US20160215781A1

US20160215781A1 - Electric regenerative turbocharger

Info

Publication number: US20160215781A1
Application number: US15/008,008
Authority: US
Inventors: Yuuki Okuda; Hiroshi Kimura; Yuji Enomoto
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2015-01-26
Filing date: 2016-01-27
Publication date: 2016-07-28
Also published as: JP2016138451A; JP6430270B2

Abstract

An electric regenerative turbocharger includes: an exhaust gas energy regenerative unit placed in an exhaust gas path and having a power generator; and a supercharging unit placed in an intake air path of an internal combustion engine and having an electric motor, and the electric motor includes a first electricity storage unit which is driven independently from the power generator and which is electrically connected to the exhaust gas energy regenerative unit and the supercharging unit, a second electricity storage unit which is connected to the first electricity storage unit and which supplies electricity to an electric component, and an electricity converting unit placed between the first electricity storage unit and the second electricity storage unit.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an electric regenerative turbocharger, and for example, the invention relates to an electric regenerative turbocharger which is suitable as an electric regenerative turbocharger in which a turbine and a compressor are electrically connected to each other.
2. Description of the Related Art
An attempt is conventionally made to pressurize intake air of an internal combustion engine to enhance output and fuel economy. Since a general turbocharger as a supercharging unit supercharges while utilising energy of exhaust gas, rising of supercharging is not excellent; and to compensate this, an attempt is made to forcibly give a rotation driving force by mounting an electric motor.
To drive a turbocharger by the electric motor, it is necessary that the electric motor has large output. JP-2003-293782-A discloses a turbocharger having an electric motor, the turbocharger also includes a battery for driving an electric motor and another battery for driving auxiliary machines, and the electric motor increases voltage of the battery which drives the electric motor.

SUMMARY OF THE INVENTION

According to the turbocharger having the electric motor of JP-2003-293782-A, an electricity loss when the electric motor is driven is made small by driving the electric motor of the turbocharger by a power supply whose voltage is increased.
According to the turbocharger having the electric motor shown in JP-2003-293782-A, however, a unit for electrically charging the battery whose electricity is increased while the electric motor is driven is poor, and when the battery whose voltage is increased is consumed, it is necessary to charge the battery whose voltage is increased by increasing voltage from the battery which drives the auxiliary machines to the battery whose voltage is increased to supply electricity, and it is difficult to continuously supercharge by the electric motor.
In view of such a problem, it is an object of the present invention to provide an electric regenerative turbocharger capable of obtaining electricity for driving the electric motor even during the supercharging when an electric motor is used as a supercharging unit, and capable of continuing to efficiently supercharge by the electric motor.
An electric regenerative turbocharger of the present invention includes: an exhaust gas energy regenerative unit placed in an exhaust gas path and having a power generator; and a supercharging unit placed in an intake air path of an internal combustion engine and having an electric motor, and the electric motor includes first electricity storage unit which is driven independently from the power generator and which is electrically connected to the exhaust gas energy regenerative unit and the supercharging unit, a second electricity storage unit which is connected to the first electricity storage unit and which supplies electricity to an electric component, and an electricity converting unit placed between the first electricity storage unit and the second electricity storage unit.
According to the present invention, even while supercharging is continued by the supercharging unit, it is possible to efficiently obtain electricity for driving the supercharging unit, and to continue the supercharging by the electric motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram describing configurations of electric regenerative turbochargers of first and second embodiments of the present invention;

FIG. 2 is a diagram for describing a comparative example with respect to the second embodiment of the invention;

FIG. 3 is a time chart showing variation in an amount of charge of a first electricity storage unit in the second embodiment of the invention;

FIG. 4 is a diagram for describing a configuration of an electric regenerative turbocharger of a third embodiment of the invention;

FIG. 5 is a diagram for describing a configuration of an electric regenerative turbocharger of a fourth embodiment of the invention;

FIG. 6 is a diagram for describing characteristics of power generation current and power generation voltage with respect to field current of a power generator in the fourth embodiment of the invention;

FIG. 7 is a diagram for describing characteristics of power generation current, and power generation voltage with respect to the number of rotations of the power generator in the fourth embodiment of the invention;

FIG. 8 is a diagram for describing characteristics of power generation current and power generation torque with respect to field current of the power generator in the fourth embodiment of the invention;

FIG. 9 is a diagram for describing a configuration of a turbocharger when electric motion is started in a fifth embodiment of the invention;

FIG. 10 is a diagram for describing the number of rotations of the power generator and characteristics of power generation voltage in the fifth embodiment of the invention; and

FIG. 11 is a diagram for describing a configuration of an electric regenerative turbocharger of a sixth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of electric regenerative turbochargers of the present invention will be described below with reference to the drawings.

