector determines that a malfunction has occurred in the first voltage system if a current equal to or higher than a predetermined value is detected by the current detector.
If a malfunction occurs in the first voltage system, the voltage of the first voltage system begins to drop. Therefore, by detecting current that flows via the second voltage conversion device, provided for causing current to begin to flow at a time point when the voltage of the first voltage system becomes equal to or lower than the predetermined output voltage, any malfunction in the first voltage system may be detected.
Furthermore, the electric power source system of the aspect of the invention may have a construction in which current flows in the second direction via either of the first voltage conversion device or the second voltage conversion device that has a greater output voltage in the second direction. In addition, the target output voltage in the second direction set for the first voltage conversion device is higher than the target output voltage in the second direction set for the second voltage conversion device.
When the direction of current that flows via the first voltage conversion device switches from the first direction to the second direction, the voltage conversion device that causes current to flow in the second direction may be quickly switched from the second voltage conversion device to the first voltage conversion device. That is, causing current to flow in the second direction via the first voltage conversion device may be given priority, and causing current to flow in the second direction via the second voltage conversion device may be limited to a short time.
A concrete example of the first voltage conversion device is a switching regulator, and a concrete example of the second voltage conversion device is a linear regulator or a resistor.

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Toyota’s patent US7923889 deals with rotor of an electric motor and method of manufacturing the same – toyota jidosha kabushiki kaisha .

1. Field of the Invention

The invention relates to a manufacturing method of a rotor for an electric motor and a rotor for an electric motor that includes a core formed of stacked steel plates interposed between a first end plate, which is disposed on a lower side of the core, and a second end plate, which is disposed on an upper side of the core.

2. Description of the Related Art

Japanese Patent Application Publication No. 2004-32958 (JP-A-2004-32958) describes a structure of a rotor for an electric motor as a related art in which a core formed of stacked steel plates is pressed by end plates from both sides of the core in the stacking direction of the steel plates. The applicant has used the invention shown in FIG. 10, which shows the configuration of the rotor of the related art in which the core formed of the stacked steel plates is pressed by the end plates from the both sides in the stacking direction. A shaft53includes an inner shaft53aand an outer shaft53bformed on a bottom53c. A flange portion53dis formed on an outer periphery of the bottom53c. A first end plate55and a core54are stacked on the flange portion53din the axial direction of the shaft53. The core54includes a plurality of steel plates that are identically formed and stacked. The first end plate55and the core54are fitted onto the outer shaft53bby inserting the outer shaft53bthrough a center hole55aof the first end plate55and through a center hole54aof the core54. A second end plate52is placed on and pressed against the core54at a pressure A so as to make the first end plate55closely contact the core54, and also make the stacked steel plates of the core54closely contact each other. While the pressure A is applied to the second end plate52, a pressure B is applied to a deformation punch51to deform a deformed portion53eof the shaft53, whereby the deformed portion53eis deformed to fit a no core-side edge portion52bof an inner edge of the second end plate52(this process will be hereinafter referred to as deformation process). The deformed portion53eis thus deformed to fit the no core-side portion52bof the inner edge of the second end plate52, whereby the first end plate55, the core54, and the second end plate52are caused to closely contact each other.

The Toyota patent solves the following problem:

