JP7803256B2 - Control device for internal combustion engine - Google Patents

Description

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

The exhaust passage is equipped with an exhaust treatment device that purifies the exhaust from the internal combustion engine and a temperature sensor that detects the temperature (see, for example, Patent Document 1).

JP 2019-120238 A

Condensed water forms in the exhaust passage when moisture in the exhaust condenses. This can cause the temperature sensor to become wet, resulting in increased error in temperature measurement by the temperature sensor. The condensed water moves and distributes inside the exhaust passage. The likelihood of water exposure varies depending on the location of the condensed water. Therefore, the objective is to provide a control device for an internal combustion engine that can detect the distribution of condensed water in the exhaust passage.

The above objective can be achieved by a control device for an internal combustion engine, in which an exhaust treatment device that purifies exhaust from an internal combustion engine is provided in the exhaust passage, and which includes a generation amount acquisition unit that acquires the amount of condensed water generated in the exhaust passage, and a distribution amount acquisition unit that acquires the distribution amount of condensed water at positions in the exhaust passage upstream of the exhaust treatment device, downstream of the exhaust treatment device, and between the upstream and downstream sides.

The generation amount acquisition unit may acquire the amount of condensed water generated during the period the internal combustion engine was stopped based on the time the internal combustion engine was stopped and the temperature of the exhaust passage upstream of the exhaust treatment device, and the distribution amount acquisition unit may acquire the distribution amount of condensed water during the period the internal combustion engine was stopped based on the attitude of the vehicle in which the internal combustion engine is mounted.

The distribution amount acquisition unit may update the distribution amount of the condensed water while the internal combustion engine is operating.

A first temperature sensor may be provided in the exhaust passage upstream of the exhaust treatment device, and a second temperature sensor may be provided upstream of the exhaust treatment device. A determination unit may be provided that determines whether the first temperature sensor and the second temperature sensor have been exposed to the condensed water based on the amount of condensed water distribution and the vehicle behavior.

It is possible to provide a control device for an internal combustion engine that can detect the distribution of condensed water in the exhaust passage.

FIG. 1 is a diagram illustrating a vehicle according to an embodiment. FIG. 2 is a flowchart illustrating the processing executed by the ECU. 3(a) to 3(c) are diagrams illustrating an example of an exhaust passage. 4(a) and 4(b) are diagrams illustrating the amount of condensed water.

The control device for an internal combustion engine according to this embodiment will now be described with reference to the drawings. FIG. 1 is a diagram illustrating a vehicle 100 according to this embodiment. As shown in FIG. 1, the vehicle 100 has an internal combustion engine 10 and an ECU (Electronic Control Unit) 30.

An internal combustion engine 10 burns fuel, such as gasoline, to generate power. An intake passage 12 and an exhaust passage 14 are connected to the internal combustion engine 10. Air flows through the intake passage 12 and is introduced into the internal combustion engine 10. A throttle valve 16 and an air flow meter 18 are provided in the intake passage 12, arranged in this order from upstream to downstream. As the opening of the throttle valve 16 increases, the air flow rate in the intake passage increases. As the opening decreases, the air flow rate decreases. The air flow meter 18 detects the air flow rate. An acceleration sensor 26 detects the attitude and acceleration of the vehicle 100 in which the internal combustion engine 10 is installed.

Exhaust gas generated by combustion flows through the exhaust passage 14 and is discharged outside the vehicle. A temperature sensor 22 (first temperature sensor), an exhaust treatment device 20, and a temperature sensor 24 (second temperature sensor) are provided in the exhaust passage 14, arranged in this order from upstream to downstream. The exhaust treatment device 20 may have, for example, a GPF (Gasoline Particulate Filter) to capture particulate matter in the exhaust. The exhaust treatment device 20 may also include a catalyst. The catalyst purifies substances such as carbon monoxide (CO) and nitrogen oxides (NOx). The exhaust treatment device 20 may also have a DPF (Diesel Particulate Filter).

The portion of the exhaust passage 14 upstream of the exhaust treatment device 20 is referred to as region 14a, and the portion downstream of the exhaust treatment device 20 is referred to as region 14c. The position between regions 14a and 14c is referred to as region 14b. Temperature sensor 22 is located in region 14a upstream of the exhaust treatment device 20 and detects the temperature on the upstream side. Temperature sensor 24 is located in region 14c downstream of the exhaust treatment device 20 and detects the temperature on the downstream side. Temperature sensors 22 and 24 are inserted from the outside to the inside of the exhaust passage 14 and are provided on, for example, the upper half of the wall of the exhaust passage 14. Down is the direction in which gravity acts, and up is the opposite direction to down.

