JP4654752B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  It is known that the wall surface temperature of the combustion chamber and the coolant temperature of the internal combustion engine affect the operating state of the internal combustion engine. And if this wall surface temperature and cooling water temperature can be calculated | required, since it will become possible to perform operation control of an internal combustion engine based on these values, an appropriate driving | running state can be obtained.

Here, a technique for estimating the combustion chamber wall temperature based on the heat transfer from the combustion gas in the combustion chamber to the combustion chamber wall and the heat transfer model from the combustion chamber wall to the cooling water is known (for example, Patent Documents). 1). According to this prior art, it is stated that the heat transfer rate from the combustion chamber wall to the cooling water should be corrected according to the flow rate of the cooling water. It is a function of number. The heat transfer coefficient from the combustion gas to the combustion chamber wall is also constant.
Japanese Patent No. 2666366 Japanese Patent No. 2816440 JP 11-218043 A

  Therefore, as described in the prior art, it is possible to estimate the coolant temperature more accurately by changing the heat transfer rate from the combustion chamber wall to the coolant according to the flow rate of the coolant. In particular, when the cooling water is circulated by the electric pump, the circulation of the cooling water may be stopped or the flow rate may be extremely low, so that the heat transfer rate may change greatly. Therefore, it is highly necessary to change the heat transfer coefficient according to the flow rate of the cooling water.

  In the prior art, the cooling water temperature is measured by a water temperature sensor, and this water temperature sensor is attached in the vicinity of the cooling water outlet of the internal combustion engine. Here, since the flow of the cooling water stops when the electric pump is stopped, the temperature of the cooling water in the internal combustion engine rises due to heat transfer from the combustion chamber and the port. However, since the position where the water temperature sensor is attached is away from the heat source, the amount of heat received by the cooling water at this position is small, so the temperature rise of the cooling water is small. For this reason, there is a difference between the temperature of the cooling water inside the internal combustion engine and the temperature of the cooling water measured by the water temperature sensor.

  Further, the heat transfer rate from the combustion gas to the combustion chamber wall changes between when the internal combustion engine is cold and after the warm-up is completed. That is, the heat transfer coefficient is affected by the combustion gas temperature and pressure, but the temperature of the combustion chamber wall is different between cold and after the warm-up is completed, and the heat flow rate from the combustion gas to the combustion chamber wall increases during cold. Therefore, the combustion gas temperature is also affected.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of more accurately obtaining the combustion chamber wall temperature and the cooling water temperature in the control device for an internal combustion engine. To do.

In order to achieve the above object, a control apparatus for an internal combustion engine according to the present invention employs the following means. That is,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Gas temperature estimating means for estimating the gas temperature in the combustion chamber from the operating state of the internal combustion engine detected by the operating state detecting means;
A first expression for calculating the amount of change in the temperature of the combustion chamber wall from the difference between the amount of heat received by the combustion chamber wall from the combustion gas and the amount of heat given to the cooling water from the combustion chamber wall and the heat capacity of the combustion chamber wall, and cooling from the combustion chamber wall A second equation for calculating the amount of change in the coolant temperature from the amount of heat received by the water and the heat capacity of the coolant, and an estimation means for simultaneously estimating the combustion chamber wall temperature and the coolant temperature inside the internal combustion engine based on the second equation;
It is provided with.

  Here, the temperature of the combustion gas in the combustion chamber changes according to the operating state of the internal combustion engine. When the temperature of the combustion gas changes, the amount of heat received by the combustion chamber wall also changes. Thereby, the cooling water temperature also changes. Thus, the temperature of the combustion gas affects the combustion chamber wall temperature and the cooling water temperature.

  Since the temperature of the combustion chamber wall is lower than that of the combustion gas, heat transfer occurs from the combustion gas to the combustion chamber wall. Further, since the temperature of the combustion chamber wall is higher than that of the cooling water, heat transfer occurs from the combustion chamber wall to the cooling water. The amount of heat that the combustion chamber wall has is the difference between the amount of heat that enters the combustion chamber wall and the amount of heat that exits the combustion chamber wall, that is, It can be expressed as “difference between” and “. Further, the amount of change in the temperature of the combustion chamber wall varies depending on the heat capacity of the combustion chamber wall. Therefore, the first change is to determine the amount of change in the temperature of the combustion chamber wall from the “difference between the amount of heat received by the combustion chamber wall from the combustion gas and the amount of heat given from the combustion chamber wall to the cooling water” and the “heat capacity of the combustion chamber wall” It is a formula.