In a manufacturing method of a rotor for an electric motor including: a core (4) formed of stacked steel plates, each of which has a center hole (4a); and a shaft (3) inserted through the center hole (4a) of the core (4), the shaft (3) is deformed to fit a second end plate (2) in a state where the second end plate (2) is pressed against the core (4), and a deformed portion (3e) of the shaft (3) that engages with an edge (2a,2b) of the second end plate (2) is deformed along a core-side edge portion (2a) and a no core-side edge portion (2b) of the edge (2a,2b) of the second end plate (2) so that the deformed portion (3e) is deformed into the deformed shape that fits the shape of the edge (2a,2b) of the second end plate (2).
The invention provides a manufacturing method of a rotor for an electric motor, and a rotor for an electric motor, with which it is possible to prevent an outer edge of the second end plate from being lifted and firmly fasten stacked steel plates.
A first aspect of the invention relates to a manufacturing method of a rotor for an electric motor including a core formed of stacked steel plates, each of which has a center hole, and a shaft inserted through the center hole of the core. In the manufacturing method, the shaft is deformed to fit an end plate in a state where the end plate is pressed against the core. The manufacturing method includes deforming a deformed portion of the shaft that engages with an edge of the end plate, along a core-side edge portion and a no core-side edge portion of the edge of the end plate with respect to the thickness direction of the edge of the end plate.
Further, in the manufacturing method according to the first aspect of the invention, the deformed portion may be in the same shape as a shape of the edge of the end plate.
With the manufacturing method according to the first aspect of the invention, it is possible to manufacture the rotor for an electric motor in which the deformed portion is formed into the same shape as that of the edge of the end plate, by deforming the deformed portion of the shaft that engages with the edge of the end plate, along the core-side edge portion and the no core-side edge portion with respect to the thickness direction of the edge of the end plate. When the rotor for an electric motor is manufactured using the manufacturing method according to the first aspect, it is possible to cancel a pressing force applied to the deformed portion on the no core-side edge portion-side by deforming the deformed portion to fit the core-side edge portion, as well as the no core-side edge portion. Canceling the pressing force applied on the no core-side edge portion-side suppresses concentration of a load on an inner portion of the core, which is applied on the no core-side edge portion-side of the end plate. This makes it possible to prevent the outer edge of the end plate from being lifted. As a result, it is possible to suppress creation of a gap between the outer edge of the end plate and the core, thereby suppressing reduction of torque of the rotor for an electric motor. Further, because the deformed portion is deformed to fit the core-side edge portion of the edge of the end plate, as well as the no core-side edge portion, it is possible to suppress excessive pressing of the end plate against the core on the no core-side edge portion-side, thereby suppressing breakage of the magnets in the core.
Further, in the manufacturing method according to the first aspect, the deformed portion of the shaft may be deformed by a deforming device, which includes a portion formed along the shape of the edge of the end plate.
Further, in the manufacturing method according to the first aspect, the deforming device may be a mandrel, and the deformed portion of the shaft may be deformed by moving the mandrel in a circumferential direction relative to the shaft while moving the mandrel away from the axis of the shaft.
With the manufacturing method according to the first aspect, the mandrel that includes a portion formed along the shape of the edge of the end plate is moved in the circumferential direction relative to the shaft so as to move away from the axis of the shaft. This makes it possible to uniformly deform the entire circumference of the deformed portion so as to fit the end plate, and further, to reliably and firmly deform the deformed portion so as to fit the end plate.
Further, in the manufacturing method according to the first aspect, the deforming device that includes a first deforming structure for deforming the deformed portion so as to fit the core-side edge portion of the edge of the end plate, which is a portion of the edge on a core side with respect to an innermost position of the edge, and a second deforming structure for deforming the deformed portion to fit the no core-side edge portion of the end plate, which is a portion on a side opposite to the core side with respect to the innermost position of the edge, may be used. Further, the deforming may include deforming the core-side edge portion with respect to the thickness direction of the edge of the end plate by the first deforming structure and deforming the no core-side edge portion with respect to the thickness direction of the edge of the end plate by the second deforming structure while the first deforming structure is positioned at a deformation position.
With the manufacturing method according to the first aspect, it is possible to simplify the manufacturing apparatus of the rotor for an electric motor. This makes it possible to manufacture the rotor for an electric motor at lower costs.
Further, in the manufacturing method according to the first aspect, the end plate may include a first end plate and a second end plate so that the core is pressed by the first end plate and the second end plate from both sides in a stacking direction of the steel plates, and the shaft may be provided with the deformed portion at a position that corresponds to one of the first end plate and the second end plate.
A rotor for an electric motor according to a second aspect of the invention includes a core formed of stacked steel plates, each of which includes a center hole, and a shaft inserted into the center hole. In the rotor, the shaft is deformed to fit an end plate in a state where the end plate is pressed against the core. In the rotor, a deformed portion of the shaft that engages with an edge of the end plate is deformed along a core-side edge portion and a no core-side edge portion of the edge with respect to the thickness direction of the edge of the end plate.
Further, in the rotor for an electric motor according to the second aspect, the deformed portion of the shaft may be in the same shape as a shape of the edge of the end plate.
With the rotor according to the second aspect of the invention, it is possible to cancel a pressing force applied to the deformed portion on the no core-side edge portion-side of the end plate by deforming the deformed portion to fit the core-side edge portion, as well as the no core-side edge portion. Canceling the pressing force applied on the no core-side edge portion-side of the end plate suppresses concentration of a load, which is applied on the no core-side edge portion-side of the end plate, on an inner portion of the core. This makes it possible to prevent the outer edge of the end plate from being lifted. As a result, it is possible to suppress creation of a gap between the outer edge of the end plate and the core, thereby suppressing reduction of torque of the rotor for an electric motor. Further, the deformed portion is deformed to fit the core-side edge portion of the edge of the end plate, as well as the no core-side edge portion, it is possible to suppress excessive pressing of the end plate against the core on the no core-side edge portion-side, thereby suppressing breakage of the magnets in the core. This makes it possible to cause the rotor for an electric rotor to generate a magnetic force in a normal condition.