First Embodiment

A configuration of an internal combustion engine 100 having an electric regenerative turbocharger of a first embodiment is shown in FIG. 1. An intake air path of the internal combustion engine is provided with a supercharging unit (e.g., compressor) 101 and an electric motor 102 for driving the supercharging unit 101, The electric motor 102 can normally and reversely drive and stop.
The supercharging unit 101 is not limited, and pressurizes or depressurises air and sends the air into the internal combustion engine 100. It is only necessary that the supercharging unit 101 can increase or reduce a flow rate of intake air, and the supercharging unit may be the above-described compressor, a turbo-compressor such as an axial fan, a screw compressor, and a positive-displacement compressor such as a Lysholm compressor.
The intake air path of the internal combustion engine 100 is provided with an intake manifold 104 for appropriately distributing air sucked into the internal combustion engine 100, and a pressure sensor 105 for measuring pressure in the intake manifold 104. The intake manifold 104 extending to the compressor 101 may be provided with a throttle valve 103 which controls output of the internal combustion engine 100.
An exhaust gas path of the internal combustion engine 100 is provided with an exhaust gas energy regenerative unit 106 (e.g., turbine) which is driven by exhaust gas energy, and a power generator 107 which is driven by the exhaust gas energy regenerative unit 106.
The exhaust gas energy regenerative unit 106 is not especially limited only if the exhaust gas energy regenerative unit 106 is driven by exhaust gas and can obtain a rotation force from at least exhaust gas energy, and the turbine or a windmill can be used as the exhaust gas energy regenerative unit 106.
A path of the exhaust gas energy regenerative unit 106 extending to the internal combustion engine 100 may be provided with a catalyst device (not shown), and the catalyst device may be provided downstream of the exhaust gas energy regenerative unit 106. In addition, the path of the exhaust gas energy regenerative unit 106 extending to the internal combustion engine 100 may be provided with an exhaust gas recirculation path which bypasses the intake air path for recirculating exhaust gas. The exhaust gas recirculation path may be provided downstream of the exhaust gas energy regenerative unit 106.
The electric motor 102 and the power generator 107 are electrically connected to a first electricity storage unit 108. A second electricity storage unit 110 is connected to the first electricity storage unit 108 through an electricity converting unit 109.
The second electricity storage unit 110 supplies electricity to the internal combustion engine 100, a controller 111 which controls the electric regenerative turbocharger of the invention, and electric components such as auxiliary machines 112 which are necessary for controlling the internal combustion engine 100. The above-described control is performed by programs provided in the controller 111. The controller 111 includes a microcomputer which can execute various kinds of programs, ROM in which the programs are stored, and RAM for storing temporal information during execution of the programs.
The second electricity storage unit 110 is charged with electricity which is obtained from the first electricity storage unit 108 through the electricity converting unit 109. In addition, the second electricity storage unit 110 is electrically charged by a third power generator 114 which is driven by winding using a belt or a transfer mechanism using a gear from an output shaft 113 of the internal combustion engine 100.
The first electricity storage unit 108 is provided with a state-monitoring sensor 115. The state-monitoring sensor 115 evaluates a charging state and soundness of the electricity storage unit from voltage of the first electricity storage unit 108, current of charging and discharging, temperature and the like. The second electricity storage unit 110 is also provided with a similar state-monitoring sensor. The state- monitoring sensors 115 and 116 send a charging state and soundness of the second electricity storage unit 110 to the controller 111.
According to this embodiment, the first electricity storage unit 108 which supplies electricity to the electric motor 102 and the second electricity storage unit 110 which supplies electricity to the controller 111 and the auxiliary machines 112 of the internal combustion engine 100 are separated from each other.
According to this configuration, voltage variation of the first electricity storage unit 108 generated when the electric motor 102 is driven with large electricity does not exert influence on the second electricity storage unit 110, and the controller 111 arid the auxiliary machines 112 of the internal combustion engine 100 can stably be managed.
Further, according to this configuration, it is possible to reduce a harness diameter which connects the first electricity storage unit 108 and the second electricity storage unit 110 to each other to reduce the costs, and to employ power supplies having different characteristics for the first and second electricity storage unit by increasing operation voltage of the first electricity storage unit 108 and the second electricity storage unit 110 and by increasing rated voltage of the electric motor 102 and the power generator 107 and by reducing current.
