U.S. patent application number 17/329150 was filed with the patent office on 2021-12-16 for engine device.
The applicant listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Daigo ANDO, Masanao IDOGAWA, Sohichi IMAI, Shigeki NAKAYAMA.
Application Number | 20210388795 17/329150 |
Document ID | / |
Family ID | 1000005638784 |
Filed Date | 2021-12-16 |
United States Patent
Application |
20210388795 |
Kind Code |
A1 |
IMAI; Sohichi ; et
al. |
December 16, 2021 |
ENGINE DEVICE
Abstract
In an engine device, when executing normal control that performs
fuel injection and ignition as control of an engine, a controller
estimates, in the case of a stoichiometric air-fuel ratio, an
exhaust gas temperature based on first thermal energy that is based
on a combustion gas temperature, a combustion gas quantity, and
specific heat of combustion gas, estimates, in the case of a lean
air-fuel ratio, the exhaust gas temperature based on the first
thermal energy and second thermal energy that is based on an air
temperature, a surplus air quantity, and specific heat of air, and
estimates, in the case of a rich air-fuel ratio, the exhaust gas
temperature based on the first thermal energy and third thermal
energy that is based on a fuel temperature, a surplus fuel
quantity, specific heat of fuel, and evaporation latent heat of
fuel.
Inventors: |
IMAI; Sohichi; (Toyota-shi,
JP) ; NAKAYAMA; Shigeki; (Toyota-shi, JP) ;
IDOGAWA; Masanao; (Toyota-shi, JP) ; ANDO; Daigo;
(Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Aichi-Ken |
|
JP |
|
|
Family ID: |
1000005638784 |
Appl. No.: |
17/329150 |
Filed: |
May 25, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 2200/0802 20130101;
F02D 41/1447 20130101; F02D 2200/0804 20130101; F02D 43/04
20130101 |
International
Class: |
F02D 43/04 20060101
F02D043/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2020 |
JP |
2020-102774 |
Claims
1. An engine device, comprising an engine including an intake port,
a combustion chamber, and an exhaust port; and a controller
configured to control the engine and estimate an exhaust gas
temperature that is a temperature of exhaust gas discharged from
the combustion chamber and flowing through the exhaust port,
wherein when executing normal control that performs fuel injection
and ignition as control of the engine, the controller is configured
to estimate the exhaust gas temperature based on first thermal
energy in a case of a stoichiometric air-fuel ratio, the first
thermal energy being based on a combustion gas temperature, a
combustion gas quantity, and specific heat of combustion gas,
estimate the exhaust gas temperature based on the first thermal
energy and second thermal energy in a case of a lean air-fuel
ratio, the second thermal energy being based on an air temperature,
a surplus air quantity with respect to the case of the
stoichiometric air-fuel ratio, and specific heat of air, and
estimate the exhaust gas temperature based on the first thermal
energy and third thermal energy in a case of a rich air-fuel ratio,
the third thermal energy being based on a fuel temperature, a
surplus fuel quantity with respect to the case of the
stoichiometric air-fuel ratio, specific heat of fuel, and
evaporation latent heat of fuel.
2. The engine device according to claim 1, wherein when executing
the normal control as the control of the engine, the controller is
configured to estimate the exhaust gas temperature by dividing the
first thermal energy by first thermal capacity in the case of the
stoichiometric air-fuel ratio, the first thermal energy being
obtained as a product of the combustion gas temperature, the
combustion gas quantity, and the specific heat of combustion gas,
the first thermal capacity being obtained as a product of the
combustion gas quantity and the specific heat of combustion gas,
estimate the exhaust gas temperature by dividing a sum of the first
thermal energy and the second thermal energy by a sum of the first
thermal capacity and second thermal capacity in the case of the
lean air-fuel ratio, the second thermal energy being obtained as a
product of the air temperature, the surplus air quantity, and the
specific heat of air, the second thermal capacity being obtained as
a product of the surplus air quantity and the specific heat of air,
and estimate the exhaust gas temperature by dividing a sum of the
first thermal energy and the third thermal energy by a sum of the
first thermal capacity and third thermal capacity in the case of
the rich air-fuel ratio, the third thermal energy being obtained by
subtracting a product of the surplus fuel quantity and the
evaporation latent heat of fuel from a product of the fuel
temperature, the surplus fuel quantity, and the specific heat of
fuel, the third thermal capacity being obtained as a product of the
surplus fuel quantity and the specific heat of fuel.
3. The engine device according to claim 1, wherein when executing
non-ignition injection control that performs the fuel injection
without performing the ignition as the control of the engine, the
controller is configured to estimate the exhaust gas temperature
based on the second thermal energy and the third thermal energy,
the second thermal energy being obtained by using the quantity of
air passing through the combustion chamber and flowing to the
exhaust port as the surplus air quantity, the third thermal energy
being obtained by using the fuel injection quantity as the surplus
fuel quantity.
4. The engine device according to claim 3, wherein when executing
the non-ignition injection control as the control of the engine,
the controller is configured to estimate the exhaust gas
temperature by dividing a sum of the second thermal energy and the
third thermal energy by a sum of the second thermal capacity and
the third thermal capacity, the second thermal energy being
obtained as a product of the air temperature, the surplus air
quantity, and the specific heat of air, the third thermal energy
being obtained by subtracting a product of the surplus fuel
quantity and the evaporation latent heat of fuel from a product of
the fuel temperature, the surplus fuel quantity, and the specific
heat of fuel, the second thermal capacity being obtained as a
product of the surplus air quantity and the specific heat of air,
the third thermal capacity being obtained as a product of the
surplus fuel quantity and the specific heat of fuel.
