CN110621866B - Temperature prediction device and temperature prediction method of internal combustion engine - Google Patents

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 of internal combustion engine

technical field

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

Background technique

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

Here, in the case of adopting feedback control in which a dedicated temperature sensor is disposed on the main body of the internal combustion engine and the ECU performs the control of the internal combustion engine by using the measurement result of the temperature sensor, there is a possibility of a change from the measurement time of the temperature sensor to the response time of the ECU. delay, it is difficult to perform appropriate control of the internal combustion engine.

Therefore, a method has been proposed for predicting the temperature of the engine body at an arbitrary time using the temperature of the engine body at the time of starting the engine, the temperature of the intake pipe at an arbitrary time, and a simulation model (for example, refer to Patent Document 1). In the prior art described in Patent Document 1, as a structure for knowing the temperature of the internal combustion engine body at the time of starting the internal combustion engine, there has been proposed a method of disposing a dedicated temperature sensor on the casing of the internal combustion engine body and using the temperature sensor to directly detect the internal combustion engine body. A direct detection structure for temperature, and an indirect detection structure for indirectly detecting the temperature of the internal combustion engine main body by directly detecting the temperature of the engine oil or the temperature of the cooling water of the internal combustion engine, and through temperature prediction based on the detection result.

In addition, a method has been proposed for predicting the temperature of the intake pipe based on the pressure in the cylinder of the internal combustion engine and the atmospheric temperature around the internal combustion engine, assuming that the temperature in the intake pipe at the time of starting the internal combustion engine matches the atmospheric temperature (for example, refer to Patent Document 2).

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2005-83240

Patent Document 2: Japanese Patent Laid-Open No. 2006-132526

SUMMARY OF THE INVENTION

The problem 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 heat-resistant temperature sensor capable of withstanding the temperature rise of the engine body. In addition, it is necessary to perform work such as machining of a hole for mounting the temperature sensor on the surface of the internal combustion engine body, work for mounting the temperature sensor, and the like. In addition, when the above-mentioned indirect detection structure is applied to know the temperature of the internal combustion engine body, it is necessary to prepare a heat-resistant temperature sensor capable of withstanding the temperature rise of the engine oil or the cooling water, as described above, and the above-mentioned operation is also required.

That is, in the prior art described in Patent Document 1, in order to know the temperature of the internal combustion engine body, even if either of the direct detection structure and the indirect detection structure is applied, there is a possibility that the wiring and parts are enlarged due to the increase in wiring and components. This leads to an increase in manufacturing cost and work load. As a result, component and manufacturing costs are likely to remain high.

In the prior art 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 is equal to 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 prediction accuracy of the temperature may deteriorate. Therefore, for example, in the prior art described in Patent Document 1, when the temperature of the engine body is predicted by using the temperature of the intake pipe predicted by applying the prior art described in Patent Document 2, the temperature of the engine body is predicted to vary. The prediction accuracy is likely to deteriorate further.

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

means of solving problems

A temperature predicting device for an internal combustion engine of the present invention predicts the temperature of an internal combustion engine configured to perform an intake stroke in which external air is drawn into a combustion chamber from an intake pipe, and fuel injected into the external air drawn in the intake stroke. ignition to cause combustion in the combustion chamber, wherein the temperature predicting device includes an outside air pressure obtaining unit that obtains timing during a period from when the internal combustion engine starts from a stopped state to when the internal combustion engine starts to rotate , the intake air pressure in the intake pipe is obtained as the external air pressure; the intake representative pressure obtaining unit, the intake representative pressure obtaining unit obtains the intake air pressure as an intake air representative pressure; a parameter information obtaining unit that obtains the rotational speed per unit time of the internal combustion engine; an initial temperature predicting unit that is based on the outside air pressure, the intake air obtained by the outside air pressure obtaining unit The intake air representative pressure acquired by the representative pressure acquisition unit and the rotational speed acquired by the parameter information acquisition unit are used to predict the initial temperature of the internal combustion engine in the period from the start of the start to the start of combustion; and a temperature prediction unit that uses the initial temperature prediction The initial temperature predicted by the part is used to predict the temperature of the internal combustion engine after the start of combustion.

The method for predicting the temperature of an internal combustion engine of the present invention predicts the temperature of an internal combustion engine configured to perform an intake stroke in which external air is drawn into a combustion chamber from an intake pipe and inject fuel into the external air drawn in the intake stroke. ignition to cause combustion in the combustion chamber, wherein the temperature prediction method includes acquiring the intake air pressure in the intake pipe as the outside air pressure at a timing during a period from when the internal combustion engine is started from a stopped state to when the internal combustion engine starts to rotate The step of obtaining the intake air pressure as the intake air representative pressure and the step of obtaining the rotational speed per unit time of the internal combustion engine at the timing during the period from the start of rotation of the internal combustion engine to the start of combustion; based on the obtained outside air pressure, intake air The step of predicting the initial temperature of the internal combustion engine during the period from the start of the start to the start of combustion, representing the pressure and the rotational speed, and the step of predicting the temperature of the internal combustion engine after the start of combustion using the predicted initial temperature.

effect of invention

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

Description of drawings

1 is a configuration diagram of an internal combustion engine including a temperature prediction device for an internal combustion engine according to Embodiment 1 of the present invention.

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

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

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

5 is a schematic diagram showing a pressure change in an intake pipe of an internal combustion engine according to Embodiment 2 of the present invention.

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

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

8 is a flowchart showing a series of operations for predicting the initial temperature of the internal combustion engine temperature predicting device according to Embodiment 4 of the present invention.

