JPWO2010119545A1 - Control device for internal combustion engine - Google Patents

Abstract

The control device for an internal combustion engine according to the present embodiment is provided on a path through which the cooling water circulates, and circulates the cooling water, cooling devices 40L and 40R that cool the exhaust gas of the internal combustion engine by circulating the cooling water. A pump 76 and ECUs 7L and 7R that estimate the amount of heat of the exhaust and determine whether the operation of the pump 76 after the ignition switch 30 is detected off according to the estimated amount of heat of the exhaust are provided.

Description

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

  There is a cooling device for cooling the exhaust of an internal combustion engine. Some cooling devices are provided between an exhaust port of an internal combustion engine and an exhaust manifold, and others are provided around the exhaust manifold (see Patent Document 1). The exhaust water is cooled by circulating the cooling water inside the cooling device.

JP-A 63-208607

  Such a cooling device is disposed on a path through which cooling water flows. The cooling water is circulated through the path by a pump. Moreover, a part of the heat quantity of the exhaust is stored in such a cooling device. When the internal combustion engine is stopped, the pump is also stopped and the cooling water does not circulate. For this reason, the quantity of heat stored in the cooling device is transmitted to the cooling water, and the cooling water may boil.

  The objective of this invention is providing the control apparatus of the internal combustion engine which suppresses boiling of cooling water.

  The purpose is to provide a cooling device that is provided on a path through which the cooling water circulates and cools the exhaust of the internal combustion engine by circulating the cooling water, a pump that circulates the cooling water, and an estimation of the heat quantity of the exhaust And a control unit that determines whether or not the pump can be operated after detection of the ignition switch being turned off according to the estimated heat quantity of the exhaust gas. Thus, for example, when the amount of heat of the exhaust is high, even if it is detected that the ignition switch is turned off, the cooling water is circulated by operating the pump, and the cooling water is caused by the amount of heat stored in the cooling device. Can be prevented from boiling.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which suppresses boiling of cooling water can be provided.

FIG. 1 is an explanatory diagram of a control device for an internal combustion engine. FIG. 2 is a diagram illustrating a path of cooling water. FIG. 3 is a flowchart showing an example of control executed by the ECU. FIG. 4A is a map for calculating the exhaust gas temperature, and FIG. 4B is a map for calculating the idle operation period. FIG. 5 is a timing chart for explaining the control executed by the ECU. FIG. 6 is a timing chart for explaining the control executed by the ECU. FIG. 7 is a diagram illustrating a cooling water path of the control device for the internal combustion engine according to the second embodiment. FIG. 8 is a flowchart illustrating an example of control executed by the ECU. FIG. 9 is an explanatory diagram of a cooling water path of the control device for the internal combustion engine according to the third embodiment. FIG. 10 is a flowchart illustrating an example of control executed by the ECU.

  Hereinafter, a plurality of embodiments will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of a control device for an internal combustion engine. The engine 10 has a pair of banks 12L and 12R. The banks 12L and 12R are arranged to be inclined with respect to each other. The engine 10 is a so-called V-type engine. The bank 12L has a cylinder group including three cylinders 14L. Similarly, the bank 12R has a cylinder 14R.

  The bank 12L is provided with a fuel injection valve 15L that directly injects fuel into the cylinder 14L. Similarly, the bank 12R is also provided with a fuel injection valve 15R that directly injects fuel into the cylinder 14R. An intake passage 4L and an exhaust manifold 5L are connected to the bank 12L, and an intake passage 4R and an exhaust manifold 5R are connected to the bank 12R. The intake passages 4L and 4R merge on the upstream side, and a throttle valve 6 for adjusting the intake air amount and an air flow meter 18 for detecting the intake air amount are provided at the merged portion.

  Catalysts 20L and 20R are provided at the lower ends of the exhaust manifolds 5L and 5R, respectively. The catalysts 20L and 20R purify exhaust exhausted from the cylinders on the banks 12L and 12R side, respectively. Air-fuel ratio sensors 9L and 9R are attached to the exhaust manifolds 5L and 5R, respectively.

  A cooling device 40L is provided between the exhaust port (not shown) of the bank 12L and the exhaust manifold 5L. Similarly, a cooling device 40R is provided between the exhaust port (not shown) of the bank 12R and the exhaust manifold 5R.