That is, it is preferable to employ, for the first electricity storage unit, a power supply such as a capacitor capable of handling high power supply response such as output of large electricity and regeneration. Examples of such a capacitor are a lithium ion capacitor which is a hybrid capacitor, and an electric double-layered capacitor which employs activated carbon electrodes for both positive and negative electrodes. In the lithium ion capacitor, lithium ion is inserted into carbon material in which activated carbon electrode can be detachably inserted into a positive electrode, and lithium ion can be detachably inserted into a negative electrode.
Any of the capacitors accumulate electric charge by physical reaction in which, electric charge absorbs and separates to and from an electric double-layer generated in an electrode interface in an electricity storage element. Therefore, any of the capacitors are suitable for repeated charging/discharging such as output of large electricity and regeneration.
If the electric motor 102 can be driven with large electricity, it is possible to further enhance the response of the supercharging unit 101, and response of output adjustment of the internal combustion engine 100.
A driving force of the exhaust gas energy regenerative unit 106 is increased by increasing an amount of new air which is supercharged by the supercharging unit 101, and the power generation amount of the power generator 107 is increased. Therefore, the electric motor 102 is driven by supplying electricity stored in the first electricity storage unit 108 until a driving operation of the power generator 107 is waited.
FIG. 2 shows a time chart illustrating variation, in an amount of charge of the first electricity storage unit 108 in the first embodiment of the invention. At time t1, if the electric motor 102 is controlled further toward a normal rotation side, i.e., if a supercharging amount is controlled in its increasing direction and the output of the internal combustion engine 100 is controlled in an increasing direction, an exhaust gas flow rate increases in a delayed fashion. As the exhaust gas flow rate increases, a power generation amount of the power generator 107 which is driven by the exhaust gas energy regenerative unit 106 also increases, During that time, at time t1, output and an amount of discharge of the electric motor 102 increase, and an amount of charge of the first electricity storage unit 108 falls into reduction. Thereafter, at time t2, the power generation amount of the power generator 107 increases, and if the power generation amount of the power generator 107 exceeds the output of the electric motor 102, the electric charging operation is again carried out. Then, at time t3, the electric motor 102 is controlled in a reversely rotating direction, and when an amount of new air into the internal combustion engine 100 reduces and output is suppressed, the exhaust gas flow rate of the internal combust ion engine 100 is reduced again in a delayed fashion and from time t4, the power generation amount of the power generator 107 also reduces. Since the exhaust gas flow rate reduces and the electric motor 102 is driven in the reversely rotating direction, more electricity is discharged by the first electricity storage unit 108. Thereafter, at time t5, the electric motor 102 is controlled in the normal rotating direction again, the exhaust gas flow rate increases and at time t6, the power generation amount of the power generator 107 increases, and the amount of charge of the first electricity storage unit 108 is recovered.
That is, charge and discharge of the first, electricity storage unit 108 are repeated as shown in the time chart in FIG. 2. From the standpoint of this also, it is preferable that a power supply such as a capacitor is employed for the first electricity storage unit 108.
On the other hand, it is possible to manage a general lead battery for the second electricity storage unit as an in-vehicle power supply by a conventionally known method.
It is preferable that the lead battery or a lithium ion secondary battery which can inexpensively attain large capacity is employed as the second electricity storage unit 110. The lead battery can inexpensively attain large capacity and is suitable. The lithium ion secondary battery has high energy density, and can attain large capacity in a lighter-weighted manner than the lead battery. Therefore, when the present invention is applied to a vehicle engine, the lithium ion secondary battery contributes to reduction in weight of the vehicle.
The first electricity storage unit 108 and the second electricity storage unit 110 are connected to each other through the electricity converting unit 109. The state-monitoring sensors 115 and 116 interchange electricity of the first electricity storage unit 108 and the second electricity storage unit 110 based on the electric charging stage of the second electricity storage unit 110.