Detailed ways

Hereinafter, embodiments of the temperature prediction device and the temperature prediction method for an internal combustion engine disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, in description of drawings, the same code|symbol is attached|subjected to the same part or a corresponding part, and the repeated description is abbreviate|omitted.

In addition, the following embodiment is an example, and this invention is not limited by these embodiment. In addition, the internal combustion engine to which the present invention is applied is, for example, a vehicle internal combustion engine, and the following embodiments illustrate a case where the present invention is applied to a vehicle internal combustion engine.

Embodiment 1.

The temperature prediction device 121 of the 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: by performing an intake stroke in which the external air is drawn into the combustion chamber 105 from the intake pipe 101a, and by igniting the fuel injected into the external air drawn in the intake stroke, combustion is performed. Combustion is caused in the chamber 105 . More specifically, the internal combustion engine 100 is a four-stroke gasoline internal combustion engine that operates four strokes of 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 injection valve 110 , intake valve 111 , spark plug 112 , piston 113 , piston rod 114 , crankshaft 115 , exhaust valve 116 , exhaust passage 117 , crank angle sensor 118 , three-way catalyst 119 , oxygen sensor 120 and temperature prediction device 121 .

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

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

The intake pressure sensor 104 detects the intake pressure of the gas in the intake pipe 101 a 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 predicting device 121 to be described later, and provides a detection result thereof to the temperature predicting device 121 as intake pressure information.

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

In the intake pipe 101a, on the downstream side of the intake pressure sensor 104, an injector 110 that injects and supplies the fuel drawn from the fuel tank 109 by the fuel pump 108 to the vicinity of the intake port is provided. The ejector 110 is communicably connected to a temperature prediction device 121 to be described later.

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

In the upper part of the combustion chamber 105, a spark plug 112 with protruding electrodes is provided. The spark plug 112 is communicably connected to a temperature prediction device 121 to be described later. In the lower part of the combustion chamber 105, a piston 113 that reciprocates up and down is provided. The piston 113 is connected to the crankshaft 115 via a piston rod 114 .

In the vicinity of the crankshaft 115, a crank angle sensor 118 that detects the rotation angle of the crankshaft 115 is provided. The crank angle sensor 118 is communicably connected to a temperature predicting device 121 to be described later, and provides the detection result to the temperature predicting device 121 as crank angle information.

On the downstream side of the exhaust passage 117, a three-way catalyst 119 that purifies NOx, HC, and CO in the combustion exhaust gas from the combustion chamber 105 is provided. In the exhaust passage 117, on the upstream side of the three-way catalyst 119, an oxygen sensor 120 that detects the oxygen concentration in the exhaust gas is provided. The oxygen sensor 120 is communicably connected to a temperature prediction device 121 to be described later, and provides the detection result to the temperature prediction device 121 as oxygen information.

The throttle valve 103 adjusts the opening degree of the throttle valve. Air from which dust has been 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 driver, the throttle valve 103 controls the opening degree of the throttle valve according to the operation amount of the accelerator (not shown) operated by the driver. In addition, the idle control valve 107 provided in the bypass flow path 106 adjusts the flow rate of air flowing in the bypass flow path 106 in order to control the rotational speed of the internal combustion engine 100 during the idling operation of the internal combustion engine 100 .

The injector 110 injects fuel to the air flowing through the intake pipe 101a in front of the intake valve 111 to form an air-fuel mixture. The intake valve 111 supplies the formed air-fuel mixture to the combustion chamber 105 . The spark plug 112 provided in the combustion chamber 105 ignites the air-fuel mixture supplied to the combustion chamber 105 with a discharge spark, and combusts the air-fuel mixture.

Through the combustion of the mixed gas, work is done to the outside. Specifically, the crankshaft 115 rotates via the piston 113 and the piston rod 114 to extract rotational energy from the combustion of the air-fuel mixture. The exhaust valve 116 discharges the exhaust gas generated by the combustion of the air-fuel mixture into the exhaust passage 117 by opening operation.

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

Further, on the outer peripheral portion of the rotor, a tooth-missing portion is provided in which some of the protrusions provided at equal intervals are in a missing state. With this configuration, when the crankshaft 115 rotates at a maximum of 360 degrees, the temperature prediction device 121 can determine the position of the piston 113 based on the detection value of the crank angle sensor 118 . Therefore, the temperature prediction device 121 can recognize that the piston 113 has reached the top dead center and the bottom dead center. In addition, if the internal combustion engine 100 is a four-stroke internal combustion engine, the temperature predicting device 121 can determine the four strokes (that is, the intake stroke, the compression stroke) of the internal combustion engine body 100 a based on the detection value of the crank angle sensor 118 and the detection value of the intake pressure sensor 104 . , expansion stroke and exhaust stroke) and identify the detailed position of the piston 113.

The temperature prediction device 121 controls the internal combustion engine 100 such as the fuel injection amount and the air-fuel ratio by outputting a fuel injection command to the injector 110 according to the position of the piston 113 .

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

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

The temperature prediction device 121 predicts the temperature of the internal combustion engine main body 100a (hereinafter, referred to as the main body temperature) based on the detection value of the intake pressure sensor 104 . In addition, the temperature prediction device 121 controls the fuel injection amount from the injector 110 based on the predicted body temperature.

Next, starting of the internal combustion engine 100 will be described with reference to FIG. 2 . FIG. 2 is a schematic diagram illustrating a pressure change in the intake pipe 101a of the internal combustion engine 100 according to Embodiment 1 of the present invention. In FIG. 2 , the horizontal axis shows the crank number indicating the position of the piston, and the vertical axis shows the intake pressure Pm which is the internal pressure of the intake pipe 101a.