  The cooling devices 40L and 40R are configured such that cooling water flows around the pipes of the exhaust manifolds 5L and 5R, respectively. The cooling devices 40L and 40R will be described later in detail.

  The opening degree of the throttle valve 6 is individually controlled for each of the banks 12L and 12R by ECUs (Electronic Control Units) 7L and 7R. Further, the amount of fuel injected from the fuel injection valves 15L and 15R is also individually controlled by the ECUs 7L and 7R. The ECUs 7L and 7R can cut the fuel injected from the fuel injection valves 15L and 15R. The ECUs 7L and 7R correspond to an estimation unit and a control unit, which will be described in detail later. The ECUs 7L and 7R can communicate bidirectionally via the communication line 8. By exchanging information via the communication line 8, the ECUs 7 </ b> L and 7 </ b> R can refer to information related to operation states of other banks for operation control of the banks in charge.

  The air-fuel ratio sensors 9L and 9R output detection signals corresponding to the exhaust air-fuel ratio to the ECUs 7L and 7R, respectively. The ECUs 7L and 7R perform feedback control of the air-fuel ratio by controlling the fuel injection amounts to the cylinders 14L and 14R based on the outputs from the air-fuel ratio sensors 9L and 9R, respectively. The feedback control is to control the fuel injection amount so that the detected air-fuel ratio of the exhaust gas becomes the target air-fuel ratio.

  The water temperature sensor 52 outputs a detection signal corresponding to the temperature of cooling water described later to the ECR 7L. The water temperature sensor 52 is placed at an arbitrary position on the path through which the cooling water circulates. The ignition switch 30 outputs an on signal and an off signal to the ECU 7L.

  FIG. 2 is a diagram illustrating a path of cooling water. As shown in FIG. 2, a radiator 72, an inlet 74, a pump 76, and the like are arranged on the cooling water path. The main path 82 circulates cooling water in the order of the inlet 74, the pump 76, the engine 10, and the radiator 72. The main path 82 circulates cooling water from the rear joint portion 19 of the engine 10 to the radiator 72. The auxiliary path 88 circulates cooling water in the order of the inlet 74, the pump 76, the engine 10, the cooling devices 40L and 40R, and the V bank pipe 60. The auxiliary path 88 includes branch paths 86L and 86R that branch from the rear joint portion 19 and allow cooling water to flow through the cooling devices 40L and 40R, respectively.

  The pump 76 is a mechanical pump that operates in conjunction with the rotation of the engine 10. The cooling water flows from the inlet 74 to the engine 10. The cooling water first flows into the block-side water jacket 11w of the engine 10, and then flows into the head-side water jackets 12Lw and 12Rw. The cooling water discharged from the head side water jackets 12 </ b> Lw and 12 </ b> Rw joins at the rear joint unit 19. A main path 82 and an auxiliary path 88 are connected to the rear joint portion 19. The cooling water flowing through the main path 82 flows from the rear joint portion 19 to the radiator 72, and the cooling water radiates heat at the radiator 72.

  A cooling device 40L is disposed on the branch path 86L. Cooling water flows through the cooling device 40L. When the cooling water flows through the cooling device 40L, the temperature of the exhaust discharged from the cylinder 14L of the bank 12L can be lowered. The same applies to the branch path 86R and the cooling device 40R.

FIG. 3 is a flowchart showing an example of control executed by the ECUs 7L and 7R.
The ECUs 7L and 7R detect the cooling water temperature based on the output from the water temperature sensor 52 (step S1). Note that the cooling water temperature may be estimated by a known method without depending on the output from the water temperature sensor 52.

  Next, the ECUs 7L and 7R calculate the exhaust gas temperature and the exhaust gas amount (step S2). The exhaust gas temperature is calculated based on, for example, the map shown in FIG. 4A. FIG. 4A is a map for calculating the exhaust gas temperature, and is stored in advance in the ECUs 7L and 7R. As shown in FIG. 4A, the vertical axis indicates the rotation speed of the engine 10, and the horizontal axis indicates the load of the engine 10. The exhaust gas temperature is calculated to be higher as the rotational speed and load of the engine 10 are larger.

  The exhaust gas amount (g / sec) is based on the intake air amount detected based on the output from the air flow meter 18 and the air-fuel ratio detected based on the air-fuel ratio sensors 9L and 9R. The exhaust gas amount is calculated.

