Exhaust control device for internal combustion engine

Abstract

To improve regeneration efficiency of a filter in an exhaust control device for an internal combustion engine.SOLUTION: An exhaust control device for an internal combustion engine 2 includes: a filter 9 interposed in an exhaust passage 7 of the internal combustion engine 2 to collect particulate matters in exhaust gas; a heater 11 that consumes electric power to raise a temperature of the filter 9; and a control device 10. In filter regeneration control for burning and removing the particulate matters collected in the filter 9, the control device 10 can perform heater temperature rise control for raising the temperature of the filter 9 by using the heater 11 and normal temperature rise control for raising the temperature of the filter 9 by using means other than the heater 11. The control device 10 estimates a rate C of an estimated soot generation amount B to an estimated temperature rise amount A when the normal temperature rise control is performed for a predetermined time on the basis of an operating state of the internal combustion engine 2, performs the normal temperature rise control if the rate C is less than a predetermined value D, and performs the heater temperature rise control when the rate C is the predetermined value D or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an exhaust control device that performs regeneration control of a filter disposed in an exhaust passage of an internal combustion engine. [Background technology]

[0002] In internal combustion engines such as diesel engines and gasoline engines, a filter is known that is installed in the exhaust passage to remove particulate matter (PM, particulate matter) contained in exhaust gas. The particulate matter collected on the filter is incinerated and removed by exposure to high-temperature exhaust gas. On the other hand, if an operating state in which the exhaust gas temperature is low continues for a long period of time, the amount of particulate matter accumulated increases, and the filter may become clogged. Therefore, control is implemented to forcibly incinerate the accumulated particulate matter depending on the amount of accumulated particulate matter, etc. This type of control is called filter regeneration control (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-104974 A Summary of the Invention [Problem to be solved by the invention]

[0004] In filter regeneration control, for example, control is implemented to increase the temperature of exhaust gas flowing into the filter by increasing the amount of fuel injection, retarding the injection timing, retarding the ignition timing, exhaust pipe injection, etc. However, depending on the operating state of the internal combustion engine, such control may promote further generation of particulate matter. As a result, it takes longer to burn off the particulate matter on the filter, and the efficiency of filter regeneration decreases.

[0005] One of the objectives of the present invention, which has been devised in light of the above-mentioned problems, is to provide an exhaust control device for an internal combustion engine that can improve the efficiency of filter regeneration. However, in addition to this objective, another objective of the present invention is to achieve an effect derived from each configuration shown in the "Description of Embodiments" described later, which cannot be obtained by conventional techniques. [Means for solving the problem]

[0006] The disclosed exhaust control device for an internal combustion engine can be realized as the following disclosed aspects (application examples), which solve at least part of the above problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected additionally as appropriate, and each of the aspects can be omitted. None of the aspects from aspect 2 onwards discloses an essential aspect or configuration for the present case.

[0007] Aspect 1. The disclosed exhaust control device for an internal combustion engine includes a filter that is disposed in an exhaust passage of the internal combustion engine and captures particulate matter in exhaust gas, and a heater that consumes power to heat the filter. The device also includes a control device that is capable of performing heater temperature control for heating the filter with the heater and normal temperature control for heating the filter with a means other than the heater during filter regeneration control for burning and removing the particulate matter captured by the filter.

[0008] The control device estimates the ratio of the estimated soot generation amount to the estimated temperature rise amount when the normal heating control is performed for a predetermined time based on the operating state of the internal combustion engine, and performs the normal heating control if the ratio is less than a predetermined value, and performs the heater heating control if the ratio is equal to or greater than the predetermined value.

[0009] In the above embodiment including embodiment 1, it is preferable that the control device determines that the ratio is equal to or greater than the predetermined value when the operating point of the internal combustion engine is within a first region on a rotation load map. Also, it is preferable that the first region is a region where the engine load is equal to or greater than a first load and the engine speed is equal to or greater than a first speed.

[0010] Aspect 3. In an aspect including the aspect 2 described above, it is preferable that the control device expands the first region by correcting the first load or the first rotation speed in a decreasing direction as the temperature of the internal combustion engine decreases.

[0011] Aspect 4. In the aspect including Aspect 2 above, it is preferable that the control device determines that the ratio is equal to or greater than the predetermined value when the operating point of the internal combustion engine is within a second region on the rotation load map. It is also preferable that the second region is a region in which the engine load is equal to or less than a second load lower than the first load and the engine speed is equal to or less than a second speed lower than the first speed.

[0012] Aspect 5. In aspects including the above aspect 4, it is preferable that the control device calculates an estimated filter temperature when the normal temperature rise control is performed for a predetermined time when the operating point of the internal combustion engine is within the second region. Also, if the estimated filter temperature is less than a first temperature that is lower than the regeneration temperature of the filter and is equal to or higher than a second temperature that is lower than the first temperature, it is preferable to perform the normal temperature rise control simultaneously with the heater temperature rise control. If the estimated filter temperature is equal to or higher than the first temperature or less than the second temperature, it is preferable to perform only the heater temperature rise control.

[0013] Aspect 6. In aspects including the above aspect 4, it is preferable that the exhaust control device includes a generator that is driven by the internal combustion engine to generate electricity, a traction motor, and a battery connected to the traction motor and the generator. Also, it is preferable that the control device increases the amount of electricity generated by the generator to move the operating point of the internal combustion engine out of the second region and executes the normal temperature rise control in a situation where the internal combustion engine drives the generator to generate electricity, even if the operating point of the internal combustion engine is within the second region.