In addition, in FIG. 2 , since the case where the crankshaft 115 rotates twice in one combustion cycle is considered, for each of the plurality of protrusions provided at intervals of 30° on the outer peripheral portion of the rotor that rotates integrally with the crankshaft 115, Crank number indicating the amount of two revolutions. As shown in FIG. 2 , in a combustion cycle, in the first cycle of the crankshaft 115 (ie, the compression stroke and the expansion stroke), numbers from 0 to 11 are sequentially marked on the protrusions, and on the second cycle of the crankshaft 115 (ie, the row air stroke and intake stroke), and the numbers 12 to 23 are marked on each protrusion in sequence.

When the internal combustion engine 100 is stopped and the power supply of the internal combustion engine 100 is turned OFF, the power supply of the temperature prediction device 121 is also turned OFF, and the power supply to the temperature prediction device 121 is stopped. In this case, the respective pieces of information acquired by the temperature prediction device 121 from the intake pressure sensor 104, the crank angle sensor 118, and the oxygen sensor 120 so far will disappear unless they are stored in the memory.

Next, when the power source of the temperature predicting device 121 is turned on in accordance with the power-on (ON) of the internal combustion engine 100 , the power supply to the temperature predicting device 121 is performed. In this case, the temperature prediction device 121 starts to acquire each piece of information from the intake pressure sensor 104 , the crank angle sensor 118 , and the oxygen sensor 120 . The intake pressure information obtained from the intake 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, when the internal combustion engine body 100a is started, the crankshaft 115 is rotated by a starter motor or the like to move the piston 113. During the startup 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 .

During the intake stroke, the piston 113 descends to the bottom dead center, the intake valve 111 is opened, and the exhaust valve 116 is closed, so 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. pressure. When the piston 113 passes the bottom dead center, the intake valve 111 is closed, and after that, it is shifted from the intake stroke to the compression stroke.

The compression stroke is a stroke in which the gas in the combustion chamber 105 is compressed by the piston 113 that moves in the vertical direction in the cylinder with the rotation of the crankshaft 115 . The expansion stroke transferred from the compression stroke is a stroke in which the piston 113 expands the gas in the combustion chamber 105 .

More specifically, in the compression stroke, the gas whose main component is the air introduced into the combustion chamber 105 is compressed in the combustion chamber 105 along with the rise of the piston 113 . Then, when the piston 113 reaches the vicinity of the top dead center, the fuel is injected by the injector 110 and the intake valve 111 is opened, so that the fuel is introduced into the combustion chamber 105 . Combustion is then induced when the intake valve 111 is closed and the fuel is ignited within the combustion chamber 105 by the spark plug 112 . During this period, in a state in which both the intake valve 111 and the exhaust valve 116 are closed, an expansion stroke occurs, and the piston 113 descends to the bottom dead center. After that, when the piston 113 reaches the vicinity of the bottom dead center, the exhaust valve 116 is opened, and the combustion gas in the combustion chamber 105 is exhausted through the exhaust passage 117 .

On the other hand, the inside of the intake pipe 101a in the compression stroke, expansion stroke, and exhaust stroke shifted from the intake stroke before ignition by the spark plug 112 is in a state in which the intake valve 111 is closed and the throttle valve 103 is closed. During this period, outside air flows in from the gap of the throttle valve 103 or the like, and the inside of the intake pipe 101a changes to substantially atmospheric pressure. In addition, 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 the gas due to the pressure difference caused by the vertical movement of the piston 113 and the opening and closing of the valve associated therewith.

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

Note that the initial temperature referred to here refers to the main body temperature of the internal combustion engine 100 during the period after the power supply of the internal combustion engine 100 is switched from OFF to ON and the internal combustion engine 100 starts from the stopped state until the combustion in the combustion chamber 105 starts.

Therefore, focusing on the gas pressure inside the intake pipe 101a before the fuel is injected into the internal combustion engine 100, a test was carried out assuming different times elapsed after the internal combustion engine 100 was completely stopped. Specifically, a single-cylinder gasoline internal combustion engine was used as the internal combustion engine 100, and five initial temperatures (specifically, 25° C., 60° C., 80° C., 100° C., and 115° C.) were set. Fluctuation of intake pressure until combustion starts.

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 represents the atmospheric pressure, the outside air pressure (ambient pressure) outside the internal combustion engine 100 can be 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 internal combustion engine body 100a, the crankshaft 115 is rotated by a starter motor or the like, and the piston 113 starts to move. The pressure of the intake pipe 101a during the period after the start of the internal combustion engine 100 until the rotation of the crankshaft 115 substantially represents the atmospheric pressure.

Then, when the intake stroke starts with the rotation of the crankshaft 115, the gas in the intake pipe 101a is drawn into the combustion chamber 105, so the gas pressure in the intake pipe 101a drops from atmospheric pressure to about 40 kPa. The pressure change in this intake stroke is rapid, and no difference in pressure change can be seen for the 5 initial temperatures.

As can be seen from the above, the intake air pressure detected by the intake air pressure sensor 104 during the period from when the internal combustion engine 100 is started from the stopped state until the rotation of the crankshaft 115 is started can be used as the outside air pressure.

On the other hand, at the bottom dead center from the intake stroke to the compression stroke, a correlation was observed between the initial temperature and the intake pressure, showing a tendency that the higher the initial temperature, the higher the intake pressure at the bottom dead center. higher. Therefore, the intake air pressure detected by the intake air pressure sensor 104 when the piston 113 is located at the bottom dead center of the transition from the intake stroke to the compression stroke is used as the intake air representative pressure.

The above-mentioned temperature test was carried out under the arrangement environment of the internal combustion engine 100 , that is, in an environment in which the outside air temperature and outside air pressure were 25° C. and 1 atmosphere, respectively. In addition, the intake air pressure is affected by the outside air pressure and outside air temperature. In addition, 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 rotation speed per unit time of the engine body 100a (hereinafter referred to as engine rotation speed).