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Toyota’s patent US7923945 deals with voltage control of upconverter in a motored vehicle drive – toyota jidosha kabushiki kaisha .

In recent years, as environmental issues, energy issues and other similar issues are addressed, hybrid vehicles, electric vehicles, fuel cell vehicles and other similar motored vehicles are gaining attention. These motored vehicles have a direct current power supply implemented by a secondary battery or a fuel cell, an inverter and a motor driven by the inverter as a power source.

Japanese Patent Laying-Open No. 2004-203218 discloses a control device that is provided in a motored vehicle provided with a transmission between a motor generating driving force and an output member and corrects a torque output of the motor when the transmission is shifting gears. When the transmission is shifting gears, the control device corrects the torque of the motor in a direction that suppresses variation of the torque of the output member to prevent the torque of an output shaft from dropping as the transmission shifts gears.

Furthermore, as motors increasingly provide larger outputs, the above described motored vehicle is also known that is provided with an upconverter receiving direct current voltage from a direct current power supply to upconvert the received voltage to supply the upconverted voltage to an inverter.

Japanese Patent Laying-Open No. 2004-208409 discloses a vehicular power control device including such an upconverter. The vehicular power control device includes a driving, rotating electric machine, an inverter circuit driving the driving, rotating electric machine, and a DC-DC converter receiving voltage from a battery to upconvert the received voltage to supply the inverter circuit with the upconverted voltage. This vehicular power control device can reduce an up-conversion ratio of the DC-DC converter in accordance with the electric power consumption of the driving, rotating electric machine in driving the driving, rotating electric machine with small electric power. The vehicular power control device can thus reduce a loss in a circuit.

If a motored vehicle provided with a transmission between a motor generating driving force and a driving wheel is provided between a direct current power supply and an inverter with an upconverter outputting a voltage, which corresponds to that input to the inverter, controlled in accordance with the output of the motor, and as the transmission shifts gears, the output of the motor abruptly varies and accordingly the voltage output from the upconverter, i.e., that input to the inverter, is modified, then, for some motor control modes, there is a possibility that the motor is unstably controlled.