For example, when electricity stored in the first electricity storage unit 108 is sufficient and the exhaust gas energy regenerative unit 106 and the power generator 107 are driven, the controller 111 controls the electricity converting unit 109, moves electricity of the first electricity storage unit 108 to the second electricity storage unit 110, and electrically charges the second electricity storage unit 110. By providing control in this manner, a driving chance of the third power generator 114 which is driven by the winding or the gear transfer mechanism from the output shaft, of the internal combustion engine 100 and according to this, a load of the internal combustion engine 100 is reduced, and it is possible to expect that output of the internal combustion engine 100 is enhanced and fuel economy of the engine 100 is enhanced.
Since the electricity converting unit 109 is interposed, operation voltages of the first electricity storage unit 108 and the second electricity storage unit 110 can be made different from each other. In addition, even if the operation voltages of the first electricity storage unit 108 and the second electricity storage unit 110 are the same, since the power supply having different characteristics such as the capacitor is used as the first electricity storage unit, it is also possible to manage the first electricity storage unit such that it is electrically discharged more deeply as compared with the second electricity storage unit.
For example, when the first electricity storage unit 108 is managed at higher voltage than the second electricity storage unit 110, it is estimated that the second electricity storage unit 110 is managed at general 12 V or 24 V as the in-vehicle power supply. On the other hand, when the first electricity storage unit 108 may be managed at high voltage and discharge of about 1 kW and regeneration are carried out, it is more preferable to select such voltage that system current becomes lower than 50 A. As such voltage, 24 V or higher is suitable, and power supply voltage such as 36 V or 48 V can be employed, but these voltages are one example and the voltages should riot be limited.
An upper limit value of the operation voltage of the first electricity storage unit should be 60 V or 300 V. If the voltage of about 60 V is set to the upper limit, it is possible to restrain a voltage difference from the second electricity storage unit 110 from increasing, and a loss caused by transformation can be reduced.
If the operation voltage of the first electricity storage unit 108 is set to about 300 V, it is possible to form the system of this embodiment, while diverting parts for a hybrid electric vehicle for example, and if widely distributed parts are used, it is possible to expect that costs are reduced.
When the operation voltages of the first electricity storage unit 108 and the second electricity storage unit 110 are set equal to each other and the first electricity storage unit 108 is electrically discharged more deeply, since the second electricity storage unit 110 is managed at high voltage with respect to the first electricity storage unit 108, it is more preferable that the electricity converting unit 109 is selected as a unit which reduces (or increases) pressure in one direction, or as a unit which increases (or reduces) pressure in both directions in accordance with a managing type of the electricity storage unit. That is, the electric regenerative turbocharger includes the exhaust gas energy regenerative unit which is provided in the exhaust gas path and which includes a power generator, the supercharging unit which is provided in the intake air path of the internal combustion engine and which includes the electric motor capable of independently driving from the power generator, the first, electricity storage unit which is electrically connected to the exhaust gas energy regenerative unit and the supercharging unit, the second electricity storage unit which is connected to the first electricity storage unit and which supplies electricity to the electric component, and the electricity converting unit placed between the first electricity storage unit and the second electricity storage unit.
According to this configuration, voltage variation caused when the electric motor 102 is driven does not pose a problem for operations of other auxiliary machines. It is possible to employ, as the first electricity storage unit 108, a capacity capable of carry out discharge of large electricity and regeneration and having excellent repeatedly electrically charging and discharging, and it is possible to employ, as the second electricity storage unit 110, the lead battery capable of inexpensively attaining large capacity or the lithium ion secondary battery capable of attaining large capacity in a light-weighted manner. In addition, by increasing the operation voltage of the first storage battery, it is possible to drive the electric motor 102 at high voltage, and response of the supercharging unit 101 is enhanced. Further, since voltage of the first electricity storage unit is increased, it is possible to reduce the harness diameter and costs.