Therefore, verification tests were carried out under different outside air temperatures and different outside air pressures, and an experimental formula taking the above parameters into consideration was obtained. The result is shown in formula (1). 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/P ₀ -b) ^c ·T ₀ ^d ·N _e ^e (1)

Among them, in formula (1),

T _ENG ⁰ represents the initial temperature of the engine body,

P ₀ represents the outside air pressure,

P represents the intake pressure,

T ₀ represents the outside air temperature,

_Ne is the engine speed,

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

As can be seen from the above formula (1) and FIG. 3 , it was found that the initial temperature can be uniquely predicted using the intake air pressure detected by the intake air pressure sensor 104 .

In addition, as can be seen from the above, even if the internal combustion engine main body 100a is not provided with a dedicated sensor, wiring, thermoelectric converter, etc. for obtaining the initial temperature, if the outside air pressure, the representative intake air pressure, the outside air temperature, and the engine speed are known, the The initial temperature that also corresponds to the operating environment of the internal combustion engine 100 can also be predicted from the equation (1).

Here, the outside air pressure is the intake air pressure (hereinafter referred to as the first pressure) detected by the intake pressure sensor 104 during the period when the internal combustion engine 100 is started from the stopped state until the rotation of the crankshaft 115 is started. The temperature predicting device 121 is configured to acquire the intake air pressure as the outside air pressure at the timing between the start of the internal combustion engine 100 from the stopped state and the start of the rotation of the internal combustion engine body 100a. In addition, the function of acquiring the outside air pressure is undertaken by the outside air pressure acquiring unit included in the temperature prediction device 121 .

The intake air representative pressure is the intake air pressure (hereinafter referred to as the second pressure) detected by the intake air pressure sensor 104 when the piston 113 is at the bottom dead center of the transition from the intake stroke to the compression stroke. The temperature predicting device 121 is configured to acquire the intake air pressure as the intake air representative pressure at a timing between when the engine body 100a starts to rotate until the combustion starts in the combustion chamber 105 . In Embodiment 1, as a specific example of the above-described timing, the timing at which the piston 113 reaches the bottom dead center of the transition from the intake stroke to the compression stroke is exemplified. In addition, the function of acquiring the representative intake air pressure is performed by the intake air representative pressure acquiring unit included in the temperature prediction device 121 .

The outside air temperature is a value obtained by a method of direct detection using an outside air temperature sensor, a method of indirectly predicting using detection values of other sensors, or the like. The temperature prediction device 121 is configured to acquire the outside air temperature by this method. In addition, the function of acquiring the outside air temperature is undertaken by the outside air temperature acquiring unit included in the temperature prediction device 121 .

The engine rotational speed is calculated based on the crank angle information detected by the crank angle sensor 118 . Further, in order to calculate the engine speed, specifically, in addition to the crank angle sensor 118, a timer for measuring the time taken until a certain crank angle is detected is required. The temperature prediction device 121 is configured to acquire the engine rotational speed by this method at the timing during the period from the start of rotation of the engine body 100a to the start of combustion in the combustion chamber 105 . In addition, the function of acquiring the rotational speed of the internal combustion engine is undertaken by the parameter information acquiring unit included in the temperature predicting device 121 .

The temperature prediction device 121 stores the constants a to e related to the above equations (1) and (1) in the nonvolatile memory, or stores the mapping table determined from the equation (1) and the constants in the nonvolatile memory . As described above, the temperature prediction device 121 acquires the outside air pressure, the representative intake air pressure, the outside air temperature, and the engine speed. The temperature prediction device 121 uses these acquired parameters and stored constants a to e to calculate the initial temperature according to equation (1) to perform prediction. In addition, the function of predicting the initial temperature is assumed by the initial temperature predicting unit included 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 until the start of combustion is equivalent to the initial temperature predicted by the above-described method.

On the other hand, after the combustion in the combustion chamber 105 starts, the main body temperature is predicted by the following method. That is, the prediction is made based on the energy balance of the internal combustion engine main body 100a and the main body temperature after the calculation time Δt.

Here, let the main body temperature at time t be T _ENG (t), the main body temperature at time t+Δt after Δt from time t is T _ENG (t+Δt), and be T _ENG ( When t+Δt)−T _ENG (t)=ΔT _ENG , ΔT _ENG /Δt can be expressed as Equation (2). In addition, the total amount Q _OUT of the energy output from the internal combustion engine main body 100a can be expressed as Equation (3). In addition, in Equation (3), the second term on the right side represents the amount of heat dissipation, and the first term on the right side represents other output energy.

M·C _P ·ΔT _ENG /Δt=Q _IN -Q _OUT (2)

Q _OUT =Σ(Qj)+β(T _ENG (t)-T ₀ ) (3)

Among them, in formula (2) and formula (3),

M represents the weight (kg) of the internal combustion engine main body 100a,

C _P represents the specific heat (J/(kg·k)) of the internal combustion engine main body 100a,

Q _IN represents the sum (J/s) of energy input to the internal combustion engine main body 100a,

Q _OUT represents the total amount (J/s) of energy output from the internal combustion engine main body 100a,

Qj represents the output energy from the individual element j of the internal combustion engine main body 100a,

T ₀ represents the outside air temperature (K),

t represents time (s),

β represents a constant (W/K).

In addition, with respect to Q _IN , a part or all of Q _IN becomes the energy of the fuel flow rate supplied to the internal combustion engine 100 .