When the transmission is shifting gears, the transmission has a friction element re-engaged and accordingly the motor rotates at an increased rate. If this is prevented by exerting control to temporarily decrease a torque output of the motor when the transmission is shifting gears, (hereinafter also referred to as torque reduction control), then when the transmission is shifting gears, the motor provides an output decreasing and increasing (or recovering) for the former and latter halves, respectively, of shifting gears, and modifying the voltage output from the upconverter, i.e., that input to the inverter as the output of the motor abruptly varies when the transmission is shifting gears, allows the inverter to receive a voltage decreasing for the former half of shifting gears as the output of the motor decreases and increasing for the latter half of shifting gears as the output of the motor increases. Note that if the motor is controlled in a rectangular-wave control mode, which has a larger interval in timing to control the motor than a PWM control mode and is based on that the inverter receives constant voltage, the switching operation in the inverter cannot follow the abrupt variation in the voltage input and the motor is unstably controlled.

The Toyota patent solves the following problem:

When an ECU receives a transmission signal having a high level from a transmission, the ECU exerts torque reduction control to reduce a torque control value for a motor generator. Furthermore the ECU sets an optimum (or target) value of a voltage as based on the torque control value and a motor rotation speed and controls an upconverter. Herein, when the transmission is shifting gears, the ECU controls the upconverter to allow the voltage to be constant regardless of whether the torque reduction control is exerted to reduce the torque control value.

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Toyota’s patent US7923951 deals with vehicle power controller – toyota jidosha kabushiki kaisha .

A vehicle mounting a power train referred to as a hybrid system, in which an engine (possibly a known mechanism such as a gasoline engine or a diesel engine) and a motor are combined, has been developed and commercially available. Further, a vehicle (electric vehicle, fuel cell electric vehicle) mounting a power train using only the motor as the running source and not mounting any engine, has also been developed. Such a vehicle mounts an electric storage mechanism (a battery or a capacitor) for motor drive. At the time of acceleration of the vehicle, the motor is driven by the electric power supplied from the electric storage mechanism, to increase the vehicle speed. At the time of braking of the vehicle, the motor functions as a generator, and the generated regenerative energy is stored in the electric storage mechanism. Thus, the kinetic energy of the vehicle is recovered as electric energy, and the regenerative braking force acts on the vehicle. In a vehicle including a battery and a capacitor as electric storage mechanism, at the time of acceleration of the vehicle speed requiring instantaneous high output, it is preferred to supply electric power from the capacitor to the motor, as the capacitor has superior instantaneous output characteristic to the battery. If the capacitor is not sufficiently charged at the time of acceleration, however, it is impossible to supply sufficient electric power from the capacitor to the motor. Japanese Patent Laying-Open No. 05-030608 discloses a technique of charging the capacitor to be ready for vehicle acceleration, in an electric vehicle including a battery and a capacitor.

The hybrid system of electric vehicle disclosed in Japanese Patent Laying-Open No. 05-030608 is applied to an electric vehicle having a DC power source, a motor attached to a wheel, a converter connected to the DC power source and driving the motor, and a controller controlling the converter. The hybrid system includes a battery and a capacitor (a condenser of large capacity) as DC power sources, a switching unit for switching charging/discharging of the battery and the capacitor dependent on acceleration/deceleration, and a limiting unit limiting charging to the battery in a charging mode with regenerative braking, to increase the burden of rapid discharge/charge shared by the capacitor.

According to the hybrid system of electric vehicle disclosed in Japanese Patent Laying-Open No. 05-030608, in the charge mode with regenerative braking, the switching unit is controlled such that the burden of rapid discharge/charge shared by the capacitor having instantaneous output characteristic better than the battery is increased. Thus, rapid charging of the battery is avoided to reduce deterioration of the battery and, in addition, it becomes possible to charge the capacitor beforehand to be ready to supply power from the capacitor at the time of vehicle acceleration when instantaneous high output is required. Therefore, at the time of acceleration, it is possible to increase the vehicle speed with good response.

In the hybrid system for an electric vehicle disclosed in Japanese Patent Laying-Open No. 05-030608, however, it is not always possible to recover maximum regenerative energy. Specifically, if the regenerative energy is stored in the capacitor, the amount of charges to the battery is limited. In some situations in which regenerative energy is large, however, it is possible to charge the battery without limiting the charging amount and to fully charge the capacitor with extra electric power that cannot be stored in the battery any more. If the charging amount to the battery is limited in such a case, the amount of charges to the battery would decrease though the amount of charges to the capacitor is the same, and full recovery of regenerative energy becomes impossible.