5. The engine device according to claim 1, wherein when executing
fuel cut control that does not perform the fuel injection and the
ignition as the control of the engine, the controller is configured
to estimate the exhaust gas temperature based on a coolant
temperature of the engine, and a temperature of the exhaust pipe of
the engine.
6. The engine device according to claim 1, wherein: the engine
further includes a turbocharger having a turbine disposed in an
exhaust pipe and a compressor disposed in an intake pipe being
coupled through a coupling shaft; and when executing fuel cut
control that do not perform the fuel injection and the ignition as
the control of the engine, the controller is configured to estimate
the exhaust gas temperature based on a coolant temperature of the
engine, and a temperature of a turbine housing that houses the
turbine.
7. The engine device according to claim 5, wherein when executing
the fuel cut control as the control of the engine, the controller
is configured to estimate the exhaust gas temperature in
consideration of a flow velocity of air passing through the exhaust
port.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Japanese Patent
Application No. 2020-102774 filed on Jun. 15, 2020, incorporated
herein by reference in its entirety.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to an engine device.
2. Description of Related Art
[0003] As an engine device of this type, a device configured to
estimate exhaust gas temperature by using parameters has
conventionally been proposed, the parameters including a cylinder
gas temperature at the time of a bottom dead center of an engine, a
fuel injection quantity, an engine speed, the quantity of a
cylinder intake gas that is taken into a combustion chamber, and
specific heat of air (see, for example, Japanese Patent Application
Publication No. 2013-238147).
SUMMARY
[0004] The aforementioned engine device can accurately estimate the
exhaust gas temperature when an air fuel ratio is stoichiometric.
However, when the air fuel ratio is lean or rich, i.e., when air or
fuel is surplus with respect to the case of the stoichiometric air
fuel ratio, the exhaust gas temperature may be estimated less
accurately.
[0005] A primary object of the engine device of the present
disclosure is to accurately estimate exhaust gas temperature in the
case of a lean or rich air fuel ratio, in addition to the case of a
stoichiometric air fuel ratio.
[0006] The engine device of the present disclosure adopts following
means in order to accomplish the aforementioned primary object.
[0007] An engine device of the present disclosure includes an
engine and a controller. The engine includes an intake port, a
combustion chamber, and an exhaust port. The controller is
configured to control the engine, and estimate an exhaust gas
temperature that is a temperature of exhaust gas discharged from
the combustion chamber and flowing through the exhaust port. When
executing normal control that performs fuel injection and ignition
as control of the engine, the controller is configured to estimate
the exhaust gas temperature based on first thermal energy in the
case of a stoichiometric air-fuel ratio, the first thermal energy
being based on a combustion gas temperature, a combustion gas
quantity, and specific heat of combustion gas, estimate the exhaust
gas temperature based on the first thermal energy and second
thermal energy in the case of a lean air-fuel ratio, the second
thermal energy being based on an air temperature, a surplus air
quantity with respect to the case of the stoichiometric air-fuel
ratio, and specific heat of air, and estimate the exhaust gas
temperature based on the first thermal energy and third thermal
energy in the case of a rich air-fuel ratio, the third thermal
energy being based on a fuel temperature, a surplus fuel quantity
with respect to the case of the stoichiometric air-fuel ratio,
specific heat of fuel, and evaporation latent heat of fuel.
[0008] When executing normal control that performs fuel injection
and ignition as control of the engine, the engine device of the
present disclosure may be configured to estimate the exhaust gas
temperature based on first thermal energy in the case of a
stoichiometric air-fuel ratio, the first thermal energy being based
on a combustion gas temperature, a combustion gas quantity, and
specific heat of combustion gas, estimate the exhaust gas
temperature based on the first thermal energy and second thermal
energy in the case of a lean air-fuel ratio, the second thermal
energy being based on an air temperature, a surplus air quantity
with respect to the case of the stoichiometric air-fuel ratio, and
specific heat of air, and estimate the exhaust gas temperature
based on the first thermal energy and third thermal energy in the
case of a rich air-fuel ratio, the third thermal energy being based
on a fuel temperature, a surplus fuel quantity with respect to the
case of the stoichiometric air-fuel ratio, specific heat of fuel,
and evaporation latent heat of fuel. Hence, the exhaust gas
temperature can accurately be estimated in the case of the lean
air-fuel ratio (air is surplus with respect to the case of the
stoichiometric air-fuel ratio) and the case of the rich air-fuel
ratio (fuel is surplus with respect to the case of the
stoichiometric air-fuel ratio), in addition to the case of the
stoichiometric air-fuel ratio.
[0009] In the engine device of the present disclosure, when
executing the normal control as the control of the engine, the
controller may be configured to estimate the exhaust gas
temperature by dividing the first thermal energy by first thermal
capacity in the case of the stoichiometric air-fuel ratio, the
first thermal energy being obtained as a product of the combustion
gas temperature, the combustion gas quantity, and the specific heat
of combustion gas, the first thermal capacity being obtained as a
product of the combustion gas quantity and the specific heat of
combustion gas, estimate the exhaust gas temperature by dividing a
sum of the first thermal energy and the second thermal energy by a
sum of the first thermal capacity and second thermal capacity in
the case of the lean air-fuel ratio, the second thermal energy
being obtained as a product of the air temperature, the surplus air
quantity, and the specific heat of air, the second thermal capacity
being obtained as a product of the surplus air quantity and the
specific heat of air, and estimate the exhaust gas temperature by
dividing a sum of the first thermal energy and the third thermal
energy by a sum of the first thermal capacity and third thermal
capacity in the case of the rich air-fuel ratio, the third thermal
energy being obtained by subtracting a product of the surplus fuel
quantity and the evaporation latent heat of fuel from a product of
the fuel temperature, the surplus fuel quantity, and the specific
heat of fuel, the third thermal capacity being obtained as a
product of the surplus fuel quantity and the specific heat of
fuel.
