JP2014080925A - Control device of internal combustion engine and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of preventing local boiling of cooling water inside an EGR cooler at the time of warming up an engine and a control method thereof.SOLUTION: A control device 30a of an internal combustion engine is applied to an internal combustion engine having an EGR cooler. The control device 30a has a fuel control unit 41a for controlling a fuel injection amount. The fuel control unit 41a controls the fuel injection amount in an operation region defined as a region where local boiling of cooling water occurs inside the EGR cooler at a warming-up operation.

Description

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

Conventionally, an EGR (exhaust gas recirculation device) has been provided as one method for reducing the NOx emission amount from an internal combustion engine.
In general, the internal combustion engine is provided with a cooling water circulation circuit that circulates the cooling water in the internal combustion engine in order to maintain the temperature of each part of the internal combustion engine at an appropriate temperature. FIG. 2 is a diagram showing an example of a general cooling water circulation circuit. As shown in FIG. 2, in the cooling water circulation circuit 20, cooling water is circulated by a cooling water pump 21.

  The cooling water circulation circuit 20 has a first circulation flow path L1 returning from the radiator 22 to the crankcase 23, an oil cooler 24 provided in the crankcase 23, and further to the radiator 22 via the cylinder head 2a. A radiator bypass flow path B1 that bypasses the radiator 22 is connected to the first circulation flow path L1. A thermostat 25 is provided at a connection portion between the radiator bypass channel B1 and the first circulation channel L1. Further, in the first circulation flow path L1, a part of the cooling water sent to the oil cooler 24 is supplied to the EGR cooler 11, and the cooling water that has passed through the EGR cooler 11 is joined to the first circulation flow path L1. Two flow paths L2 are connected.

JP 2011-190743 A

  In the cooling water circulation circuit 20 as described above, when the engine is warming up, the thermostat 25 is closed and the amount of cooling water flowing through the radiator bypass passage B1 is increased to cool the radiator 22 in order to promote an increase in the cooling water temperature. Reducing water circulation has been done. Usually, the pipe cross-sectional area of the radiator bypass flow path B1 is designed to be smaller than the pipe cross-sectional area of the first circulation flow path L1. Therefore, during the warm-up operation, the discharge flow rate of the cooling water pump 21 decreases, and the amount of cooling water supplied from the oil cooler 24 to the EGR cooler 11 decreases. In such a state, when the engine becomes a high load operation and the temperature of the EGR gas flowing into the EGR cooler 11 becomes high, the cooling water locally boils inside the EGR cooler, and in the worst case, the EGR cooler is damaged. There was a possibility.

  Further, in order to ensure a sufficient amount of water even when the engine is warming up, measures such as increasing the pipe cross-sectional area of the radiator bypass passage B1 can be considered. However, if the pipe cross-sectional area of the radiator bypass passage B1 is increased and the amount of bypass is increased, the temperature rise efficiency of the cooling water is lowered, the warm-up time is lengthened, and fuel consumption is deteriorated.

  The present invention has been made in view of such circumstances, and provides a control device for an internal combustion engine and a control method therefor capable of preventing local boiling of cooling water inside the EGR cooler during engine warm-up. The purpose is to provide.

  A first aspect of the present invention is a control device applied to an internal combustion engine having an EGR cooler, comprising fuel control means for controlling a fuel injection amount, wherein the fuel control means is the EGR cooler during warm-up operation. It is a control device for an internal combustion engine that limits the amount of fuel injection in an operation region defined as a region where local boiling of cooling water occurs.

  According to this aspect, since the fuel injection amount is limited in the operation region defined as the region where the local boiling of the cooling water occurs in the EGR cooler during the warm-up operation, the temperature of the exhaust gas in the operation region is reduced. It becomes possible. Thereby, the calorie | heat amount of EGR gas which flows in into an EGR cooler can be reduced. As a result, local boiling of the cooling water in the EGR cooler can be avoided.

  In the control device for an internal combustion engine, the fuel control means has maximum fuel information that is used at the time of warm-up operation and that associates the rotational speed and the maximum fuel injection amount, and at the time of warm-up operation, the maximum fuel information The maximum fuel injection amount corresponding to the rotational speed is acquired from the engine, the fuel injection amount is limited to be equal to or less than the acquired maximum fuel injection amount, and the maximum fuel injection amount of the maximum fuel information is determined by cooling water inside the EGR cooler. It is good also as setting beforehand to the value which does not produce local boiling of.

  The maximum fuel information set so that local boiling of the cooling water does not occur inside the EGR cooler is prepared in advance, and the fuel injection amount is limited using this maximum fuel information. Therefore, the cooling water inside the EGR cooler is limited. It is possible to easily avoid local boiling of the water.

  In the control device for an internal combustion engine, the maximum fuel information is associated with a rotational speed, a cooling water temperature, and a maximum fuel injection amount, and the fuel control means is configured to control the maximum fuel according to the rotational speed and the cooling water temperature. The injection amount may be obtained from the maximum fuel information.

  By controlling the fuel injection amount based on the cooling water temperature and the rotational speed, it is possible to set the range for limiting the fuel injection amount finely. As a result, compared with the case where the maximum fuel injection amount is set only in association with the engine speed, it is possible to narrow the range of output limitation and increase the upper limit output that can be taken out during warm-up operation. It becomes.

  The control apparatus for an internal combustion engine includes a temperature acquisition unit that measures or estimates a coolant temperature at the outlet of the EGR cooler, and the fuel control unit has a temperature acquired by the temperature acquisition unit equal to or higher than a predetermined temperature threshold value. In this case, the fuel injection amount may be controlled so that the temperature does not exceed the temperature threshold.

  The outlet temperature of the EGR cooler is directly measured or estimated, and the fuel injection amount is limited based on this temperature, so that the range for limiting the output is made narrower than when the output is limited based on the rotational speed or the like. It becomes possible. This makes it possible to further increase the upper limit output that can be taken out during the warm-up operation while avoiding local boiling of the cooling water inside the EGR cooler.

  A second aspect of the present invention is a control device applied to an internal combustion engine having an EGR cooler and an EGR valve for adjusting the EGR gas amount, and has an EGR control means for controlling the EGR gas amount, The EGR control means is a control device for an internal combustion engine that limits the amount of EGR gas in an operation region that is defined as a region where local boiling of cooling water occurs in the EGR cooler during warm-up operation.

  According to this aspect, since the EGR gas amount is limited in the operation region defined as the region where the local boiling of the cooling water occurs in the EGR cooler during the warm-up operation, the EGR gas that passes through the EGR cooler in the operation region The amount can be reduced. Thereby, in the EGR cooler 11, the amount of cooling water heat required for cooling the EGR gas can be reduced. As a result, local boiling of the cooling water in the EGR cooler can be avoided.