  Next, the ECUs 7L and 7R estimate the heat quantity P of the exhaust gas (step S3). Specifically, it is estimated by the following formula.

  P = M * Cp * (Tex-Tair) (1)

  M represents the exhaust gas amount, Cp represents the specific heat of the exhaust gas, Tex represents the exhaust gas temperature, and Tair represents the outside air temperature. The amount of heat P is calculated by substituting the exhaust gas amount and the exhaust gas temperature calculated in step S2 into M and Tex, respectively. The outside air temperature may be detected using a known temperature sensor, or may be estimated or calculated by other known methods.

  Next, the ECUs 7L and 7R determine whether or not the cooling water temperature exceeds the determination value D1 (step S4). When exceeding, ECU7L, 7R determines whether the calorie | heat amount of exhaust gas exceeds the determination value D2 (step S5). The heat quantity of the exhaust gas here is the heat quantity calculated in step S3. When exceeding, the ECUs 7L and 7R set a value obtained by adding 1 to the previous first counter value T1 as the current first counter value T1 (step S6). The first counter value T1 is a value used for measuring a period during which the amount of heat of the exhaust gas exceeds the determination value D2.

  Next, the ECUs 7L and 7R determine whether or not the first counter value T1 exceeds the determination value D3 (step S7). If exceeded, the ECUs 7L and 7R turn on a flag for performing idle operation after detecting the ignition switch 30 being turned off (step S8). The reason why the idle operation is executed after the detection of the ignition switch 30 being turned off is that the amount of heat stored in the cooling devices 40L and 40R by operating the pump 76 for a predetermined period even after the ignition switch 30 is turned off by performing the idle operation. This is to prevent the cooling water from boiling due to the above.

  Next, the ECUs 7L and 7R calculate an idle operation period (step S9). Specifically, the ECUs 7L and 7R calculate an idle operation period corresponding to the first counter value T1, as shown in FIG. 4B. FIG. 4B is a map for calculating the idle operation period. In the map of FIG. 4B, the vertical axis represents the idle operation period, and the horizontal axis represents the first counter value T1. As shown in FIG. 4B, the idle operation period is set longer as the first counter value T1 is larger. This is because it seems that the larger the first counter value T1, the more heat is stored in the cooling devices 40L and 40R. For example, when the first counter value T1 is 1000, 2000, 3000, and 4000, the idle operation period is set to 30, 60, 90, and 120 (sec), respectively. The first counter value T1 corresponds to a period in which the amount of heat of the exhaust gas exceeds the determination value D2. Therefore, the idle operation period is set according to the period during which the estimated heat quantity of the exhaust gas exceeds the determination value D2. That is, the operation period of the pump 76 is set according to the period when the heat quantity of the exhaust gas exceeds the determination value D2.

  Next, the ECUs 7L and 7R determine whether or not an off signal is detected from the ignition switch 30 (step S10). In a negative determination, the ECUs 7L and 7R execute Step S1 again. When the ECUs 7L and 7R detect an off signal from the ignition switch 30, the ECUs 7L and 7R execute an idle operation (step S11). By performing the idle operation, the pump 76 operates in conjunction with the engine 10. Therefore, even if the ignition switch 30 is turned off, the pump 76 operates for a predetermined period, and the cooling water circulates on the path. Thereby, it is possible to prevent the cooling water from boiling due to the influence of the amount of heat stored in the cooling devices 40L and 40R.

  In step S4, when the coolant temperature is lower than the determination value D1, the ECUs 7L and 7R turn off the idle operation execution flag (step S15). This is because if the cooling water temperature is low to some extent, the cooling water is less likely to boil even after the ignition switch 30 is turned off.

  In step S5, when the heat quantity of the exhaust gas is less than the determination value D2, the ECUs 7L and 7R determine whether or not the idle operation execution flag is on (step S12). In the case of a negative determination, the ECUs 7L and 7R execute step S15. In the case of an affirmative determination, the ECUs 7L and 7R calculate a value obtained by adding 1 to the previous second counter value T2 as the current second counter value T2 (step S13). The second counter value T2 is used for measuring a period during which the amount of heat of the exhaust gas is less than the determination value D1.