[0010] In the engine device of the present disclosure, when
executing non-ignition injection control that performs the fuel
injection without performing the ignition as the control of the
engine, the controller may be configured to estimate the exhaust
gas temperature based on the second thermal energy and the third
thermal energy, the second thermal energy being obtained by using
the quantity of air passing through the combustion chamber and
flowing to the exhaust port as the surplus air quantity, the third
thermal energy being obtained by using the fuel injection quantity
as the surplus fuel quantity. With the above configuration, when
non-ignition injection control is executed, the exhaust gas
temperature can accurately be estimated.
[0011] In this case, when executing the non-ignition injection
control as the control of the engine, the controller may be
configured to estimate the exhaust gas temperature by dividing a
sum of the second thermal energy and the third thermal energy by a
sum of the second thermal capacity and the third thermal capacity,
the second thermal energy being obtained as a product of the air
temperature, the surplus air quantity, and the specific heat of
air, the third thermal energy being obtained by subtracting a
product of the surplus fuel quantity and the evaporation latent
heat of fuel from a product of the fuel temperature, the surplus
fuel quantity, and the specific heat of fuel, the second thermal
capacity being obtained as a product of the surplus air quantity
and the specific heat of air, the third thermal capacity being
obtained as a product of the surplus fuel quantity and the specific
heat of fuel.
[0012] In the engine device of the present disclosure, when
executing fuel cut control that does not perform the fuel injection
and the ignition as the control of the engine, the controller may
be configured to estimate the exhaust gas temperature based on a
coolant temperature of the engine, and a temperature of the exhaust
pipe of the engine. With this configuration, when fuel cut control
is considered, the exhaust gas temperature can accurately be
estimated. In this case, when executing the fuel cut control as the
control of the engine, the controller may be configured to estimate
the exhaust gas temperature in consideration of a flow velocity of
the air passing through the exhaust port. This makes it possible to
estimate the exhaust gas temperature more accurately.
[0013] In the engine device of the present disclosure, the engine
may further include a turbocharger having a turbine disposed in an
exhaust pipe and a compressor disposed in an intake pipe being
coupled through a coupling shaft. When executing fuel cut control
that does not perform the fuel injection and the ignition as the
control of the engine, the controller may be configured to estimate
the exhaust gas temperature based on a coolant temperature of the
engine, and the temperature of a turbine housing that houses the
turbine. Accordingly, in the configuration where the engine
includes a turbocharger, the exhaust gas temperature can accurately
be estimated even when the engine is executing the fuel cut
control. In this case, when executing the fuel cut control as the
control of the engine, the controller may be configured to estimate
the exhaust gas temperature in consideration of the flow velocity
of the air passing through the exhaust port. This makes it possible
to estimate the exhaust gas temperature more accurately.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Features, advantages, and technical and industrial
significance of exemplary embodiments of the present disclosure
will be described below with reference to the accompanying
drawings, in which like numerals denote like elements, and
wherein:
[0015] FIG. 1 is a block diagram showing an outlined configuration
of an engine device 10 of the present disclosure;
[0016] FIG. 2 is an explanatory view showing examples of input
output signals of an electronic control unit 70;
[0017] FIG. 3 is a flowchart showing an example of an exhaust gas
temperature estimation routine;
[0018] FIG. 4 is an explanatory view showing an example of a
reflection coefficient setting map;
[0019] FIG. 5 is a block diagram showing an outlined configuration
of an engine device 10B of a modification;
[0020] FIG. 6 is a block diagram showing an outlined configuration
of a turbocharger 40;
[0021] FIG. 7 is a block diagram showing an outlined configuration
of a cooling device 65;
[0022] FIG. 8 is an explanatory view showing examples of input
output signals of the electronic control unit 70; and
[0023] FIG. 9 is a flowchart showing an example of an exhaust gas
temperature estimation routine.
DETAILED DESCRIPTION OF EMBODIMENTS
[0024] Now, aspects for carrying out the present disclosure will be
described based on an embodiment.
[0025] FIG. 1 is a block diagram showing an outlined configuration
of an engine device 10 of the present disclosure. FIG. 2 is an
explanatory view showing examples of input output signals of an
electronic control unit 70. The engine device 10 of an embodiment
is mounted on general automobiles or various kinds of hybrid
automobiles. As shown in FIGS. 1 and 2, the engine device 10
includes an engine 12, a cooling device 60, and an electronic
control unit 70 as a controller.
[0026] The engine 12 is configured as a multi-cylinder (such as
4-cylinder, and 6-cylinder) internal combustion engine using
hydrocarbon fuel, such as gasoline and light oil, to output motive
power through four strokes including an intake stroke, a
compression stroke, an expansion stroke, and an exhaust stroke. In
the engine 12, an air cleaned by an air cleaner 22 is taken into an
intake pipe 23, and is allowed to pass through a throttle valve 26
and a surge tank 27 in this order. The air is then guided to an
intake port 29 connected to the intake pipe 23. Then, the air is
taken into the combustion chamber 30 from the intake port 29
through an intake valve 29a, and is exposed to fuel that is
injected from a cylinder injection valve 28 attached to the
combustion chamber 30. Accordingly, the air and the fuel are mixed,
and combusted by an electric spark provided by an ignition plug 31.
The energy of combustion pushes down a piston 32 to cause
reciprocating movement, which is converted into rotational movement
of a crankshaft 14. Exhaust gas is discharged from the combustion
chamber 30 to an exhaust port 34 through an exhaust valve 34a, and
is discharged to the ambient air through an exhaust pipe 35
connected to the exhaust port 34. The exhaust pipe 35 is equipped
with an exhaust gas control apparatus 37 and an exhaust gas control
apparatus 38 provided in this order from an upstream-side. The
exhaust gas control apparatuses 37, 38 have catalysts (three-way
catalysts) 37a, 38a, respectively, for removing harmful components
including carbon monoxides (CO), hydrocarbon (HC), and nitrogen
oxides (NOx).