Second Embodiment

A second embodiment will be described using FIG. 1.
The internal combustion engine 100 controls output by an amount of new air introduced into the internal combustion engine 100. The supercharging unit 101 and the electric motor 102 are normally or reversely rotated, thereby varying the supercharging pressure. For example, the supercharging pressure is increased by normally rotating the supercharging unit 101 and the electric motor 102, and the supercharging pressure is reduced by reversely rotating the supercharging unit 101 and the electric motor 102.
The term “supercharging” mentioned here unit that intake pipe pressure of the internal combustion engine 100 is varied using the supercharging unit 101 and the electric motor 102 and therefore, the term “supercharging” also includes intent ion to reduce pressure lower than atmospheric pressure. In this embodiment, supercharging pressure also includes a state where it becomes negative pressure which is reduced lower than the atmospheric pressure unless otherwise specified.
Variation in this supercharging pressure can be detected by the pressure sensor 105, and can also be detected by an intake amount flow rate detecting unit (not shown) provided in an intake air path. As the intake amount flow rate detecting unit, it is possible to use an air flow meter using a hot wire, and a flap type or swirl type flowmeter
By varying the supercharging pressure, it is possible to adjust the amount, of new air introduced into the internal combustion engine 100. If the supercharging pressure is set high for example, new air is compressed and introduced into a cylinder of the internal combustion engine 100. Therefore, more new air is introduced. If the supercharging pressure is set lower or is reduced to a level lower than the atmospheric pressure on the other hand, new air introduced into the cylinder of the internal combustion engine 100 becomes thin, and an amount of new air introduced into the internal combustion engine 100 is reduced.
Although it is not illustrated in the drawings, it is possible to adjust the amount of new air introduced into the internal combustion engine also by combining change of an intake valve lift and changes of opening timing and closing timing of an intake valve of the internal combustion engine 100. The adjustment of the amount of new air into the internal combustion engine 100 by changing the intake valve lift and opening timing and closing timing of the intake valve can be achieved by a conventionally known method. In addition to the valve-operating mechanism (change of intake valve lift, exhaust gas valve lift, and changes of opening timing and closing timing of the intake valve, exhaust gas valve), it is possible to control more delicately by combining adjustment of the supercharging pressure supplied to the supercharging unit 101 and the electric motor 102.
When the internal combustion engine 100 is driven with extremely low rotation for example, a loss of the pump of the internal combustion engine 100 is reduced by increasing the supercharging pressure and brings pressure in the intake pipe into negative pressure during the intake stroke, or by reducing the negative pressure. Further, by reducing the supercharging pressure immediately before the internal combustion engine 100 is stopped, decompression effect can be expected when the internal combustion engine 100 is restarted.
Further, by reversely driving the supercharging unit, it is possible to increase a loss of the pump of the internal combustion engine 100. This means that when engine brake utilising the internal combustion engine 100 is used, stronger engine brake can be operated.
By normally and reversely driving the supercharging unit 101 and the electric motor 102 in this manner, it is possible to control the output of the internal combustion engine 100. This function can be provided by controlling the supercharging unit 101 and the electric motor 102 independently from the exhaust gas energy regenerative unit 106.
That is, according to a mechanical turbocharger in which a driving shaft of an exhaust, gas energy regenerative unit (e.g., turbine) and a driving shaft of the supercharging unit 101 (e.g., compressor) are configured on the same axis so that an operation state of the turbocharger is varied in accordance with an operation state of the exhaust gas energy regenerative unit, since the supercharging unit cannot reversely be driven, it can be said that it is difficult to control the output of the internal combustion engine by controlling the supercharging pressure.
In the above-described case, if an electric motor 202 which can normally and reversely rotate is provided on a driving axis as shown in FIG. 3 as a comparative example 1 for example, it is possible to provide output control of an internal combustion engine 200 by controlling supercharging pressure by normally and reversely driving at least a supercharging unit 201, but the following problems occur.
That is, if the supercharging unit 201 is normally and reversely driven by an electric motor 202, an exhaust gas turbine 206 is also normally and reversely driven at the same time. Therefore, when the exhaust gas turbine 206 is normally and reversely driven, back pressure increases and a pump loss of the internal combustion engine 200 is increased. This means that the back pressure increases and a push-out work against exhaust gas is generated in a scavenging stroke of the internal combustion engine 200, and output of the internal combustion engine 200 is reduced and fuel economy of the engine is deteriorated.
Electricity of a power supply 208 is consumed while the electric motor 202 is reversely driven. To electrically charge the power supply, a power generator 214 which is driven by winding using a belt or a transfer mechanism using a gear from an output shaft 213 of the internal combust ion engine 200 is driven for example, a load of the internal combustion engine 200 is increased, output of the internal combustion engine 200 is reduced and fuel economy of the engine is deteriorated.
Therefore, if the configuration shown in the second embodiment is employed, it is possible to drive the supercharging unit 101 and the electric motor 102 independently from the exhaust, gas energy regenerative unit 106 and the power generator 107 in FIG. 1 again, the exhaust gas energy regenerative unit 106 is driven by exhaust gas energy irrespective of normal and reversal rotations of the supercharging unit 101, and the power generator 107 can be driven. According to this, the exhaust gas energy regenerative unit does not reversely rotate, back pressure does riot increase more than necessary, and the power generator 107 can be driven. Therefore, it is possible to suppress the above-described reduction in output of the internal combustion engine 200, and to suppress deterioration in fuel economy, and it is possible to continuously drive the electric motor 102. That is, according to the second embodiment, pressure and a flow rate of new air introduced into the internal combustion engine 100 can be controlled mainly by normally and reversely driving the supercharging unit 101 and the electric motor 102, and electricity created by the power generator 107 can be supplied to the electric motor 102 through the first electricity storage unit 108 via the exhaust gas energy regenerative unit 106 irrespective of a driving state of the electric motor 102. According to this, even while supercharging carried out by the supercharging unit is continued, electricity for driving the supercharging unit can efficiently be obtained, and supercharging carried out by the supercharging unit 101 can be continued through the electric motor 102. In addition to this, the first electricity storage unit 108 which supplied electricity mainly to the electric motor 102 and the second electricity storage unit 110 which drives mainly the controller 111 and the auxiliary machines 112 of the internal combustion engine 100 are separated from each other. According to this, it is possible to stably drive the controller 111 and the auxiliary machines 112, and it is possible to employ, for the first electricity storage unit 108, a capacitor which electrically discharges with large electricity and regeneration, and which repeatedly electrically charges and discharges excellently. According to this, even while supercharging carried out by the supercharging unit is continued, it is possible to efficiently obtain electricity for driving the supercharging unit, and to continue the supercharging carried out by the supercharging unit 101 through the electric motor 102 without exerting influence to other electric components.