The ECU 30 is a control device that includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and other storage devices, and performs various controls by executing programs stored in the ROM and storage devices.

The ECU 30 controls the opening of the throttle valve 16. The ECU 30 obtains the air flow rate (intake volume) from the air flow meter 18. The ECU 30 obtains the attitude and acceleration of the vehicle 100 from the acceleration sensor 26. The ECU 30 obtains the temperature of the exhaust passage 14 from the temperature sensors 22 and 24.

Exhaust gas contains moisture. When cooled, the moisture condenses, producing condensed water. ECU 30 functions as a generation amount acquisition unit that acquires the amount of condensed water produced in exhaust passage 14. ECU 30 functions as a distribution amount acquisition unit that acquires the distribution amount of condensed water in each of regions 14a, 14b, and 14c. ECU 30 functions as a determination unit that determines whether temperature sensors 22 and 24 have been exposed to condensed water. Exposure to water means that water has fallen on the sensors.

Figure 2 is a flowchart illustrating the processing executed by the ECU 30. Assume that the internal combustion engine 10 is stopped (soaking) at the start of the processing. The ECU 30 acquires the amount of condensed water generated based on, for example, the temperature of the region 14a of the exhaust passage 14 and the stop time (soak time) of the internal combustion engine 10 (step S10). The lower the temperature and the longer the stop time, the greater the amount of condensed water generated. The ECU 30 acquires the distribution amount of condensed water in each of the regions 14a, 14b, and 14c during the stop period based, for example, on the posture of the vehicle 100 (step S12). When the internal combustion engine 10 starts operating, exhaust gas flows into the exhaust passage 14. The condensed water is blown away by the exhaust and moves downstream in the exhaust passage 14. The condensed water may also be blown outside the vehicle 100 or may evaporate. As the operating time of the internal combustion engine 10 increases, the condensed water evaporates and decreases. The ECU 30 updates the distribution amount based on the driving time, intake volume, etc. (step S14).

Acceleration and deceleration of the vehicle 100 can cause condensed water to move and get on the temperature sensors 22 and 24. The ECU 30 determines whether the temperature sensors 22 and 24 are wet (step S16). If it is determined that neither the temperature sensors 22 nor 24 are wet, a negative determination (No) is made in step S16. If a negative determination is made, the processing in FIG. 2 ends. If it is determined that either the temperature sensor 22 or 24 is wet, a positive determination (Yes) is made in step S16. If a positive determination is made, the ECU 30 makes a correction (step S18). This correction may involve correcting the output value of the wetted temperature sensor or correcting a value calculated from the temperature. The corrected value is used, for example, to determine whether the exhaust treatment device 20 has been removed. After step S18, the processing ends.

Table 1 shows an example of the amount of condensed water generated. The temperatures are those in the region 14a, and are designated T1, T2, and T3 in ascending order. The time is the elapsed time after the internal combustion engine 10 is stopped, and elapses from 0 to ta and tb.

As shown in Table 1, when the elapsed time is 0, the amount of condensed water generated is 0. When the time is ta and the temperature is T1, the amount generated is W1. When the time is ta and the temperature is T2, the amount generated is W2. When the time is ta and the temperature is T3, the amount generated is W3. The amount generated W1 is greater than W2 and W3. The amount generated W2 is greater than W3. When the time is tb and the temperature is T1, the amount generated is W4. When the time is tb and the temperature is T2, the amount generated is W5. When the time is tb and the temperature is T3, the amount generated is W6. The amount generated W4 is greater than W1 and W5. The amount generated W5 is greater than W2 and W6. The amount generated W6 is greater than W3. The lower the temperature, the greater the amount of condensed water generated. The longer the elapsed time, the greater the amount generated. The ECU 30 stores a data table, such as that shown in Table 1, and references the data table to obtain the amount of condensed water generated (step S10 in Figure 2).

Figures 3(a) to 3(c) are diagrams illustrating the exhaust passage 14. The X-axis represents the horizontal direction. The left side of the X-axis is the direction in which the vehicle 100 moves forward. The right side is the direction in which the vehicle 100 moves backward. The Y-axis represents the up-down direction. Gravity acts downward on the Y-axis. Assume that condensed water 40, 42, and 44 has formed in the exhaust passage 14. Condensed water 40 accumulates in area 14a and is located upstream (forward) of the temperature sensor 22. Condensed water 42 accumulates near the exhaust treatment device 20. Condensed water 44 accumulates in area 14c and is located downstream (rear) of the temperature sensor 24.