[0027] The cooling device 60 cools an engine body 13 of the engine
12. The cooling device 60 includes a radiator 61, a circulation
passage 62 of the coolant, and a motor pump 63. The radiator 61
cools the coolant with running wind, an electric fan, or the like.
The circulation passage 62 is formed so as to include the radiator
61, a cylinder block, a cylinder head, and the like, of the engine
body 13. The motor pump 63 is provided in the circulation passage
62, and pumps the coolant.
[0028] The electronic control unit 70 is configured as a
microprocessor having a CPU as a main component. The electronic
control unit 70 includes, in addition to the CPU, a ROM that stores
processing programs, a RAM that temporarily stores data,
input-output ports, and a communication port. As shown in FIG. 2,
the electronic control unit 70 receives signals from various
sensors through the input port.
[0029] Examples of the signals input into the electronic control
unit 70 may include a crank angle .theta.cr from a crank position
sensor 14a that detects the rotational position of the crankshaft
14 of the engine 12, and a throttle opening TH from a throttle
position sensor 26a that detects the opening degree of the throttle
valve 26. Examples of the signals may also include a cam position
.theta.ca from an unillustrated cam position sensor that detects
the rotational position of an intake camshaft which opens and
closes the intake valve 29a and the rotational position of an
exhaust camshaft which opens and closes the exhaust valve 34a.
Examples of the signals may also include an intake air quantity Qin
from an air flowmeter 23a attached to the intake pipe 23 on the
upstream side of the throttle valve 26, an intake temperature Tin
from an intake temperature sensor 23t that is attached to the
intake pipe 23 on the upstream-side of the throttle valve 26, and
an intake pressure Pin from an intake pressure sensor 23b that is
attached to the intake pipe 23 on the upstream-side of the throttle
valve 26. Examples of the signals may also include a surge pressure
Ps from a surge pressure sensor 27a attached to a surge tank 27,
and a surge temperature (temperature of air) Ts from a surge
temperature sensor 27b attached to the surge tank 27. Examples of
the signals may also include a fuel temperature Tf from a fuel
temperature sensor 28a that detects the temperature of fuel
supplied to the cylinder injection valve 28. Examples of the
signals may also include an air-fuel ratio AF from an air-fuel
ratio sensor 39a attached to the exhaust pipe 35 on the
upstream-side of the exhaust gas control apparatus 37, and an
oxygen signal O2 from an oxygen sensor 39b attached to the exhaust
pipe 35 between the exhaust gas control apparatuses 37, 38.
Examples of the signals may also include a coolant temperature Tw
from a coolant temperature sensor 62t that detects the temperature
of the coolant in the circulation passage 62 of the cooling device
60. Examples of the signals may also include an atmospheric
pressure Pout from an atmospheric pressure sensor 71, and an
outside air temperature Tout from an outside air temperature sensor
72.
[0030] The electronic control unit 70 outputs various control
signals through the output port. Examples of the signals output
from the electronic control unit 70 may include a control signal to
the throttle valve 26 of the engine 12, a control signal to the
cylinder injection valve 28, and a control signal to the ignition
plug 31. Examples of the signals may also include a control signal
to the motor pump 63 of the cooling device 60. The electronic
control unit 70 calculates a speed Ne of the engine 12 based on the
crank angle .theta.cr from the crank position sensor 14a. The
electronic control unit 70 also calculates a load ratio (a ratio of
the volume of air actually taken in one cycle to a stroke volume of
the engine 12 per cycle) KL based on an intake air quantity Qa from
the air flowmeter 23a and the speed Ne of the engine 12.
[0031] In the thus-configured engine device 10 of the embodiment,
the electronic control unit 70 basically executes normal control as
control of the engine 12. In the normal control, the electronic
control unit 70 performs control such as intake air quantity
control that controls the opening degree of the throttle valve 26,
fuel injection control that controls the quantity of fuel injection
from the cylinder injection valve 28, and ignition control that
controls ignition timing of the ignition plug 31, based on a
request load factor KL* of the engine 12.
[0032] The electronic control unit 70 also executes non-ignition
injection control as control of the engine 12, when warm-up of the
catalysts 37a, 38a in the exhaust gas control apparatuses 37, 38 is
requested in the state where a fuel cut condition is established.
The electronic control unit 70 executes the fuel cut control as
control of the engine 12, when warm-up of the catalysts 37a and 38a
is requested. Examples of the fuel cut condition includes a
condition that the accelerator is turned off during travel of a
vehicle mounted with the engine device 10. The warm-up of the
catalysts 37a, 38a is request when it is assumed that the catalysts
37a, 38a are not activated, such as when the coolant temperature Tw
is equal to or less than a threshold Twref. In the non-ignition
injection control, the electronic control unit 70 performs
injection of a minute quantity of fuel from the cylinder injection
valve 28, and does not perform ignition by the ignition plug 31. In
the fuel cut control, the electronic control unit 70 performs
neither the fuel injection from the cylinder injection valve 28 nor
ignition by the ignition plug 31.
[0033] Description is now given of operation of the thus-configured
engine device 10 of the embodiment, and operation of estimating an
exhaust gas temperature Teg in particular. The exhaust gas
temperature Teg is a temperature of the exhaust gas (gas including
at least one of combustion gas, surplus air, and surplus fuel
(surplus evaporated fuel) described later) discharged from the
combustion chamber 30 and flowing through the exhaust port 34. FIG.