[0014] Aspect 7. In an aspect including aspect 6 above, when the operating point of the internal combustion engine is within the second region and the internal combustion engine is driving the generator to generate electricity, it is preferable that the control device performs the heater heating control if the charging rate of the battery is equal to or higher than a predetermined charging rate, and if the charging rate of the battery is less than the predetermined charging rate, the control device increases the power generation amount of the generator to move the operating point of the internal combustion engine outside the second region and performs the normal heating control. Effect of the Invention

[0015] According to the disclosed exhaust control device for an internal combustion engine, when the ratio of the estimated soot generation amount to the estimated temperature increase amount is equal to or greater than a predetermined value, the heater temperature increase control is performed, thereby suppressing the generation of particulate matter caused by the normal temperature increase control. Also, when the ratio is less than the predetermined value, the normal temperature increase control is performed, thereby promoting the increase in filter temperature without consuming power. Therefore, the regeneration efficiency of the filter can be improved. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a configuration of a vehicle to which an exhaust control device is applied; [Diagram 2] 3 is a rotational load map showing the output characteristics of the internal combustion engine. [Diagram 3] 4 is a flowchart showing an example of a filter regeneration control. [Figure 4] 4 is a flowchart showing an example of a filter regeneration control. [Diagram 5] 4 is a flowchart showing an example of a filter regeneration control. [Figure 6] 4 is a flowchart showing an example of a filter regeneration control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [1. Equipment configuration] 1 is a block diagram illustrating the configuration of a hybrid vehicle 1 (also simply referred to as vehicle 1) according to an embodiment. The vehicle 1 is a hybrid vehicle (hybrid electric vehicle, HEV) or a plug-in hybrid vehicle (plug-in hybrid electric vehicle, PHEV) equipped with an internal combustion engine 2 as a drive source, a traction motor 3, a generator 5, and a battery 4 as an electricity storage device. A plug-in hybrid vehicle refers to a hybrid vehicle in which the battery 4 can be externally charged or externally supplied with power from the battery 4. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable through which power is supplied from an external charging facility, and a socket (outlet) for external power supply.

[0018] The internal combustion engine 2 is, for example, a gasoline engine or a diesel engine. An oxidation catalyst device 8 and a filter 9 are provided in an exhaust passage 7 of the internal combustion engine 2. The oxidation catalyst device 8 is a device that incorporates a catalyst that promotes the oxidation reaction of unburned fuel components contained in the exhaust gas. Specific examples of the oxidation catalyst device 8 include DOC and TWC. The oxidation catalyst device 8 can be omitted, or can be integrated with the filter 9.

[0019] The filter 9 is a filtering device that captures particulate matter contained in exhaust gas and removes the captured particulate matter by burning it. A catalyst (such as a precious metal catalyst or a trap catalyst) is supported on the surface of the filter 9 for efficiently removing (burning, incinerating) the particulate matter. The filter 9 may be a forced regeneration filter that burns particulate matter with oxygen, or a continuous regeneration filter that burns particulate matter with nitrogen dioxide.

[0020] The filter 9 is provided with a heater 11 (electric heater) that consumes power from the battery 4 or a power source (not shown) to heat the filter 9. The heater 11 is a heating device that can heat the filter 9 to a temperature (regeneration temperature T0) at which the particulate matter trapped on the filter 9 can be incinerated, regardless of the temperature of the exhaust gas. The heater 11 may be disposed inside the filter 9, outside the filter 9 (at the outer periphery), or upstream of the filter 9 (for example, between the oxidation catalyst device 8 and the filter 9).

[0021] A generator 5 is connected to the drive shaft of the internal combustion engine 2. The generator 5 in this embodiment is an electric motor / generator that combines a function of rotating the internal combustion engine 2 by being driven by electric power from the battery 4 and a function of generating electricity by using the driving force of the internal combustion engine 2. The generated electric power of the generator 5 is used to drive the travel motor 3 and to charge the battery 4. A speed change mechanism (not shown) may be provided on the power transmission path connecting the internal combustion engine 2 and the generator 5.

[0022] The traction motor 3 is an electric motor / generator that has both the function of propelling the vehicle 1 using the power of the battery 4 and the power generated by the generator 5, and the function of charging the battery 4 with power generated by regeneration. The battery 4 is a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride battery, and is connected to the traction motor 3 and the generator 5. The battery 4 is capable of supplying power to at least the traction motor 3, and is also capable of being charged with power generated by at least the traction motor 3 and the generator 5. The battery 4 in this embodiment is also capable of supplying power to the generator 5. The drive shaft of the traction motor 3 is connected to the drive wheels of the vehicle 1. A speed change mechanism (not shown) may be provided on a power transmission path connecting the traction motor 3 and the drive wheels.

[0023] A clutch 6 is interposed on the power transmission path connecting the internal combustion engine 2 and the traction motor 3. The internal combustion engine 2 is connected to the drive wheels via the clutch 6, and the traction motor 3 is disposed closer to the drive wheels than the clutch 6. The generator 5 is connected to the internal combustion engine 2 closer to the clutch 6. When the clutch 6 is disengaged (released), the internal combustion engine 2 and the generator 5 are disconnected from the drive wheels, and the traction motor 3 is connected to the drive wheels. When the clutch 6 is engaged (connected), the internal combustion engine 2, the traction motor 3, and the generator 5 are all connected to the drive wheels.

