CN110621866B

CN110621866B - Temperature prediction device and temperature prediction method for internal combustion engine

Info

Publication number: CN110621866B
Application number: CN201780090825.9A
Authority: CN
Inventors: 筱木俊雄; 茶园史也; 川尻和彦; 友松允令; 入江太津治; 米泽宪一郎
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-05-26
Filing date: 2017-05-26
Publication date: 2020-07-14
Anticipated expiration: 2037-05-26
Also published as: CN110621866A; JP6261840B1; WO2018216211A1; JPWO2018216211A1

Abstract

A temperature prediction device and a temperature prediction method for an internal combustion engine are configured such that: an initial temperature of the internal combustion engine is predicted based on an intake pressure obtained as an external air pressure at a timing during a period from start of the internal combustion engine from a stopped state to start of rotation of the internal combustion engine, an intake pressure obtained as an intake representative pressure at a timing during a period from start of rotation of the internal combustion engine to start of combustion in the combustion chamber, and an engine speed obtained at the timing, and a temperature of the internal combustion engine after start of combustion is predicted using the predicted initial temperature.

Description

Temperature prediction device and temperature prediction method for internal combustion engine

Technical Field

The present invention relates to a temperature prediction device and a temperature prediction method for predicting the temperature of an internal combustion engine using the intake pressure in an intake pipe.

Background

Conventionally, an electronic control device called an ECU is mounted on a vehicle. The ECU is mainly configured using a microcomputer, and controls the operation of the vehicle internal combustion engine related to driving. Various parameters are associated with the operation control of such an internal combustion engine. As one of the parameters associated with the control, temperature information of the internal combustion engine is known.

Here, in the case of using feedback control in which a dedicated temperature sensor is disposed in the engine main body and the ECU performs control of the engine using the measurement result of the temperature sensor, it is difficult to perform appropriate control of the engine because a delay occurs from the measurement timing of the temperature sensor to the response timing of the ECU.

Therefore, the following methods are proposed: the temperature of the engine body at an arbitrary time is predicted using the temperature of the engine body at the time of engine startup, the temperature of the intake pipe at the arbitrary time, and a model for simulation (see patent document 1, for example). In the conventional technology described in patent document 1, as a configuration for knowing the temperature of the engine main body at the time of engine startup, there are proposed a direct detection configuration in which a dedicated temperature sensor is disposed in a housing of the engine main body and the temperature of the engine main body is directly detected by the temperature sensor, and an indirect detection configuration in which the temperature of the engine oil or the temperature of the cooling water of the engine is directly detected and the temperature of the engine main body is indirectly detected by temperature prediction based on the detection result.

In addition, the following methods are proposed: assuming that the temperature in the intake pipe at the time of starting the internal combustion engine coincides with the atmospheric temperature, the temperature of the intake pipe is predicted based on the pressure in the cylinder of the internal combustion engine and the atmospheric temperature around the internal combustion engine (for example, see patent document 2).

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-83240

Patent document 2: japanese patent laid-open No. 2006-132526

Disclosure of Invention

Problems to be solved by the invention

However, when the above-described direct detection structure is applied in order to know the temperature of the engine body, it is necessary to prepare a temperature sensor having heat resistance capable of withstanding the temperature rise of the engine body. Further, it is necessary to perform a work such as a work of drilling a hole for mounting the temperature sensor on the surface of the engine main body, a work of mounting the temperature sensor, and the like. In addition, when the indirect detection structure is applied to know the temperature of the engine body, it is necessary to prepare a heat-resistant temperature sensor capable of withstanding a temperature rise of the engine oil or the cooling water, as described above, and to perform the above operation.

That is, in the conventional technique described in patent document 1, even when either a direct detection structure or an indirect detection structure is applied in order to know the temperature of the engine main body, there is a possibility that the manufacturing cost and the work load are increased due to the increase in the number of wires and components. As a result, the component and manufacturing costs may be high.

In the conventional technique described in patent document 2, as described above, it is assumed that the temperature in the intake pipe at the time of starting the internal combustion engine matches the atmospheric temperature. Therefore, based on the time interval between when the internal combustion engine is started and when the internal combustion engine is stopped, the assumed range deviates, and the accuracy of prediction of the temperature may deteriorate. Therefore, for example, in the conventional technique described in patent document 1, when the temperature of the engine main body is predicted using the temperature of the intake pipe predicted by applying the conventional technique described in patent document 2, the accuracy of predicting the temperature of the engine main body may be further deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a temperature prediction device and a temperature prediction method for an internal combustion engine, which can predict the temperature of the internal combustion engine at a relatively low cost without using a dedicated temperature sensor that is compatible with high temperatures.

Means for solving the problems

A temperature prediction device for an internal combustion engine according to the present invention predicts a temperature of the internal combustion engine configured to cause combustion in a combustion chamber by performing an intake stroke in which outside air is taken into the combustion chamber from an intake pipe and igniting fuel injected into the outside air taken into the intake stroke, the temperature prediction device comprising: an external air pressure acquisition unit that acquires an intake air pressure in an intake pipe as an external air pressure at a timing during a period from when an internal combustion engine starts to start from a stopped state to when the internal combustion engine starts to rotate; an intake representative pressure acquisition unit that acquires an intake pressure as an intake representative pressure at a timing during a period from start of rotation of the internal combustion engine to start of combustion; a parameter information acquisition unit that acquires a rotation speed per unit time of an internal combustion engine; an initial temperature prediction unit that predicts an initial temperature of the internal combustion engine during a period from start-up to start of combustion based on the external air pressure acquired by the external air pressure acquisition unit, the representative intake air pressure acquired by the representative intake air pressure acquisition unit, and the rotation speed acquired by the parameter information acquisition unit; and a temperature prediction unit that predicts a temperature of the internal combustion engine after start of combustion using the initial temperature predicted by the initial temperature prediction unit.

A temperature prediction method for an internal combustion engine according to the present invention predicts a temperature of the internal combustion engine, the internal combustion engine being configured to perform an intake stroke in which outside air is taken into a combustion chamber from an intake pipe, and ignite fuel injected into the outside air taken into the intake stroke, thereby causing combustion in the combustion chamber, the temperature prediction method comprising: acquiring an intake pressure in an intake pipe as an external air pressure at a timing during a period from when the internal combustion engine starts to start from a stopped state to when the internal combustion engine starts to rotate; acquiring an intake pressure as an intake representative pressure at a timing during a period from start of rotation of the internal combustion engine to start of combustion, and acquiring a rotation speed per unit time of the internal combustion engine; predicting an initial temperature of the internal combustion engine during a period from start-up to start of combustion based on the acquired external air pressure, the representative intake air pressure, and the rotation speed; and a step of predicting the temperature of the internal combustion engine after the start of combustion using the predicted initial temperature.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to obtain a temperature prediction device and a temperature prediction method for an internal combustion engine, which can predict the temperature of the internal combustion engine at a relatively low cost without using a dedicated temperature sensor that can cope with high temperatures.

Drawings

Fig. 1 is a configuration diagram of an internal combustion engine provided with a temperature prediction device for an internal combustion engine according to embodiment 1 of the present invention.

Fig. 2 is a schematic diagram showing changes in pressure of an intake pipe of an internal combustion engine according to embodiment 1 of the present invention.

Fig. 3 is a schematic diagram showing the correlation between the intake air pressure and the body temperature in embodiment 1 of the present invention.