3 is a flowchart showing an example of an exhaust gas temperature
estimation routine which is repeatedly executed by the electronic
control unit 70, when normal control or non-ignition injection
control is executed as control of the engine 12.
[0034] When the exhaust gas temperature estimation routine of FIG.
3 is executed, the electronic control unit 70 first determines
which control, out of normal control, non-ignition injection
control, and fuel cut control, is executed as control of the engine
12 (step S100). When determining that the normal control is
executed as control of the engine 12, the electronic control unit
70 inputs data such as a combustion gas temperature Tc, an air
temperature Ta, a fuel temperature Tf, a combustion gas quantity
Qst, a surplus air quantity Qsa, and a surplus fuel quantity Qsf
(step S110).
[0035] Here, the combustion gas temperature Tc is the temperature
of combustion gas that is the gas combusted in the combustion
chamber 30 and discharged to the exhaust port 34. As the combustion
gas temperature Tc, a value estimated based on the speed Ne and the
load ratio KL of the engine 12 can be input. The air temperature Ta
is the temperature of surplus air that is the air (surplus with
respect to the case of the stoichiometric air-fuel ratio)
discharged to the exhaust port 34 without contributing to
combustion in the combustion chamber 30. As the air temperature Ta,
the coolant temperature Tw detected by the coolant temperature
sensor 62t can be input. This is because the temperature of air
approaches the coolant temperature Tw (temperature of the engine
body 13), when the air flows through the intake port 29, the
combustion chamber 30, and the exhaust port 34 in this order. The
fuel temperature Tf is the temperature of surplus fuel that is the
fuel (surplus with respect to the case of the stoichiometric
air-fuel ratio) discharged to the exhaust port 34 without
contributing to combustion in the combustion chamber 30. As the
fuel temperature Tf, a value detected by the fuel temperature
sensor 28a can be input.
[0036] As the combustion gas quantity Qst, the surplus air quantity
Qsa, and the surplus fuel quantity Qsf, values estimated based on
the intake air quantity Qin and the fuel injection quantity Qf can
be input. The surplus air quantity Qsa takes a positive value in
the case of the lean air-fuel ratio, and takes a value zero in the
case of the stoichiometric or rich air-fuel ratio. The surplus fuel
quantity Qsf takes a positive value in the case of the rich
air-fuel ratio, and takes a value zero in the case of the
stoichiometric or lean air-fuel ratio.
[0037] When data input is performed in this way, the electronic
control unit 70 estimates the exhaust gas temperature Teg by an
expression (1) using the input parameters including the combustion
gas temperature Tc, the combustion gas quantity Qst, the air
temperature Ta, the surplus air quantity Qsa, the fuel temperature
Tf, and the surplus fuel quantity Qsf (step S120). Then, the
electronic control unit 70 ends the present routine. Here, in the
expression (1), "Cc" is specific heat of combustion gas, "Ca" is
specific heat of air (specific heat of surplus air), "Cf" is
specific heat of fuel (specific heat of surplus fuel), and "Lf" is
evaporation latent heat of fuel (evaporation latent heat of surplus
fuel). In a numerator on the right side of the expression (1), a
first term represents thermal energy of combustion gas (first
thermal energy), a second term represents thermal energy of surplus
air (second thermal energy), and third and fourth terms represent
thermal energy of surplus fuel (third thermal energy). In a
denominator on the right side of the expression (1), a first term
represents thermal capacity of combustion gas (first thermal
capacity), a second term represents thermal capacity of surplus air
(second thermal capacity), and a third term represents thermal
capacity of surplus fuel (third thermal capacity).
[ Expression .times. .times. 1 ] ##EQU00001## Teg = Tcc .times. Qsf
.times. Cc + Ta .times. Qsa .times. Ca + Tf .times. Qsf .times. Cf
- Qsf .times. Lf Qst .times. Cc + Qsa .times. Ca + Qsf .times. Cf (
1 ) ##EQU00001.2##
[0038] In the case of the stoichiometric air-fuel ratio, the
surplus air quantity Qsa and the surplus fuel quantity Qsf take a
value zero. Hence, the second term, the third term, and the fourth
term in the numerator, and the second term and the third term in
the denominator on the right side of the expression (1) take a
value zero. Therefore, the expression (1) can be expressed as an
expression (2). In the case of the lean air-fuel ratio, the surplus
fuel quantity Qsf takes a value zero. Hence, the third term and the
fourth term in the numerator and the third term in the denominator
on the right side of the expression (1) take a value zero, and
therefore the expression (1) can be expressed as an expression (3).
In the case of the rich air-fuel ratio, the surplus air quantity
Qsa takes a value zero. Hence, the second term in the numerator and
the second term in the denominator on the right side of the
expression (1) take a value zero, and therefore the expression (1)
can also be expressed as an expression (4). By estimating the
exhaust gas temperature Teg in this way, when the normal control is
executed, the exhaust gas temperature Teg can accurately be
estimated in the case of the lean and rich air-fuel ratios as well
as in the case of the stoichiometric air-fuel ratio.
[ Expression .times. .times. 2 ] Teg = Tc .times. Qsf .times. Cc
Qst .times. Cc ( 2 ) Teg = Tc .times. Qsf .times. Cc + Ta .times.