Third Embodiment

A third embodiment is characterised in that, a thermoelectric conversion unit is provided on a latter part of the regenerative unit, in addition to the configuration of the above-described second embodiment.
The third embodiment will be described using FIG. 4. In the description of this configuration, description of the above-described configuration will be omitted. A thermoelectric conversion unit 317 is provided on a latter part of an exhaust gas energy regenerative unit 306 provided in an exhaust gas path of an internal combustion engine 300. The thermoelectric conversion unit 317 is a thermoelectric conversion element which is heated by combustion gas of the internal combustion engine 300, and which obtains electricity by a temperature difference with respect to cooling water (not shown). As such a thermoelectric conversion element, it is possible to employ a turbine power generator utilizing a Seebec element or Rankine cycle using a combination of different metals or a semiconductor.
The exhaust gas energy regenerative unit 306 obtains a driving force of a power generator 307 utilising kinetic energy of exhaust gas of exhaust gas energy mainly of the internal combustion engine 300. The thermoelectric conversion unit 317 is driven by thermal energy of exhaust gas of the internal combustion engine 300 which could not recovered by the exhaust gas energy regenerative unit 306. The thermoelectric conversion unit 317 exchanges heat. Therefore, an internal flow path structure thereof is not substantially straight flow path, and the thermoelectric conversion unit 317 is provided with a meandering portion for exhaust gas flow and a spreading portion for reducing a flow rate of the exhaust gas, and kinetic energy of exhaust gas after it passes through the thermoelectric conversion unit 317 becomes small.
Therefore, it is not preferable to provide the thermoelectric conversion unit 317 upstream of the exhaust gas energy regenerative unit 306, and the thermoelectric conversion unit should be placed downstream of the exhaust gas energy regenerative unit which is placed in the exhaust gas path of the internal combustion engine as shown in this embodiment.
According to this, an electric motor 302 and a supercharging unit 301 are reversely driven, and even when a flow rate of exhaust gas is reduced, electricity generated by the thermoelectric conversion unit 317 can be supplied to a first electricity storage unit 308 in addition to electricity generated by the power generator 307 which is driven by the exhaust gas energy regenerative unit 306, and it is possible to more stably and continuously drive the electric motor 302.
That is, it is possible to suppress increase in a driving chance of a third power generator 314 which is driven by the winding or the gear transfer mechanism by an output shaft 313 of the internal combustion engine 300 while suppressing consumption of the first electricity storage unit 308, and it is possible to drive the supercharging unit 301 through the electric motor 302 without increasing a load of the internal combustion engine 300. Therefore, it is possible to efficiently and continuously drive the supercharging unit 301 through the electric motor 302.

Fourth Embodiment

A fourth embodiment is characterized in that it includes an exhaust gas recirculation path in addition to the configuration shown in the second and third embodiments, a power generator driven by the exhaust gas energy regenerative unit, controls field current, and the field current is increased when the electric motor and supercharging unit are controlled such that supercharging pressure is reduced to a level lower than atmospheric pressure.
A basic configuration of the fourth embodiment is the same as those of the above-described embodiments.
In FIG. 5, a power generator 407 can control power generation voltage by controlling the field current. By controlling the field current of the power generator 407, power generation characteristics of the power generator 407 become as shown in FIG. 6 when it is assumed that the number of rotations (or exhaust gas flow rate) of the exhaust gas energy regenerative unit 406 is constant. On the other hand, FIG. 7 shows characteristics of the power generator 407 obtained when it is assumed that the field current is constant. As described in FIGS. 6 and 7, when the power generator 407 can control the field current, it is possible to change the power generation characteristics in accordance with quantity of field current.
Therefore, when supercharging unit 401 and electric motor 402 are controlled such that intake air pipe pressure is reduced to a level lower than the atmospheric pressure, the field current is increased, and a control valve 419 provided in an exhaust gas recirculation path 418 is controlled in its opening direction.
In a state where at least the electric motor 402 is reversely driven and when pressure in the intake manifold 404 detected by an intake air pressure sensor 405 is less than the atmospheric pressure and when the output of the electric motor 402 and power generation output of the power generator 407 are compared with each other and the output of the electric motor 402 is higher than the power generation output of the power generator 407, field current of the power generator 407 is controlled into the increasing direction.
According to this, the supercharging unit 401 and the electric motor 402 are controlled such that the supercharging pressure is reduced to the level lower than the atmospheric pressure, the exhaust gas flow rate is reduced, and a driving force of the exhaust gas energy regenerative unit 406 is lowered.
Therefore, according to the fourth embodiment, even, when the power generation amount of the power generator 407 is lowered, it is possible to increase the power generation amount by increasing the field current, and to continuously drive the electric motor 402.
In a state where the electric motor is at least reversely driven and when pressure in the intake manifold 404 becomes lower than the atmospheric pressure, a large pump loss is generated in the internal combustion engine 400.
In this case, a rate of new air is relatively lowered by introducing exhaust gas toward an intake side through the exhaust gas recirculation path 418, and it is possible to obtain the same effect as that when pressure in the intake manifold 404 is made lower than the atmospheric pressure and density of intake air is lowered. In this case, it is effective to increase the back pressure to recirculate more exhaust gas toward the intake air. Power generation torque of the power generator 407 is increased based on a relation shown in FIG. 8 by increasing the field current of the power generator 407 and increasing the power generation amount.
Consequently, rotation speed of the exhaust gas energy regenerative unit 406 is reduced and back pressure can be increased, exhaust gas pressure can be increased with respect to pressure in the intake manifold 404, more exhaust gas can be recirculated, it is possible to suppress electricity which is necessary to reversely drive the electric motor 402, and it is possible to continuously drive the electric motor 402.