The temperature predicting device 121 stores the above-mentioned equations (2) and (3), the constants M and _CP related to the equation (2), and the constant β related to the equation (3) in the nonvolatile memory. The temperature prediction device 121 calculates the above-mentioned Q _IN , Q _OUT and Qj, and further obtains the outside air temperature. The temperature predicting device 121 calculates ΔT _ENG by solving equations (2) and (3) by using the calculated Q _IN , Q _OUT and Qj, the acquired outside air temperature, and the stored M, C _P and β. And using this ΔT _ENG , the bulk temperature T _ENG (t+Δt) is predicted.

In addition, the above-mentioned time Δt represents, for example, the time interval of the fuel injection timing of the internal combustion engine 100 . In addition, in the above calculation, the temperature in the initial state, that is, the outside air temperature is used. The temperature prediction device 121 obtains the outside air temperature by applying a method of direct detection using an outside air temperature sensor, a method of indirectly predicting using a detection value of another sensor, or the like.

In this way, the temperature prediction device 121 uses the predicted initial temperature to predict the main body temperature after the start of combustion in the combustion chamber 105 from the energy balance of the internal combustion engine main body 100a. In addition, the function of predicting the temperature of the main body after the start of combustion is performed by the temperature predicting unit included in the temperature predicting device 121 .

Next, a series of operations of the temperature prediction device 121 according to the first embodiment will be described with reference to FIG. 4 . 4 is a flowchart showing a series of operations of the internal combustion engine temperature prediction device 121 according to Embodiment 1 of the present invention.

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

In step S102, the temperature prediction device 121 ^acquires various parameters required for predicting the initial temperature _TENG0 , and the process proceeds to step S103. Specifically, the temperature predicting device 121 obtains the first pressure and the second pressure from the intake pressure sensor 104 as the outside air pressure and the intake air representative pressure, respectively, and obtains the outside air temperature and the engine speed by the above method. In addition, the temperature prediction device 121 acquires the constants a to e related to the equation (1) and the equation (1) from the nonvolatile memory.

In step S103, the temperature prediction device 121 predicts the initial temperature _TENG0 according to the formula (1 ⁾ using the various parameters and constants a to e acquired in step S102, and the process proceeds to step S104.

In step S104, the temperature prediction device 121 sets the initial temperature _TENG0 predicted in step ^S103 as the main body temperature _TENG (t), and the process proceeds to step S105.

In step S105, the temperature prediction device 121 acquires various parameters necessary for calculating Q _IN , Q _OUT and Qj, and the process proceeds to step S106.

In step S106, the temperature prediction device 121 calculates Q _IN , Q _OUT and Qj using the various parameters acquired in step S105, and the process proceeds to step S107.

In step _S107 , the temperature predicting device 121 _predicts the main body temperature _{T ENG} ( t+Δt). After that, the process proceeds to step S108, and returns to step S104 in order to predict the temperature of the main body after further elapse of time.

In step S108, the temperature prediction device 121 controls the fuel injection amount from the injector 110 based on the body temperature _TENG (t+Δt) predicted in step S107.

When the process returns from step S107 to step S104, the temperature predicting device 121 sets the body temperature T _ENG (t+Δt) predicted in step S107 as the body temperature T _ENG (t), and performs the processing after step S104 again. . In this way, the temperature predicting device 121 uses the initial temperature T _ENG ⁰ predicted in step S103 to repeat the processing of step S104 and subsequent steps, thereby sequentially predicting the body temperature and controlling the fuel injection amount over time.

In this way, the temperature prediction device 121 controls the fuel injection at the time of fuel injection based on the predicted body temperature. In addition, the function of controlling the fuel injection is performed by the fuel injection control unit included in the temperature prediction device 121 .

As described above, according to the first embodiment, the intake pressure obtained as the outside air pressure based on the timing in the period from the start of the internal combustion engine from the stopped state to the time when the internal combustion engine starts to rotate is configured to be in the combustion chamber after the internal combustion engine starts to rotate. The timing in the period until the start of combustion is obtained as the intake air pressure as the representative intake air pressure, and the engine speed obtained at the timing, the initial temperature of the engine body is predicted, and the predicted initial temperature is used to predict the internal combustion engine after the start of combustion. The body temperature of the body.

Conventionally, a temperature sensor is attached to the internal combustion engine body, and combustion conditions (for example, throttle opening adjustment for setting the air flow rate, etc.) are controlled according to the temperature state of the internal combustion engine body. On the other hand, in the first embodiment, since the configuration is as described above, even if the temperature sensor is not attached to the engine body, the temperature of the engine body after the start of combustion can be predicted.

With the above-described configuration, a dedicated temperature sensor for dealing with the high temperature of the internal combustion engine body is not required, and as a result, the processing of the internal combustion engine body accompanying the installation of the temperature sensor is not required, and wiring is not required. Therefore, the temperature of the internal combustion engine body can be predicted at relatively low cost.

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

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

For example, it may be operated in such a manner that the intake valve 111 and the exhaust valve 116 are simultaneously opened at the point of transition from the exhaust stroke to the intake stroke. In addition, the opening and closing operation of the intake valve 111 or the exhaust valve 116 may be performed before the piston 113 reaches the top dead center or the bottom dead center. In addition, the opening and closing timing of the valve is often determined according to the camshaft in accordance with the rotation of the crankshaft 115 . However, for example, regarding the control of a so-called variable valve mechanism that changes the valve opening and closing timing, the temperature predicting device 121 may control the period until the internal combustion engine 100 reaches a preset temperature based on the predicted initial temperature. valve opening and closing timing.

In addition, the rotational speed of the internal combustion engine mentioned in Embodiment 1 may be set as a local rotational speed in time calculated from the adjacent protrusions provided on the crankshaft 115 .