[0024] The operating states of the internal combustion engine 2, traction motor 3, battery 4, generator 5, clutch 6, and filter 9 are controlled by a control device 10. The control device 10 is one of the computers (electronic control units, ECUs) mounted on the vehicle 1, and has a built-in processor (arithmetic processing device) and memory (storage device). The contents of the control (control program) performed by the control device 10 are stored in the memory, and the contents are appropriately read into the processor and executed.

[0025] An upstream temperature sensor 12, a downstream temperature sensor 13, an engine management device 14, and a battery management device 15 are connected to the control device 10. Information obtained by these sensors and devices 12 to 15 is transmitted to the control device 10. The upstream temperature sensor 12 detects a filter upstream temperature T U The downstream temperature sensor 13 detects the temperature in the exhaust passage downstream of the filter 9, i.e., the temperature in the exhaust passage downstream of the filter 9. D It is a sensor that detects.

[0026] The engine management device 14 detects or calculates engine parameters, which are parameters related to the state of the internal combustion engine 2, and is, for example, an engine ECU. The engine parameters referred to here include, for example, the engine speed N, engine load L (engine torque), engine temperature, outside air temperature, humidity, intake air flow rate, fuel injection amount, fuel injection timing, ignition timing, etc. Furthermore, the engine temperature includes the engine coolant temperature, oil temperature (engine oil temperature), cylinder block temperature, etc.

[0027] The battery management unit 15 is, for example, a BMU, which detects or calculates battery parameters related to the state of the battery 4. The battery parameters here include, for example, input / output current, input / output voltage, open circuit voltage, battery temperature, power supply circuit temperature, charging rate (SOC), deterioration level (state of health, SOH), etc.

[0028] [2. Control configuration] In this embodiment, a detailed description will be given of filter regeneration control, which is one of the controls performed by the control device 10. When a start condition for the filter regeneration control (filter regeneration condition) is satisfied, the control device 10 performs filter regeneration control to burn and remove particulate matter trapped in the filter 9. Specific examples of the filter regeneration condition are shown below. The amount of particulate matter accumulated on the filter is equal to or greater than the standard amount. The estimated amount of particulate matter on the filter is equal to or greater than the standard amount. The pressure difference (pressure loss) before and after the filter is equal to or greater than the standard pressure difference. The operation time of the internal combustion engine is equal to or longer than the reference time.

[0029] A specific example of the termination condition for the filter regeneration control is given below. The amount of particulate matter deposited on the filter is equal to or less than the second standard amount. The estimated amount of particulate matter on the filter is equal to or less than the second standard amount. The pressure difference (pressure loss) before and after the filter is less than the second standard pressure difference. The filter regeneration control is performed for a second reference time or longer.

[0030] The control device 10 controls the temperature of the filter 9 (filter temperature T F The first temperature rise control is a heater temperature rise control, and the second temperature rise control is a normal temperature rise control. These controls are performed to raise at least the filter temperature T FThis is performed when the temperature at which particulate matter can be incinerated (the regeneration temperature T0) has not yet reached the filter temperature T F is the temperature upstream of the filter T U and the downstream temperature T D It can be calculated based on the following:

[0031] In addition, the filter temperature T F After the filter temperature T reaches the regeneration temperature T0, these temperature raising controls may be continued until the particulate matter is incinerated. F When the filter temperature T reaches the regeneration temperature T0, the temperature increase control may be terminated, and normal operation of the internal combustion engine 2 may be continued to incinerate the particulate matter. F If the filter temperature T is already equal to or higher than the regeneration temperature T0, the temperature increase control does not need to be performed. F The temperature rise control may be performed so that an amount of heat sufficient to maintain the above condition is supplied to the filter 9.

[0032] Filter temperature T F When the heater temperature increase control is performed after the regeneration temperature T0 is reached, the filter upstream temperature T U and the downstream temperature T D For example, the duty control based on the filter upstream temperature T U and the temperature downstream of the filter T D Temperature difference (T D -T U The duty ratio of the heater 11 may be gradually increased until the filter temperature T F After the regeneration temperature T0 is reached, the temperature difference (T D -T U When the temperature difference between the first and second electrodes 11 and 12 reaches a predetermined temperature difference or more, it may be determined that the particulate matter is being sufficiently combusted on the filter 9, and the increase in the duty ratio may be stopped.

[0033] The heater temperature rise control is a control for raising the temperature of the filter 9 by the heater 11, and is a control (active temperature rise control) for actively raising the temperature of the filter 9 by utilizing the heat generated by the heater 11. The amount of heat generated by the heater 11 per unit time can be adjusted, for example, by changing the duty ratio (the ratio of the energization time width to the energization cycle of the heater 11) in the PWM control. By performing the heater temperature rise control, the generation of particulate matter in the internal combustion engine 2 is suppressed compared to the case where normal temperature rise control is performed.

[0034] The normal temperature rise control is a control for raising the temperature of the filter 9 by means other than the heater 11. The means other than the heater 11 include the internal combustion engine 2 and the attached devices and auxiliary machines of the internal combustion engine 2. The normal temperature rise control of this embodiment is a control (passive temperature rise control) for passively raising the temperature of the filter 9 by utilizing the heat generated by the internal combustion engine 2 (heat of the exhaust gas). Specific means for raising the temperature of the exhaust gas by the normal temperature rise control include increasing the amount of fuel injection (main injection amount), performing a post injection (expansion stroke injection), performing a post injection (exhaust stroke injection), retarding the fuel injection timing (main injection timing), retarding the ignition timing, etc.