  In the control apparatus for an internal combustion engine, the EGR control means has EGR valve opening information associated with the rotational speed, the fuel injection amount, and the EGR valve opening, which is used during warm-up operation, and is used during warm-up operation. The EGR valve opening according to the rotational speed and the fuel injection amount is acquired from the EGR valve opening information, the EGR valve opening is controlled by the acquired EGR valve opening, and the EGR valve opening in the maximum fuel information is The EGR cooler may be preset to a value that does not cause local boiling of the cooling water.

  Since EGR valve opening information set so that local boiling of the cooling water does not occur inside the EGR cooler is prepared in advance, and the EGR valve opening information is limited using this EGR valve opening information. It becomes possible to easily avoid local boiling of the cooling water inside the cooler.

  In the control device for an internal combustion engine, the EGR valve opening information is associated with a rotational speed, a fuel injection amount, a coolant temperature, and an EGR valve opening, and the EGR control means includes the rotational speed and the fuel injection amount. The EGR valve opening corresponding to the coolant temperature may be obtained from the EGR valve opening information.

  By controlling the EGR valve opening based on the cooling water temperature, the rotation speed, and the fuel injection amount, it is possible to set the range for limiting the EGR valve opening finely. As a result, compared with the case where the EGR valve opening is controlled only in association with the rotational speed and the fuel injection amount, the range for limiting the EGR valve opening can be narrowed, and the NOx suppression effect during the warm-up operation can be reduced. Can be suppressed.

  The control apparatus for an internal combustion engine includes a temperature acquisition unit that measures or estimates a coolant temperature at the outlet of the EGR cooler, and the EGR control unit has a temperature acquired by the temperature acquisition unit equal to or higher than a predetermined temperature threshold value. In this case, the EGR valve may be controlled so that the temperature does not exceed the temperature threshold.

  Since the outlet temperature of the EGR cooler is directly measured or estimated, and the EGR valve opening is limited based on this temperature, the range for limiting the output is narrower than when the output is limited based on the rotational speed or the like. It becomes possible to do. As a result, it is possible to further suppress a reduction in the NOx suppression effect during the warm-up operation while avoiding local boiling of the cooling water inside the EGR cooler.

  A third aspect of the present invention is a control device applied to an internal combustion engine having an EGR cooler, the flow rate adjusting means for adjusting the flow rate of cooling water flowing into the EGR cooler, and the cooling water control for controlling the flow rate adjusting means. The cooling water control means increases the flow rate of the cooling water flowing into the EGR cooler in an operation region defined as a region where local boiling of the cooling water occurs in the EGR cooler during the warm-up operation. An internal combustion engine control device that controls the flow rate adjusting means.

  According to this aspect, since the cooling water flow rate is increased in the operation region defined as the region where the local boiling of the cooling water occurs in the EGR cooler during the warm-up operation, the local boiling of the cooling water in the EGR cooler is reduced. It can be avoided.

  In the control apparatus for an internal combustion engine, the cooling water control unit has operation amount information associated with the rotation speed, the fuel injection amount, and the operation amount of the flow rate adjustment unit, which is used during warm-up operation, During operation, an operation amount corresponding to the rotational speed and the fuel injection amount is acquired from the operation amount information, and the flow rate adjusting means is controlled by the acquired operation amount. The operation amount in the operation amount information is stored in the EGR cooler. It may be preset to a value that does not cause local boiling of the cooling water.

  The operation amount information set so that local boiling of the cooling water does not occur inside the EGR cooler is prepared in advance, and the flow rate adjusting means is controlled using this operation amount information, so the cooling water inside the EGR cooler is controlled. It is possible to easily avoid local boiling of the water.

  In the control apparatus for an internal combustion engine, the operation amount information is associated with a rotation speed, a fuel injection amount, a cooling water temperature, and an operation amount, and the cooling water control means includes the rotation speed, the fuel injection amount, and the cooling water. An operation amount corresponding to the temperature may be acquired from the operation amount information.

  By controlling the flow rate adjusting means based on the coolant temperature, the rotation speed, and the fuel injection amount, it is possible to set the range for controlling the flow rate adjusting means finely.

  The control apparatus for an internal combustion engine includes a temperature acquisition unit that measures or estimates a cooling water temperature at the outlet of the EGR cooler, and the cooling water control unit is configured such that the temperature acquired by the temperature acquisition unit is a predetermined temperature threshold value. In the case described above, the flow rate adjusting means may be controlled so that the temperature does not exceed the temperature threshold.

  Since the outlet temperature of the EGR cooler is directly measured or estimated and the cooling water flow rate is controlled based on this temperature, the flow rate control range is further narrowed compared to the case where the flow rate control is performed based on the rotational speed or the like. It becomes possible.

  In the control apparatus for an internal combustion engine, the flow rate adjusting means is, for example, a flow rate adjusting valve that is connected to a cooling water flow path that circulates an EGR cooler and that is provided in a thermostat bypass flow path that bypasses the thermostat.

  By controlling the cooling water flow rate with the flow rate adjusting valve, only the cooling water flow rate flowing into the EGR cooler can be controlled.

  In the control device for an internal combustion engine, the flow rate adjusting means is, for example, an electric pump for circulating cooling water.

  By controlling the cooling water flow rate with the electric pump, it is possible to eliminate the need for additional installation of a flow rate control valve, and to avoid the generation of additional costs.

  In the control device for an internal combustion engine, the cooling water temperature at the outlet of the EGR cooler is, for example, the downstream side of the cooling water flow at the junction where the cooling water flowing out from the cylinder head and the cooling water flowing out from the EGR cooler merge And the ratio of the flow rate of cooling water flowing into the EGR cooler with respect to the total flow rate of cooling water.

  By estimating the cooling water temperature at the outlet of the EGR cooler in this way, an existing temperature sensor can be used. Thereby, the additional installation of a temperature sensor can be made unnecessary.

  In the control device for an internal combustion engine, the temperature of the cooling water at the outlet of the EGR cooler is, for example, an arithmetic expression using EGR gas inlet temperature, EGR gas flow rate, EGR cooler cooling water flow rate, and EGR cooler cooling water inlet temperature as parameters. Estimated.

  By estimating the coolant temperature at the outlet of the EGR cooler in this way, existing sensors can be used. Thereby, the additional installation of a temperature sensor can be made unnecessary.

  According to a fourth aspect of the present invention, there is provided a control method applied to an internal combustion engine having an EGR cooler, in an operation region defined as a region where local boiling of cooling water occurs in the EGR cooler during warm-up operation. A control method for an internal combustion engine that limits the fuel injection amount.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the local boiling of the cooling water inside an EGR cooler at the time of engine warm-up can be prevented.