The Toyota patent solves the following problem:

An ECU executes a program including the steps of: calculating regenerative power value P based on a brake pressure; calculating limit charging power WIN(B) to a battery; calculating limit charging power WIN(C) to a capacitor; when it is determined that regenerative power value P is larger than the sum of WIN(B) and WIN(C), estimating that a large regenerative energy sufficient to fully charge the capacitor even if the battery is charged with priority would be generated; and transmitting a control signal to set output voltage of a boost converter to be not higher than the voltage of the capacitor so as to charge the battery with priority.

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Toyota’s patent US7923961 deals with vehicle equipped with motor and inverter – toyota jidosha kabushiki kaisha .

1. Field of the Invention

This invention relates to a vehicle, particularly to a vehicle equipped with an inverter to drive a motor for driving the vehicle and a control device thereof.

2. Description of the Background Art

In recent years, an eco-friendly vehicle to use a motor for driving the vehicle such as an electric vehicle, a hybrid vehicle and a fuel cell vehicle is drawing public attention.

Japanese Patent Laying-Open No. 09-070195 discloses a control device of a motor capable of handling even in a case where rapid heat generation is caused in a switching device. In a case where a rotation speed of the motor is sufficiently low, this motor control device determines that the motor is locked by external force and switches carrier frequency of a PWM (pulse width modulation) signal from a normal value of 10 kHz to 1.25 kHz. In accordance with a decrease in the carrier frequency of the PWM signal, switching frequency of the switching device of an inverter is decreased and a switching loss is reduced. Therefore, there is no risk that rapid heat generation is caused in the each switching device of the inverter even when the motor is locked.

In the inverter for driving the vehicle, there are strong demands for downsizing and reducing cost. Therefore, it is not possible to sufficiently increase carrier frequency fc relative to output frequency fv in order to suppress the switching loss. Originally, the pulse number in PWM control is desirably about 15 pulses or more per one cycle of output frequency fv. Particularly when high torque is generated, an inverter conduction loss is increased and a heat generation amount is also increased. Therefore, there is a need for preventing overheat and reducing the heat generation in this region. However, when the inverter is designed so as to drive with high carrier frequency in all operating regions, size of the inverter becomes bigger and the cost of the inverter is increased.

When carrier frequency fc is simply decreased in order to reduce the switching loss, a controllability of the motor is deteriorated. Therefore, since there is a risk of vibration of the vehicle due to pulsation of the torque and breakage of parts due to out-of-control on an electric current, it is not allowable to simply decrease carrier frequency fc. Synchronous PWM control is sometimes adapted in order to ensure the controllability at the low pulse number. However, conversely at the time of low torque such as steady traveling with little noise inside the vehicle, there is a possibility that an electromagnetic sound by inverter switching is annoying. Although frequency of the sound can be changed by changing the pulse number, it is not possible to arbitrarily change the frequency due to restriction of synchronization.

Losses in the inverter and the motor are changed by carrier frequency fc so as to influence over efficiency of the inverter and motor. Therefore, even with an operating condition without problem in the controllability and the noise, there is a need for properly determining carrier frequency fc. Particularly for a purpose of the vehicle, when the efficiency is improved in a practical region with relatively low torque highly frequently used, fuel consumption is improved.

Since there is a subject of achieving ensuring of the controllability, reduction of the cost, reduction of the noise inside the vehicle and further improvement of the efficiency at the same time, an inverter control method suitable for a way of using the vehicle is desired.

Here, as shown in Japanese Patent Laying-Open No. 2006-217776, in a case where the synchronous PWM control is adapted, in order to prevent distortion of even harmonics from overlapping with output voltage, carrier frequency fc is selected to be an odd multiple of output frequency fv or multiples of three of the carrier frequency in order to match the output voltage of a three-phase inverter; and two kinds of carriers which are inversion and non-inversion are provided. Therefore, the carrier frequency fc has only discrete value.