[0035] In the filter regeneration control of this embodiment, heater temperature rise control and normal temperature rise control are used selectively or in combination, based on the ratio of the amount of soot generation to the amount of temperature rise when the temperature of the filter 9 is raised. In filter regeneration control, the control device 10 estimates a ratio C of the estimated amount of soot generation B to the estimated amount of temperature rise A when normal temperature rise control is performed for a predetermined time. Each of the estimated amount of temperature rise A, the estimated amount of soot generation B, and the ratio C can be estimated based on the operating state of the internal combustion engine 2, and can be estimated based on, for example, the fuel injection amount (main injection amount, rear injection amount, post injection amount), fuel injection timing, cooling water temperature, oil temperature, intake air temperature, intake air humidity, etc. The above-mentioned predetermined time is determined based on the filter temperature T F may be a predicted value until the regeneration temperature T0 is reached, a preset fixed value (for example, 1 to 2 minutes), or a variable value that is set according to the running state of the vehicle 1, etc.

[0036] Fig. 2 is a rotational load map showing the output characteristics of the internal combustion engine 2. The curve shown by the thick solid line in Fig. 2 is a torque curve of the internal combustion engine 2 (a curve showing the relationship between the engine speed N and the maximum torque that can be output at that engine speed N). The horizontal axis of the rotational load map shown in Fig. 2 represents the engine speed N (corresponding to the vehicle speed when traveling at the output of the internal combustion engine 2), and the vertical axis represents the engine load L (corresponding to the engine output torque or the engine required torque).

[0037] The above-mentioned ratio C can also be grasped based on the position of the operating point on the rotation load map. The operating point is a point whose horizontal coordinate is the engine speed N of the internal combustion engine 2 at a certain point in time and whose vertical coordinate is the engine load L of the internal combustion engine 2 at the same time. Each of the first and second regions in FIG. 2 is an operating region in which the ratio C is equal to or greater than a predetermined value D. It is assumed that it has been previously confirmed by tests or experiments that the ratio C is equal to or greater than the predetermined value D in the first and second regions. The predetermined value D may be a fixed value set in advance, or may be a variable value set according to the running state of the vehicle 1, etc.

[0038] The first region is an operating region of relatively high load and high rotation speed, where at least the engine load L is equal to or greater than a first load L1 and the engine rotation speed N is equal to or greater than a first rotation speed N1. When normal temperature rise control is performed in the first region, a relatively large estimated temperature rise amount A is obtained, but the estimated soot generation amount B is also likely to increase significantly, and as a result, the rate C becomes equal to or greater than a predetermined value D. By performing heater temperature rise control when the operating point of the internal combustion engine 2 is within the first region, the temperature of the filter 9 can be raised while suppressing soot generation, and the regeneration efficiency of the filter 9 can be improved.

[0039] Note that a portion of the region where the engine load L is equal to or greater than a first load L1 and the engine speed N is equal to or greater than a first speed N1 may be defined as the first region. The first region may also be defined based on the temperature and flow rate of the exhaust gas discharged from the internal combustion engine 2. That is, the first region may be defined as an operating region where the exhaust gas temperature is equal to or greater than a first temperature and the exhaust flow rate is equal to or greater than a first flow rate under standard atmospheric conditions. In the first region, the exhaust gas temperature is high but the exhaust flow rate is also large, making it easy for soot to be generated.

[0040] The second region is an operating region with a relatively low load and low rotation speed, where at least the engine load L is equal to or less than a second load L2 lower than the first load L1 and the engine rotation speed N is equal to or less than a second rotation speed N2 lower than the first rotation speed N1. When normal temperature rise control is performed in the second region, the estimated soot generation amount B is small but the estimated temperature increase amount A is quite small, and as a result, the ratio C becomes equal to or greater than the predetermined value D. By performing heater temperature rise control when the operating point of the internal combustion engine 2 is within the second region, the temperature of the filter 9 can be raised quickly and the regeneration efficiency of the filter 9 can be improved.

[0041] In addition, a part of the region where the engine load L is equal to or less than the second load L2 and the engine speed N is equal to or less than the second speed N2 may be defined as the second region. The second region may also be defined based on the temperature and flow rate of the exhaust gas discharged from the internal combustion engine 2. That is, the operating region where the exhaust gas temperature is less than the second temperature and the exhaust flow rate is less than the second flow rate under standard atmospheric conditions may be defined as the second region. In the second region, the exhaust flow rate is small and soot is less likely to be generated, but the exhaust gas temperature is also low, resulting in a state in which the regeneration efficiency of the filter 9 is poor. Alternatively, the region that hits the smoke limiter (region where smoke is likely to be generated) may be defined as the second region.

[0042] The values ​​of the first load L1 and the first rotation speed N1, which are thresholds defining the boundaries between inside and outside the first region, may be fixed values ​​set in advance, or may be variable values ​​set according to the operating state of the internal combustion engine 2, etc. The same applies to the values ​​of the second load L2 and the second rotation speed N2, which are thresholds defining the boundaries between inside and outside the second region. Each of the first region and the second region may be modified according to the combustion characteristics of the internal combustion engine 2, and may be set to be larger as the internal combustion engine 2 becomes less likely to perform combustion, for example.