  The amount of heat that the cooling water has is expressed as the amount of heat that the cooling water has received from the combustion chamber wall. The second equation is to obtain the temperature change amount of the cooling water from the “heat amount received by the cooling water from the combustion chamber wall” and the heat capacity of the cooling water.

  Since the amount of change in the combustion chamber wall temperature varies depending on the cooling water temperature, and the amount of change in the cooling water temperature varies depending on the combustion chamber wall temperature, the first equation and the second equation influence each other. Yes. Therefore, the first equation and the second equation can be solved as a differential equation of a two-dimensional variable. By solving this differential equation, the combustion chamber wall temperature and the cooling water temperature can be obtained simultaneously.

The present invention further includes a pump capable of circulating the cooling water of the internal combustion engine and changing the flow rate of the cooling water,
The estimation means can change the estimation method of the combustion chamber wall temperature based on the flow rate of the cooling water.

  For example, the combustion chamber wall temperature may be estimated using a conventional equation when the pump is operating, and the combustion chamber wall temperature and the cooling water temperature may be estimated from the first equation and the second equation when the pump is stopped.

Furthermore, in the present invention, a cooling water passage for circulating the cooling water of the internal combustion engine to the outside of the internal combustion engine,
Cooling water temperature measuring means for measuring the temperature of the cooling water flowing out from the internal combustion engine to the cooling water passage;
Further comprising
The estimating means simultaneously estimates the combustion chamber wall temperature and the cooling water temperature inside the internal combustion engine based on the first and second expressions when the pump is stopped, and the cooling water temperature measuring means when the pump is operating. The combustion chamber wall temperature can be estimated based on the coolant temperature measured by the above.

  Here, when the pump is stopped, the cooling water inside the internal combustion engine receives heat from the walls and ports of the combustion chamber and the temperature rises. However, since the cooling water whose temperature is measured by the cooling water temperature measuring means is away from the combustion chamber wall and the port, the temperature does not increase immediately. Therefore, there is a possibility that a difference occurs between the actual cooling water temperature inside the internal combustion engine and the cooling water temperature measured by the cooling water temperature measuring means. Therefore, a more accurate value can be obtained by estimating the cooling water temperature than by measuring the cooling water temperature by the cooling water temperature measuring means.

  On the other hand, when the pump is operated, the cooling water whose temperature has risen due to heat from the combustion chamber wall or port reaches the cooling water outlet of the internal combustion engine in a short time. The difference between the cooling water temperature and the cooling water temperature measured by the cooling water temperature measuring means is small. Therefore, an accurate value can be obtained even if the coolant temperature measured by the coolant temperature measuring means is used. Further, the combustion chamber wall temperature can be calculated based on the cooling water temperature measured by the cooling water temperature measuring means.

  In this invention, the said estimation means can correct | amend the heat transfer rate from a combustion chamber wall to cooling water based on the flow volume and / or cooling water temperature of cooling water.

  That is, since the heat transfer coefficient from the combustion chamber wall to the cooling water changes according to the cooling water flow rate and the cooling water temperature, the combustion chamber is corrected by correcting the heat transfer coefficient according to the cooling water flow rate and the cooling water temperature. The estimation accuracy of the wall temperature can be improved.

  In the present invention, the estimating means can correct the heat transfer rate from the combustion gas to the combustion chamber wall and / or the combustion gas temperature based on the combustion chamber wall temperature.

  When the internal combustion engine is cold, since the combustion chamber wall temperature is low, the amount of heat transfer from the combustion gas to the combustion chamber wall is large, so that the temperature drop of the combustion gas increases. This also changes the heat transfer coefficient. Therefore, by correcting the heat transfer coefficient and / or the combustion gas temperature based on the combustion chamber wall temperature, it is possible to improve the estimation accuracy of the combustion chamber wall temperature and the cooling water temperature.

  In practice, the combustion gas temperature, the combustion chamber wall temperature, and the heat transfer rate from the combustion gas to the combustion chamber wall interact, but the heat transfer from the combustion gas to the combustion chamber wall based on the combustion chamber wall temperature. Simplification is possible by correcting the rate.

  The control apparatus for an internal combustion engine according to the present invention can determine the combustion chamber wall temperature and the coolant temperature more accurately.