Fig. 4 is a flowchart showing a series of operations of the temperature prediction device for an internal combustion engine according to embodiment 1 of the present invention.

Fig. 5 is a schematic diagram showing changes in pressure in the intake pipe of the internal combustion engine according to embodiment 2 of the present invention.

Fig. 6 is a schematic diagram showing changes in pressure in the intake pipe of the internal combustion engine according to embodiment 3 of the present invention.

Fig. 7 is a schematic diagram showing changes in pressure in the intake pipe of the internal combustion engine according to embodiment 4 of the present invention.

Fig. 8 is a flowchart showing a series of operations of predicting the initial temperature by the temperature prediction apparatus for an internal combustion engine according to embodiment 4 of the present invention.

Detailed Description

Hereinafter, embodiments of a temperature prediction device and a temperature prediction method for an internal combustion engine disclosed in the present application will be described in detail with reference to the drawings. In the description of the drawings, the same reference numerals are given to the same or corresponding portions, and redundant description is omitted.

The following embodiments are examples, and the present invention is not limited to these embodiments. The internal combustion engine to which the present invention is applied is, for example, a vehicle internal combustion engine, and the following embodiments exemplify a case where the present invention is applied to a vehicle internal combustion engine.

Embodiment 1.

A temperature prediction device 121 for an internal combustion engine according to embodiment 1 will be described with reference to fig. 1. Fig. 1 is a configuration diagram of an internal combustion engine 100 including an internal combustion engine temperature prediction device 121 according to embodiment 1 of the present invention.

The internal combustion engine 100 is a power machine configured as follows: combustion is caused in the combustion chamber 105 by performing an intake stroke in which outside air is drawn into the combustion chamber 105 from the intake pipe 101a, and igniting fuel injected into the outside air drawn in the intake stroke. More specifically, the internal combustion engine 100 is a four-stroke gasoline internal combustion engine that operates with four strokes, i.e., an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, as one combustion cycle.

The internal combustion engine 100 includes an intake passage 101, an air cleaner 102, a throttle valve 103, an intake pressure sensor 104, a combustion chamber 105, a bypass passage 106, an idle speed control valve 107, a fuel pump 108, a fuel tank 109, an injector 110, an intake valve 111, an ignition plug 112, a piston 113, a piston rod 114, a crankshaft 115, an exhaust valve 116, an exhaust passage 117, a crank angle sensor 118, a three-way catalyst 119, an oxygen sensor 120, and a temperature prediction device 121.

The engine body 100a includes a piston 113 covered with a cylinder, a piston rod 114, a crankshaft 115, an intake valve 111, an exhaust valve 116, and an ignition plug 112 attached to a cylinder head, and a combustion chamber 105 located above the piston 113 and sandwiched between the piston 113 and the cylinder head.

An intake passage 101 of the internal combustion engine 100 is provided with an air cleaner 102, a throttle valve 103, and an intake pressure sensor 104 in this order from the upstream side.

The intake pressure sensor 104 detects the intake pressure of the gas in the intake pipe 101a corresponding to the intake passage 101 on the downstream side of the throttle valve 103. The intake air pressure sensor 104 is communicably connected to a temperature prediction device 121 described later, and supplies the detection result thereof to the temperature prediction device 121 as intake air pressure information.

In the intake passage 101, a bypass flow passage 106 and an idle speed control valve 107 are provided so as to communicate with the upstream side and the downstream side of the throttle valve 103.

An injector 110 for injecting and supplying fuel drawn up from a fuel tank 109 by a fuel pump 108 to the vicinity of the intake port is provided in the intake pipe 101a on the downstream side of the intake pressure sensor 104. The injector 110 is communicably connected to a temperature prediction device 121 described later.

An intake valve 111 for intake is provided in a combustion chamber 105 of the engine main body 100a, and the intake passage 101 is connected to the combustion chamber 105 via the intake valve 111. Further, an exhaust valve 116 for exhaust is provided in the combustion chamber 105, and the combustion chamber 105 is connected to an exhaust passage 117 via the exhaust valve 116.

An ignition plug 112 having an electrode protruding therefrom is provided in an upper portion of the combustion chamber 105. The ignition plug 112 is connected to a temperature estimation device 121 described later so as to be able to communicate with it. A piston 113 that reciprocates vertically is provided below the combustion chamber 105. Piston 113 is coupled to crankshaft 115 via piston rod 114.

A crank angle sensor 118 that detects the rotation angle of the crankshaft 115 is provided near the crankshaft 115. The crank angle sensor 118 is communicably connected to a temperature prediction device 121 described later, and supplies the detection result to the temperature prediction device 121 as crank angle information.

A three-way catalyst 119 for purifying NOx, HC, and CO in the combustion exhaust gas from the combustion chamber 105 is provided on the downstream side of the exhaust passage 117. An oxygen sensor 120 that detects the oxygen concentration in the exhaust gas is provided in the exhaust passage 117 upstream of the three-way catalyst 119. The oxygen sensor 120 is communicably connected to a temperature estimation device 121 described later, and supplies the detection result thereof to the temperature estimation device 121 as oxygen information.

The throttle valve 103 adjusts the opening degree of the throttle valve. The air from which dust is removed by the air cleaner 102 is supplied to the combustion chamber 105 through the intake passage 101. The throttle valve 103 controls the flow rate of air supplied to the combustion chamber 105 by adjusting the opening degree of the throttle valve. From the viewpoint of the driving side, the throttle valve 103 performs control for adjusting the opening degree of the throttle valve in accordance with the operation amount of an accelerator (not shown) operated by the driver. The idle speed control valve 107 provided in the bypass passage 106 adjusts the flow rate of air flowing through the bypass passage 106 in order to control the rotation speed of the internal combustion engine 100 during the idle operation of the internal combustion engine 100.

Injector 110 injects fuel into the air flowing through intake pipe 101a in front of intake valve 111 to form a mixture. The intake valve 111 supplies the formed mixture gas to the combustion chamber 105. The ignition plug 112 provided in the combustion chamber 105 ignites the mixture gas supplied to the combustion chamber 105 by a discharge spark to burn the mixture gas.

Work is applied to the outside by combustion of the mixed gas. Specifically, crankshaft 115 rotates via piston 113 and piston rod 114, and extracts rotational energy from combustion of the air-fuel mixture. The exhaust valve 116 discharges exhaust gas generated by combustion of the mixture gas into an exhaust passage 117 by an opening action.

A plurality of projections are provided at equal intervals in the circumferential direction on the outer circumferential portion of the rotor that rotates integrally with crankshaft 115. When the protrusions cross the crank angle sensor 118, the crank angle sensor 118 outputs a rectangular crank signal as crank angle information. In embodiment 1, as a specific example, the plurality of projections are provided at intervals of 30 degrees with respect to the center of the crankshaft 115.

The rotor has a plurality of projections provided at equal intervals, and the projections are partially arranged on the outer periphery of the rotor. With this configuration, temperature predicting device 121 can determine the position of piston 113 based on the detection value of crank angle sensor 118 if crankshaft 115 rotates 360 degrees at maximum. Therefore, the temperature predicting device 121 can recognize that the piston 113 reaches the top dead center and the bottom dead center. Further, if the internal combustion engine 100 is a four-stroke internal combustion engine, the temperature prediction device 121 can identify the detailed position of the piston 113 by determining the four strokes (i.e., the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke) of the engine body 100a based on the detection value of the crank angle sensor 118 and the detection value of the intake pressure sensor 104.