[0043] The dashed lines in FIG. 2 exemplify the contours of the first and second regions when the engine temperature (engine coolant temperature, oil temperature, cylinder block temperature, etc.) is equal to or lower than a reference temperature. In the first region, the first load L1 or the first rotation speed N1 may be corrected in a decreasing direction as the temperature of the internal combustion engine 2 becomes lower. This causes the first region to expand as the temperature of the internal combustion engine 2 becomes lower. In the second region, the second load L2 or the second rotation speed N2 may be corrected in an increasing direction as the temperature of the internal combustion engine 2 becomes lower. This causes the second region to expand as the temperature of the internal combustion engine 2 becomes lower. Note that when the humidity of the intake air exceeds a predetermined humidity, the first and second regions also expand as shown by the dashed lines in FIG. 2.

[0044] Regarding the control when the operating point of the internal combustion engine 2 is in the second region, since the operating state of the internal combustion engine 2 is low load and low rotation speed, it is expected that it will take time to heat the filter 9 to the regeneration temperature T0 by the heater temperature rise control alone. Therefore, the heater temperature rise control may be performed simultaneously with the normal temperature rise control so that the filter 9 reaches the regeneration temperature T0 in a shorter time. In other words, when the operating point of the internal combustion engine 2 is in the second region, the heater temperature rise control and the normal temperature rise control may be used together to heat the filter 9.

[0045] However, if the engine temperature or the outside air temperature is extremely low when the filter regeneration control is started, it is expected that the temperature rise time will not be significantly shortened even if the heater temperature rise control and the normal temperature rise control are used in combination. Therefore, the estimated filter temperature T E Calculate the estimated filter temperature T EIt may be determined whether to use both the heater temperature increase control and the normal temperature increase control according to the situation. First, a first temperature T1 (for example, around 400 °C) lower than the regeneration temperature T0 (for example, around 500 to 600 °C) of the filter 9 and a second temperature T2 (for example, around 300 °C) lower than this are set in advance.

[0046] Subsequently, if the estimated filter temperature T when only the normal temperature increase control is carried out for a predetermined time E is calculated, the estimated filter temperature T E is compared with the first temperature T1 and the second temperature T2. If T2 ≤ T E < T1, both the heater temperature increase control and the normal temperature increase control are used. On the other hand, if T E < T2, it is considered that the temperature increase time does not change significantly compared with the case where only the heater temperature increase control is carried out, and there is a possibility that the additional fuel injection and increase due to the normal temperature increase control may be wasted. Therefore, only the heater temperature increase control is carried out. Also, if T1 ≤ T E , since it is expected that the temperature increase time is short even without carrying out the normal temperature increase control, only the heater temperature increase control is carried out. By such control, the filter 9 is efficiently heated.

[0047] Also, when the operating point of the internal combustion engine 2 is in the second region and it is possible to move the operating point of the internal combustion engine 2, the normal temperature increase control may be carried out after moving the operating point outside the second region. For example, in a situation where the internal combustion engine 2 drives the generator 5 to generate electricity in the generator 5 (during series driving or power generation for external power supply, etc.), the engine load L changes by changing the power generation amount. Therefore, the operating point of the internal combustion engine 2 may be moved outside (above) the second region in FIG. 2 by increasing the power generation amount to increase the engine load L. As a result, since the ratio C becomes less than the predetermined value D, the filter 9 can be efficiently heated without generating much soot by carrying out the normal temperature increase control, and the regeneration efficiency of the filter 9 can be improved.

[0048] However, in order for the generator 5 to function as a load device for the internal combustion engine 2, the generated power needs to be charged into an electricity storage device such as the battery 4 or consumed by another device. Therefore, the amount of power generation may be increased on condition that the charging rate of the battery 4 is less than a predetermined charging rate (for example, a charging rate close to full charge). In other words, when the operating point of the internal combustion engine 2 is within the second region and the internal combustion engine 2 is driving the generator 5 to generate power, if the charging rate of the battery 4 is equal to or higher than the predetermined charging rate, the heater temperature increase control is performed.

[0049] On the other hand, if the charging rate of the battery 4 is less than the predetermined charging rate, the heater temperature increase control is not performed, and the power generation amount of the generator 5 is increased to move the operating point of the internal combustion engine 2 out of the second region, and normal temperature increase control is performed. This type of control makes it possible to suppress overcharging of the battery 4, and to increase the engine load L more reliably, thereby efficiently increasing the temperature of the filter 9 without generating much soot, and improving the regeneration efficiency of the filter 9. Note that even if the charging rate of the battery 4 is equal to or higher than the predetermined charging rate, the heater temperature increase control may be performed if external power is being fed.

[0050] [3. Flowchart] Each of Figs. 3 to 6 is a flowchart showing an example of filter regeneration control. The flowchart in Fig. 3 shows a control flow in which two types of temperature rise control are used depending on the ratio C of the estimated soot generation amount B to the estimated temperature rise amount A. In step A1, it is determined whether or not the filter regeneration condition is satisfied. If the filter regeneration condition is satisfied, the process proceeds to step A2, and if not, the control of this flowchart ends.

[0051] In step A2, an estimated temperature rise amount A and an estimated soot generation amount B when normal temperature rise control is performed for a predetermined time are calculated. Also, in step A3, a ratio C (estimated soot generation amount B ÷ estimated temperature rise amount A) of the estimated soot generation amount B to the estimated temperature rise amount A is calculated. In the subsequent step A4, it is determined whether the ratio C is equal to or greater than a predetermined value D. Here, if C ≥ D, the process proceeds to step A5, and heater temperature rise control is started (performed). On the other hand, if C < D, the process proceeds to step A6, and normal temperature rise control is started (performed).