It is the figure which showed schematic structure of the internal combustion engine at the time of applying a diesel engine as an example of the internal combustion engine of this invention. It is the figure which showed an example of the general cooling water circulation circuit. It is the figure which showed an example of the hardware constitutions of the control apparatus of the internal combustion engine which concerns on 1st Embodiment of this invention. 1 is a functional block diagram of a control device for an internal combustion engine according to a first embodiment of the present invention. It is the figure which showed an example of the maximum fuel information which concerns on 1st Embodiment of this invention. It is the figure which showed the axial torque with respect to engine speed, and is a figure which showed an example of the range in which fuel injection amount is restrict | limited. It is the figure which showed an example of the maximum fuel information which concerns on 2nd Embodiment of this invention. It is the figure which showed the axial torque with respect to an engine speed, and is a figure which showed an example of the maximum torque curve of each cooling water temperature at the time of warming-up operation. It is the figure which showed the cooling water circulation circuit which concerns on 3rd Embodiment of this invention. Thermostat opening / closing timing, EGR cooler cooling water amount, cylinder head outlet cooling water temperature, EGR cooler outlet cooling water temperature, fuel injection when control by the control device for an internal combustion engine according to the third embodiment of the present invention is performed It is the figure which showed an example of the timing chart of quantity. It is a figure for demonstrating estimation of the exit temperature of an EGR cooler. It is a functional block diagram of the control apparatus of the internal combustion engine which concerns on 4th Embodiment of this invention. It is the figure which showed the axial torque with respect to an engine speed, and is a figure which showed an example of the driving | running area | region where restriction | limiting of an EGR valve opening degree is performed. It is the figure which showed an example of the internal schematic structure of an EGR control part. Thermostat opening / closing timing, EGR cooler cooling water amount, cylinder head outlet cooling water temperature, EGR cooler outlet cooling water temperature, EGR valve when control is performed by the control apparatus for an internal combustion engine according to the sixth embodiment of the present invention It is the figure which showed an example of the timing chart of an opening degree. It is the figure which showed the cooling water circulation circuit which concerns on 7th Embodiment of this invention. It is a functional block diagram of the control apparatus of the internal combustion engine which concerns on 7th Embodiment of this invention. It is the figure which showed an example of the flow control valve opening degree information. It is the figure which showed the axial torque with respect to engine speed, and is a figure which showed an example of the driving | running area | region where the restriction | limiting control of the flow control valve opening degree is performed. It is the figure which showed an example of the flow control valve opening degree information which concerns on 8th Embodiment of this invention. Thermostat opening / closing timing, EGR cooler cooling water amount, cylinder head outlet cooling water temperature, EGR cooler outlet cooling water temperature, flow rate adjustment when control by the control apparatus for an internal combustion engine according to the ninth embodiment of the present invention is performed It is the figure which showed an example of the timing chart which showed the opening / closing timing of the valve.

[First Embodiment]
Hereinafter, a control device and a control method for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine when a diesel engine is applied as an example of the internal combustion engine. As shown in FIG. 1, a diesel engine (hereinafter referred to as an “engine”) 1 is a piston 3 that is fitted in a cylinder 2 so as to be freely slidable, and a reciprocating motion of the piston 3 is rotated via a connecting rod 4. A crankshaft (not shown) for conversion is provided.
The engine 1 forms a combustion chamber 5 that is defined between the upper surface of the piston 3 and the inner surface of the cylinder 2. An intake passage 6 is connected to the combustion chamber 5 and an intake valve 7 for opening and closing the intake port is provided. Further, an exhaust passage 8 is connected to the combustion chamber 5 and an exhaust valve 9 for opening and closing the exhaust port is provided.

  In the middle of the exhaust passage 8, an EGR (exhaust gas recirculation) passage 10 for recirculating a part of the exhaust gas flowing through the exhaust passage 8 to the intake passage 6 is connected. The EGR passage 10 is provided with an EGR cooler 11 that cools the EGR gas and an EGR valve 12 that controls the EGR gas flow rate. In the intake passage 6, an intake throttle valve 13 is provided on the upstream side of the air flow from the connection portion of the EGR passage 10.

  Further, the combustion chamber 5 is provided with a fuel injection port 14 for injecting the fuel whose pressure has been increased by a fuel injection pump (not shown) into the combustion chamber 5. Here, a common rail system may be adopted instead of the fuel injection pump. The fuel injection amount and the injection timing by the fuel injection port 14 are controlled by controlling a fuel injection valve 15 provided on the upstream side of the fuel flow from the fuel injection port 14 by a control device 30a described later.

  An air flow meter 16 for detecting the amount of intake air taken into the combustion chamber 5 through the intake passage 6 is provided on the upstream side of the air flow of the intake throttle valve 13 in the intake passage 6. In the EGR passage 10, an EGR gas flow meter 17 for detecting the amount of EGR gas flowing from the EGR passage 10 into the intake passage 6 is provided on the exhaust gas flow upstream side of the EGR valve 12.

An intake manifold pressure sensor 18 and an intake manifold temperature sensor 19 for detecting the pressure and temperature in the intake manifold, respectively, are provided in the intake manifold at the front end portion of the intake passage 6 on the combustion chamber 5 side.
The values measured by the air flow meter 16, the EGR gas flow meter 17, the intake manifold pressure sensor 18, and the intake manifold temperature sensor 19 are input to the control device 30a.

  The engine 1 is provided with a cooling water circulation circuit 20 (see FIG. 2) for circulating the cooling water in order to maintain the temperature of each part of the engine 1 at an appropriate temperature. In the cooling water circulation circuit 20, the cooling water is circulated by a cooling water pump 21. The cooling water circulation circuit 20 has a first circulation flow path L1 returning from the radiator 22 to the crankcase 23, an oil cooler 24 provided in the crankcase 23, and further to the radiator 22 via the cylinder head 2a.

  A radiator bypass flow path B1 that bypasses the radiator 22 is connected to the first circulation flow path L1. A thermostat 25 is provided at a connection portion between the radiator bypass channel B1 and the first circulation channel L1. Although FIG. 2 shows an example in which the thermostat 25 is provided on the outlet side of the cylinder head 2 a, the thermostat 25 may be provided on the inlet side of the oil cooler 24 instead.

  Furthermore, a part of the cooling water sent to the oil cooler 24 is supplied to the EGR cooler 11 in the first circulation channel L1, and the cooling water that has passed through the EGR cooler 11 is supplied from the thermostat 25 in the first circulation channel L1. Also, a second flow path L2 that joins the upstream side of the cooling water flow is connected. Moreover, in FIG. 2, the code | symbol 26 is an oil pan.

Next, the control device 30a shown in FIG. 1 will be described. The control device 30a is, for example, a microcomputer and, as shown in FIG. 3, a central processing unit 31, a main storage device 32 such as a RAM (Random Access Memory), an auxiliary storage device 33, an output device 34, an input device 35, And a communication device 36 for exchanging information by communicating with external devices.
The auxiliary storage device 33 is a computer-readable recording medium, such as a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, or a semiconductor memory. Various programs are stored in the auxiliary storage device 33, and the central processing unit 31 reads out the programs from the auxiliary storage device 33 to the main storage device 32 and executes them to implement various processes.