For example, a case where there is a restriction that carrier frequency fc is sixfold, ninefold, twelvefold, fifteenfold . . . of output frequency fv will be described. Hereinafter, the term pulse number will be used in the description, e.g. when the carrier frequency is sixfold of output frequency fv, the pulse number is six pulses. In order to distribute carrier frequency fc, high carrier frequency fc is used such as nine pulses of 1.5 times more or twelve pulses of 2 times more than minimum-required six pulses. Therefore, the switching loss is increased, a problem of overheat in the inverter is caused, and hence there is a cost problem in order to prepare an inverter resistant to the above problem.

A method of selecting carrier frequency fc in an operating state capable of achieving the controllability and the reduction of the noise at the same time is not clearly stated. Therefore, in a case where carrier frequency fc is set to be higher than necessary, there is a possibility of an increase in the loss and a deterioration of the fuel consumption. In other words, since too much importance is conventionally given to improvement of the controllability and the reduction of the noise, there is sometimes a case where the cost of the inverter is high and there is some room for improving the fuel consumption.

The Toyota patent solves the following problem:

A vehicle includes a motor for driving wheels WH, an inverter to drive the motor, and a control device to perform PWM control of the inverter. The control device performs synchronous PWM control in a case where an electric current supplied to the motor by the inverter or torque generated in the motor is larger than a threshold value; and performs the synchronous PWM control or non-synchronous PWM control in a case where the electric current or the torque is smaller than the threshold value and sets carrier frequency or a pulse number of the PWM control to be higher than the case where the electric current or the torque is larger than the threshold value. Thereby, it is possible to provide a vehicle of achieving reduction of noise, reduction of cost and improvement of fuel consumption in a balanced manner.
An object of this invention is to provide a vehicle of achieving reduction of noise, reduction of cost and improvement of fuel consumption in a balanced manner.
According to the present invention, a vehicle includes a motor for driving wheels, an inverter to drive the motor, and a control device to perform pulse width modulation (PWM) control of the inverter. The control device performs synchronous PWM control in a case where an electric current supplied to the motor by the inverter or torque generated in the motor is larger than a threshold value; and performs the synchronous PWM control or non-synchronous PWM control in a case where the electric current or the torque is smaller than the threshold value and sets carrier frequency of the PWM control to be higher than the case where the electric current or the torque is larger than the threshold value.
In other aspect of this present invention, a vehicle includes a motor for driving wheels, an inverter to drive the motor, and a control device to perform pulse width modulation (PWM) control of the inverter. The control device determines carrier frequency of the PWM control so that heat generation of the inverter is minimized in a case where an electric current supplied to the motor by the inverter or torque generated in the motor is larger than a threshold value; and determines the carrier frequency so that a total of a loss in the inverter and a loss in the motor is minimized in a case where the electric current or the torque is smaller than the threshold value.
In further other aspect of this present invention, a vehicle includes a motor for driving wheels, an inverter to drive the motor, and a control device to perform pulse width modulation (PWM) control of the inverter. The control device determines carrier frequency of the PWM control so that heat generation of the inverter is minimized when an operating region of the motor defined by torque and rotation speed is a first region to protect the inverter from overheat; determines the carrier frequency of the PWM control so that noise of the motor is less detected by human when the operating region of the motor is a second region to reduce the noise of the motor; and determines the carrier frequency so that a total of a loss in the inverter and a loss in the motor is minimized when the operating region of the motor is a third region other than the first and second regions to reduce the noise of the motor.
Preferably, the control device performs synchronous PWM control in the first region; and performs the synchronous PWM control or non-synchronous PWM control in the second and third regions.
According to the present invention, it is possible to realize the vehicle of achieving the reduction of the noise, the reduction of the cost and the improvement of the fuel consumption in a balanced manner.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

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Toyota’s patent US7853398 deals with fuel pressure control apparatus for an internal combustion engine – toyota jidosha kabushiki kaisha .