  Hereinafter, specific embodiments of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine 1 to which the control device for an internal combustion engine according to the present embodiment is applied.

  Moreover, FIG. 2 is a figure which shows schematic structure inside the internal combustion engine 1 which concerns on a present Example.

  The internal combustion engine 1 is a four-cycle engine and includes a cylinder head 2 and a cylinder block 3.

  A water jacket 4 for circulating cooling water is formed inside the internal combustion engine 1. The internal combustion engine 1 is connected to a passage for circulating cooling water. The passage for circulating the cooling water includes a first circulation passage 6 that circulates through the radiator 5, a second circulation passage 8 that circulates through the heater core 7, and a third circulation passage 10 that circulates through the bypass passage 9. Yes. A part of each circulation passage has a portion shared with other circulation passages. For example, the water jacket 4 is included in all circulation passages.

  The first circulation passage 6 includes a radiator 5, a thermostat 11, an electric pump 12, and a water jacket 4. The thermostat 11 causes the cooling water to flow through the first circulation passage 6 when the cooling water temperature is high, and causes the cooling water to flow through the third circulation passage 10 when the cooling water temperature is low.

  In the first circulation passage 6, the cooling water discharged from the electric pump 12 flows in the order of the water jacket 4, the radiator 5, and the thermostat 11.

  The second circulation passage 8 includes a heater core 7, an electric pump 12, and a water jacket 4.

  In the second circulation passage 8, the cooling water discharged from the electric pump 12 flows in the order of the water jacket 4 and the heater core 7.

  The third circulation passage 10 includes a bypass passage 9, a thermostat 11, an electric pump 12, and a water jacket 4.

  In the third circulation passage 10, the cooling water discharged from the electric pump 12 flows in the order of the water jacket 4, the bypass passage 9, and the thermostat 11.

  Cooling water temperature that outputs a signal corresponding to the temperature of the cooling water in the first circulation passage 6 and the second circulation passage 8 near the outlet of the first circulation passage 6 and the second circulation passage 8 from the internal combustion engine 1. A sensor 13 is attached.

  The internal combustion engine 1 configured as described above is provided with an ECU 14 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 14 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  In addition to the coolant temperature sensor 13, the ECU 14 includes an accelerator opening sensor 15 that outputs a signal corresponding to the accelerator opening, that is, the engine load, a crank position sensor 16 that outputs a signal corresponding to the rotational speed of the internal combustion engine 1, and an internal combustion engine. An air flow meter 17 that outputs a signal corresponding to the intake air amount of the engine 1 is connected via electric wiring, and output signals of these sensors are input to the ECU 14.

  On the other hand, the electric pump 12 is connected to the ECU 14 via electric wiring, and the ECU 14 controls the electric pump 12. The electric pump 12 can adjust the discharge amount of the cooling water, that is, the flow rate of the cooling water, by adjusting the power supplied to the electric pump 12. Further, the electric pump 12 can be stopped even during the operation of the internal combustion engine 1.

A cylinder 20 is formed in the cylinder block 3. A piston 21 is inserted into the cylinder 20. A combustion chamber 22 is formed by the cylinder head 2, the cylinder 20, and the piston 21. That is, the combustion chamber 22 is formed by a space surrounded by the combustion chamber wall 23 at the top, the piston 21 at the bottom, and the cylinder 20 at the side. The combustion chamber wall 23 is a partition wall between the combustion chamber 22 and the water jacket 4 formed in the cylinder head 2 and the cylinder block 3.

  Here, according to Japanese Patent No. 2666366, the amount of change in the temperature of the combustion chamber wall 23 is obtained by the following model equation.

CcΔTc = Hc (Tg−Tc) −Hw (Tc−Tw) (1) where Cc is the heat capacity of the combustion chamber wall 23, ΔTc is the amount of change in the temperature of the combustion chamber wall 23, and Hc is from the combustion gas. Heat transfer coefficient to the combustion chamber wall 23 (hereinafter referred to as combustion gas side heat transfer coefficient), Tg is the temperature of the combustion gas, Tc is the temperature of the combustion chamber wall 23, and Hw is the heat from the combustion chamber wall 23 to the cooling water. Transfer coefficient (hereinafter referred to as cooling water side heat transfer coefficient), Tw is the temperature of the cooling water. Here, the cooling water temperature Tw is a measured value obtained from the cooling water temperature sensor 13 when the electric pump 12 is operated. Further, the heat capacity Cc, the combustion gas side heat transfer coefficient Hc, and the cooling water side heat transfer coefficient Hw of the combustion chamber wall 23 are values obtained by experiments. Further, the cooling water side heat transfer coefficient Hw is a constant value for simplification, and the combustion gas temperature Tg is substantially constant at around 200 ° C. The heat capacity Cc of the combustion chamber wall 23 may be the heat capacity of the internal combustion engine 1.