  FIG. 4 is a functional block diagram of the control device 30. As shown in FIG. 4, the control device 30 a controls the fuel injection valve 15, thereby controlling the fuel control unit 41 a that controls the fuel injection amount and the injection timing into the combustion chamber 5 and the EGR valve 12. And an EGR control unit 43a for controlling the amount of EGR gas.

  The fuel control unit 41a has maximum fuel information in which the engine speed and the maximum fuel injection amount are associated with each other, acquires the maximum fuel injection amount according to the engine speed from the maximum fuel information, and obtains the maximum fuel information. The fuel injection amount is limited to be equal to or less than the injection amount.

  The maximum fuel information includes maximum fuel information used during warm-up operation and maximum fuel information used during normal operation. Here, the time of normal operation means, for example, a state in which the thermostat 25 is fully opened in the cooling water circulation circuit 20 shown in FIG.

  FIG. 5 shows an example of maximum fuel information. In FIG. 5, as indicated by the shaded portion, during the warm-up operation, the maximum fuel injection amount in the engine speed region where local boiling of the cooling water is assumed to occur inside the EGR cooler is the normal operation. Limited compared to the maximum fuel information at the time. The maximum fuel information is registered in the fuel control unit 41 as, for example, a look-up table or an arithmetic expression.

For example, the maximum fuel information during the warm-up operation specifies an engine speed region in which local boiling of cooling water occurs in the EGR cooler during the warm-up operation in the preliminary test, and the EGR cooler in the specified engine speed region. It is created by determining the maximum fuel injection amount that does not cause local boiling of cooling water inside, and associating the fuel injection amount with the engine speed.
Therefore, during the warm-up operation, it is possible to easily prevent local boiling of the cooling water inside the EGR cooler by controlling the fuel injection amount using the maximum fuel information during the warm-up operation. It becomes.

In such a control device 30, the engine speed is input to the fuel control unit 41 at a predetermined sampling period, and reference is made to the maximum fuel information for warm-up operation during warm-up operation and for normal operation during normal operation. The maximum fuel injection amount corresponding to the engine speed is acquired. Then, the fuel injection amount is limited to be equal to or less than the maximum fuel injection amount.
Thus, during the warm-up operation, the fuel injection amount is limited in the engine speed region where local boiling occurs in the cooling water inside the EGR cooler, so the combustion temperature in the combustion chamber 5 decreases and the exhaust gas temperature is reduced. It can be reduced. Thereby, the calorie | heat amount of EGR gas which flows in into the EGR cooler 11 can be reduced, and it becomes possible to prevent that a cooling water boils locally.

  As described above, according to the control apparatus and control method for an internal combustion engine according to the present embodiment, during the warm-up operation, the operation in the operation region in which the local boiling of the cooling water inside the EGR cooler is avoided. Such maximum fuel information is prepared in advance, and the fuel injection amount is controlled using this maximum fuel information during warm-up operation. This makes it possible to easily prevent local boiling of the cooling water inside the EGR cooler.

  FIG. 6 is a diagram illustrating the shaft torque with respect to the engine speed, and an example of a full load torque curve is indicated by a solid line, and an example of a maximum torque curve during warm-up operation is indicated by a broken line. As can be seen from FIG. 6, in the region where the engine speed is equal to or higher than the predetermined engine speed, the fuel injection amount is limited and the shaft torque is suppressed.

[Second Embodiment]
Next, a control device and a control method for an internal combustion engine according to a second embodiment of the present invention will be described. The maximum fuel information according to the first embodiment described above is associated with the maximum fuel injection amount and the engine speed as shown in FIG. 5, but the maximum fuel information in the present embodiment is as shown in FIG. Further, the coolant temperature is further added as a parameter, and the maximum fuel injection amount is set for each engine speed and each coolant temperature. In FIG. 7, the shaded portion is the operating region where the fuel injection amount is limited. Further, the maximum fuel injection amount is set to a fuel injection amount that does not cause local boiling of the cooling water inside the EGR cooler by a preliminary test or the like, as in the first embodiment.

  The cooling water temperature is the temperature of the cooling water circulating in the cooling water circulation circuit 20 shown in FIG. 2, and the measurement location is not particularly limited. For example, a temperature measured by a temperature sensor (not shown) provided between the junction of the second flow path L2 and the first circulation flow path L1 and the thermostat 25 is used.

Thus, by setting the maximum fuel injection amount in association with the cooling water temperature, it is possible to finely set the range for limiting the fuel injection amount. As a result, compared with the case where the maximum fuel injection amount is set only in association with the engine speed, it is possible to narrow the range of output limitation and increase the upper limit output that can be taken out during warm-up operation. It becomes.
FIG. 8 is a diagram showing the shaft torque with respect to the engine speed, and an example of a full load torque curve is indicated by a solid line, and an example of a maximum torque curve of each cooling water temperature during warm-up operation is indicated by a broken line.

[Third Embodiment]
Next, a control device and a control method for an internal combustion engine according to a third embodiment of the present invention will be described. In the first or second embodiment described above, the fuel injection amount is limited by changing the maximum fuel injection amount in accordance with the engine speed or the like. However, in this embodiment, the coolant temperature at the outlet of the EGR cooler A temperature sensor for measuring the fuel injection amount is provided, and the fuel injection amount is limited when the measured value of the temperature sensor exceeds a predetermined threshold value during warm-up operation.
Hereinafter, the control device for an internal combustion engine and the control method thereof according to the present embodiment will be described mainly with respect to differences from the first embodiment described above.

As shown in FIG. 9, the cooling water circulation circuit 20 a according to the present embodiment is provided with a temperature sensor 28 for measuring the outlet temperature of the EGR cooler 11. The fuel control unit of the control device has an EGR cooler outlet temperature at which local boiling of the cooling water occurs in the EGR cooler during a warm-up operation, or a temperature threshold set near the temperature, and a temperature sensor When the measured value by 28 is equal to or greater than the threshold, the fuel injection amount is limited. For example, the fuel injection amount is feedback controlled so that the measured value by the temperature sensor 28 does not exceed the temperature threshold value.
Further, in addition to the cooling water temperature, when the rate of increase of the cooling water temperature exceeds a predetermined threshold value, feedback control may be performed so that the measurement value by the temperature sensor 28 does not exceed the threshold value. Good.

  As described above, according to the control device and control method for an internal combustion engine according to the present embodiment, the outlet temperature of the EGR cooler is directly measured or estimated, and the fuel injection amount is limited based on this temperature. Compared with the first or second embodiment, it is possible to further narrow the range in which the output is limited. This makes it possible to further increase the upper limit output that can be taken out during the warm-up operation while avoiding local boiling of the cooling water inside the EGR cooler.