Furthermore, in Embodiment 1, the configuration in which the temperature prediction device 121 executes the temperature prediction of the internal combustion engine 100 and the operation control based on the temperature prediction has been described, but it is not limited to this configuration. That is, for example, a configuration may be adopted in which an ECU is provided independently of the temperature prediction device 121, and the ECU executes the operation control based on the temperature prediction.

Embodiment 2.

In Embodiment 2 of the present invention, the temperature predicting device 121 in which the process for obtaining the representative pressure of intake air is different from that in Embodiment 1 will be described. In addition, in this Embodiment 2, the description of the same point as the previous Embodiment 1 is abbreviate|omitted, and the point which is different from the previous Embodiment 1 is mainly demonstrated.

In the second embodiment, the basic structure of the internal combustion engine 100 is the same as that of the previous embodiment 1. On the other hand, a control program of the temperature predicting device 121 is incorporated. The acquisition process is different from the previous Embodiment 1.

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

As in the previous Embodiment 1, the crankshaft 115 is rotated by the starter motor or the like with the start of the internal combustion engine main body 100a. At this time, the temperature predicting device 121 detects the bottom dead center of the transition from the intake stroke to the compression stroke of the internal combustion engine body 100a using the respective information from the intake pressure sensor 104 and the crank angle sensor 118 . The temperature predicting device 121 acquires the intake air pressure from the intake air pressure sensor 104 at the timing when the crank angle sensor 118 detects the protrusion of the crank number 2, for example, after detecting the bottom dead center, and uses the intake air pressure as an intake air representative. pressure.

Here, in the previous Embodiment 1, the temperature prediction device 121 is configured to acquire the intake air pressure from the intake air pressure sensor 104 at the timing when the position of the piston 113 reaches the bottom dead center, and to use the intake air pressure as the intake air represents stress. However, in the actual internal combustion engine body 100a, since the timing at which the position of the piston 113 reaches the bottom dead center is the timing of transition from the intake stroke to the compression stroke, it can be considered that the intake valve 111 is in the opening and closing operation rather than the timing. many. In this case, since the amount of gas movement between the intake pipe 101a and the combustion chamber 105 is determined according to the gap between the combustion chamber 105 and the intake valve 111 , variations in intake pressure are likely to occur.

Therefore, in the second embodiment, the intake pressure is used 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 is closed until the exhaust valve 116 opens near the top dead center. The intake air pressure detected by the sensor 104 is taken as the intake air representative pressure.

That is, the temperature prediction device 121 does not reach the bottom dead center at the time when the position of the piston 113 reaches the bottom dead center as in the first embodiment, but after the time when the piston 113 reaches the bottom dead center of the transition from the intake stroke to the compression stroke. The piston 113 acquires the intake air pressure as the intake air representative pressure at a timing during the period from the top dead center of the transition from the compression stroke to the expansion stroke to the next bottom dead center. Thereby, the intake air pressure having a relatively stable value that is not affected by the opening and closing of the valve can be used as the intake air representative pressure.

Furthermore, in the expansion stroke, since the intake air pressure gradually approaches the outside air pressure, the difference in intake air pressure caused by the difference in body temperature or outside air temperature is small. Therefore, in consideration of accuracy, the intake pressure detected by the intake pressure sensor 104 at the timing of the compression stroke after the intake valve 111 is closed is preferably used as the intake representative pressure.

As described above, according to the second embodiment, compared to the configuration of the previous first embodiment, the configuration is such that after the piston reaches the bottom dead center of the transition from the intake stroke to the compression stroke until the piston passes the top dead center of the transition from the compression stroke to the expansion stroke At the timing during the period until the next bottom dead center, the intake air pressure is acquired as the intake air representative pressure. Even in the case of configuring in this way, the same effects as those in the first embodiment can be obtained.

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

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

Embodiment 3.

In Embodiment 3 of the present invention, the temperature prediction device 121 in which the process for obtaining the representative pressure of intake air is different from that in Embodiments 1 and 2 above will be described. In addition, in this Embodiment 3, description of the same point as the previous Embodiment 1, 2 is abbreviate|omitted, and the point different from the previous Embodiment 1, 2 is mainly demonstrated.

In the third embodiment, the basic structure of the internal combustion engine 100 is the same as that of the previous embodiments 1 and 2. On the other hand, the control program incorporated in the temperature prediction device 121, specifically, the intake air representative executed by the temperature prediction device 121 The pressure acquisition process is different from the previous Embodiments 1 and 2.

FIG. 6 is a schematic diagram showing a pressure change in the intake pipe 101a of the internal combustion engine 100 according to Embodiment 3 of the present invention.

As in the previous Embodiment 1, the crankshaft 115 is rotated by the starter motor or the like with the start of the internal combustion engine main body 100a. At this time, the temperature predicting device 121 detects the bottom dead center of the transition from the intake stroke to the compression stroke of the internal combustion engine body 100a using the respective information from the intake pressure sensor 104 and the crank angle sensor 118 . After the temperature predicting device 121 detects the bottom dead center, the crank angle sensor 118 detects the timings of the protrusions with the crank numbers No. 2 and No. 5, respectively, and obtains the first intake air pressure and the second intake air pressure from the intake pressure sensor 104, respectively. Two intake pressures, the difference between the two intake pressures is used as the intake representative pressure.

That is, the temperature predicting device 121 is in the period after the piston 113 reaches the bottom dead center of the transition from the intake stroke to the compression stroke until the piston 113 passes the top dead center of the transition from the compression stroke to the expansion stroke and reaches the next bottom dead center The first intake pressure and the second intake pressure are obtained respectively at two timings that are different in time. The temperature prediction device 121 acquires the differential pressure of the first intake air pressure and the second intake air pressure acquired in this manner as the intake air representative pressure.