Conventionally, an amount of fuel injected to an engine is controlled by controlling a period of injection of the fuel from an injector. In the injector, an electric current is supplied to a solenoid to slide a needle blocking the injection hole of the injector so as to open the injection hole. Thus, the fuel injection period from the injector is decided according to the period during which an electric current is supplied to the solenoid. When this current-supplying period to the solenoid is sufficiently long, the needle will move accurately, and thus, the fuel injection period and, hence, the fuel injection amount can be controlled appropriately. If the current-supplying period to the solenoid is short, the amount of movement of the needle is insufficient, causing unstable movement thereof. This may lead to unstable fuel injection period and, hence, unstable fuel injection amount. Accordingly, a lower limit is provided for the fuel injection period. With provision of such a lower limit for the fuel injection period, however, it is not possible to reduce the fuel injection amount by reducing the fuel injection period beyond the lower limit. As such, there is a technique to reduce the amount of the fuel injected per unit time by lowering the pressure of the fuel (fuel pressure) in the case where the fuel injection period becomes short to reach the lower limit (when the fewer fuel injection amount is required).

Japanese Patent Laying-Open No. 09-021369 discloses a fuel injection control apparatus for an internal combustion engine, which includes a fuel pressurizing portion that pressurizes fuel, a fuel injection portion that injects the fuel pressurized by the fuel pressurizing portion, a fuel injection amount setting portion that sets the amount of the fuel to be injected by the fuel injection portion in accordance with an engine operation state, an injection start timing setting portion that sets the injection start timing with respect to a prescribed injection end timing based on the fuel injection amount set by the fuel injection amount setting portion, and a pressure changing portion that lowers the pressure of the fuel pressurizing portion when the fuel injection amount set by the fuel injection amount setting portion is small.

According to the fuel injection control apparatus described in this publication, the injection start timing setting portion sets the injection start timing with respect to a prescribed injection end timing, based on the injection amount set by the fuel injection amount setting portion in accordance with the engine operation state. When the fuel injection amount set by the fuel injection amount setting portion is small, the pressure changing portion controls to lower the pressurizing force of the fuel pressurizing portion, and thus, the fuel pressure is lowered. As such, it is possible to reduce the amount of the fuel injected per unit time.

When the pressure of the fuel pressurizing portion, i.e., the fuel pressure, is lowered as in the fuel injection control apparatus described in Japanese Patent Laying-Open No. 09-021369, however, atomization of the fuel would be degraded (the fuel injected in the atomized state would decrease). With degradation in atomization of the fuel, the combustion state of the air-fuel mixture would change, leading to large variation in output of the engine.

The Toyota patent solves the following problem:

The engine ECU executes a program including the step of setting an upper limit guard value of a fuel pressure by executing low fuel pressure control in the case where a low fuel pressure control execution condition is satisfied with fulfillment of conditions that execution of the low fuel pressure control is permitted, that engine speed NE is lower than a threshold value, and that the atmospheric pressure is higher than a threshold value, and the step of controlling the fuel pressure to be a target fuel pressure within a range not exceeding the upper limit guard value.

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Toyota’s patent US7925417 deals with control apparatus and method for internal combustion engine – toyota jidosha kabushiki kaisha .

1. Field of the Invention

The invention relates generally to a control apparatus and method for an internal combustion engine, and, more specifically to a control apparatus and method that enables an internal combustion engine installed in a vehicle to start in an appropriate manner.

2. Description of the Related Art

There is an engine control apparatus that is employed in an economy running vehicle equipped with an economy running system or in a hybrid vehicle where the driving source can be switched between the engine and a motor, and that stops the engine when a predetermined engine-stop condition is satisfied and restarts the engine when a predetermined engine-restart condition is satisfied.