  FIG. 10 shows the opening / closing timing of the thermostat, the amount of cooling water of the EGR cooler, the outlet cooling water temperature of the cylinder head, the outlet cooling water temperature of the EGR cooler, and the fuel injection when the control by the control device for the internal combustion engine according to the present embodiment is performed. It is the figure which showed an example of the timing chart of quantity. As shown in FIG. 10, when the outlet temperature of the EGR cooler exceeds the temperature threshold at time t1, the fuel injection amount is limited. At time t2, when the outlet coolant temperature of the cylinder head reaches a predetermined value set in advance, the thermostat is fully opened, and accordingly, the coolant flow rate of the EGR cooler increases. The restriction on the injection amount is lifted.

In addition, instead of the measured value by the temperature sensor 28, the outlet temperature of the EGR cooler 11, as shown in FIG. 11, is greater than the confluence of the first circulation flow path L1 and the second flow path L2. The temperature sensor 27 may be provided on the downstream side and in the vicinity of the junction, and the outlet temperature of the EGR cooler 11 may be estimated from the measured value of the temperature sensor 27. In this case, the total amount of water discharged from the cooling water pump 21 and the flow rate ratio flowing into the EGR cooler 11 are stored as information in advance, and the outlet temperature of the EGR cooler 11 is estimated from the flow rate ratio and the measured value of the temperature sensor 27. To do.
In general, a temperature sensor 27 is provided on the downstream side of the cooling water flow from the junction of the first circulation channel L1 and the second channel L2 and in the vicinity of the junction. Therefore, according to this method, the measurement value by the existing temperature sensor can be diverted, and installation of a new temperature sensor becomes unnecessary. Thereby, cost reduction can be achieved.

  In addition, the outlet temperature of the EGR cooler 11 may be estimated using the EGR gas inlet temperature, the EGR gas flow rate, the EGR cooler cooling water flow rate, and the EGR cooler inlet cooling water temperature. In this case, a relational expression between the above parameters and the outlet temperature of the EGR cooler 11 is obtained in advance by numerical analysis or the like, and the outlet temperature of the EGR cooler is estimated using the relational expression and measured values or calculated values of various parameters. To do.

The EGR gas inlet temperature can be estimated using, for example, a map obtained by associating the engine speed, the fuel injection amount, and the EGR gas temperature with a preliminary test.
The EGR gas flow rate may be estimated using, for example, a map or an arithmetic expression that associates the engine speed, the load, the EGR valve opening, and the EGR gas flow rate by a preliminary test or the like. Is possible. Alternatively, a map or an arithmetic expression that correlates the intake air flow rate, the intake manifold pressure and temperature, the volumetric efficiency, and the EGR gas flow rate may be obtained by a preliminary test or the like, and may be estimated using the map or the arithmetic expression.

The EGR cooler cooling water flow rate can be estimated using, for example, a map or an arithmetic expression in which the engine speed and the EGR cooler cooling water flow rate are associated with each other by a preliminary test or the like. .
The EGR cooler inlet cooling water temperature is estimated by, for example, obtaining a map or an arithmetic expression that associates the cylinder head outlet cooling water temperature and the EGR cooler inlet cooling water temperature by a preliminary test or the like, and using the map or the arithmetic expression. Is possible.

  As described above, by using the EGR gas inlet temperature, the EGR gas flow rate, the EGR cooler cooling water flow rate, and the EGR cooler inlet cooling water temperature, it is possible to estimate the outlet temperature of the EGR cooler by diverting the measurement value of the existing sensor. It becomes possible. Thereby, it is not necessary to install a new sensor or the like, and generation of additional costs can be avoided.

[Fourth Embodiment]
Next, a control device and a control method for an internal combustion engine according to a fourth embodiment of the present invention will be described. In the first to third embodiments described above, local boiling of the cooling water inside the EGR cooler is avoided by limiting the fuel injection amount, but in this embodiment, the EGR gas amount is limited. This avoids local boiling of the cooling water inside the EGR cooler. Hereinafter, description of points common to the first embodiment will be omitted, and different points will be mainly described.

  FIG. 12 is a functional block diagram of the control device 30b according to the present embodiment. As shown in FIG. 12, the control device 30 b controls the fuel injection valve 15, thereby controlling the fuel control unit 41 b that controls the fuel injection amount and the injection timing into the combustion chamber 5 and the EGR valve 12. And an EGR control unit 43b for controlling the EGR gas amount.

  The EGR control unit 43b has EGR valve opening information in which the engine speed, the fuel injection amount, and the EGR valve opening are associated with each other, and the EGR valve opening information corresponds to the engine speed and the fuel injection amount from the EGR valve opening information. The EGR valve opening degree is acquired, and the valve opening degree of the EGR valve 12 is limited by the EGR valve opening degree.

  The EGR valve opening information includes EGR valve opening information used during warm-up operation and EGR valve opening information used during normal operation. The EGR valve opening information during the warm-up operation indicates that the EGR valve opening in the operation region defined as the region where the local boiling of the cooling water occurs within the EGR cooler is the EGR valve in the same operation region during the normal operation. A value smaller than the valve opening is set. The EGR valve opening information is registered in the EGR control unit 43b as, for example, a three-dimensional map or an arithmetic expression.

For example, the EGR valve opening information at the time of warm-up operation specifies the operation region specified by the engine speed and the fuel injection amount at which local boiling of cooling water occurs in the EGR cooler during the warm-up operation in the preliminary test. The maximum EGR valve opening that does not cause local boiling of cooling water in the EGR cooler in the specified operating region is obtained, and the EGR valve opening is created by associating it with the engine speed and the fuel injection amount. .
Therefore, during warm-up operation, local boiling of the cooling water inside the EGR cooler is easily prevented by controlling the EGR valve opening degree using the EGR valve opening degree information during such warm-up operation. It becomes possible.

  FIG. 13 is a diagram illustrating an example of an operation region where local boiling of cooling water occurs in the EGR cooler during the warm-up operation, in other words, an operation region where the EGR valve opening degree is limited. In FIG. 13, the horizontal axis is the engine speed, the vertical axis is the shaft torque, and the shaded area is the range where the EGR valve opening is limited.

In such a control device 30b, the engine speed and the fuel injection amount are input to the EGR control unit 43b at a predetermined sampling period, and EGR for warm-up operation during warm-up operation and EGR for normal operation during normal operation. The valve opening information is referred to, the EGR valve opening corresponding to the engine speed and the fuel injection amount is acquired, and the EGR valve 12 is controlled by the EGR valve opening.
As described above, during the warm-up operation, the EGR valve opening degree is limited in the operation region where the local boiling occurs in the cooling water inside the EGR cooler. Therefore, in the operation region where the local boiling occurs, the EGR cooler It is possible to reduce the amount of EGR gas flowing into the gas generator 11. Thereby, the amount of cooling water heat required for heat exchange in the EGR cooler 11 can be reduced, and boiling of the cooling water can be avoided.

  As described above, according to the control apparatus and control method for an internal combustion engine according to the present embodiment, during the warm-up operation, the operation in the operation region in which the local boiling of the cooling water inside the EGR cooler is avoided. Such EGR valve opening information is prepared in advance, and during the warm-up operation, the opening degree of the EGR valve is controlled using this EGR valve opening information. This makes it possible to easily prevent local boiling of the cooling water inside the EGR cooler.