  Next, the ECUs 7L and 7R determine whether or not the second counter value T2 exceeds the determination value D4 (step S14). When the second counter value T2 exceeds the determination value D4, the ECUs 7L and 7R execute step S15. This is because in this case, it is estimated that the amount of heat stored in the cooling devices 40R and 40L is small. When the second counter value T2 is less than the determination value D2, the ECUs 7L and 7R turn on the idle operation flag (step S8). In this case, it is estimated that the amount of heat stored in the cooling devices 40R and 40L is still sufficient. The second counter value T2 corresponds to a period in which the amount of heat of the exhaust gas is less than the determination value D2. Accordingly, whether or not the idle operation can be performed is determined according to a period in which the estimated heat quantity of the exhaust gas is less than the determination value D2 and a period in which the estimated heat quantity of the exhaust gas exceeds the determination value D2. That is, whether or not the pump 76 can be operated after the ignition switch 30 is turned off depends on a period in which the estimated heat quantity of the exhaust gas is less than the determination value D2 and a period in which the estimated heat quantity of the exhaust gas exceeds the determination value D2. It is determined. Thereby, it is possible to determine whether the pump 76 can be operated in consideration of the operating state of the engine 10 before the ignition switch 30 is turned off.

  As described above, the ECUs 7L and 7R estimate the amount of heat of the exhaust gas, and determine whether or not the idle operation can be performed after the ignition switch 30 is detected to be off according to the estimated amount of heat. Thereby, when the heat quantity of the exhaust gas is high, the pump 76 is operated after the ignition switch 30 is detected to be turned off, and the cooling water is circulated. Therefore, it is possible to prevent the cooling water from boiling due to the amount of heat stored in the cooling devices 40L and 40R.

  Next, control executed by the ECUs 7L and 7R will be described with reference to a timing chart. 5 and 6 are timing charts for explaining control executed by the ECUs 7L and 7R. 5 and 6 show the heat quantity P of the exhaust gas, the temperatures Tc of the cooling devices 40L and 40R, and the temperature Tw of the cooling water. The temperature Tw of the cooling water indicates the temperature of the cooling water around the cooling devices 40L and 40R.

  FIG. 5 is a timing chart in the case where the idle operation period is executed after detection of the ignition switch 30 being turned off. For example, when the vehicle goes up a slope or the like and the high rotation and high load operation is continuously executed, the heat amount P of the exhaust gas rises and exceeds the determination value D2. When the ignition switch 30 is turned off in a state where the heat quantity P exceeds the determination value D2, the engine 10 is idled. When the temperature Tc of the cooling devices 40L and 40R when the ignition switch 30 is turned off is 200 ° C., the heat amount P of the exhaust gas rapidly decreases due to the idling operation, and the temperature Tc of the cooling devices 40L and 40R is also 200. Gradually lower from ℃. Further, when the idling operation is performed, the pump 76 operates and the cooling water circulates on the path, so that the temperature of the cooling water does not change largely before and after the ignition switch 30 is turned off, and is maintained at about 90 ° C. To do. In this way, it is possible to prevent the cooling water from boiling due to the amount of heat stored in the cooling devices 40L and 40R.

  Assume that the pump 76 is stopped when the ignition switch 30 is turned off. In this case, since the pump 76 is stopped, the cooling water does not circulate, and the cooling water staying in the cooling devices 40L and 40R or around the cooling devices 40L and 40R is stored in the cooling devices 40L and 40R. There is a risk of boiling due to the amount of heat. However, in the present embodiment, the idling operation is performed for a predetermined period even after the ignition switch 30 is turned off, so that the cooling water is circulated until the amount of heat stored in the cooling devices 40L and 40R decreases. This can prevent the cooling water from boiling.

  Next, a case where idle operation is not executed will be described. FIG. 6 is a timing chart when the idle operation period is not executed after detection of the ignition switch 30 being turned off. As shown in FIG. 6, for example, when the vehicle is in a low rotation and low load operation after the high rotation and high load operation and the ignition switch 30 is turned off, the heat amount P of the exhaust gas has already reached the determination value D2 by the low rotation and low load operation. It is below. For this reason, idling is not performed in such a state. This is because the amount of heat stored in the cooling devices 40L and 40R is estimated to be small because the amount of heat P of the exhaust gas is reduced. Therefore, in such a case, idle operation is not executed.