In the example of Figure 3(a), the vehicle 100 is located on a horizontal road. The exhaust passage 14 is approximately parallel to the X-axis. When the vehicle 100 accelerates, the condensed water tends to move rearward. When the vehicle 100 decelerates, the condensed water tends to move forward.

In the example of Figure 3(b), the vehicle 100 is located on a downhill slope. The exhaust passage 14 is inclined relative to the X-axis and faces diagonally downward. The angle of inclination from the X-axis is designated as a. Condensed water tends to move upstream of the exhaust passage 14.

In the example of Figure 3(c), the vehicle 100 is located on an uphill slope. The exhaust passage 14 is inclined relative to the X-axis and faces diagonally upward. The angle of inclination from the X-axis is b. Condensed water tends to move downstream of the exhaust passage 14.

Tables 2 and 3 are tables showing examples of the amount of condensed water movement. In Table 2, the vehicle 100 is tilted downward as shown in Figure 3(b). The angle a of the exhaust passage 14 from the X axis is set to 0, a1, and a2, from the smallest angle.

As shown in Table 2, when angle a is 0, the amount of condensed water moving from region 14c to region 14b and from region 14b to region 14a is 0. When angle a is a1, the amount of condensed water moving from region 14c to region 14b is D1. The amount of condensed water moving from region 14b to region 14a is D2. For example, D1 is greater than or equal to D2. When angle a is a2, the amount of condensed water moving from region 14c to region 14b is D3. The amount of condensed water moving from region 14b to region 14a is D4. For example, D3 is greater than or equal to D1 and D4.

In Table 3, the posture of the vehicle 100 is tilted upward as shown in Fig. 3(c). The angle b of the exhaust passage 14 from the X axis is set to 0, b1, and b2, in ascending order.

As shown in Table 3, when angle b is 0, the amount of condensed water moving from region 14a to region 14b and from region 14b to region 14c is 0. When angle b is b1, the amount of condensed water moving from region 14a to region 14b is D5. The amount of condensed water moving from region 14b to region 14c is D6. D5 is greater than or equal to D6. When angle b is b2, the amount of condensed water moving from region 14a to region 14b is D7. The amount of condensed water moving from region 14b to region 14c is D8. For example, D7 is greater than or equal to D5 and D8.

When the vehicle 100 is tilted, condensed water moves within the exhaust passage 14. The greater the angle, the greater the amount of movement. The ECU 30 stores data tables such as Tables 2 and 3, and obtains the amount of condensed water movement based on the tilt angle. The distribution of condensed water by region can be obtained based on the amount of condensed water generated and the amount of movement (step S12 in Figure 2).

Figures 4(a) and 4(b) are diagrams illustrating the amount of condensed water. Figure 4(a) shows the change in the amount of condensed water in regions 14a, 14b, and 14c from the start of the internal combustion engine 10. The horizontal axis represents the elapsed time since start-up. The vertical axis represents the amount of condensed water accumulated since start-up. Condensation occurs when moisture in the exhaust condenses. The lower the temperature of the exhaust passage 14, the more likely condensation occurs. Condensation occurs in regions 14a, 14b, and 14c, in that order. The condensed water is blown away by the exhaust and moves downstream in the exhaust passage 14. The amount of condensed water in region 14a decreases, while the amount of condensed water in region 14b increases. As the condensed water in region 14b moves downstream, the amount of condensed water in region 14c increases. The greater the amount of intake air into the internal combustion engine 10, the greater the exhaust volume. The greater the exhaust volume, the more likely condensed water moves rearward.

Figure 4(b) shows the amount of condensed water in region 14c after the internal combustion engine 10 has been restarted. The horizontal axis represents the cumulative intake air volume since the internal combustion engine 10 was restarted. The vertical axis represents the amount of condensed water in region 14c. Assume that the internal combustion engine 10 is stopped at time t1 in Figure 4(a). The amount of condensed water in region 14c is V1. While the internal combustion engine 10 is stopped, the amount of condensed water in region 14c remains at V1. After the internal combustion engine 10 has been restarted, the exhaust gas generated by the internal combustion engine 10 flows into the exhaust passage 14. The condensed water evaporates due to the heat of the exhaust and is blown out of the vehicle 100 by the exhaust. As a result, the amount of condensed water decreases.