[Fifth Embodiment]
Next, a control device and a control method for an internal combustion engine according to a fifth embodiment of the present invention will be described. In the above-described fourth embodiment, the EGR valve opening is determined according to the engine speed and the fuel injection amount. However, in this embodiment, the EGR valve opening is further adjusted according to the coolant temperature. This is different from the fourth embodiment described above. Here, about the cooling water temperature, it is the same as that of 2nd Embodiment mentioned above.

  For example, the EGR control unit has a four-dimensional map or an arithmetic expression in which the engine speed, the fuel injection amount, the coolant temperature, and the EGR valve opening are associated, and the engine is calculated from the four-dimensional map or the arithmetic expression. The EGR valve opening according to the rotation speed, the fuel injection amount, and the coolant temperature is acquired.

  In addition, for example, the EGR valve opening is acquired from a three-dimensional map or an arithmetic expression in which the engine speed, the fuel injection amount, and the EGR valve opening are associated, and the EGR valve opening is determined according to the cooling water. It is good also as obtaining the final EGR valve opening degree by correct | amending using a value. An example of an internal schematic configuration of the EGR control unit in this case is shown in FIG.

As shown in FIG. 14, the EGR control unit includes an EGR valve opening degree acquiring unit 51, a corrected opening degree acquiring unit 52, and a correcting unit 53.
The EGR valve opening degree acquiring unit 51 acquires the EGR valve opening degree from EGR valve opening degree information (three-dimensional map, arithmetic expression, etc.) in which the engine speed, the fuel injection amount, and the EGR valve opening degree are associated. The EGR valve opening information used here is EGR valve opening information during the warm-up operation.

The correction opening degree obtaining unit 52 obtains a correction coefficient using a table or an arithmetic expression in which the coolant temperature and the correction coefficient are associated with each other, and this correction coefficient is obtained from the EGR valve opening degree obtaining unit 51. The corrected opening is obtained by multiplying the degree.
The correction unit 53 adds the EGR valve opening degree acquired by the EGR valve opening degree acquisition unit 51 and the correction opening degree acquired by the correction opening degree acquisition unit 52 to thereby obtain the corrected EGR valve opening degree. obtain.

  In FIG. 14, the EGR valve opening degree acquisition unit 51 uses the EGR valve opening degree information at the time of warm-up operation, but instead of this, the EGR valve opening degree information at the time of normal operation may be used. Good. In this case, the correction opening acquired by the correction opening acquisition unit 52 may be determined according to the engine speed, the fuel injection amount, and the coolant temperature.

  Thus, by controlling the EGR valve opening according to the cooling water temperature, it is possible to finely set the range for limiting the EGR valve opening. As a result, it is possible to narrow the range for limiting the amount of EGR gas compared to the case where the cooling water temperature is not used, and it is possible to suppress a decrease in the NOx suppression effect during the warm-up operation.

[Sixth Embodiment]
Next, a control device and a control method for an internal combustion engine according to a sixth embodiment of the present invention will be described. In the fourth embodiment described above, the EGR valve opening degree is controlled according to the engine speed or the like, but in this embodiment, a predetermined temperature threshold value at which the coolant temperature at the EGR cooler outlet is set in advance. When it becomes above, the EGR valve opening degree is limited.

Specifically, when the outlet temperature of the EGR cooler 11 becomes equal to or higher than the threshold value, the EGR valve opening degree is controlled so as to close, so that the outlet temperature of the EGR cooler 11 does not become higher than the temperature threshold value. Feedback control.
Here, the threshold value setting, the EGR cooler outlet temperature measurement, and the estimation method are based on the method in the third embodiment described above. That is, as for the EGR cooler outlet temperature, in addition to using the measured value of the temperature sensor 28 (see FIG. 9), the estimated value based on the measured value of the temperature sensor 27 (see FIG. 11), or the EGR gas inlet temperature, EGR gas flow rate, EGR The temperature estimated using the cooler coolant flow rate and the EGR cooler inlet coolant temperature may be used.

  According to the control apparatus and control method for an internal combustion engine according to the present embodiment, the outlet temperature of the EGR cooler 11 is directly measured or estimated, and the EGR valve opening is limited based on this temperature. Compared to the embodiment, the range for limiting the EGR valve opening can be further narrowed.

  FIG. 15 shows the opening / closing timing of the thermostat, the amount of cooling water of the EGR cooler, the outlet cooling water temperature of the cylinder head, the outlet cooling water temperature of the EGR cooler, and the EGR valve when the control by the control device for the internal combustion engine according to the present embodiment is performed. It is the figure which showed an example of the timing chart of an opening degree. As shown in FIG. 15, when the outlet cooling water temperature of the EGR cooler exceeds the threshold value at time t1, the EGR valve opening degree is limited. At time t2, when the temperature of the coolant coolant at the cylinder head reaches a predetermined value set in advance, the thermostat is fully opened, and the coolant flow rate of the EGR cooler increases accordingly. Sufficient cooling water will be supplied, and the restriction on the EGR valve opening will be released.

[Seventh Embodiment]
Next, a control device and a control method for an internal combustion engine according to a seventh embodiment of the present invention will be described. In the first to third embodiments described above, local boiling of the cooling water inside the EGR cooler is avoided by limiting the fuel injection amount. However, in the present embodiment, the fuel is introduced into the EGR cooler 11. By increasing the amount of cooling water, local boiling of the cooling water inside the EGR cooler is avoided. Hereinafter, description of points common to the first embodiment will be omitted, and different points will be mainly described.

  FIG. 16 is a diagram showing a cooling water circulation circuit 20c according to the present embodiment. As shown in FIG. 16, in the second flow path L2, a thermostat bypass that joins a part of the cooling water sent to the EGR cooler 11 to the downstream side of the cooling water flow from the thermostat 25 in the first circulation flow path L1. A flow path B2 is connected. The thermostat bypass channel B2 is provided with a flow rate adjusting valve 29 for adjusting the bypass flow rate.

  FIG. 17 is a functional block diagram of the control device 30c according to the present embodiment. As shown in FIG. 17, the control device 30 c controls the fuel injection valve 15, thereby controlling the fuel control unit 41 b that controls the fuel injection amount and the injection timing into the combustion chamber 5 and the EGR valve 12. An EGR control unit 43a that controls the amount of EGR gas and a cooling water control unit 45 that controls the amount of cooling water by controlling the valve opening degree of the flow rate adjusting valve 29 are provided.

The cooling water control unit 45 has flow rate control valve opening information used during warm-up operation. The flow control valve opening information is a map or an arithmetic expression in which the engine speed, the fuel injection amount, and the opening of the flow control valve 29 are associated with each other. The cooling water control unit 45 acquires the flow rate control valve opening according to the engine speed and the fuel injection amount from the flow rate control valve opening information, and restricts the valve opening of the flow rate control valve by this flow rate control valve opening. To do.
During normal operation, the flow control valve is in a fully closed state or a constant opening state.