Next, a control device for an internal combustion engine according to a second embodiment will be described.
FIG. 7 is a diagram illustrating a cooling water path of the control device for the internal combustion engine according to the second embodiment.
In the control device for the internal combustion engine of the second embodiment, a pump 76a is employed. The pump 76a is an electric pump that operates based on commands from the ECUs 7L and 7R. Therefore, even after the engine 10 is stopped, the pump 76a operates based on the commands from the ECUs 7L and 7R.

Next, control executed by the ECUs 7L and 7R will be described. FIG. 8 is a flowchart showing an example of control executed by the ECUs 7L and 7R.

When the ECUs 7L and 7R execute steps S1 to S7, the ECUs 7L and 7R turn on an effective flag for operating the pump 76a after the ignition switch 30 is detected to be off (step S8a). Next, the operation period of the pump 76a is calculated (step S9a). The operation period of the pump 76a is calculated based on the first counter value T1 as in the first embodiment. When it is detected that the ignition switch 30 is turned off, the ECUs 7L and 7R stop the engine 10 and operate the pump 76a (step S11a).

  In this manner, by operating the pump 76a for a predetermined period after the ignition switch 30 is turned off, it is possible to prevent the cooling water from boiling due to the amount of heat stored in the cooling devices 40L and 40R. If the determination in step S7 is negative or the determination in step S14 is affirmative, the effective flag for the operation of the pump 76a after turning off the ignition switch 30 is turned off (step S15a).

Next, a control device for an internal combustion engine according to a third embodiment will be described.
FIG. 9 is an explanatory diagram of a cooling water path of the control device for the internal combustion engine according to the third embodiment.
As shown in FIG. 9, the cooling water path has a main path 82 that passes through the engine 10 and a sub path 86 that is connected in parallel with the main path 82 and passes through the cooling devices 40L and 40R. . A control valve 78 is provided on the main path 82 between the pump 76 a and the engine 10. The control valve 78 can control the flow rate of the cooling water passing through the main path 82 in accordance with commands from the ECUs 7L and 7R. Specifically, the control valve 78 can be maintained at a predetermined opening degree according to a command from the ECUs 7L and 7R.

FIG. 10 is a flowchart showing an example of control executed by the ECUs 7L and 7R.
The ECUs 7L and 7R execute steps S1 to S10. When the ignition switch 30 is detected to be off, the ECUs 7L and 7R drive the pump 76a (step S11a) and close the control valve 78 (step S11b). As a result, the cooling water does not flow in the engine 10 and the cooling water flows in the sub-path 86. As a result, the flow rate of the cooling water flowing through the cooling devices 40L and 40R increases. Thereby, the cooling devices 40L and 40R are cooled in a short period of time by the cooling water that has flowed in a large amount. Therefore, it is possible to prevent the cooling water from boiling due to the amount of heat stored in the cooling devices 40L and 40R. Instead of completely closing the control valve 78, the flow rate of the cooling water passing through the engine 10 may be suppressed by controlling the control valve 78 to a predetermined opening degree.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Claims (6)

A cooling device that is provided on a path through which the cooling water circulates and cools the exhaust gas of the internal combustion engine by circulating the cooling water;
A pump for circulating the cooling water;
An estimation unit for estimating the amount of heat of the exhaust;
A control unit for an internal combustion engine, comprising: a control unit that determines whether or not the pump can be operated after detection of turning off of an ignition switch according to the estimated heat quantity of the exhaust gas. The pump is a mechanical pump linked to the internal combustion engine;
2. The control device for an internal combustion engine according to claim 1, wherein the control unit operates the pump by performing an idle operation after detecting that the ignition switch is turned off.   The control device for an internal combustion engine according to claim 1, wherein the pump is an electric pump that operates according to a command from the control unit. The path includes a main path that passes through the internal combustion engine, and a sub-path that is connected in parallel to the main path and passes through the cooling device,
A control valve capable of controlling the flow rate of cooling water flowing through the main path;
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control unit controls a flow rate of the cooling water flowing through the main path by controlling the control valve after detecting that the ignition switch is turned off. .   The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control unit sets an operation period of the pump according to a period during which the estimated amount of heat of the exhaust gas exceeds a determination value.   The control unit is configured to detect after the ignition switch is turned off according to a period in which the estimated amount of heat of the exhaust gas exceeds a determination value and a period in which the estimated amount of heat of the exhaust gas is less than the determination value. 4. The control device for an internal combustion engine according to claim 1, wherein whether or not the pump is operable is determined.

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