  When this equation (1) is discretized after deformation, the following equation (2) can be obtained.

この（２）式をＥＣＵ１４に格納しておき、該（２）式に冷却水温度Ｔｗを代入することにより燃焼室壁温度Ｔｃを得ることができる。

The equation (2) is stored in the ECU 14, and the combustion chamber wall temperature Tc can be obtained by substituting the cooling water temperature Tw into the equation (2).

  On the other hand, in this embodiment, the combustion chamber wall temperature and the coolant temperature in the water jacket 4 are estimated simultaneously when the electric pump 12 is stopped. The model formula is shown below.

CcΔTc = Hc (Tg−Tc) −Hw (Tc−Tw2) (3) Formula CwΔTw2 = Hw (Tc−Tw2) (4) where Tw2 is the cooling water temperature when the electric pump 12 is stopped. , Cw is the heat capacity of the cooling water in the water jacket 4. Here, Cc, Cw, Hc, and Hw are values obtained by experiments, respectively. Further, the combustion gas temperature Tg is a value estimated from the engine speed and the engine load, and is obtained in advance through experiments or the like, further mapped, and stored in the ECU 14. Further, since the amount of cooling water in the water jacket 4 is constant when the electric pump 12 is stopped, the value of Cw is constant.

In the equation (3), the heat transfer amount from the combustion gas to the combustion chamber wall 23 when the electric pump 12 is stopped is represented by Hc (Tg−Tc), and the heat transfer amount from the combustion chamber wall 23 to the cooling water is Hw ( Tc−Tw2), and the heat balance of the combustion chamber wall 23 is represented as Hc (Tg−Tc) −Hw (Tc−Tw2). The amount of change ΔTc in the combustion chamber wall temperature can be obtained from this heat balance and the heat capacity Cc of the combustion chamber wall 23.

  In addition, in equation (4), the amount of heat transfer from the combustion chamber wall 23 to the cooling water when the electric pump 12 is stopped is represented by Hw (Tc−Tw2). And the amount of change ΔTw2 in the temperature of the cooling water in the water jacket 4 can be obtained from this heat transfer amount and the heat capacity Cw of the cooling water.

  Note that, when the electric pump 12 is stopped, the equations (3) and (4) affect each other, resulting in a two-dimensional differential equation. The following equation (5) can be obtained by modifying equations (3) and (4).

ここで、（５）式を簡略化するために、（５）式の各項を以下の記号に置き換える。

Here, in order to simplify Equation (5), each term in Equation (5) is replaced with the following symbols.

ｕ＝Ｔｇ
また、

u = Tg
Also,

とする。

And

That is, equation (5) is
CΔT = A ・ T + B ・ u
It is represented by If this equation is transformed,

となり、この式をサンプルタイムをｔとして離散化すると、次の（６）式を得ることができる。

When this equation is discretized with the sample time as t, the following equation (6) can be obtained.

この（６）式をＥＣＵ１４に格納しておき、該（６）式の各項へ値を代入することにより、燃焼室壁温度Ｔｃおよび冷却水温度Ｔｗ２を同時に得ることができる。

By storing this equation (6) in the ECU 14 and substituting values into the terms of the equation (6), the combustion chamber wall temperature Tc and the cooling water temperature Tw2 can be obtained simultaneously.

  Thus, according to this embodiment, the combustion chamber wall temperature Tc and the cooling water temperature Tw2 can be obtained simultaneously when the electric pump 12 is stopped. The ECU 14 can control the internal combustion engine 1 based on the combustion chamber wall temperature Tc and the cooling water temperature Tw2 obtained in this way.

  In the present embodiment, the combustion chamber wall temperature estimation model is changed between when the electric pump 12 is stopped and when it is operating.

  That is, when the electric pump 12 is operated, the combustion chamber wall temperature is estimated by the equation (2). Further, when the electric pump 12 is stopped, the combustion chamber wall temperature and the cooling water temperature are obtained simultaneously by the equation (6).