The temperature prediction device 121 outputs a command for fuel injection to the injector 110 in accordance with the position of the piston 113, thereby controlling the internal combustion engine 100 such as the fuel injection amount and the air-fuel ratio.

As described above, the temperature estimation device 121 is communicably connected to the intake pressure sensor 104, the injector 110, the ignition plug 112, the crank angle sensor 118, the oxygen sensor 120, and the like.

The temperature prediction device 121 is implemented by, for example, a microcomputer that executes arithmetic processing, a ROM (Read Only Memory) that stores data such as program data and fixed value data, a RAM (Random Access Memory) that updates and sequentially rewrites the stored data, a power supply, an output processing circuit, an input processing circuit, an a/D conversion circuit, a power device, a communication IC, and the like.

The temperature prediction device 121 predicts the temperature of the engine body 100a (hereinafter, referred to as body temperature) based on the detection value of the intake pressure sensor 104. The temperature predicting device 121 also performs control of the fuel injection amount from the injector 110 based on the predicted body temperature.

Next, the start of the internal combustion engine 100 will be described with reference to fig. 2. Fig. 2 is a schematic diagram showing changes in pressure in an intake pipe 101a of an internal combustion engine 100 according to embodiment 1 of the present invention. In fig. 2, the horizontal axis shows a crank number indicating a position of a piston, and the vertical axis shows an intake pressure Pm that is an internal pressure of the intake pipe 101 a.

In fig. 2, in consideration of the case where the crankshaft 115 rotates twice in one combustion cycle, a crank number corresponding to two revolutions is assigned to each of the plurality of projections provided at intervals of 30 ° on the outer peripheral portion of the rotor that rotates integrally with the crankshaft 115. As shown in fig. 2, in one combustion cycle, the protrusions are numbered 0 to 11 in order in the first cycle (i.e., the compression stroke and the expansion stroke) of the crankshaft 115, and the protrusions are numbered 12 to 23 in order in the second cycle (i.e., the exhaust stroke and the intake stroke) of the crankshaft 115.

When the internal combustion engine 100 is stopped and the power supply of the internal combustion engine 100 is turned OFF (OFF), the power supply of the temperature estimation device 121 is also turned OFF, and the power supply to the temperature estimation device 121 is stopped. In this case, the information items that the temperature estimation device 121 has acquired from the intake pressure sensor 104, the crank angle sensor 118, and the oxygen sensor 120 will disappear unless otherwise specified, unless they are stored in a memory.

Next, when the power supply of the temperature estimation device 121 is turned ON with the power supply of the internal combustion engine 100 turned ON (ON), the electric power is supplied to the temperature estimation device 121. In this case, the temperature estimation device 121 starts to acquire information from the intake pressure sensor 104, the crank angle sensor 118, and the oxygen sensor 120. Intake air pressure information acquired from the intake air pressure sensor 104 immediately after the power supply of the internal combustion engine 100 is turned ON can be processed as atmospheric pressure information around the vehicle ON which the internal combustion engine 100 is mounted.

Next, in starting the engine main body 100a, the starter motor or the like moves the piston 113 by rotating the crankshaft 115. During the start of the engine body 100a as described above, the temperature predicting device 121 detects that the engine body 100a is in the intake stroke using the respective pieces of information acquired from the crank angle sensor 118 and the intake pressure sensor 104.

In the intake stroke, the piston 113 moves down toward the bottom dead center, the intake valve 111 opens, and the exhaust valve 116 closes, so that the gas in the intake pipe 101a is introduced into the combustion chamber 105, and the gas pressure in the intake pipe 101a becomes negative. When piston 113 passes the bottom dead center, intake valve 111 closes, and thereafter, a transition is made from the intake stroke to the compression stroke.

The compression stroke is a stroke in which the piston 113 moving in the vertical direction in the cylinder with the rotation of the crankshaft 115 compresses the gas in the combustion chamber 105. The expansion stroke transferred from the compression stroke is a stroke for expanding gas in the combustion chamber 105 by the piston 113.

More specifically, in the compression stroke, the gas containing air introduced into the combustion chamber 105 as a main component is compressed in the combustion chamber 105 in accordance with the rise of the piston 113. When piston 113 reaches the vicinity of the top dead center, fuel is injected by injector 110 and intake valve 111 opens, so that the fuel is introduced into combustion chamber 105. Then, when the intake valve 111 is closed and the fuel is ignited in the combustion chamber 105 by the ignition plug 112, combustion is caused. During this period, in a state where both the intake valve 111 and the exhaust valve 116 are closed, an expansion stroke is formed, and the piston 113 descends toward the bottom dead center. Thereafter, when piston 113 reaches near bottom dead center, exhaust valve 116 opens, and combustion gas in combustion chamber 105 is discharged through exhaust passage 117.

On the other hand, the inside of the intake pipe 101a in the compression stroke, the expansion stroke, and the exhaust stroke, which are shifted from the intake stroke before the ignition by the ignition plug 112, is a state in which the intake valve 111 is closed and the throttle valve 103 is closed. During this period, outside air flows in through a gap of the throttle valve 103, and the inside of the intake pipe 101a changes to substantially atmospheric pressure. Before the transition from the compression stroke to the expansion stroke and before the start of fuel injection, the inside of the intake pipe 101a moves gas by a pressure difference caused by the vertical movement of the piston 113 and the opening and closing of the valve accompanying the vertical movement.

Here, the temperature of the subject predicted by the temperature prediction device 121 is a very important parameter in controlling the internal combustion engine 100. The initial temperature differs depending on the operating conditions under which the internal combustion engine 100 is stopped before starting the start of the internal combustion engine 100 and the elapsed time from the stop.

The initial temperature referred to herein is the temperature of the main body of the internal combustion engine 100 during the period from when the power supply of the internal combustion engine 100 is switched from OFF to ON and the internal combustion engine 100 starts to start from a stopped state until combustion starts in the combustion chamber 105.

Therefore, a test assuming that a different time has elapsed after the internal combustion engine 100 has completely stopped is performed focusing on the gas pressure inside the intake pipe 101a before fuel is injected in the internal combustion engine 100. Specifically, a gasoline internal combustion engine using a single cylinder was used as the

internal combustion engine

100, 5 kinds of initial temperatures (specifically, 25 ℃, 60 ℃, 80 ℃, 100 ℃, and 115 ℃) were set, and the fluctuation of the intake pressure after the start of the internal combustion engine 100 and until the start of combustion was examined.

When the power supply of the internal combustion engine 100 is switched from OFF to ON, detection signals from the intake pressure sensor 104, the crank angle sensor 118, and the oxygen sensor 120 provided in the internal combustion engine 100 are input to the temperature prediction device 121. At this time, since the pressure of the intake pipe 101a indicates the atmospheric pressure, the external air pressure (ambient pressure) outside the internal combustion engine 100 is known from the detection result of the intake pressure sensor 104.

When the power supply of the internal combustion engine 100 is switched from OFF to ON, the internal combustion engine 100 is started from a stopped state. When starting the engine body 100a, the starter motor or the like rotates the crankshaft 115, and the piston 113 starts moving. The pressure in the intake pipe 101a during a period from the start of the internal combustion engine 100 to the rotation of the crankshaft 115 approximately indicates the atmospheric pressure.