  FIG. 18 shows an example of the flow control valve opening information. As shown in FIG. 18, the flow control valve opening information is in an operation region (specified by the engine speed and the fuel injection amount) defined as a region where local boiling of cooling water occurs inside the flow control cooler. The valve opening is set to be fully open. In addition, the valve opening degree may be set to a value according to the operating state. In this case, the higher the rotation speed, the larger the fuel injection amount.

  Here, in order to avoid local boiling of the cooling water inside the EGR cooler, it is only necessary to supply an amount of cooling water sufficient to lower the temperature. It is sufficient to control it to be fully open. However, for example, if a large amount of cooling water is supplied with respect to the amount of EGR gas, water vapor contained in the amount of EGR gas is condensed in the EGR cooler 11 to generate condensed water, and this condensed water generates the inside of the EGR cooler. There is a risk that corrosion will occur. Therefore, in order to avoid such an event, it is preferable to adjust the cooling water amount in accordance with the EGR valve opening degree, the fuel injection amount, and the like.

  FIG. 19 is a diagram illustrating an example of an operation region in which local boiling of cooling water occurs in the EGR cooler during warm-up operation, in other words, an operation region in which restriction control of the flow rate control valve opening is performed. In FIG. 19, the horizontal axis is the engine speed, the vertical axis is the shaft torque, and the shaded area is the range in which the opening degree of the flow control valve 29 is adjusted.

In such a control device 30c, during the warm-up operation, the engine speed and the fuel injection amount are input to the cooling water control unit 45 at a predetermined sampling period, and the flow rate adjustment valve according to the engine speed and the fuel injection amount. The opening is acquired from the flow control valve opening information, and the flow control valve 29 is controlled by this valve opening.
Thus, during the warm-up operation, the valve opening degree of the flow control valve 29 is controlled to open in the operation region where local boiling occurs in the cooling water inside the EGR cooler, so that the EGR cooler 11 can be opened. Increase cooling water flow rate. Thereby, local boiling of the cooling water inside the EGR cooler can be avoided.

  As described above, according to the control apparatus and control method for an internal combustion engine according to the present embodiment, during the warm-up operation, the operation in the operation region in which the local boiling of the cooling water in the flow rate adjustment cooler occurs. Flow control valve opening information to be avoided is prepared in advance, and the opening of the flow control valve 29 is controlled using this flow control valve opening information during warm-up operation. Thereby, local boiling of the cooling water inside the flow rate adjusting cooler can be easily prevented.

[Eighth Embodiment]
Next, a control device and a control method for an internal combustion engine according to an eighth embodiment of the present invention will be described. In the seventh embodiment described above, the flow rate control valve opening is determined according to the engine speed and the fuel injection amount. However, in this embodiment, the flow rate control valve opening is further set according to the coolant temperature. It differs from the seventh embodiment described above in that it is determined. Here, about the cooling water temperature, it is the same as that of 2nd Embodiment mentioned above.

  For example, the cooling water control unit has the flow rate control valve opening information for each cooling water temperature, and controls the flow rate control valve opening using the flow rate control valve opening information of the corresponding cooling water temperature. . FIG. 20A shows an example of flow control valve opening information when the water temperature is 50 ° C., and FIG. 20B shows an example of flow control valve opening information when the water temperature is 60 ° C. FIG. 20 shows the value of the valve opening when the fully opened state is 1.

  Thus, by controlling the flow rate control valve opening according to the cooling water temperature, it is possible to finely set the range for limiting the flow rate control valve opening.

[Ninth Embodiment]
Next, a control device and a control method for an internal combustion engine according to a ninth embodiment of the present invention will be described. In the seventh embodiment described above, the opening degree of the flow rate control valve is controlled according to the engine speed or the like, but in this embodiment, the cooling water temperature at the outlet of the EGR cooler is set to a predetermined temperature. When it becomes more than a threshold value, the flow regulating valve 29 is fully opened, and the amount of cooling water flowing to the EGR cooler 11 is increased.

  Here, the threshold value setting, the flow rate adjustment cooler outlet temperature measurement, and the estimation method are based on the method in the third embodiment described above. That is, for the flow rate adjustment cooler outlet cooling water temperature, in addition to using the measurement value of the temperature sensor 28 (see FIG. 9), the estimated value based on the measurement value of the temperature sensor 27 (see FIG. 11), the flow adjustment gas inlet temperature, the flow adjustment The temperature estimated using the gas flow rate, the flow rate adjusting cooler cooling water flow rate, and the flow rate adjusting cooler inlet cooling water temperature may be used.

  According to the control apparatus and control method for an internal combustion engine according to the present embodiment, the outlet temperature of the flow control cooler is directly measured or estimated, and the flow control valve opening is controlled based on this temperature. Compared to the eighth embodiment, it is possible to further narrow the range in which the flow control valve opening degree is limited.

  FIG. 21 shows the thermostat opening / closing timing, the EGR cooler cooling water amount, the cylinder head outlet cooling water temperature, the EGR cooler outlet cooling water temperature, and the flow rate adjustment when the control by the control apparatus for an internal combustion engine according to the present embodiment is performed. It is the figure which showed an example of the timing chart which showed the opening / closing timing of the valve. As shown in FIG. 21, when the outlet temperature of the EGR cooler 11 exceeds the threshold value at time t1, the flow control valve is fully opened. At time t2, when the outlet coolant temperature of the cylinder head reaches a predetermined value set in advance, the thermostat is fully opened, and accordingly, the coolant flow rate of the flow rate adjusting cooler is increased. Sufficient cooling water is supplied to the cooler, and the flow control valve opening is fully closed.

  In the seventh to ninth embodiments, the flow rate of the cooling water is increased by changing the opening degree of the flow rate adjusting valve 29. Instead, the rotational speed of the cooling water pump 21 is increased. It is good also as increasing the flow volume of the cooling water supplied to the EGR cooler 11 by doing. In this case, information relating the engine speed, the fuel injection amount, and the rotational speed of the cooling water pump 21 may be prepared, and the rotational speed of the cooling water pump 21 and the like may be controlled based on this information. Alternatively, when the outlet cooling water temperature of the EGR cooler exceeds the temperature threshold value, the rotational speed of the cooling water pump 21 may be feedback controlled so that the temperature becomes equal to or lower than the temperature threshold value.

  Thus, by increasing the number of rotations of the cooling water pump 21 to increase the cooling water, the flow rate adjustment valve 29 in the thermostat bypass channel B2 can be made unnecessary. Thereby, generation | occurrence | production of the additional cost by providing the flow control valve 29 can be avoided. On the other hand, if the number of rotations of the cooling water pump 21 is increased, the flow rate of the cooling water supplied to the crankcase and the like also increases. There is also the inconvenience of prolonged.