For example, Japanese Patent Application Publication No. 2002-339781 (JP-A-2002-339781) describes a control apparatus for a vehicle engine that enables the engine to restart when an engine-restart instruction is issued while the engine is off. The control apparatus includes restart control means for controlling the amount of air taken into the engine while the engine is being restarted in a manner in which the lower the pressure is in an intake pipe of the engine, the greater amount of air is taken into the engine. If an engine-restart instruction is issued when the in-cylinder pressure remains while the engine is off, the control apparatus increases the amount of air is taken into the engine to execute the instruction.

According to the method for restarting the engine described in JP-A-2002-339781, the amount of air taken into the engine while the engine is being restarted may be different each time. This may cause the following inconveniences.

For example, in a hybrid vehicle, when the vehicle is running with low engine efficiency, a motor, instead of the engine, is used as the driving source. On the other hand, when the vehicle is running with high engine efficiency, the engine, instead of the motor, is used as the driving source. When the driving source switches from the motor to the engine, the engine is restarted.

If the amount of air taken into the engine while the engine is being restarted is different each time, the torque output from the engine immediately after the engine starts self-operating may also be different each time. Accordingly, for example, when the torque output from the engine abruptly increases, a driver may sense undesirable vibrations.

Further, if the amount of the air taken into the engine while the engine starts up varies, the air-fuel ratio of the air-fuel mixture to be burned may also vary. This may vary the amount of pollutants in the exhaust gas emitted while the engine starts up. However, JP-A-2002-339781 does not address such inconveniences.

The Toyota patent solves the following problem:

An engine ECU (280) and an HV_ECU (320) control a throttle motor (296) such that the throttle valve opening degree (TH) does not exceed a prescribed limit (THlim) and a rate of increase (Ta/t) in the throttle valve opening degree is equal to or lower than a predetermined opening degree increase rate (Tb/t) for a predetermined time period after start-up of the engine (120) is initiated. Thus, power output from the engine is controlled so as not to increase significantly for the predetermined time period. Accordingly, while the engine starts up, a shock that can be felt by a driver can be suppressed. In addition, variation in the amount of air taken into the engine when the engine is started is also reduced, which reduces variation in the amount of pollutants in the exhaust gas emitted while the engine starts up.
The invention provides a control apparatus and method for an internal combustion engine, which enables an internal combustion engine installed in a vehicle to start in an appropriate manner.
An aspect of the invention relates to a control apparatus and method for an internal combustion engine installed in a vehicle. The internal combustion engine is provided with a throttle valve that adjusts the amount of air taken into the internal combustion engine. The control apparatus includes a throttle valve drive unit and a start-up control unit. The throttle valve drive unit drives the throttle valve to change the opening degree of the throttle valve. The start-up control unit controls the throttle valve drive unit such that the opening degree does not exceed a prescribed limit and the rate of increase in the opening degree is equal to or lower than a predetermined opening degree increase rate for a predetermined time period after start-up of the internal combustion engine is initiated.
The start-up control unit may include an opening degree command unit and an output power control unit. The opening degree command unit calculates a target opening degree based on a required power to be output from the internal combustion engine and commands the throttle valve drive unit to open the throttle valve by the target opening degree. The output power control unit executes a limiting control that changes the required power such that the rate of increase in the required power is equal to or lower than a predetermined power increase rate.
The output power control unit may include a vehicle power calculation unit and a limiting control unit. The vehicle power calculation unit calculates, based on at least the accelerator pedal operation amount, the vehicle power required to drive the vehicle. The limiting control unit starts the limiting control when the vehicle power exceeds a predetermined value, terminates the limiting control when the predetermined time period has elapsed after start-up of the internal combustion engine is initiated, and causes the required power to follow the vehicle power after the limiting control is completed.
The internal combustion engine may be a driving source that produces power to drive the wheels of the vehicle. The vehicle includes a motor that can be used as the driving source and a power transfer mechanism that transfers the driving force from at least one of the internal combustion engine and the motor to the wheel.
The invention enables the internal combustion engine installed in a vehicle to start in an appropriate manner.

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