Then, when the intake stroke is started in accordance with the rotation of crankshaft 115, the gas in intake pipe 101a is introduced into combustion chamber 105, and therefore the gas pressure in intake pipe 101a decreases from atmospheric pressure to about 40 kPa. The pressure change in the intake stroke is fast, and the difference in pressure change cannot be seen for 5 initial temperatures.

As is apparent from the above, the intake air pressure detected by the intake air pressure sensor 104 during the period from the start of the internal combustion engine 100 from the stop state to the start of the rotation of the crankshaft 115 can be used as the external air pressure.

On the other hand, at the bottom dead center at which the intake stroke is changed to the compression stroke, a correlation is observed between the initial temperature and the intake pressure, exhibiting the following tendency: the higher the initial temperature, the higher the intake pressure at the bottom dead center becomes. Therefore, the intake pressure detected by the intake pressure sensor 104 when the piston 113 is at the bottom dead center at which the intake stroke is shifted to the compression stroke is used as the intake representative pressure.

The temperature test is performed in an environment where the internal combustion engine 100 is disposed, that is, in an environment where the outside air temperature and the outside air pressure are 25 ℃ and 1 atm, respectively. Further, the intake air pressure is affected by the outside air pressure and the outside air temperature. The moving speed of the gas flowing into the intake pipe 101a and the moving speed of the gas discharged from the intake pipe 101a and moving to the combustion chamber 105 depend on the number of revolutions per unit time of the engine body 100a (hereinafter, referred to as the engine speed).

Therefore, the experimental formula in which the above parameters are taken into consideration is obtained by performing the verification test at different outside air temperatures and different outside air pressures. The results are shown in formula (1). Fig. 3 is a schematic diagram showing the correlation between the intake air pressure and the body temperature in embodiment 1 of the present invention.

T_ENG ⁰＝a(P/P₀-b)^c·T₀ ^d·N_e ^e(1)

Wherein, in the formula (1),

T_ENG ⁰which indicates the initial temperature of the engine main body,

P₀which is indicative of the external air pressure,

p represents the intake air representative pressure,

T₀which represents the temperature of the outside air,

N_ethe rotational speed of the internal combustion engine is indicated,

a. b, c, d and e represent constants.

As is clear from the above formula (1) and fig. 3, the following are found: using the intake pressure detected by the intake pressure sensor 104, the initial temperature can be uniquely predicted.

As is clear from the above, even if the engine main body 100a is not provided with a dedicated sensor, wiring, a thermoelectric converter, and the like for obtaining the initial temperature, if the outside air pressure, the intake air representative pressure, the outside air temperature, and the engine speed are known, the initial temperature corresponding to the operating environment of the engine 100 can be predicted from the equation (1).

Here, the external air pressure is an intake air pressure (hereinafter referred to as a first pressure) detected by the intake air pressure sensor 104 during a period from the start of the internal combustion engine 100 from a stopped state to the start of rotation of the crankshaft 115. The temperature prediction device 121 is configured to: the intake pressure is acquired as the external air pressure at a timing during a period from when the internal combustion engine 100 starts to start from a stopped state to when the engine main body 100a starts to rotate. The function of acquiring the external air pressure is carried out by an external air pressure acquiring unit provided in the temperature predicting device 121.

The intake representative pressure is an intake pressure (hereinafter referred to as a second pressure) detected by intake pressure sensor 104 when piston 113 is at bottom dead center at which the transition from the intake stroke to the compression stroke occurs. The temperature prediction device 121 is configured to: the intake pressure is acquired as the intake representative pressure at a timing during a period from when the engine main body 100a starts rotating to when combustion starts in the combustion chamber 105. In embodiment 1, a specific example of the timing described above is a timing at which the piston 113 reaches bottom dead center at which the intake stroke shifts to the compression stroke. The function of acquiring the representative intake air pressure is performed by an intake air representative pressure acquiring unit provided in the temperature predicting device 121.

The outside air temperature is a value obtained by a method of direct detection by an outside air temperature sensor, a method of indirect prediction by a detection value of another sensor, or the like. The temperature predicting device 121 is configured to obtain the outside air temperature by this method. The function of acquiring the outside air temperature is performed by an outside air temperature acquiring unit provided in the temperature predicting device 121.

The engine speed is calculated based on the crank angle information detected by the crank angle sensor 118. In order to calculate the engine speed, specifically, a timer for measuring the time taken until a certain crank angle is detected is required in addition to the crank angle sensor 118. The temperature prediction device 121 is configured to: the engine speed is obtained by this method at a timing during a period from when the engine main body 100a starts rotating to when combustion starts in the combustion chamber 105. The function of acquiring the engine speed is carried out by a parameter information acquisition unit provided in the temperature estimation device 121.

The temperature prediction device 121 stores constants a to e according to the above equations (1) and (1) in a nonvolatile memory, or stores a mapping table determined based on the equations (1) and the constants in the nonvolatile memory. As described above, the temperature prediction device 121 acquires the external air pressure, the intake representative pressure, the external air temperature, and the engine speed. The temperature predicting device 121 calculates the initial temperature according to equation (1) using the acquired parameters and the stored constants a to e, and predicts the initial temperature. The function of predicting the initial temperature is carried out by an initial temperature predicting unit provided in the temperature predicting device 121.

Next, a method of sequentially predicting the main body temperature after the start of combustion using the predicted initial temperature as an initial value will be described. The main body temperature during the period from the start of the internal combustion engine 100 to the start of combustion is equivalent to the initial temperature predicted by the above method.

In contrast, after the start of combustion in the combustion chamber 105, the body temperature is predicted by the following method. That is, the body temperature after the time Δ t is calculated from the energy balance of the engine body 100a, and is predicted.

Here, let T be the body temperature at time T_ENG(T) the body temperature at time T + Δ T after Δ T has elapsed from time T is denoted by T_ENG(T + Δ T) and is set to T_ENG(t+Δt)-T_ENG(t)＝ΔT_ENGTime, Delta T_ENGThe,/Δ t can be expressed as in the formula (2). In addition, the total Q of the energy output from the engine body 100a_OUTCan be expressed as in the formula (3). In equation (3), the right-hand term 2 represents the heat dissipation amount, and the right-hand term 1 represents other output energy.

M·C_P·ΔT_ENG/Δt＝Q_IN-Q_OUT(2)

Q_OUT＝Σ(Qj)+β(T_ENG(t)-T₀) (3)

Wherein, in the formula (2) and the formula (3),

m represents the weight (kg) of the engine body 100a,

C_Prepresents the specific heat (J/(kg. k)) of the engine body 100a,

Q_INindicates the total sum (J/s) of the energy input to the engine body 100a,

Q_OUTrepresents the sum (J/s) of the energies output from the engine body 100a,

qj represents the output energy from the individual element j of the engine body 100a,

T₀represents the outside air temperature (K),

t represents the time(s),

β denotes a constant (W/K).

In addition, for Q_INIn other words, Q_INBecomes energy of the fuel flow rate supplied to the internal combustion engine 100.

The temperature prediction device 121 uses the constant M, C of the above equation (2), equation (3), and equation (2)_PAnd a constant β according to the expression (3) is stored in the nonvolatile memory the temperature predicting device 121 calculates the Q_IN、Q_OUTAnd Qj, and further obtaining the outside air temperature. Q obtained by using calculation by temperature prediction device 121_IN、Q_OUTAnd Qj, the obtained outside air temperature, and stored M, C_PAnd β solving equations (2) and (3) to calculate Δ T_ENGAnd use the Δ T_ENGPredicting the temperature T of the subject_ENG(t+Δt)。

The time Δ t represents, for example, a time interval of the fuel injection timing of the internal combustion engine 100. In the above calculation, the outside air temperature, which is the temperature in the initial state, is used. The temperature prediction device 121 obtains the outside air temperature by applying a method of direct detection by an outside air temperature sensor, a method of indirect prediction by a detection value of another sensor, or the like.