  Therefore, for example, the coolant flow rate may be increased by controlling both the flow rate control valve 29 and the coolant pump 21. For example, when the opening degree of the flow rate control valve 29 is first fully opened and the cooling water boils inside the EGR cooler even in this state, the number of rotations of the cooling water pump 21 is increased to increase the cooling water. The flow rate may be further increased.

DESCRIPTION OF SYMBOLS 1 Diesel engine 2a Cylinder head 11 EGR cooler 20, 20a, 20b, 20c Cooling water circulation circuit 21 Cooling water pump 22 Radiator 25 Thermostat 27, 28 Temperature sensor,
29 Flow control valves 30a, 30b, 30c Control devices 41a, 41b Fuel control units 43a, 43b EGR control unit 45 Cooling water control unit 51 EGR valve opening acquisition unit 52 Correction opening acquisition unit 53 Correction unit B1 Radiator bypass flow path B2 Thermostat bypass channel L1 First circulation channel L2 Second channel

Claims (17)

A control device applied to an internal combustion engine having an EGR cooler,
Fuel control means for controlling the fuel injection amount;
The fuel control means is a control device for an internal combustion engine that limits a fuel injection amount in an operation region defined as a region where local boiling of cooling water occurs inside the EGR cooler during warm-up operation. The fuel control means includes
It holds the maximum fuel information that is associated with the number of revolutions and the maximum fuel injection amount that is used during warm-up operation,
During warm-up operation, the maximum fuel injection amount corresponding to the rotational speed is acquired from the maximum fuel information, the fuel injection amount is limited to be equal to or less than the acquired maximum fuel injection amount,
2. The control device for an internal combustion engine according to claim 1, wherein the maximum fuel injection amount of the maximum fuel information is set in advance to a value that does not cause local boiling of cooling water inside the EGR cooler. In the maximum fuel information, the rotation speed, the coolant temperature, and the maximum fuel injection amount are associated,
The control apparatus for an internal combustion engine according to claim 2, wherein the fuel control means acquires a maximum fuel injection amount according to a rotation speed and a coolant temperature from the maximum fuel information. A temperature acquisition means for measuring or estimating the cooling water temperature at the outlet of the EGR cooler;
2. The fuel control unit according to claim 1, wherein the fuel control unit controls the fuel injection amount so that the temperature does not exceed the temperature threshold when the temperature acquired by the temperature acquisition unit is equal to or higher than a predetermined temperature threshold. Control device for internal combustion engine. A control device applied to an internal combustion engine having an EGR cooler and an EGR valve for adjusting an EGR gas amount,
EGR control means for controlling the amount of EGR gas,
The control device for an internal combustion engine, wherein the EGR control means limits the flow rate of EGR gas in an operation region defined as a region where local boiling of cooling water occurs in the EGR cooler during warm-up operation. The EGR gas control means includes:
EGR valve opening information associated with the rotational speed, the fuel injection amount, and the EGR valve opening is used during warm-up operation.
During warm-up operation, the EGR valve opening according to the rotational speed and the fuel injection amount is acquired from the EGR valve opening information, and the EGR valve is controlled with the acquired EGR valve opening.
6. The control apparatus for an internal combustion engine according to claim 5, wherein the EGR valve opening degree in the maximum fuel information is preset to a value that does not cause local boiling of cooling water inside the EGR cooler. In the EGR valve opening information, the rotational speed, the fuel injection amount, the coolant temperature, and the EGR valve opening are associated,
The control device for an internal combustion engine according to claim 6, wherein the EGR control means acquires an EGR valve opening degree according to a rotation speed, a fuel injection amount, and a coolant temperature from the EGR valve opening degree information. A temperature acquisition means for measuring or estimating the cooling water temperature at the outlet of the EGR cooler;
6. The EGR control unit according to claim 5, wherein the EGR control unit controls the EGR valve so that the temperature does not exceed the temperature threshold when the temperature acquired by the temperature acquisition unit is equal to or higher than a predetermined temperature threshold. Control device for internal combustion engine. A control device applied to an internal combustion engine having an EGR cooler,
Flow rate adjusting means for adjusting the flow rate of cooling water flowing into the EGR cooler;
Cooling water control means for controlling the flow rate adjusting means,
The cooling water control means is configured to increase the flow rate of cooling water flowing into the EGR cooler in an operation region defined as a region where local boiling of cooling water occurs in the EGR cooler during warm-up operation. A control device for an internal combustion engine for controlling the flow rate adjusting means. The cooling water control means includes
Possessing manipulated variable information associated with the rotational speed, fuel injection amount, and manipulated variable of the flow rate adjusting means used during warm-up operation;
During the warm-up operation, an operation amount corresponding to the rotation speed and the fuel injection amount is acquired from the operation amount information, and the flow rate adjusting means is controlled with the acquired operation amount.
The control device for an internal combustion engine according to claim 9, wherein the operation amount in the operation amount information is set in advance to a value that does not cause local boiling of the cooling water inside the EGR cooler. In the manipulated variable information, the rotation speed, the fuel injection amount, the coolant temperature, and the manipulated variable are associated,
The control apparatus for an internal combustion engine according to claim 10, wherein the cooling water control unit acquires an operation amount corresponding to a rotation speed, a fuel injection amount, and a cooling water temperature from the operation amount information. A temperature acquisition means for measuring or estimating the cooling water temperature at the outlet of the EGR cooler;
The cooling water control means controls the flow rate adjustment means so that the temperature does not exceed the temperature threshold when the temperature acquired by the temperature acquisition means is equal to or higher than a predetermined temperature threshold. The internal combustion engine control device described.   The internal combustion engine according to any one of claims 9 to 12, wherein the flow rate adjusting means is a flow rate adjusting valve that is connected to a cooling water flow path that circulates through an EGR cooler and is provided in a thermostat bypass flow path that bypasses the thermostat. Control device.   The control apparatus for an internal combustion engine according to any one of claims 9 to 12, wherein the flow rate adjusting means is an electric pump for circulating cooling water.   The temperature of the cooling water at the outlet of the EGR cooler is such that the cooling water temperature at the downstream side of the cooling water flow at the confluence where the cooling water flowing out from the cylinder head and the cooling water flowing out from the EGR cooler merge, The control apparatus for an internal combustion engine according to any one of claims 4, 8, and 12, which is estimated using a ratio of a cooling water flow rate flowing into the EGR cooler with respect to a total flow rate.   The temperature of the cooling water at the outlet of the EGR cooler is estimated using an arithmetic expression having parameters of an EGR gas inlet temperature, an EGR gas flow rate, an EGR cooler cooling water flow rate, and an EGR cooler cooling water inlet temperature. Or the control apparatus for an internal combustion engine according to any one of 12 and 12. A control method applied to an internal combustion engine having an EGR cooler,
A control method for an internal combustion engine that limits a fuel injection amount in an operation region defined as a region where local boiling of cooling water occurs in the EGR cooler during warm-up operation.

Images