Qsa .times. Ca Qst .times. Cc + Qsa .times. Ca ( 3 ) Teg = Tc
.times. Qsf .times. Cc + Tf .times. Qsf .times. Cf - Qsf .times. Lf
Qst .times. Cc + Qsf .times. Cf ( 4 ) ##EQU00002##
[0039] When determining in step S100 that the non-ignition
injection control is executed as control of the engine 12, the
electronic control unit 70 inputs data such as the air temperature
Ta, the fuel temperature Tf, the surplus air quantity Qsa, and the
surplus fuel quantity Qsf (step S130). Here, the air temperature Ta
and the fuel temperature Tf can be input as in the process of step
S110. As the surplus air quantity Qsa, the intake air quantity Qin
detected by the air flowmeter 23a can be input. As the surplus fuel
quantity Qsf, the fuel injection quantity Qf from the cylinder
injection valve 28 can be input. When the non-ignition injection
control is executed, combustion does not occur in the combustion
chamber 30. Hence, the air taken in the combustion chamber 30 can
be regarded as the surplus air, and the fuel injected from the
cylinder injection valve 28 can be regarded as the surplus
fuel.
[0040] When data is input in this way, the electronic control unit
70 estimates the exhaust gas temperature Teg by an expression (5)
using input parameters including the air temperature Ta, the
surplus air quantity Qsa, the fuel temperature Tf, and the surplus
fuel quantity Qsf (step S120). Then, the electronic control unit 70
ends the present routine. Here, the expression (5) is obtained by
removing the first term of the numerator and the first term of the
denominator on the right side of the expression (1), considering
that combustion does not occur in the combustion chamber 30
(thermal energy and thermal capacity of the combustion gas can be
set to a value zero) when the non-ignition injection control is
executed. Since the exhaust gas temperature Teg is estimated in
this way, the exhaust gas temperature Teg can accurately be
estimated even when the non-ignition injection control is
executed.
[ Expression .times. .times. 3 ] ##EQU00003## Teg = Ta .times. Qsa
.times. Ca + Tf .times. Qsf .times. Cf - Qsf .times. Lf Qsa .times.
Ca + Qsf .times. Cf ( 5 ) ##EQU00003.2##
[0041] When determining that the fuel cut control is executed as
control of the engine 12 in step S100, the electronic control unit
70 inputs data such as a coolant temperature Tw of the engine 12,
an exhaust gas flow velocity Veg that is the flow velocity of
exhaust gas flowing through the exhaust port 34, and an exhaust
pipe temperature Tex that is the temperature of the exhaust pipe 35
(step S150). Here, as the coolant temperature Tw, a value detected
by the coolant temperature sensor 62t can be input. As the exhaust
gas flow velocity Veg, a value estimated based on the speed Ne of
the engine 12 can be input. As the exhaust pipe temperature Tex, a
value estimated based on the exhaust gas temperature Teg, the
outside air temperature Tout from the outside air temperature
sensor 72, and the like, can be input.
[0042] Once data is input in this way, the electronic control unit
70 sets a reflection coefficient keg based on the input exhaust gas
flow velocity Veg (step S160). Here, the reflection coefficient keg
can be set by applying the exhaust gas flow velocity Veg to a
reflection coefficient setting map. The reflection coefficient
setting map is set in advance as relationship between the exhaust
gas flow velocity Veg and the reflection coefficient keg through
experiments or analysis. FIG. 4 is an explanatory view showing an
example of the reflection coefficient setting map. As shown in FIG.
4, the reflection coefficient keg is set to be larger as the
exhaust gas flow velocity Veg is larger in the range larger than a
value zero and smaller than a value one. The reason thereof will be
described later.
[0043] Next, the electronic control unit 70 estimates the exhaust
gas temperature Teg by an expression (6) using the coolant
temperature Tw, the exhaust pipe temperature Tex, and the
reflection coefficient keg (step S170), and then ends the present
routine. Here, in the expression (6), the coolant temperature Tw is
used because the temperature of air approaches the coolant
temperature Tw (temperature of the engine body 13), when the air
flows through the intake port 29, the combustion chamber 30, and
the exhaust port 34 in this order. The exhaust pipe temperature Tex
is used because air receives heat from the exhaust pipe 35 having a
large thermal capacity, when flowing through the exhaust port 34.
By setting the reflection coefficient keg as described above, the
exhaust gas temperature Teg is estimated to be closer to the
coolant temperature Tw as the exhaust gas flow velocity Veg is
larger. This is because as the exhaust gas flow velocity Veg is
larger, the exhaust gas receives less heat quantity from the
exhaust pipe 35. By estimating the exhaust gas temperature Teg in
this way, the exhaust gas temperature Teg (temperature of the
exhaust gas flowing into the exhaust pipe 35 through the exhaust
port 34 to be specific) can accurately be estimated even when the
fuel cut control is executed.
[Expression 4]
Teg=Tex+(Tw-Tex).times.keg (6)
[0044] In the engine device 10 of the embodiment described in the
foregoing, when executing normal control as control of the engine
12 in the case of the stoichiometric air-fuel ratio, the electronic
control unit 70 estimates the exhaust gas temperature Teg based on
the thermal energy of the combustion gas based on the combustion
gas temperature Tc, the combustion gas quantity Qst, and the
specific heat of combustion gas Cc. When executing normal control
in the case of the lean air-fuel ratio, the electronic control unit
70 estimates the exhaust gas temperature Teg based on the thermal
energy of combustion gas and thermal energy of surplus air that is
based on the air temperature Ta, the surplus air quantity Qsa, and
a specific heat of air Ca. When executing the normal control in the
case of the rich air-fuel ratio, the electronic control unit 70
further estimates the exhaust gas temperature Teg based on the
thermal energy of combustion gas and the thermal energy of the
surplus fuel that is based on the fuel temperature Tf, the surplus
fuel quantity Qsf, a specific heat of fuel Cf, and an evaporation
latent heat of fuel Lf. Accordingly, during execution of the normal
control, the exhaust gas temperature Teg can accurately be
estimated in the case of the lean and rich air-fuel ratios, as well
as in the case of the stoichiometric air-fuel ratio.