In this way, the temperature prediction device 121 predicts the body temperature after the start of combustion in the combustion chamber 105 from the energy balance of the engine body 100a using the predicted initial temperature. The function of predicting the main temperature after the start of combustion is performed by a temperature predicting unit provided in the temperature predicting device 121.

Next, a series of operations of the temperature estimation device 121 according to embodiment 1 will be described with reference to fig. 4. Fig. 4 is a flowchart showing a series of operations of the temperature prediction device 121 for an internal combustion engine according to embodiment 1 of the present invention.

In step S101, when the power supply of the engine main body 100a is switched from OFF to ON, the process proceeds to step S102.

In step S102, the temperature predicting device 121 obtains the initial temperature T to predict_ENG ⁰The process proceeds to step S103 for various parameters required. Specifically, the temperature prediction device 121 obtains the first pressure and the second pressure from the intake pressure sensor 104 as the external air pressure and the intake representative pressure, respectively, and obtains the external air temperature and the engine speed by the above-described method. The temperature prediction device 121 acquires constants a to e according to equations (1) and (1) from the nonvolatile memory.

In step S103, the temperature prediction device 121 predicts the initial temperature T according to the equation (1) using the various parameters and constants a to e acquired in step S102_ENG ⁰The process advances to step S104.

In step S104, the temperature prediction means 121 predicts the initial temperature T predicted in step S103_ENG ⁰Set as the main body temperature T_ENG(t), the process advances to step S105.

In step S105, the temperature estimation device 121 obtains Q for calculation_IN、Q_OUTAnd Qj, the process proceeds to step S106.

In step S106, the temperature estimation device 121 calculates Q using the various parameters acquired in step S105_IN、Q_OUTAnd Qj, the process advances to step S107.

In step S107, the temperature predicting device 121 uses Q calculated in step S106_IN、Q_OUTAnd Qj, and constant M, C_PAnd β, predicting the body temperature T according to the formula (2) and the formula (3)_ENG(t + Δ t). Thereafter, the process proceeds to step S108, and returns to step S104 in order to predict the body temperature after the further elapse of time.

In step S108, the temperature prediction means 121 predicts the temperature T of the subject based on the temperature T predicted in step S107_ENG(t + Δ t), the fuel injection amount from the injector 110 is controlled.

When the process returns from step S107 to step S104, the temperature prediction means 121 predicts the body temperature T predicted in step S107_ENG(T + Deltat) is set to the body temperature T_ENG(t), the process from step S104 onward is performed again. Thus, the temperature predicting means 121 predicts the initial temperature T by using the temperature T predicted in step S103_ENG ⁰The processing from step S104 onward is repeated to sequentially predict the body temperature and control the fuel injection amount as time elapses.

In this way, the temperature predicting means 121 controls fuel injection when fuel is injected, based on the predicted body temperature. The function of controlling the fuel injection is performed by a fuel injection control unit provided in the temperature prediction device 121.

As described above, according to embodiment 1, the configuration is such that: an initial temperature of an internal combustion engine main body is predicted based on an intake pressure obtained as an external air pressure at a timing during a period from start of the internal combustion engine from a stopped state to start of rotation of the internal combustion engine, an intake pressure obtained as an intake representative pressure at a timing during a period from start of rotation of the internal combustion engine to start of combustion in a combustion chamber, and an engine speed obtained at the timing, and a main body temperature of the internal combustion engine main body after start of combustion is predicted using the predicted initial temperature.

Conventionally, the structure is as follows: a temperature sensor is attached to the engine body, and combustion conditions (for example, adjustment of a throttle opening for setting an air flow rate) are controlled in accordance with a temperature state of the engine body. In contrast, in embodiment 1, since the configuration is as described above, the temperature of the engine main body after the start of combustion can be predicted without providing a temperature sensor to the engine main body.

With the above configuration, a dedicated temperature sensor for coping with a high temperature of the engine main body is not required, and as a result, processing of the engine main body accompanying mounting of the temperature sensor is not required, and wiring is not required. Therefore, the temperature of the engine main body can be predicted at a relatively low cost.

Although not mentioned in embodiment 1, the detection value of the oxygen sensor 120 provided in the exhaust passage 117 may be used for air-fuel ratio control of the internal combustion engine 100 or the like, or may be used as a limit value of the air-fuel ratio.

In embodiment 1, an example of the operation of the engine main body 100a is shown, but the present invention is not limited to this, and the opening/closing timing and the order of the exhaust valve 116 or the intake valve 111 may be changed in accordance with the characteristics of the engine main body 100 a.

This can be done, for example, as follows: at the time point of transition from the exhaust stroke to the intake stroke, the intake valve 111 and the exhaust valve 116 are simultaneously opened. Further, the opening and closing operations of intake valve 111 or exhaust valve 116 may be performed before piston 113 reaches the top dead center or the bottom dead center. The valve opening/closing timing is often determined by a camshaft that matches the rotation of crankshaft 115. However, for example, in the control of a so-called variable valve mechanism that changes the opening/closing timing of the valve, the temperature predicting device 121 may control the opening/closing timing of the valve until the internal combustion engine 100 reaches a preset temperature based on the predicted initial temperature.

The engine speed mentioned in embodiment 1 may be a local speed calculated from the time between adjacent protrusions provided on crankshaft 115.

In embodiment 1, the configuration in which the temperature prediction device 121 performs the temperature prediction of the internal combustion engine 100 and the operation control based on the temperature prediction has been described, but the configuration is not limited to this configuration. That is, for example, the following configuration may be adopted: an ECU that performs operation control based on temperature prediction is provided separately from the temperature prediction device 121.

Embodiment 2.

In embodiment 2 of the present invention, a temperature prediction device 121 for acquiring the intake air representative pressure is described, which is different from that of embodiment 1. Note that in embodiment 2, the description of the same points as those in embodiment 1 above is omitted, and the description is mainly focused on the differences from embodiment 1 above.

In embodiment 2, the basic configuration of the internal combustion engine 100 is the same as that of embodiment 1, but the control program incorporated in the temperature estimation device 121, specifically, the process of acquiring the intake air representative pressure executed by the temperature estimation device 121 is different from that of embodiment 1.

Fig. 5 is a schematic diagram showing changes in pressure in the intake pipe 101a of the internal combustion engine 100 according to embodiment 2 of the present invention.

As in embodiment 1, the starter motor or the like rotates the crankshaft 115 in accordance with the start of the engine main body 100 a. At this time, the temperature predicting device 121 detects the bottom dead center at which the engine body 100a shifts from the intake stroke to the compression stroke, using the information from the intake pressure sensor 104 and the crank angle sensor 118. After detecting the bottom dead center, the temperature predicting device 121 obtains the intake pressure from the intake pressure sensor 104 at the timing when the crank angle sensor 118 detects the projection with the crank number, for example, No. two, and sets the intake pressure as the intake representative pressure.