This differential pressure can be replaced by the flow rate of the outside air flowing into the intake pipe 101a, and is accompanied by a time term. Here, when the time difference between the two timings is short, the outside air flowing into the intake duct 101a is less affected by the temperature of the body. On the contrary, when the time difference between the two timings is long, the Outside air is susceptible to body temperature. Therefore, it is necessary to consider the effect of the warming from the internal combustion engine to the inflowing outside air depending on the time difference of these timings in terms of thermofluidics, but there is an advantage in that the inflowing outside air can be organized in a dimension accompanied by a time term , as a result, it is possible to predict the body temperature with higher accuracy.

As described above, according to the third embodiment, compared with the configuration of the previous first embodiment, the configuration is such that after the piston reaches the bottom dead center of the transition from the intake stroke to the compression stroke until the piston passes the top dead center of the transition from the compression stroke to the expansion stroke The first intake pressure and the second intake pressure are obtained at different timings during the period until the next bottom dead center, and the difference between the obtained first intake pressure and the second intake pressure is taken as The intake air is obtained on behalf of the pressure. Even in the case of configuring in this way, the same effects as those in the first embodiment can be obtained.

In addition, in Embodiment 3, the timings at which the first intake pressure and the second intake pressure are obtained from the intake pressure sensor 104, respectively, are used as the crank angle sensor 118 after the bottom dead center to detect that the crank numbers are No. 2 and No. 5, respectively. The timing of the protrusion of the number is not limited to this.

That is, the timing for acquiring these two intake pressures may be the timing from the compression stroke to the completion of the expansion stroke and the exhaust stroke after the bottom dead center of the transition from the intake stroke to the compression stroke. However, it is preferable that the timing at which the first intake air pressure (ie, the first intake air pressure) is obtained is the timing at which the influence of the internal combustion engine body 100a appears conspicuously, that is, the bottom dead center of transition from the intake stroke to the compression stroke later and as close as possible to the timing of the bottom dead center.

Embodiment 4.

In Embodiment 4 of the present invention, the temperature prediction device 121 that predicts the initial temperature by a method different from that of the previous Embodiments 1 to 3 will be described. In addition, in this Embodiment 4, description of the same point as the previous Embodiment 1-3 is abbreviate|omitted, and the point different from the previous Embodiment 1-3 is mainly demonstrated.

In the fourth embodiment, the basic configuration of the internal combustion engine 100 is the same as that of the previous embodiments 1 to 3. On the other hand, a control program of the temperature prediction device 121 is incorporated, specifically, the predicted initial temperature executed by the temperature prediction device 121 The operation is different from the previous Embodiments 1 to 3.

FIG. 7 is a schematic diagram showing pressure changes in the intake pipe 101 a of the internal combustion engine 100 according to Embodiment 4 of the present invention.

In FIG. 7 , an example in which the piston 113 is stopped in the middle of the intake stroke when the internal combustion engine 100 is in a stopped state is assumed. As in the previous Embodiment 1, the crankshaft 115 is rotated by the starter motor or the like with the start of the internal combustion engine main body 100a. At this time, the temperature predicting device 121 uses the respective information from the intake pressure sensor 104 and the crank angle sensor 118 to detect the first bottom stop of the first time the engine body 100a transitions from the intake stroke to the compression stroke after the engine body 100a is started. point. After the temperature predicting device 121 detects the first bottom dead center, the internal combustion engine main body 100a shifts from the compression stroke to the expansion stroke through the first top dead center, from the expansion stroke to the exhaust stroke through the second bottom dead center, and from the exhaust stroke to the exhaust stroke. The air stroke is transferred to the intake stroke through the second top dead center.

After the internal combustion engine main body 100a transitions from the intake stroke to the compression stroke through the third bottom dead center, the temperature prediction device 121 obtains the information from the intake pressure sensor 104 at the timing at which the crank angle sensor 118 detects a protrusion with a crank number of, for example, No. 2. air pressure, and the intake air pressure is regarded as the intake air representative pressure.

Here, when the internal combustion engine 100 is started from the state where 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, compared with the case where the intake is completely charged during the intake stroke, The volume is also smaller and the intake pressure is also higher.

Therefore, in the fourth embodiment, the temperature predicting device 121 uses the information from the intake pressure sensor 104 and the crank angle sensor 118 to detect the bottom dead center of the transition from the intake stroke to the compression stroke, and then the crank angle sensor 118 The timing of the protrusion whose crank number is No. 2 is detected, and the intake pressure is acquired from the intake pressure sensor 104 . When the acquired intake air pressure is higher than a preset pressure value, the temperature prediction device 121 performs control so that the rotation of the crankshaft 115 is continued.

Next, the temperature predicting device 121 does not operate the injector 110 and the spark plug 112, acquires the intake air pressure detected by the intake air pressure sensor 104 in the second compression stroke after the third bottom dead center, and uses the intake air pressure as Intake air represents pressure.

That is, the temperature prediction device 121 is configured so that after the piston 113 reaches the bottom dead center of the transition from the intake stroke to the compression stroke until the piston 113 passes the top dead center of the transition from the compression stroke to the expansion stroke and reaches the next bottom dead center At the timing of the period of time, the intake air pressure is obtained as the intake air representative pressure. When the obtained intake air representative pressure is higher than the set pressure value, at the timing of the next period, the intake air pressure is obtained again as the intake air representative pressure. Intake air represents pressure.

Such a configuration is effective, for example, when the piston 113 is stopped in the middle of the intake stroke as described above, when a reading error of the detected value of the intake pressure sensor 104 occurs, or the correct detection value cannot be obtained. As a result, the reliability of the intake air representative pressure is improved.