[0052] In step A7 following steps A5 and A6, the filter temperature T F is determined whether it has reached the regeneration temperature T0. If the filter temperature T F has not reached the regeneration temperature T0, the temperature rise control started in steps A5 and A6 is continued. After the filter temperature T F has reached the regeneration temperature T0, the process proceeds to step A8, and the particulate matter collected by the filter 9 is incinerated and removed. Note that the temperature rise control started in steps A5 and A6 may be terminated when proceeding to step A8, or may be continued until the particulate matter is incinerated. In the subsequent step A9, it is determined whether the end condition of the filter regeneration control is satisfied, and the filter regeneration control is performed until the end condition is satisfied. When the condition of step A9 is satisfied, the filter regeneration control ends, and the control of this flowchart ends.

[0053] The flowchart of FIG. 4 shows the control flow in which two types of temperature rise controls are selectively used based on the rotational load map of the internal combustion engine 2. Steps A1, A5 to A9 in FIG. 4 correspond to steps A1, A5 to A9 in FIG. 3, and the description will be omitted as appropriate. In step A1, it is determined whether the filter regeneration condition is satisfied. If the filter regeneration condition is satisfied, the process proceeds to step B1, and if not, the control of this flowchart ends.

[0054] In step B1, information on engine temperature, engine speed N, and engine load L is acquired. In step B2, a first region and a second region on a rotation load map as shown in FIG. 2 are set based on the engine temperature. In step B2, the first region and the second region may be set based on the humidity of the intake air in addition to (or instead of) the engine temperature. In the following step B3, it is determined whether or not the operating point corresponding to the engine speed N and engine load L acquired in step B1 is within the first region. If this condition is met, the process proceeds to step A5, where heater temperature rise control is performed. If the condition in step B3 is not met, the process proceeds to step B4.

[0055] In step B4, it is determined whether the operating point corresponding to the engine speed N and engine load L acquired in step B1 is within the second region. If this condition is met, the process proceeds to step A5, where heater temperature rise control is performed. If the condition of step B4 is not met, the process proceeds to step A6, where normal temperature rise control is performed. In this way, by using the rotation load map of the internal combustion engine 2, it is possible to instantly use two types of temperature rise control separately without calculating the estimated temperature rise amount A, the estimated soot generation amount B, and the ratio C each time.

[0056] The flowchart in FIG. 5 differs from the flowchart in FIG. 4 in that the estimated filter temperature T E 3. The flowchart of Fig. 5 is different from the flowchart of Fig. 4 in the content of the temperature rise control performed when the operating point is in the second region. Steps A1, A5 to A9 in Fig. 5 correspond to steps A1, A5 to A9 in Fig. 3, and steps B1 to B4 in Fig. 5 correspond to steps B1 to B4 in Fig. 4.

[0057] In step B4, it is determined whether the operating point corresponding to the engine speed N and engine load L acquired in step B1 is within the second region. If this condition is met, the process proceeds to step C1, where the estimated filter temperature T E In the next step C2, the estimated filter temperature TE It is determined whether the temperature T is equal to or greater than the second temperature T2 and less than the first temperature T1.

[0058] If the condition of step C2 is satisfied, the process proceeds to step C3, where the heater temperature increase control and the normal temperature increase control are performed in combination. If the condition of step C2 is not satisfied, the process proceeds to step A5, where the heater temperature increase control is performed. In this way, the estimated filter temperature T E By using the heater temperature rise control and the normal temperature rise control in combination in response to the above, the temperature rise time of the filter 9 is shortened, and the filter regeneration control can be performed efficiently.

[0059] The flowchart in Fig. 6 is obtained by adding an operation for moving the operating point of the internal combustion engine 2 to the flowchart in Fig. 4. In the flowchart in Fig. 6, the contents of the temperature rise control performed when the operating point is in the second region are different from those in the flowchart in Fig. 4. Steps A1, A5 to A9 in Fig. 6 correspond to steps A1, A5 to A9 in Fig. 3, and steps B1 to B4 in Fig. 6 correspond to steps B1 to B4 in Fig. 4.

[0060] In step B4, it is determined whether or not the operating point corresponding to the engine speed N and engine load L acquired in step B1 is within the second region. If this condition is met, the process proceeds to step D1, where it is determined whether or not the internal combustion engine 2 is driving the generator 5 to cause the generator 5 to generate electricity (series running state). If this condition is met, the process proceeds to step D2, and if not, the process proceeds to step A5, where heater temperature rise control is performed.

[0061] In step D2, it is determined whether the charging rate of the battery 4 is less than a predetermined charging rate. If this condition is met, the process proceeds to step D3, where control is performed to increase the power generation amount of the generator 5 and raise the engine load L. This moves the operating point of the internal combustion engine 2 out of the second region. In the following step A6, normal temperature increase control is performed. If the condition of step D2 is not met, the process proceeds to step A5, where heater temperature increase control is performed.

[0062] In this way, by moving the operating point of the internal combustion engine 2 outside the second region and performing the normal temperature rise control, the temperature rise efficiency of the filter 9 is improved. In addition, by checking the charging rate of the battery 4 when moving the operating point of the internal combustion engine 2 outside the second region, overcharging of the battery 4 is suppressed and the increase in the engine load L is more reliable. Note that if the capacity of the battery 4 is sufficiently large or if it is considered that there is a margin for the charging rate, the determination of step D2 may be omitted. In this case, step D3 may be performed at the time when the condition of step D1 is established. Also, after the processing of step D3, a determination similar to that of step B4 may be performed to confirm that the operating point has moved outside the second region before performing the normal temperature rise control.