Here, in embodiment 1 above, the temperature prediction device 121 is configured to: at the timing when the position of the piston 113 reaches the bottom dead center, the intake pressure is acquired from the intake pressure sensor 104, and this intake pressure is taken as the intake representative pressure. However, in the actual engine main body 100a, the timing at which the position of the piston 113 reaches the bottom dead center is the timing at which the intake stroke shifts to the compression stroke, and therefore it is considered that the intake valve 111 is often in the opening and closing operation. In this case, since the amount of gas movement between intake pipe 101a and combustion chamber 105 is determined by the clearance between combustion chamber 105 and intake valve 111, a variation in intake pressure is likely to occur.

Therefore, in embodiment 2, the intake pressure detected by the intake pressure sensor 104 in the compression stroke and the expansion stroke after the position of the piston 113 exceeds the bottom dead center and the intake valve 111 closes until the exhaust valve 116 opens near the top dead center is set as the intake representative pressure.

That is, temperature estimation device 121 obtains the intake pressure as the intake representative pressure at a timing not at the time point when the position of piston 113 reaches bottom dead center as in embodiment 1 but during a period from the time point when piston 113 reaches bottom dead center at which the intake stroke shifts to the compression stroke until piston 113 passes through top dead center at which the compression stroke shifts to the expansion stroke and reaches the next bottom dead center. This makes it possible to use the intake air pressure, which has a relatively stable value and is not affected by the opening and closing of the valve, as the intake air representative pressure.

Further, in the expansion stroke, since the intake pressure gradually approaches the external air pressure, the difference in the intake pressure caused by the difference in the body temperature or the external air temperature is small. Therefore, when accuracy is taken into consideration, it is preferable to use the intake pressure detected by the intake pressure sensor 104 at the timing of the compression stroke after the intake valve 111 closes as the intake representative pressure.

As described above, according to embodiment 2, compared to the configuration of embodiment 1, the configuration is such that: the intake pressure is acquired as the intake representative pressure at a timing during a period from when the piston reaches bottom dead center at which the intake stroke is shifted to the compression stroke until when the piston passes through top dead center at which the compression stroke is shifted to the expansion stroke and reaches the next bottom dead center. Even in the case of such a configuration, the same effects as those of embodiment 1 can be obtained.

In embodiment 2, a case has been described in which one intake pressure detected by the intake pressure sensor 104 is used as the representative intake pressure at a certain specific timing, but the present invention is not limited to this.

That is, the average value of the plurality of intake pressures detected by the intake pressure sensor 104 at a plurality of consecutive timings may be used as the intake representative pressure. In this case, even when noise enters the detection value of the intake air pressure sensor 104, there is an effect that the noise can be mitigated.

Embodiment 3.

In embodiment 3 of the present invention, a temperature prediction device 121 for acquiring the intake air representative pressure is described, which is different from the processes of

embodiments

1 and 2. Note that in embodiment 3, the description of the same points as those in

embodiments

1 and 2 is omitted, and the description is mainly focused on the differences from

embodiments

1 and 2.

In embodiment 3, the basic configuration of the internal combustion engine 100 is the same as that of

embodiments

1 and 2 described above, but the control program incorporated in the temperature estimation device 121, specifically, the process of acquiring the intake air representative pressure executed by the temperature estimation device 121 is different from that of

embodiments

1 and 2 described above.

Fig. 6 is a schematic diagram showing changes in pressure in the intake pipe 101a of the internal combustion engine 100 according to embodiment 3 of the present invention.

As in embodiment 1, the starter motor or the like rotates the crankshaft 115 in accordance with the start of the engine main body 100 a. At this time, the temperature predicting device 121 detects the bottom dead center at which the engine body 100a shifts from the intake stroke to the compression stroke, using the information from the intake pressure sensor 104 and the crank angle sensor 118. After detecting the bottom dead center, the temperature predicting device 121 obtains the first intake pressure and the second intake pressure from the intake pressure sensor 104 at the timing when the crank angle sensor 118 detects the protrusions with the crank numbers, for example, No. two and No. five, respectively, and sets the differential pressure between these two intake pressures as the intake representative pressure.

That is, temperature estimation device 121 obtains the first intake pressure and the second intake pressure at two different timings, respectively, during a period from when piston 113 reaches bottom dead center at which the intake stroke is shifted to the compression stroke until piston 113 passes top dead center at which the compression stroke is shifted to the expansion stroke and reaches the next bottom dead center. The temperature prediction device 121 acquires the differential pressure between the first intake air pressure and the second intake air pressure acquired in this way as the intake air representative pressure.

This differential pressure can be replaced with the flow rate of the outside air flowing into the intake pipe 101a, accompanied by a time term. Here, when the time difference between the two timings is short, the outside air flowing into the intake pipe 101a is less likely to be affected by the body temperature, and conversely, when the time difference between the two timings is long, the outside air is more likely to be affected by the body temperature. Therefore, the influence of warming from the internal combustion engine to the inflow external air depending on the time difference of these timings must be considered in terms of thermal fluid mechanics, but the following advantages are obtained: the inflow of the outside air can be organized in the dimension along with the time term, and as a result, the body temperature can be predicted with higher accuracy.

As described above, according to embodiment 3, compared to the configuration of embodiment 1, the configuration is such that: the first intake pressure and the second intake pressure are respectively obtained at different timings during a period from when the piston reaches a bottom dead center at which the intake stroke is shifted to the compression stroke to when the piston passes a top dead center at which the compression stroke is shifted to the expansion stroke and reaches a next bottom dead center, and a differential pressure between the obtained first intake pressure and the second intake pressure is obtained as an intake representative pressure. Even in the case of such a configuration, the same effects as those of embodiment 1 can be obtained.

In embodiment 3, the timing at which the first intake air pressure and the second intake air pressure are respectively obtained from the intake air pressure sensor 104 is the timing at which the crank angle sensor 118 detects the protrusions with the crank numbers two and five after the bottom dead center, respectively, but the present invention is not limited to this.

That is, the timing of obtaining these two intake pressures may be a timing during a period from the compression stroke to completion of the expansion stroke and the exhaust stroke after the bottom dead center at which the intake stroke is shifted to the compression stroke. However, it is preferable that the timing at which the first intake air pressure (i.e., the first intake air pressure) is obtained is a timing at which the influence of the engine body 100a significantly appears, that is, a timing after and as close as possible to bottom dead center at which the transition from the intake stroke to the compression stroke occurs.

Embodiment 4.

In embodiment 4 of the present invention, a temperature predicting apparatus 121 for predicting an initial temperature by a method different from those in embodiments 1 to 3 will be described. In embodiment 4, the same points as those in embodiments 1 to 3 are not described, and the points different from those in embodiments 1 to 3 are mainly described.

In embodiment 4, the basic configuration of the internal combustion engine 100 is the same as that of embodiments 1 to 3, but the control program incorporated in the temperature estimation device 121, specifically, the operation of estimating the initial temperature by the temperature estimation device 121 is different from that of embodiments 1 to 3.

Fig. 7 is a schematic diagram showing a change in pressure of an intake pipe 101a of an internal combustion engine 100 according to embodiment 4 of the present invention.

In fig. 7, an example is assumed in which the piston 113 stops in the middle of the intake stroke when the internal combustion engine 100 is in a stopped state. As in embodiment 1, the starter motor or the like rotates the crankshaft 115 in accordance with the start of the engine main body 100 a. At this time, the temperature predicting device 121 detects the first bottom dead center of the first transition of the engine body 100a from the intake stroke to the compression stroke after the start of the engine body 100a, using the information from the intake pressure sensor 104 and the crank angle sensor 118. After the temperature predicting device 121 detects the first bottom dead center, the engine body 100a shifts from the compression stroke to the expansion stroke through the first top dead center, shifts from the expansion stroke to the exhaust stroke through the second bottom dead center, and shifts from the exhaust stroke to the intake stroke through the second top dead center.