Next, a series of operations for predicting the initial temperature of the temperature predicting device 121 according to Embodiment 4 of the present invention will be described with reference to FIG. 8 . 8 is a flowchart showing a series of operations for predicting the initial temperature of the internal combustion engine temperature predicting device 121 according to Embodiment 4 of the present invention.

In step S201, when the power supply of the 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, 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 prediction device 121 acquires the first pressure detected by the intake pressure sensor 104 as the outside air pressure, and the process proceeds to step S204.

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

In step S205, the temperature prediction device 121 controls the crankshaft 115 to rotate by starting the motor or the like, and the process proceeds to step S206.

In step S206, the temperature predicting device 121 acquires the constants a to e related to equation (1) and equation (1) required for predicting the initial temperature from the nonvolatile memory, and the process proceeds to step S207.

In step S207, after the temperature predicting device 121 detects the bottom dead center (first bottom dead center) of the transition from the intake stroke to the compression stroke, the intake pressure is acquired from the intake pressure sensor 104 during the compression stroke, and the process proceeds to Step S208.

In step S208, the temperature prediction device 121 determines whether or not the intake air pressure acquired in step S207 is higher than the set pressure value. When 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, and then the intake pressure sensor 104 again detects the bottom dead center (third bottom dead center) during the compression stroke. The intake pressure is acquired, and the process proceeds to step S208.

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

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

In step S210, the temperature prediction device 121 sets the intake air pressure equal to or less than the set pressure value acquired in step S207 as the intake air representative pressure. Next, the temperature prediction device 121 uses the intake air representative pressure, the outside air pressure and outside air temperature acquired in steps S203 and S204, the constants a to e acquired in step S206, and the engine speed acquired in step S209, The initial temperature is predicted according to equation (1). After that, the process proceeds 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 spark plug 112 to operate at a specific timing.

In this way, the temperature predicting device 121 is configured to control the fuel injection when the fuel is injected for the first time based on the predicted initial temperature. In addition, the function of controlling the first fuel injection after the initial temperature prediction is performed by the first fuel injection control unit included in the temperature predicting device 121 .

As described above, according to the fourth embodiment, after the piston reaches the bottom dead center of the transition from the intake stroke to the compression stroke, until the piston passes the top dead center of the transition from the compression stroke to the expansion stroke and reaches the next bottom dead center At the timing of the period of time, the intake air pressure is obtained as the intake air representative pressure. When the obtained intake air representative pressure is higher than the set pressure value, at the timing of the next period, the intake air pressure is obtained again as the intake air representative pressure. Intake air represents pressure. Even in the case of configuring in this way, the same effects as those in the first embodiment can be obtained.

Embodiment 5.

In Embodiment 5 of the present invention, a temperature predicting device 121 which is different from that in Embodiment 1 will be described in terms of a method for predicting the body temperature after the start of combustion in the combustion chamber 105 . In addition, in this Embodiment 5, the description of the same point as the previous Embodiment 1-4 is abbreviate|omitted, and the point different from the previous Embodiment 1-4 is mainly demonstrated.

In the fifth embodiment, the basic configuration of the internal combustion engine 100 is the same as that of the previous embodiments 1 to 4. On the other hand, a control program of the temperature prediction device 121 is incorporated. Specifically, after the combustion is started by the temperature prediction device 121 The prediction operation of the main body temperature is different from the previous Embodiments 1 to 4. In addition, the temperature prediction device 121 in Embodiment 5 predicts the initial temperature by the method of any one of Embodiments 1 to 4 above.

The prediction operation of the body temperature after the start of combustion performed by the temperature prediction device 121 is as follows. That is, in the process of the intake air passing through the throttle valve 103 , the intake pipe 101 a , the intake valve 111 , and the combustion chamber 105 , by thermal fluid dynamics modeling using the law of conservation of mass, the state equation, and the throttle equation, etc., Intake air temperature per unit time. In addition, the intake air temperature and the body temperature have a correlation, and the body temperature can be predicted using the intake air temperature by substituting with an experimental formula.

Therefore, the temperature predicting device 121 obtains the intake air temperature by the above-described method, uses the predicted initial temperature and the obtained intake air temperature, and uses the above-described correlation to predict the main body temperature.

As described above, according to the fifth embodiment, the main body temperature of the internal combustion engine is predicted based on the correlation between the main body temperature of the internal combustion engine and the intake air temperature using the predicted initial temperature and the acquired intake air temperature. Even in the case of configuring in this way, the same effects as those of the previous Embodiments 1 to 4 can be obtained.

In addition, in each of the above-mentioned embodiments, the case where the present invention is applied to predict the temperature of the internal combustion engine main body has been described, but the present invention is not limited to this, and the present invention can also be applied to predicting an element that expresses substantially the same temperature variation as the internal combustion engine main body temperature. For example, the present invention can be applied to predict the temperature of engine oil of the internal combustion engine, the temperature of cooling water of the internal combustion engine, and the like, in addition to the temperature of the internal combustion engine main body.

In addition, the above-mentioned outside air pressure obtaining unit, intake representative pressure obtaining unit, parameter information obtaining unit, initial temperature predicting unit, and temperature predicting unit may be realized in software by a single control unit such as an ECU, or may be prepared as independent hardware.

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

Explanation of reference numerals

100 internal combustion engine, 100a internal combustion engine body, 101 intake passage, 101a intake pipe, 102 air filter, 103 throttle valve, 104 intake pressure sensor, 105 combustion chamber, 106 bypass flow passage, 107 idle speed 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 (10)

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 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 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 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, 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.

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