[0063] [4. Actions and Effects] (1) The exhaust control device according to this embodiment includes a filter 9 that is disposed in an exhaust passage 7 of an internal combustion engine 2 and captures particulate matter in exhaust gas, a heater 11 that consumes power to raise the temperature of the filter 9, and a control device 10. The control device 10 is capable of performing heater temperature rise control for raising the temperature of the filter 9 with the heater 11 and normal temperature rise control for raising the temperature of the filter 9 by means other than the heater 11 during filter regeneration control for burning and removing the particulate matter captured by the filter 9.

[0064] In addition, the control device 10 estimates a ratio C of the estimated soot generation amount B to the estimated temperature rise amount A when normal heating control is performed for a predetermined time based on the operating state of the internal combustion engine 2, and performs normal heating control if the ratio C is less than a predetermined value D, and performs heater heating control if the ratio C is equal to or greater than the predetermined value D.

[0065] In this way, by performing the heater temperature rise control when the ratio C is equal to or greater than the predetermined value D, it is possible to suppress the generation of particulate matter caused by the normal temperature rise control, and to efficiently promote the regeneration of the filter 9. Also, by performing the normal temperature rise control when the ratio C is less than the predetermined value D, it is possible to promote the regeneration of the filter 9 without consuming power. Therefore, the actual filter temperature T F While suppressing the amount of soot generated relative to the increase in filter temperature T FThe regeneration temperature can be increased to the regeneration temperature T0, and the regeneration efficiency of the filter 9 can be improved.

[0066] (2) As shown in Figs. 4 to 6, the control device 10 can determine that the ratio C is equal to or greater than a predetermined value D when the operating point of the internal combustion engine 2 is within a first region on the rotation load map. As shown in Fig. 2, the first region is a region where the engine load L is equal to or greater than a first load L1 and the engine speed N is equal to or greater than a first speed N1. By this control, it is possible to accurately grasp, with a simple configuration, an operating region of high load and high speed where the estimated soot generation amount B is likely to increase significantly. Therefore, the regeneration efficiency of the filter 9 can be improved.

[0067] (3) Regarding the control using the rotation load map, the control device 10 may expand the first region by correcting the first load L1 or the first rotation speed N1 in a decreasing direction as the temperature of the internal combustion engine 2 decreases. In this way, by expanding the first region as the temperature of the internal combustion engine 2 decreases, it is possible to improve the estimation accuracy in the state where the ratio C of the estimated soot generation amount B to the estimated temperature increase amount A is high. Therefore, it is possible to improve the regeneration efficiency of the filter 9.

[0068] (4) As shown in Figs. 4 to 6, the control device 10 can determine that the ratio C is equal to or greater than the predetermined value D when the operating point of the internal combustion engine 2 is within the second region on the rotation load map. As shown in Fig. 2, the second region is a region where the engine load L is equal to or less than a second load L2 lower than a first load L1 and the engine speed N is equal to or less than a second speed N2 lower than the first speed N1. This control makes it possible to accurately grasp the low-load / low-speed operating region, where it is difficult to obtain a satisfactory estimated temperature rise amount A, with a simple configuration. Therefore, the regeneration efficiency of the filter 9 can be improved.

[0069] (5) As shown in FIG. 5, the above-described control device 10 calculates the estimated filter temperature T E In this case, the control device 10 calculates the estimated filter temperature T EIf the estimated filter temperature T is less than a first temperature T1 that is lower than the regeneration temperature T0 of the filter 9 and is equal to or higher than a second temperature T2 that is lower than the first temperature T1, the normal temperature increase control is performed simultaneously with the heater temperature increase control. E If the temperature T1 is equal to or higher than the first temperature T1 or is lower than the second temperature T2, only the heater temperature increase control is performed.

[0070] In this way, the estimated filter temperature T E When the estimated filter temperature T is less than the first temperature T1 and equal to or greater than the second temperature T2, the heater temperature rise control and the normal temperature rise control are used in combination, so that the temperature rise time of the filter 9 can be shortened and the filter regeneration control can be performed efficiently. E When the estimated filter temperature T is equal to or higher than the first temperature T1, the temperature of the filter 9 can be sufficiently increased by only the heater temperature increase control without performing the normal temperature increase control. Therefore, by performing only the heater temperature increase control, the fuel consumption and the like can be improved, and the regeneration efficiency of the filter 9 can be improved. E is lower than the second temperature T2, the normal heating control itself may be in vain. Therefore, by performing only the heater heating control, fuel consumption and the like can be improved, and the regeneration efficiency of the filter 9 can be improved.

[0071] (6) The exhaust control device according to this embodiment includes a generator 5 that is driven by the internal combustion engine 2 to generate electricity, a travel motor 3, and a battery 4 that is connected to the travel motor 3 and the generator 5. The control device 10 can perform, for example, the control shown in Fig. 6. Even if the operating point of the internal combustion engine 2 is within the second region, in a situation in which the internal combustion engine 2 drives the generator 5 to generate electricity, the control device 10 increases the amount of power generated by the generator 5 to move the operating point of the internal combustion engine 2 out of the second region and performs normal temperature rise control.

[0072] In this way, when the operating point of the internal combustion engine 2 can be moved, the operating point is moved out of the second region and then the normal temperature increase control is performed, whereby the temperature of the filter 9 can be increased efficiently without generating much soot and consuming little power. Therefore, the regeneration efficiency of the filter 9 can be improved.