After the engine main body 100a has shifted from the intake stroke to the compression stroke through the third bottom dead center, the temperature predicting device 121 obtains the intake pressure from the intake pressure sensor 104 at the timing when the crank angle sensor 118 detects the projection of the crank number, for example, No. two, and sets the intake pressure as the intake representative pressure.

Here, when the internal combustion engine 100 is started from a state in which the piston 113 is stopped in the middle of the intake stroke, even if the piston 113 moves to the bottom dead center after the start, the volume becomes smaller and the intake pressure becomes higher than in the case of fully intake in the intake stroke.

Therefore, in embodiment 4, the temperature predicting device 121 obtains the intake pressure from the intake pressure sensor 104 at the timing when the crank angle sensor 118 detects the projection with the crank number, for example, No. two, after detecting the bottom dead center of the transition from the intake stroke to the compression stroke using the information from the intake pressure sensor 104 and the crank angle sensor 118. When the acquired intake air pressure is higher than a preset pressure value, temperature predicting device 121 performs control so that the rotation of crankshaft 115 is continued.

Next, the temperature predicting device 121 does not operate the injector 110 and the ignition plug 112, obtains the intake pressure detected by the intake pressure sensor 104 in the second compression stroke after the third bottom dead center, and sets the intake pressure as the intake representative pressure.

That is, the temperature prediction device 121 is configured to: the intake pressure is acquired as the intake representative pressure at a timing during a period from when piston 113 reaches bottom dead center at which the intake stroke is shifted to the compression stroke until piston 113 passes top dead center at which the compression stroke is shifted to the expansion stroke and reaches the next bottom dead center, and when the acquired intake representative pressure is higher than the set pressure value, the intake pressure is acquired again as the intake representative pressure at a timing during the next period.

This configuration is effective, for example, when the piston 113 is in a state of stopping in the middle of the intake stroke as described above, or when an accurate detection value cannot be obtained such as a read error of the detection value of the intake pressure sensor 104 occurs. Thereby, improvement in reliability of the intake air representative pressure is achieved.

Next, a series of operations of predicting the initial temperature by the temperature predicting device 121 according to embodiment 4 of the present invention will be described with reference to fig. 8. Fig. 8 is a flowchart showing a series of operations of the temperature prediction device 121 for an internal combustion engine according to embodiment 4 of the present invention to predict the initial temperature.

In step S201, when the power supply of internal combustion engine 100 is switched from OFF to ON, the process proceeds to step S202.

In step S202, as the power supply of the internal combustion engine 100 is turned ON in step S201, the sensors such as the intake pressure sensor 104 and the crank angle sensor 118 are activated, and the process proceeds to step S203.

In step S203, the temperature estimation device 121 acquires the first pressure detected by the intake air pressure sensor 104 as the external air pressure, and the process proceeds to step S204.

In step S204, the temperature estimation device 121 acquires the outside air temperature by the method described in embodiment 1, and the process proceeds to step S205.

In step S205, temperature prediction device 121 controls crank shaft 115 to rotate by a starter motor or the like, and the process proceeds to step S206.

In step S206, the temperature prediction device 121 acquires the constants a to e according to the expression (1) and the expression (1) necessary for predicting the initial temperature from the nonvolatile memory, and the process proceeds to step S207.

In step S207, the temperature predicting device 121 detects the bottom dead center (first bottom dead center) at which the intake stroke shifts to the compression stroke, acquires the intake pressure from the intake pressure sensor 104 in the compression stroke, and the process proceeds to step S208.

In step S208, the temperature estimation device 121 determines whether the intake pressure acquired in step S207 is higher than a set pressure value. If the intake air pressure acquired in step S207 is higher than the set pressure value, the process returns to step S207.

When the process returns to step S207, the temperature predicting device 121 detects the bottom dead center (third bottom dead center) of the next transition from the intake stroke to the compression stroke, acquires the intake pressure from the intake pressure sensor 104 again during the compression stroke, and the process proceeds to step S208.

On the other hand, when the intake air pressure acquired in step S207 is equal to or lower than the set pressure value, the process proceeds to step S209.

In step S209, the temperature estimation device 121 acquires the engine speed by the method described in embodiment 1, and the process proceeds to step S210.

In step S210, the temperature estimation device 121 sets the intake air pressure equal to or lower than the set pressure value acquired in step S207 as the intake air representative pressure. Next, the temperature prediction device 121 predicts the initial temperature according to equation (1) using the intake representative pressure, the outside air pressure and the outside air temperature acquired in step S203 and step S204, the constants a to e acquired in step S206, and the engine speed acquired in step S209. Thereafter, the process advances to step S211.

In step S211, since the temperature prediction device 121 can predict the initial temperature in step S210, the temperature prediction device 121 controls the injector 110 and the ignition plug 112 to operate at a specific timing.

In this way, the temperature prediction device 121 is configured to: fuel injection at the time of first fuel injection is controlled based on the predicted initial temperature. The function of controlling the first fuel injection after the initial temperature prediction is performed by the first fuel injection control unit provided in the temperature prediction device 121.

As described above, according to embodiment 4, the configuration is such that: the intake pressure is acquired as the intake representative pressure at a timing during a period from when the piston reaches bottom dead center at which the piston is shifted from the intake stroke to the compression stroke to when the piston passes through top dead center at which the piston is shifted from the compression stroke to the expansion stroke and reaches the next bottom dead center, and the intake pressure is acquired again as the intake representative pressure at a timing during the next period when the acquired intake representative pressure is higher than the set pressure value. Even in the case of such a configuration, the same effects as those of embodiment 1 can be obtained.

Embodiment 5.

In embodiment 5 of the present invention, a temperature predicting apparatus 121 which is different from that of embodiment 1 above in a method of predicting a main body temperature after starting combustion in a combustion chamber 105 will be described. Note that in embodiment 5, the same points as those in embodiments 1 to 4 are not described, and the points different from embodiments 1 to 4 are mainly described.

In embodiment 5, the basic configuration of the internal combustion engine 100 is the same as that of embodiments 1 to 4, but the control program incorporated in the temperature estimation device 121, specifically, the operation of estimating the main temperature after the start of combustion performed by the temperature estimation device 121 is different from that of embodiments 1 to 4. The temperature estimation device 121 according to embodiment 5 estimates the initial temperature by the method according to any one of embodiments 1 to 4 described above.

The operation of predicting the main body temperature after the start of combustion by the temperature predicting device 121 is as follows. That is, in the process in which the intake air passes through the throttle valve 103, the intake pipe 101a, the intake valve 111, and the combustion chamber 105, the intake air temperature per unit time is obtained by modeling using the law of mass conservation, the state equation, the throttle equation, and other thermodynamic properties. Further, the intake air temperature and the main body temperature have a correlation, and the main body temperature can be predicted using the intake air temperature by substitution with an experimental formula.

Therefore, the temperature predicting device 121 obtains the intake air temperature by the above method, and predicts the main body temperature by using the correlation between the predicted initial temperature and the obtained intake air temperature.