Fifth Embodiment

A basic structure of a fifth embodiment is the same as those of the second and third embodiments. The fifth embodiment will be described using FIG. 9. The fifth embodiment is characterised in that a power generator 506 which is driven by an exhaust gas energy regenerative unit 506 is a permanent magnet power generator, the exhaust gas energy regenerative unit 506 includes a bypass path 520 which bypasses an upstream side and a downstream side of the exhaust gas energy regenerative unit 506, the bypass path includes an opening degree adjusting mechanism 521 capable of controlling an exhaust gas flow rate toward the exhaust gas energy regenerative unit 506 by adjusting the opening degree, and the opening degree adjusting mechanism 521 is controlled in its opening direction based on power generation voltage of the power generator 507.
Power generation characteristics of the power generator 507 configured by the permanent magnet power generator is as shown in FIG. 10, and the number of rotations (exhaust gas flow rate) and power generation voltage are in a proportional relation. To appropriately electrically charge first electricity storage unit 508, in the power generator 507, an appropriate electromotive force constant capable of electrically charging the first electricity storage unit 508 even from relatively low speed rotation is set. At this time, as the number of rotations of the power generator 507 increases, voltage generated by the power generator 507 increases.
Therefore, the driving force of the exhaust gas energy regenerative unit increases without any limitation and there is fear that voltage exceeds an upper limit of electrically charging voltage of the first electricity storage unit 508, In view of this problem, the fifth embodiment includes the bypass path 520 of the exhaust gas energy regenerative unit 506 capable of limiting the driving force of the exhaust gas energy regenerative unit and the opening degree adjusting mechanism 521 provided in the bypass path 520.
By adjusting the opening degree of the opening degree adjusting mechanism 521 toward its opening side, an exhaust gas flow rate bypassing the exhaust gas energy regenerative unit 506 increases and as a result, the driving force of the exhaust gas energy regenerative unit 506 is limited, and increase of the rotation of the power generator 507 is suppressed. Since the number of rotations of the power generator 507 can be obtained by the generated voltage of the power generator 507 from the relation shown in FIG. 10, it is possible to control the opening degree adjusting mechanism 521 based on the generated voltage of the power generator 507.
The generated voltage of the power generator 507 which controls the opening degree adjusting mechanism 521 may be determined by withstand voltage of the first electricity storage unit 508 or by permissible number of rotations of the exhaust gas energy regenerative unit 506, and it is more preferable to employ smaller one of the number of rotations (generated voltage).
To employ such number of rotations, even if the permanent magnet power generator is employed as the power generator 507, it is possible to control the generated voltage of the power generator 507.

Sixth Embodiment

A sixth embodiment is characterized in that it has a measuring unit or an estimating unit of back pressure of the internal combustion engine in addition to the structure shown in the third embodiment.
Effects obtained by the sixth embodiment will be described using FIG. 11. FIG. 11 includes an exhaust gas pressure sensor 622 as a measuring unit of back pressure. The exhaust gas pressure sensor 622 is provided on a path extending to an exhaust gas energy regenerative unit 606 reaching an exhaust gas manifold 623 which is an aggregation portion of exhaust gas of an internal combustion engine 600. When a catalyst device (not shown) is provided on this path, it is preferable if the catalyst device is provided upstream of the catalyst device (i.e., on path of catalyst device (not shown) reaching exhaust gas manifold 623).
Increase in an engine pump loss caused when back pressure of the internal combustion engine 600 increases is described above. As the power generation output of the power generator 607 which is driven through the exhaust gas energy regenerative unit 606 increases, reverse torque which tries to stop rotation of the exhaust gas energy regenerative unit 606 increases. As a result, flow of exhaust gas is hindered, and as the output of the power generator 607 increases, the back pressure of the internal combustion engine 600 increases and the pump loss of the internal combustion engine 600 increases. As a result, there is fear that output of the internal combustion engine 600 is lowered and fuel consumption thereof is deteriorated and therefore, this situation is not preferable.
Hence, this embodiment includes the exhaust gas pressure sensor 622 as the measuring unit of back pressure. When it is determined that the pump loss of the internal combustion engine 600 increases by exhaust gas pressure obtained by estimating exhaust gas pressure from a state equation of gas based on an exhaust gas flow rate obtained from an amount of new air obtained based a measurement, result of exhaust gas pressure by the exhaust gas pressure sensor 622 or based on supercharging pressure of the supercharging unit 601 or a measurement result of an intake air pressure sensor 605 provided in the intake manifold 604 or a mass flow rate sensor of intake air (not shown), output of the power generator 607 is lowered and it is possible to suppress the rise in the back pressure.
When it is difficult to control the output of the power generator 607, it is possible to suppress the rise in exhaust gas pressure also by adjusting, toward opening side, an opening degree of the opening degree adjusting mechanism 621 provided on a bypass path 620 which bypasses an upstream side and a downstream side of the exhaust gas energy regenerative unit 606.
However, to lower the output of the power generator 607 or to control the opening degree adjusting mechanism 621 toward its opening side is to reduce the amount of charge of the first electricity storage unit 608. As a result, the first electricity storage unit 608 is consumed, the electric motor 602 cannot be driven, supercharging carried out by the supercharging unit 601 cannot be carried out, and it is not possible to continuously drive the electric motor 602.
Therefore, if an electric charging state of the first electricity storage unit 608 is on the charged side by using an electric charging state of the first electricity storage unit 608 obtained by a state-monitoring sensor 615 provided in the first electricity storage unit 608, it is possible to continuously drive the electric motor 602. Therefore, when the exhaust gas pressure of the internal combustion engine 600 increases, output of power generation of the power generator 607 is permitted to be lowered, and it is permitted to control the opening degree adjusting mechanism 621 in its opening direction. When the electric motor 602 is driven and electricity of the first electricity storage unit 608 is consumed and the electric charging state of the first electricity storage unit 608 obtained by the state-monitoring sensor 615 is consumed toward a charging-required side, reduction in power generation output of the power generator 607 and control of the opening degree adjusting mechanism 621 in its opening direction are prohibited, and this prohibited state is continued until the electric charging state of the first electricity storage unit 608 is recovered. According to this, the first electricity storage unit 608 is restrained from being consumed. On the other hand, when the electric charging state of the first electricity storage unit 608 is on the charged side and the electric motor 602 can sufficiently be driven, back pressure of the internal combustion engine 600 is restrained from rising, and it is possible to avoid a case where the pump loss of the internal combustion engine 600 is reduced arid output of the internal combustion engine 600 increases and fuel economy deteriorates by controlling the power generation output of the power generator 607 and the opening degree adjusting mechanism 621 in its opening direction.