[0045] In the engine device 10 of the embodiment, the engine 12
does not include a turbocharger. However, the engine 12 may include
a turbocharger. FIG. 5 is a block diagram showing an outlined
configuration of an engine device 10B of a modification. FIG. 6 is
a block diagram showing an outlined configuration of a turbocharger
40. FIG. 7 is a block diagram showing an outlined configuration of
a cooling device 65. FIG. 8 is an explanatory view showing examples
of the input output signals of the electronic control unit 70.
[0046] The engine device 10B including an engine 12B is different
from the engine device 10 including the engine 12 shown in FIG. 1
in the point that the engine 12B further includes component members
such as the turbocharger 40, an intercooler 25, and the cooling
device 65. Hereinafter, the configuration of the engine device 10B
different from that of the engine device 10 will be described.
[0047] As shown in FIGS. 5 and 6, the turbocharger 40 is configured
as a turbocharger including a turbine 41, a compressor 42, a
wastegate valve 44, and a blowoff valve 45. The turbine 41 is
disposed in the exhaust pipe 35 on the upstream-side of the exhaust
gas control apparatus 37. The compressor 42 is disposed in the
intake pipe 23 on the upstream-side of the throttle valve 26, and
is coupled with the turbine 41 through a coupling shaft 43.
Therefore, the compressor 42 is driven by the turbine 41. The
wastegate valve 44 is provided in a bypass pipe 36 that connects an
upstream portion and a downstream portion of the exhaust pipe 35
which are on the upstream side and the downstream side of the
turbine 41, respectively. The electronic control unit 70 controls
the wastegate valve 44. The blowoff valve 45 is provided in a
bypass pipe 24 that connects an upstream portion and a downstream
portion of the intake pipe 23 which are on the upstream side and
upstream side of the compressor 42, respectively. The electronic
control unit 70 controls the blowoff valve 45.
[0048] The turbine 41 is disposed in a turbine housing 51 of the
exhaust pipe 35. The compressor 42 is housed in a compressor
housing 52 of the intake pipe 23. The coupling shaft 43 is disposed
in a shaft housing 53 connected to the turbine housing 51 and the
compressor housing 52. The coupling shaft 43 is rotatably supported
by the shaft housing 53 through a bearing 53b. A boundary portion
between the turbine housing 51 and the shaft housing 53, and a
boundary portion between the compressor housing 52 and the shaft
housing 53 are each equipped with a seal ring 53s. In the shaft
housing 53, a passage 53w included in a circulation passage 67 of a
coolant of the cooling device 65 and an oil passage 53o that allows
lubricating oil to flow are also formed.
[0049] In the turbocharger 40, the opening degree of the wastegate
valve 44 is adjusted for adjusting a distribution ratio between the
quantity of exhaust gas flowing through the bypass pipe 36 and the
quantity of exhaust gas flowing through the turbine 41, adjusting
the rotational driving force of the turbine 41, adjusting the
quantity of air compressed by the compressor 42, and adjusting a
turbocharging pressure (intake pressure) of the engine 12. Here,
the distribution ratio is adjusted such that as the opening degree
of the wastegate valve 44 is smaller, the exhaust quantity flowing
through the bypass pipe 36 is made smaller and the exhaust quantity
flowing through the turbine 41 is made larger. When the wastegate
valve 44 is fully opened, the engine 12 operates like a natural
intake type engine that does not include the turbocharger 40.
[0050] In the turbocharger 40, when the blowoff valve 45 is opened
in the state where the pressure of the intake pipe 23 that is on
the downstream side of the compressor 42 is larger to some extent
than the pressure of the intake pipe 23 that is on the
upstream-side of the compressor 42, the surplus pressure that is on
the downstream side of the compressor 42 can be released. The
blowoff valve 45 may be configured as a check valve in place of the
valve controlled by the electronic control unit 70. The check valve
is opened when the pressure of the intake pipe 23 that is on the
downstream side of the compressor 42 becomes larger to some extent
than the pressure of the intake pipe 23 that is on the upstream
side of the compressor 42.
[0051] The intercooler 25 is disposed in the intake pipe 23 between
the compressor 42 and the throttle valve 26. As shown in FIG. 7,
the cooling device 65 cools the intercooler 25 and the shaft
housing 53 of the turbocharger 40. The cooling device 65 includes a
radiator 66, the circulation passage 67 of the coolant, and a motor
pump 68. The radiator 66 cools the coolant with running wind, an
electric fan, or the like. The circulation passage 67 is formed to
include the radiator 66, the intercooler 25, and the passage 53w in
the shaft housing 53 of the turbocharger 40 (see FIGS. 6 and 7).
The motor pump 68 is provided in the circulation passage 67 to pump
the coolant.
[0052] As shown in FIG. 8, examples of the signals input into the
electronic control unit 70 may include the same signals as in the
engine device 10. In addition, the examples of the signals may
include a turbocharging pressure Pc from a turbocharging pressure
sensor 23c that is attached to the intake pipe 23 between the
compressor 42 and the intercooler 25. The examples of the signals
output from the electronic control unit 70 may include, in addition
to the same signals as in the engine device 10, a control signal to
the wastegate valve 44, a control signal to the blowoff valve 45,
and a control signal to the motor pump 68 of the cooling device
65.
[0053] In the thus-configured engine device 10B of the
modification, when executing normal control as control of the
engine 12, the electronic control unit 70 performs intake air
quantity control, fuel injection control, and ignition control, and
additionally performs turbocharging control that controls the
opening degree of the wastegate valve 44, based on the required
load factor KL* of the engine 12. As described before, when the
wastegate valve 44 is fully opened, the engine 12 operates like a
natural intake type engine that does not include the turbocharger
40.
