U.S. patent application number 15/008008 was filed with the patent office on 2016-07-28 for electric regenerative turbocharger.
This patent application is currently assigned to Hitachi, Ltd.. The applicant listed for this patent is Hitachi, Ltd.. Invention is credited to Yuji ENOMOTO, Hiroshi KIMURA, YUUKI OKUDA.
Application Number | 20160215781 15/008008 |
Document ID | / |
Family ID | 56433997 |
Filed Date | 2016-07-28 |
United States Patent
Application |
20160215781 |
Kind Code |
A1 |
OKUDA; YUUKI ; et
al. |
July 28, 2016 |
ELECTRIC REGENERATIVE TURBOCHARGER
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.
Inventors: |
OKUDA; YUUKI; (Tokyo,
JP) ; KIMURA; Hiroshi; (Tokyo, JP) ; ENOMOTO;
Yuji; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi, Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Hitachi, Ltd.
Tokyo
JP
|
Family ID: |
56433997 |
Appl. No.: |
15/008008 |
Filed: |
January 27, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02T 10/166 20130101;
F01N 2240/36 20130101; Y02T 10/12 20130101; Y02T 10/144 20130101;
F02C 6/12 20130101; F02B 37/00 20130101; F04D 25/0673 20130101;
F04D 25/024 20130101; F04D 25/06 20130101; F04D 17/10 20130101;
Y02T 10/16 20130101; F05D 2220/62 20130101; F02B 37/18 20130101;
F01N 5/04 20130101; F05D 2220/76 20130101 |
International
Class: |
F04D 25/06 20060101
F04D025/06; F04D 17/10 20060101 F04D017/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 26, 2015 |
JP |
2015-011938 |
Claims
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.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] 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.
[0003] 2. Description of the Related Art
[0004] 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.
[0005] 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
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] FIG. 1 is a diagram describing configurations of electric
regenerative turbochargers of first and second embodiments of the
present invention;
[0012] FIG. 2 is a diagram for describing a comparative example
with respect to the second embodiment of the invention;
[0013] 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;
[0014] FIG. 4 is a diagram for describing a configuration of an
electric regenerative turbocharger of a third embodiment of the
invention;
[0015] FIG. 5 is a diagram for describing a configuration of an
electric regenerative turbocharger of a fourth embodiment of the
invention;
[0016] 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;
[0017] 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;
[0018] 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;
[0019] FIG. 9 is a diagram for describing a configuration of a
turbocharger when electric motion is started in a fifth embodiment
of the invention;
[0020] 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
[0021] 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
[0022] Embodiments of electric regenerative turbochargers of the
present invention will be described below with reference to the
drawings.
First Embodiment
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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
[0052] A second embodiment will be described using FIG. 1.
[0053] 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.
[0054] 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.
[0055] 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
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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
[0072] 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.
[0073] A basic configuration of the fourth embodiment is the same
as those of the above-described embodiments.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] 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).
[0087] 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
[0088] 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.
[0089] 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).
[0090] 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.
[0091] 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.
[0092] 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.
[0093] 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.
[0094] 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
[0095] A seventh embodiment is characterized in that the
supercharging unit and the electric motor are reversely driven
before the internal combustion engine stops.
[0096] 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.
[0097] 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.
* * * * *