While the vehicle 100 is operating, the amount of condensed water distributed within the exhaust passage 14 changes. The ECU 30 updates the amount of distribution (step S14 in Figure 2). Depending on the behavior of the vehicle 100, the condensed water may move and come into contact with the temperature sensor. Examples of such behavior include acceleration and deceleration. The ECU 30 determines whether the temperature sensor has been exposed to water.

Table 4 is a table illustrating the possibility of water exposure to the temperature sensor 22. The accelerations A1 and A2 are positive values, and A3 and A4 are negative values. The absolute value of A1 is greater than the absolute value of A2. The absolute value of A4 is greater than the absolute value of A3. When the acceleration is A1, the vehicle 100 accelerates rapidly. When the acceleration is A2, the vehicle 100 accelerates slowly. When the acceleration is A3, the vehicle 100 decelerates slowly. When the acceleration is A4, the vehicle 100 decelerates rapidly. When the acceleration is 0, the vehicle 100 is stopped or traveling at a constant speed.

One of areas 14a, 14b, and 14c is assumed to have more condensed water than the other areas. When there is a lot of condensed water in area 14a and the acceleration is A1, there is a high possibility that the temperature sensor 22 will be wet. The condensed water accumulated in area 14a will likely move rearward due to sudden acceleration and fall on the temperature sensor 22. When there is a lot of condensed water in area 14a and the acceleration is A2, there is a low possibility that the temperature sensor 22 will be wet. Although condensed water has accumulated in area 14a, the amount of condensed water that moves rearward is small because the acceleration A2 is small. The possibility of it falling on the temperature sensor 22 is low. When there is a lot of condensed water in area 14a and the acceleration is 0, A3, or A4, the possibility of the temperature sensor 22 being wet is extremely low, for example, 0. When the acceleration is 0, condensed water does not move easily and is therefore unlikely to fall on the temperature sensor 22. When the acceleration is A3 or A4, condensed water moves forward and is therefore unlikely to fall on the temperature sensor 22.

When there is a large amount of condensed water in area 14b and the acceleration is A1, A2, or 0, the possibility of the temperature sensor 22 becoming wet is extremely low. When the acceleration is A1 or A2, the condensed water moves backward from area 14b, making it less likely to reach the temperature sensor 22. When the acceleration is 0, the condensed water does not move easily, making it less likely to reach the temperature sensor 22. When the acceleration is A3, the possibility of water exposure is low. This is because a small amount of condensed water moves from area 14b to the forward area 14a. When the acceleration is A4, the possibility of water exposure is high. This is because a large amount of condensed water moves from area 14b to area 14a.

When there is a large amount of condensed water in area 14c and the acceleration is any of A1, A2, 0, and A3, the possibility of the temperature sensor 22 becoming wet is extremely low. When the acceleration is A1 and A2, the condensed water moves backward and is therefore less likely to reach the temperature sensor 22. When the acceleration is 0, the condensed water does not move easily and is therefore less likely to reach the temperature sensor 22. When the acceleration is A3, a small amount of condensed water moves forward from area 14c. Because the distance from area 14c to area 14a is large, the temperature sensor 22 is less likely to become wet. When the acceleration is A4, the possibility of water exposure is low. A large amount of condensed water moves forward from area 14c. Because the distance from area 14c to area 14a is large, it is thought that only a small amount of condensed water will reach the temperature sensor 22.

Table 5 shows an example of the possibility of the temperature sensor 24 being wet.

When there is a large amount of condensed water in area 14a and the acceleration is A2, 0, A3, or A4, the possibility of the temperature sensor 22 becoming wet is extremely low. When the acceleration is A3 or A4, the condensed water moves forward and is therefore less likely to reach the temperature sensor 24. When the acceleration is 0, the condensed water does not move easily and is therefore less likely to reach the temperature sensor 24. When the acceleration is A2, a small amount of condensed water moves backward from area 14a. Because the distance from area 14a to area 14c is large, the temperature sensor 24 is less likely to become wet. When the acceleration is A1, the possibility of water exposure is low. A large amount of condensed water moves backward from area 14a. Because the distance from area 14a to area 14c is large, it is thought that only a small amount of condensed water will reach the temperature sensor 24.