As described above, according to embodiment 5, the configuration is such that: the predicted initial temperature and the acquired intake air temperature are used to predict the temperature of the main body of the internal combustion engine from the correlation between the temperature of the main body of the internal combustion engine and the intake air temperature. Even in the case of such a configuration, the same effects as those of the previous embodiments 1 to 4 can be obtained.

In the above embodiments, the case where the present invention is applied to the prediction of the temperature of the engine main body has been described, but the present invention is not limited to this, and the present invention may be applied to the prediction of the temperature of an element indicating substantially the same temperature fluctuation as the engine main body. For example, the present invention can be applied to, for example, prediction of the temperature of engine oil of an internal combustion engine, the temperature of cooling water of the internal combustion engine, and the like, in addition to the temperature of the engine body.

The external air pressure obtaining unit, the intake representative pressure obtaining unit, the parameter information obtaining unit, the initial temperature predicting unit, and the temperature predicting unit may be implemented by software by one control unit such as an ECU, or may be prepared as separate hardware.

The present invention is not limited to the specific details and representative embodiments described and illustrated above, and modifications and effects that can be easily derived by those skilled in the art are also included in the present invention. Accordingly, various modifications may be made without departing from the scope of the general invention as defined by the scope of the claims and their equivalents.

Description of reference numerals

100 internal combustion engine, 100a internal combustion engine body, 101 intake passage, 101a intake pipe, 102 air cleaner, 103 throttle valve, 104 intake pressure sensor, 105 combustion chamber, 106 bypass flow path, 107 idle control valve, 108 fuel pump, 109 fuel tank, 110 injector, 111 intake valve, 112 spark plug, 113 piston, 114 piston rod, 115 crankshaft, 116 exhaust valve, 117 exhaust passage, 118 crank angle sensor, 119 three-way catalyst, 120 oxygen sensor, 121 temperature prediction device.

Claims

1. A temperature prediction device for an internal combustion engine configured to perform an intake stroke in which outside air is taken into a combustion chamber from an intake pipe and ignite fuel injected into the outside air taken into the intake stroke, thereby causing combustion in the combustion chamber, the temperature prediction device comprising:

an external air pressure obtaining unit that obtains an intake air pressure in the intake pipe as an external air pressure at a timing during a period from when the internal combustion engine starts to start from a stopped state to when the internal combustion engine starts to rotate;

an intake representative pressure acquisition unit that acquires the intake pressure as an intake representative pressure at a timing during a period from when the internal combustion engine starts the rotation to when the combustion starts;

a parameter information acquisition unit that acquires a rotation speed per unit time of the internal combustion engine;

an initial temperature prediction unit that predicts an initial temperature of the internal combustion engine during a period from start of the start to start of the combustion based on the external air pressure acquired by the external air pressure acquisition unit, the representative intake air pressure acquired by the representative intake air pressure acquisition unit, and the rotation speed acquired by the parameter information acquisition unit; and

a temperature prediction unit that predicts a temperature of the internal combustion engine after the start of combustion using the initial temperature predicted by the initial temperature prediction unit.

2. The temperature prediction apparatus of an internal combustion engine according to claim 1,

the temperature prediction device for an internal combustion engine further comprises an outside air temperature acquisition unit for acquiring the outside air temperature,

the initial temperature prediction unit predicts the initial temperature based on the external air pressure acquired by the external air pressure acquisition unit, the representative intake air pressure acquired by the representative intake air pressure acquisition unit, the rotation speed acquired by the parameter information acquisition unit, and the external air temperature acquired by the external air temperature acquisition unit.

3. The temperature prediction apparatus of an internal combustion engine according to claim 2,

setting the external air pressure to P₀Setting the representative intake pressure to P and the rotational speed to N_eSetting the outside air temperature to T₀Constants are set as a, b, c, d and e, and the initial temperature is set as T_ENG ⁰When the temperature of the water is higher than the set temperature,

the initial temperature predicting section predicts the initial temperature according to the following equation,

T_ENG ⁰＝a(P/P₀-b)^c·T₀ ^d·N_e ^e。

4. the temperature prediction apparatus of an internal combustion engine according to any one of claims 1 to 3,

the internal combustion engine is configured to: further performing a compression stroke in which the gas in the combustion chamber is compressed by a piston that moves in association with the rotation, and an expansion stroke in which the gas in the combustion chamber is expanded by the piston,

the intake representative pressure acquiring unit acquires the intake pressure as the intake representative pressure at a timing during a period from when the piston reaches a bottom dead center at which the piston is shifted from the intake stroke to the compression stroke to when the piston passes a top dead center at which the piston is shifted from the compression stroke to the expansion stroke and reaches a next bottom dead center.

5. The temperature prediction apparatus of an internal combustion engine according to claim 4,

the intake representative pressure acquisition unit acquires the intake pressure as the intake representative pressure at a timing when the piston reaches the bottom dead center at which the piston shifts from the intake stroke to the compression stroke.

6. The temperature prediction apparatus of an internal combustion engine according to any one of claims 1 to 3,

the intake representative pressure acquiring unit acquires a first intake pressure and a second intake pressure at different timings during a period from when the piston reaches a bottom dead center at which the piston is shifted from the intake stroke to the compression stroke to when the piston passes a top dead center at which the piston is shifted from the compression stroke to the expansion stroke and reaches a next bottom dead center, and acquires a differential pressure between the acquired first intake pressure and the acquired second intake pressure as the intake representative pressure.

7. The temperature prediction apparatus of an internal combustion engine according to any one of claims 1 to 3,

the intake representative pressure acquiring unit acquires the intake pressure as the intake representative pressure at a timing during a period from when the piston reaches a bottom dead center at which the piston is shifted from the intake stroke to the compression stroke to when the piston passes a top dead center at which the piston is shifted from the compression stroke to the expansion stroke and reaches a next bottom dead center, and acquires the intake pressure again as the intake representative pressure at a timing during the next period when the acquired intake representative pressure is higher than a set pressure value.

8. The temperature prediction apparatus of an internal combustion engine according to any one of claims 1 to 3,

the temperature prediction device for an internal combustion engine further includes a fuel injection control unit that controls fuel injection when the fuel is injected, based on the temperature of the internal combustion engine after the start of combustion predicted by the temperature prediction unit.

9. The temperature prediction apparatus of an internal combustion engine according to any one of claims 1 to 3,

the temperature prediction device for an internal combustion engine further includes a primary fuel injection control unit that controls fuel injection at a time of first injecting the fuel after prediction of the initial temperature based on the initial temperature predicted by the initial temperature prediction unit.

10. A temperature prediction method of an internal combustion engine configured to perform an intake stroke in which outside air is taken into a combustion chamber from an intake pipe and ignite fuel injected into the outside air taken into the intake stroke to cause combustion in the combustion chamber, the temperature prediction method comprising:

acquiring an intake pressure in the intake pipe as an external air pressure at a timing during a period from when the internal combustion engine starts to start from a stopped state to when the internal combustion engine starts to rotate;

a step of acquiring the intake pressure as an intake representative pressure and acquiring a rotation speed per unit time of the internal combustion engine at a timing during a period from when the internal combustion engine starts the rotation to when the combustion starts;

predicting an initial temperature of the internal combustion engine during a period from start of the start to start of the combustion based on the acquired external air pressure, the acquired representative intake air pressure, and the acquired rotational speed; and

and predicting a temperature of the internal combustion engine after the start of combustion using the predicted initial temperature.