[0073] (7) When the operating point of the internal combustion engine 2 is within the second region and the internal combustion engine 2 drives the generator 5 to generate electricity, the control device 10 can perform temperature rise control according to the charging rate of the battery 4. For example, as shown in FIG. 6, if the charging rate of the battery 4 is equal to or higher than a predetermined charging rate, the heater temperature rise control is performed. On the other hand, if the charging rate of the battery 4 is lower than the predetermined charging rate, the amount of power generated by the generator 5 is increased to move the operating point of the internal combustion engine 2 out of the second region and normal temperature rise control is performed. This control can suppress overcharging of the battery 4 and can increase the engine load L more reliably. Therefore, the filter 9 can be efficiently heated without generating much soot, and the regeneration efficiency of the filter 9 can be improved.

[0074] [5.Other] The above embodiment is merely illustrative and is not intended to exclude various modifications or application of techniques not specified in the embodiment. Each configuration of the embodiment can be modified in various ways without departing from the spirit of the embodiment. Furthermore, each configuration of the embodiment can be selected or combined as necessary.

[0075] In the above embodiment, the exhaust control device of the internal combustion engine 2 applied to the hybrid vehicle 1 has been described, but the application of the exhaust control device of the present invention is not limited to the hybrid vehicle 1. The present invention is applicable to a system including the filter 9, heater 11, and control device 10 of the internal combustion engine 2, and is applicable to, for example, automobiles such as gasoline vehicles and diesel vehicles, ships, driving force generating devices, power generating devices, etc. [Industrial Applicability]

[0076] The present invention is applicable to the exhaust control device manufacturing industry, and is applicable to the manufacturing industries of automobiles, ships, drive force generating devices, and power generating devices equipped with internal combustion engines and exhaust control devices. [Explanation of symbols]

[0077] 1 Hybrid vehicle (vehicle) 2. Internal combustion engine 3. Traction motor 4 Battery 5. Generator 6. Clutch 7 Exhaust passage 8. Oxidation Catalyst Device 9 Filters 10 Control device 11 Heater 12 Upstream temperature sensor 13 Downstream Temperature Sensor 14 Engine Management Device 15 Battery Management Device A Estimated temperature rise B. Estimated amount of soot generated C. Proportion D Predetermined value N Engine RPM N1 First RPM N2 second rotation speed L Engine load L1 first load L2 second load T U Filter upstream temperature T D Filter downstream temperature T F Filter Temperature T E Estimated Filter Temperature T0 regeneration temperature T1 first temperature T2 second temperature

Claims

1. A filter that is installed in an exhaust passage of an internal combustion engine and that collects particulate matter in exhaust gas; a heater that consumes power to heat the filter; a control device that is capable of performing a heater temperature increase control for increasing the temperature of the filter by the heater and a normal temperature increase control for increasing the temperature of the filter by a means other than the heater when performing a filter regeneration control for burning and removing the particulate matter trapped on the filter; The control device estimates a ratio of an estimated soot generation amount to an estimated temperature rise amount when the normal temperature rise control is performed for a predetermined time based on an operating state of the internal combustion engine, and performs the normal temperature rise control if the ratio is less than a predetermined value, and performs the heater temperature rise control if the ratio is equal to or greater than the predetermined value. An exhaust control device for an internal combustion engine.

2. the control device determines that the ratio is equal to or greater than the predetermined value when an operating point of the internal combustion engine is within a first region on a rotation load map; The first region is a region in which the engine load is equal to or greater than a first load and the engine speed is equal to or greater than a first speed.

2. An exhaust control device for an internal combustion engine according to claim 1.

3. The control device corrects the first load or the first rotation speed in a decreasing direction as the temperature of the internal combustion engine decreases, thereby expanding the first region.

3. An exhaust control device for an internal combustion engine according to claim 2.

4. the control device determines that the ratio is equal to or greater than the predetermined value when an operating point of the internal combustion engine is within a second region on the rotation load map; The second region is a region in which the engine load is equal to or lower than a second load that is lower than the first load, and the engine speed is equal to or lower than a second speed that is lower than the first speed.

3. An exhaust control device for an internal combustion engine according to claim 2.

5. the control device calculates an estimated filter temperature when the normal temperature rise control is performed for a predetermined time when an operating point of the internal combustion engine is within the second region, If the estimated filter temperature is lower than a first temperature that is lower than a regeneration temperature of the filter and is equal to or higher than a second temperature that is lower than the first temperature, the normal temperature rise control is performed simultaneously with the heater temperature rise control; If the estimated filter temperature is equal to or higher than the first temperature or lower than the second temperature, only the heater temperature increase control is performed.

5. An exhaust control device for an internal combustion engine according to claim 4.

6. a generator driven by the internal combustion engine to generate electricity, a driving motor, and a battery connected to the driving motor and the generator, Even if the operating point of the internal combustion engine is within the second region, in a situation where the internal combustion engine is driving the generator to generate electricity, the control device increases the amount of electricity generated by the generator to move the operating point of the internal combustion engine outside the second region and performs the normal temperature rise control.

5. An exhaust control device for an internal combustion engine according to claim 4.

7. When an operating point of the internal combustion engine is within the second region and the internal combustion engine drives the generator to generate electricity, the control device If the charging rate of the battery is equal to or higher than a predetermined charging rate, the heater temperature increase control is performed; If the charging rate of the battery is less than the predetermined charging rate, the amount of power generated by the generator is increased to move the operating point of the internal combustion engine out of the second region and the normal temperature rise control is performed.

7. An exhaust control device for an internal combustion engine according to claim 6.

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