When there is a large amount of condensed water in area 14b and the acceleration is 0, A3, or A4, the possibility of the temperature sensor 24 becoming wet is extremely low. When the acceleration is A3 or A4, the condensed water moves forward and is therefore less likely to become wet on the temperature sensor 24. When the acceleration is 0, the condensed water does not move easily and is therefore less likely to become wet on the temperature sensor 24. When the acceleration is A2, the possibility of water exposure is low. This is because a small amount of condensed water moves from area 14b to area 14c behind it. When the acceleration is A1, the possibility of water exposure is high. This is because a large amount of condensed water moves from area 14b to area 14c.

When there is a large amount of condensed water in area 14c and the acceleration is A1, A2, or 0, the possibility of the temperature sensor 24 becoming wet is extremely low. When the acceleration is A1 or A2, the condensed water moves backward and is therefore unlikely to reach the temperature sensor 24. When the acceleration is 0, the condensed water does not move easily and is therefore unlikely to reach the temperature sensor 24. When the acceleration is A3, the possibility of water exposure is low. There is a possibility that a small amount of condensed water will move forward and reach the temperature sensor 24. When the acceleration is A4, the possibility of water exposure is high. This is because a large amount of condensed water will move forward.

According to this embodiment, the ECU 30 obtains the amount of condensed water generated in the exhaust passage 14 and obtains the distribution of condensed water in each of the regions 14a, 14b, and 14c of the exhaust passage 14 (steps S10 and S12). This makes it possible to detect the distribution of condensed water in the exhaust passage 14.

As shown in Table 1, the amount of condensed water increases as the temperature decreases and the stop time increases. As shown in Tables 2 and 3, condensed water moves through the exhaust passage 14 depending on the inclination of the vehicle 100. The ECU 30 obtains the amount of condensed water generated based on the time the internal combustion engine 10 is stopped and the time detected by the temperature sensor 22. The ECU 30 obtains the distribution amount of condensed water based on the attitude of the vehicle 100. The distribution amount of condensed water during the stop period of the internal combustion engine 10 can be obtained. The ECU 30 may estimate the distribution amount based on, for example, the shape of the exhaust passage 14, as well as the attitude of the vehicle 100.

As shown in Figure 4(a), the condensed water is blown away by the exhaust and moves rearward. As shown in Figure 4(b), the condensed water evaporates and decreases due to the heat generated by the internal combustion engine 10. The greater the intake air volume, the greater the exhaust volume, making it easier for the condensed water to move rearward. The longer the internal combustion engine 10 operates, the greater the amount of heat generated. The condensed water evaporates and decreases. While the internal combustion engine 10 is operating, the ECU 30 updates the distribution amount of condensed water based on the intake air volume and operating time (step S14). The distribution amount during operation can be obtained.

Temperature sensors 22 and 24 are provided in the exhaust passage 14. Acceleration and deceleration of the vehicle 100 causes the condensed water to move. As shown in Tables 4 and 5, the ECU 30 determines whether the temperature sensors 22 and 24 have been exposed to water based on the acceleration and the amount of condensed water (step S16 in Figure 2). The temperatures output by the temperature sensors 22 and 24 change due to exposure to water and become lower than the actual temperature. The temperatures are used, for example, to determine whether the exhaust treatment device 20 has been removed. If the ECU 30 determines that water has been applied, it corrects the temperature (step S18). This improves the accuracy of determining whether the exhaust treatment device 20 has been removed.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

REFERENCE SIGNS LIST 10 internal combustion engine, 12 intake passage, 14 exhaust passage, 14a, 14b, 14c area, 16 throttle valve, 18 air flow meter, 20 exhaust treatment device 22 temperature sensor (first temperature sensor), 24 temperature sensor (second temperature sensor), 26 acceleration sensor, 30 ECU, 100 vehicle

Claims (2)

An exhaust treatment device that purifies exhaust from the internal combustion engine is provided in the exhaust passage,
a generation amount acquisition unit that acquires the generation amount of condensed water in the exhaust passage;
a distribution amount acquisition unit that acquires a distribution amount of the condensed water at each of positions in the exhaust passage upstream of the exhaust treatment device, downstream of the exhaust treatment device, and between the upstream side and the downstream side ,
the generation amount acquisition unit acquires the amount of condensed water generated during a period in which the internal combustion engine was stopped based on a time in which the internal combustion engine was stopped and a temperature in the exhaust passage upstream of the exhaust treatment device,
The distribution amount acquisition unit acquires the distribution amount of the condensed water during a period when the internal combustion engine was stopped, based on the attitude of a vehicle on which the internal combustion engine is mounted. The control device for an internal combustion engine according to claim 1 , wherein the distribution amount acquisition unit updates the distribution amount of the condensed water while the internal combustion engine is operating.