  Here, since the cooling water circulates through the first circulation passage 6 or the second circulation passage 8 during the operation of the electric pump 12, the cooling water temperature obtained by the cooling water temperature sensor 13 and the cooling in the water jacket 4. There is almost no difference with water temperature. Therefore, the value obtained by the cooling water temperature sensor 13 can be set as the cooling water temperature Tw. Thus, since it is not necessary to estimate the cooling water temperature Tw, the combustion chamber wall temperature Tc can be obtained with high accuracy by the expression (2) when the electric pump 12 is operated. As a result, the processing can be simplified.

  On the other hand, when the electric pump 12 is stopped, the difference between the cooling water temperature obtained by the cooling water temperature sensor 13 and the cooling water temperature in the water jacket 4 becomes large. Get water temperature at the same time.

  Next, an estimation flow of the combustion chamber wall temperature according to the present embodiment will be described.

  FIG. 3 is a flowchart showing an estimation flow of the combustion chamber wall temperature according to the present embodiment. This flow is repeatedly executed every predetermined time.

  In step S101, it is determined whether the electric pump 12 is operating.

  If an affirmative determination is made in step S101, the process proceeds to step S102, whereas if a negative determination is made, the process proceeds to step S103.

  In step S102, the combustion chamber wall temperature is estimated from equation (2).

  In step S103, the combustion chamber wall temperature and the cooling water temperature are simultaneously estimated by the equation (6).

  In this way, it is possible to improve the estimation accuracy of the combustion chamber wall temperature when the electric pump 12 is stopped and when the internal combustion engine is operating. Further, it is possible to suppress boiling of the cooling water in the water jacket 4 when the electric pump 12 is stopped and the internal combustion engine is operated.

  In the present embodiment, the cooling water side heat transfer coefficient Hw is changed according to the flow rate of the cooling water and / or the cooling water temperature.

  Here, the Nusselt number Nu = h · x / k, the Reynolds number Re = u · x / ν, and the Prandtl number Pr = ν / a = ν · ρ · Cp / k.

  Where h is the heat transfer coefficient, x is the representative length, k is the thermal conductivity of the fluid, a is the thermal conductivity, u is the main flow velocity, ν is the kinematic viscosity coefficient of the fluid, ρ is the fluid density, and Cp is the fluid Specific heat.

  And when the inside of the pipe is turbulent, for example, according to Colburn's empirical formula, the Nusselt number Nu is

であるから、熱伝達率ｈは次式で表すことができる。

Therefore, the heat transfer coefficient h can be expressed by the following equation.

すなわち、熱伝達率ｈは主流の流速ｕに依存するので、冷却水側熱伝達率Ｈｗは冷却水の流量に依存することが分かる。

That is, since the heat transfer coefficient h depends on the main flow velocity u, it is understood that the cooling water side heat transfer coefficient Hw depends on the flow rate of the cooling water.

  Moreover, since the heat transfer coefficient h depends on the heat conductivity k, it can be seen that the cooling water side heat transfer coefficient Hw depends on the temperature of the cooling water.

  Therefore, in this embodiment, the cooling water side heat transfer coefficient Hw is changed according to the flow rate of the cooling water and / or the cooling water temperature. The relationship between the flow rate of the cooling water and the cooling water side heat transfer coefficient Hw, and the relationship between the cooling water temperature and the cooling water side heat transfer coefficient Hw are obtained through experiments and mapped in advance and stored in the ECU 14.

  Here, FIG. 4 is a diagram showing the relationship between the flow rate of the cooling water and the cooling water side heat transfer coefficient Hw. The flow rate of the cooling water is obtained from the relationship with the electric power supplied to the electric pump 12 that has been obtained in advance. According to FIG. 4, the cooling water side heat transfer coefficient Hw can be corrected according to the flow rate of the cooling water.

  FIG. 5 is a diagram showing the relationship between the cooling water temperature and the cooling water side heat transfer coefficient Hw. According to FIG. 5, the coolant side heat transfer coefficient Hw can be corrected according to the coolant temperature.

  4 and 5, the cooling water side heat transfer coefficient Hw can be corrected according to the cooling water flow rate and the cooling water temperature.

  Thus, in this embodiment, the heat transfer coefficient can be changed according to the cooling water flow rate and / or the temperature of the cooling water, so that the estimation accuracy of the combustion chamber wall temperature Tc can be improved.