[0054] In the engine device 10B of the modification, the electronic
control unit 70 executes an exhaust gas temperature estimation
routine of FIG. 9 in place of the exhaust gas temperature
estimation routine of FIG. 3. The exhaust gas temperature
estimation routine of FIG. 9 is different from the exhaust gas
temperature estimation routine of FIG. 3 in the point that the
processes of steps S150, S170 are replaced with processes of steps
S152, S172. Hereinafter, description is given of the configuration
of the exhaust gas temperature estimation routine of FIG. 9
different from the configuration of the exhaust gas temperature
estimation routine of FIG. 3.
[0055] In the exhaust gas temperature estimation routine of FIG. 9,
when determining that the fuel cut control is executed as control
of the engine 12 in step S100, the electronic control unit 70
inputs the coolant temperature Tw and the exhaust gas flow velocity
Veg as in the process of step S150, and also inputs, in place of
the exhaust pipe temperature Tex that is the temperature of the
exhaust pipe 35, a turbine housing temperature Ttb that is the
temperature of the turbine housing 51 (step S152). Here, as the
here turbine housing temperature Ttb, a value estimated based on
the exhaust gas temperature Teg, the outside air temperature Tout
from the outside air temperature sensor 72, and the like, can be
input.
[0056] In step S160, the electronic control unit 70 sets the
reflection coefficient keg. The electronic control unit 70
estimates the exhaust gas temperature Teg by an expression (7)
using the coolant temperature Tw, the exhaust pipe temperature Tex,
and the reflection coefficient keg (step S172), and then ends the
present routine. Here, the expression (7) is different from the
expression (6) in the point that the exhaust pipe temperature Tex
is replaced with the turbine housing temperature Tth. In the
expression (7) the turbine housing temperature Tth is used in place
of the exhaust pipe temperature Tex, because when the engine
includes the turbocharger 40, the influence by the thermal capacity
of the turbine housing 51 is generally larger than the influence by
the thermal capacity of the exhaust pipe 35, and therefore when air
flows through the exhaust port 34, the air tends to receive more
heat from the turbine housing 51 than from the exhaust pipe 35. By
estimating the exhaust gas temperature Teg in this way, even when
the fuel cut control is executed in the engine including the
turbocharger 40, the exhaust gas temperature Teg (temperature of
the exhaust gas flowing into the turbine 41 through the exhaust
port 34 to be specific) can accurately be estimated.
[Expression 5]
Teg=Tth+(Tw-Tex).times.keg (7)
[0057] The engine device 10B of the modification is configured to
include the cooling device 60, and the cooling device 65. The
cooling device 60 includes the circulation passage 62 formed to
include a cylinder block, a cylinder head, and the like, of the
engine body 13. The cooling device 65 includes the circulation
passage 67 formed to include the intercooler 25 and the passage 53w
in the shaft housing 53 of the turbocharger 40. However, the engine
device 10B may include, in place of the cooling devices 60, 65, a
cooling device having a circulation passage formed to include both
the circulation passage 62 and the circulation passage 67.
[0058] In the engine device 10B of the modification, the
turbocharger 40 is configured as a turbocharger in which the
turbine 41 disposed in the exhaust pipe 35 and the compressor 42
disposed in the intake pipe 23 are coupled through the coupling
shaft 43. However, the turbocharger 40 may be configured as a
supercharger in which a compressor driven by the engine 12 or the
motor is disposed in the intake pipe 23. When the turbocharger 40
is configured as a supercharger, the turbine housing 51 (turbine
41) is not disposed in the exhaust pipe 35. In this case, the
exhaust gas temperature estimation routine of FIG. 3 may be
executed instead of the exhaust gas temperature estimation routine
of FIG. 9. When fuel cut control is executed, the exhaust gas
temperature Teg may be estimated based on the exhaust pipe
temperature Tex.
[0059] In the engine device 10 of the embodiment and the engine
device 10B of the modification, when the fuel cut control is
executed, the exhaust gas temperature Teg is estimated using the
reflection coefficient keg based on the exhaust gas flow velocity
Veg. However, in this case, the exhaust gas temperature Teg may be
estimated using a fixed reflection coefficient keg without taking
into consideration the exhaust gas flow velocity Veg.
[0060] In the engine device 10 of the embodiment and the engine
device 10B of the modification, the exhaust pipe temperature Tex
and the turbine housing temperature Tth are estimated based on the
exhaust gas temperature Teg, or the like. However, the exhaust pipe
35 and the turbine housing 51 may be equipped with temperature
sensors, and the exhaust pipe temperature Tex and the turbine
housing temperature Tth may be detected with these temperature
sensors.
[0061] In the embodiment, the engine device 10 is mounted on
general automobiles or various kinds of hybrid automobiles.
However, the engine device 10 may be mounted on vehicles other than
the automobiles, or may be mounted in stationary equipment, such as
construction equipment.
[0062] Description is given of correspondence relation between the
main elements of the embodiment and the main elements of the
present disclosure described in Summary. In the embodiment, the
engine 12 corresponds to the "engine", and the electronic control
unit 70 corresponds to the "control device".
[0063] Since the correspondence relation between the main elements
of the embodiment and the main elements of the present disclosure
described in Summary is merely an example for specific description
of the aspect for carrying out the present disclosure described in
Summary, the correspondence relation is not intended to limit the
elements of the present disclosure described in Summary More
specifically, the present disclosure disclosed in Summary should be
interpreted based on the description therein, and the embodiments
are merely specific examples of the present disclosure disclosed in
Summary
[0064] Although the aspects for carrying out the present disclosure
have been described using the embodiments, an applicable embodiment
of the present disclosure is not limited in any manner to the
embodiments disclosed. It should naturally be understood that the
present disclosure can be carried out in various aspects without
departing from the scope of the present disclosure.
[0065] The present disclosure is applicable in the fields such as
manufacturing of engine devices.
* * * * *