Seventh Embodiment

A seventh embodiment is characterized in that the supercharging unit and the electric motor are reversely driven before the internal combustion engine stops.
Before the internal combustion engine stops, the intake air amount is reduced, and air compressed in the compression stroke when the engine is started next time is reduced. According to this, it is possible to expect to replace the mechanism by a so-called decompression mechanism which makes it easy to reduce vibration when the internal combustion engine starts, and which makes it easy to start the internal combustion engine.
Therefore, as shown in this embodiment, the supercharging unit and the electric motor are reversely driven before the internal combustion engine stops, and the supercharging pressure is lowered. According to this, it is possible to expect that starting performance of the Internal combustion engine is enhanced and vibration is reduced. The above-described embodiments are described using a straight four-cylinder gasoline engine of a vehicle Otto cycle, but the internal combustion engine is not limited to this. The internal combustion engine may be a diesel engine, and the number of cylinders is not limited. The internal combustion engine is not limited to a reciprocating engine which converts reciprocating motion caused by a piston into power by a crank mechanism, and may be a Wankel engine.

Claims

What is claimed is:

1. An electric regenerative turbocharger comprising:

an exhaust gas energy regenerative unit placed in an exhaust gas path and having a power generator; and

a supercharging unit placed in an intake air path of an internal combustion engine and having an electric motor,

wherein the electric motor includes

a first electricity storage unit which is driven independently from the power generator and which is electrically connected to the exhaust gas energy regenerative unit and the supercharging unit,

a second electricity storage unit which is connected to the first electricity storage unit and which supplies electricity to an electric component, and

an electricity converting unit placed between the first electricity storage unit and the second electricity storage unit.

2. The electric regenerative turbocharger according to claim 1, wherein

the electric motor is driven independently from the power generator, the electric motor can normally and reversely be driven, and the electric motor adjusts intake air pressure and a flow rate of the internal combustion engine.

3. The electric regenerative turbocharger according to claim 2, wherein

a thermoelectric conversion unit is placed downstream of the exhaust gas energy regenerative unit which is placed in an exhaust gas path of the internal combustion engine.

4. The electric regenerative turbocharger according to claim 1, wherein

the power generator driven by the exhaust gas energy regenerative unit is a power generator which controls field current, the internal combustion engine includes an exhaust gas recirculation path, and when the electric motor and the supercharging unit are controlled to reduce a supercharging amount, the field current is increased when output of the electric motor is greater than power generation output of the power generation based on a magnitude relation between the output of the electric motor which drives the supercharging unit and the output of the power generator.

5. The electric regenerative turbocharger according to claims 1, wherein

the power generator driven by the exhaust gas energy regenerative unit is a permanent magnet power generator, the exhaust gas energy regenerative unit includes a bypass path which bypasses an upstream side and a downstream side of the exhaust gas energy regenerative unit, the bypass path includes an opening degree adjusting mechanism capable of controlling an exhaust gas flow rate toward the exhaust gas energy regenerative unit by adjusting an opening direction of the bypass path, and the opening degree adjusting mechanism is controlled into its opening degree based on generated voltage of the power generator.

6. The electric regenerative turbocharger according to claim 3, further comprising a measuring or estimating unit of back pressure of the internal combustion engine, wherein

output of the power generator is reduced based on a measurement or estimation result of the back pressure of the internal combustion engine and an electric charging state of the first electricity storage unit.

7. The electric regenerative turbocharger according to claim 2, wherein

the supercharging unit and the electric motor are reversely driven immediately before the internal combustion engine stops.