  In this embodiment, the value of the combustion gas side heat transfer coefficient Hc or the combustion gas temperature Tg is changed between when the internal combustion engine is cold and after the warm-up is completed.

Here, since the combustion gas side heat transfer coefficient Hc, the combustion gas temperature Tg, and the combustion chamber wall temperature Tc influence each other, for example, the combustion gas side heat transfer coefficient Hc is set according to the combustion chamber wall temperature Tc for simplification. Variable. This is because, when the internal combustion engine 1 is cold, the combustion chamber wall temperature is low, so the amount of heat transfer from the combustion gas to the combustion chamber wall 23 is large, and the combustion gas temperature Tg is greatly reduced.

  Here, FIG. 6 is a diagram showing the relationship between the combustion chamber wall temperature Tc and the combustion gas side heat transfer coefficient Hc according to the present embodiment. Thus, the combustion gas side heat transfer coefficient Hc is increased as the combustion chamber wall temperature Tc increases. This relationship is obtained in advance through experiments or the like, mapped, and stored in the ECU 14.

  Thus, the estimation accuracy of the combustion chamber wall temperature Tc in the entire operation region can be further improved.

It is a figure which shows schematic structure of the internal combustion engine to which the control apparatus of the internal combustion engine which concerns on an Example is applied. It is a figure which shows schematic structure inside the internal combustion engine which concerns on an Example. 6 is a flowchart showing a flow for estimating a combustion chamber wall temperature according to a second embodiment. It is the figure which showed the relationship between the flow volume of the cooling water based on Example 3, and the cooling water side heat transfer coefficient Hw. It is the figure which showed the relationship between the cooling water temperature which concerns on Example 3, and the cooling water side heat transfer coefficient Hw. It is the figure which showed the relationship between the combustion chamber wall temperature Tc which concerns on Example 4, and combustion gas side heat transfer coefficient Hc.

Explanation of symbols

1 Internal combustion engine 2 Cylinder head 3 Cylinder block 4 Water jacket 5 Radiator 6 First circulation passage 7 Heater core 8 Second circulation passage 9 Bypass passage 10 Third circulation passage 11 Thermostat 12 Electric pump 13 Cooling water temperature sensor 14 ECU
15 Accelerator opening sensor 16 Crank position sensor 17 Air flow meter 20 Cylinder 21 Piston 22 Combustion chamber 23 Combustion chamber wall

Claims (4)

An operating state detecting means for detecting an operating state of the internal combustion engine;
Gas temperature estimating means for estimating the gas temperature in the combustion chamber from the operating state of the internal combustion engine detected by the operating state detecting means;
A first expression for calculating the amount of change in the temperature of the combustion chamber wall from the difference between the amount of heat received by the combustion chamber wall from the combustion gas and the amount of heat given to the cooling water from the combustion chamber wall and the heat capacity of the combustion chamber wall, and cooling from the combustion chamber wall A second equation for calculating the amount of change in the coolant temperature from the amount of heat received by the water and the heat capacity of the coolant, and an estimation means for simultaneously estimating the combustion chamber wall temperature and the coolant temperature inside the internal combustion engine based on the second equation;
A pump capable of circulating the cooling water of the internal combustion engine and changing the flow rate of the cooling water;
With
The control device for an internal combustion engine, wherein the estimating means changes a method of estimating a combustion chamber wall temperature based on a flow rate of cooling water . A cooling water passage for circulating cooling water of the internal combustion engine to the outside of the internal combustion engine;
Cooling water temperature measuring means for measuring the temperature of the cooling water flowing out from the internal combustion engine to the cooling water passage;
Further comprising
The estimating means simultaneously estimates the combustion chamber wall temperature and the cooling water temperature inside the internal combustion engine based on the first and second expressions when the pump is stopped, and the cooling water temperature measuring means when the pump is operating. 2. The control apparatus for an internal combustion engine according to claim 1 , wherein the temperature of the combustion chamber wall is estimated based on the cooling water temperature measured by the control. 3. The control of the internal combustion engine according to claim 1, wherein the estimation unit corrects a heat transfer rate from the combustion chamber wall to the cooling water based on a flow rate of the cooling water and / or a cooling water temperature. apparatus. 3. The control of the internal combustion engine according to claim 1, wherein the estimating unit corrects a heat transfer rate from the combustion gas to the combustion chamber wall and / or a combustion gas temperature based on the combustion chamber wall temperature. apparatus.

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