JP4144557B2 - Exhaust purification device - Google Patents

Description

  The present invention relates to an exhaust emission control device used in a hybrid system, and more particularly, to a technique for estimating the amount of fine particles accumulated in a filter having a filter.

  Generally, in an internal combustion engine (engine) mounted on an automobile or the like, particularly a diesel engine, it is required to remove particulates such as soot contained in exhaust gas (hereinafter also referred to as “PM”). In response to such demands, a method of arranging a particulate filter (hereinafter sometimes referred to as “filter”) in the exhaust passage of the engine has been proposed.

  The filter is composed of a porous base material having a plurality of pores, and collects PM in the exhaust gas when the exhaust gas passes through the pores. However, as PM collected by the filter accumulates, the exhaust flow path in the filter becomes narrower and the exhaust resistance increases. And if PM accumulates excessively on a filter, exhaust pressure will rise and it will cause engine output fall. Therefore, it is necessary to perform PM regeneration processing for oxidizing and removing PM deposited on the filter at an appropriate timing to regenerate the PM collection ability of the filter.

  As a method of executing the PM regeneration process, the temperature of the filter is raised to 500 ° C. to 700 ° C., which is the temperature at which PM can be oxidized, and the inside of the filter is made an oxidizing atmosphere (that is, an oxygen-excess atmosphere). A method of oxidation and removal is common. Then, the pressure difference (differential pressure) between the upstream side and the downstream side of the filter is detected, and when the detected value exceeds a predetermined value, it is estimated that the amount of PM to be subjected to PM regeneration processing has accumulated, and PM It is known to start executing the reproduction process.

  However, in the method in which the PM regeneration amount is estimated by using only the detected value of the differential pressure between the upstream side and the downstream side of the filter and the execution of the PM regeneration process is started, the differential pressure can be accurately detected by a filter during steady operation or the like. Therefore, if the other operating conditions continue for a long period of time, the differential pressure of the filter cannot be accurately detected when the other operating state continues for a long period of time. May accumulate. Further, when the PM regeneration process is performed in a state where PM is excessively accumulated, a large amount of PM is oxidized and removed, so that the filter may be overheated and damaged.

On the other hand, the differential pressure and the intake air amount are detected, and the detected differential pressure is divided by the detected intake air amount, so that the fluctuation due to the change in the operating state is removed, and the acceleration / deceleration filter There has been proposed a technique for accurately estimating the degree of filter clogging (PM accumulation amount) even under operating conditions in which the amount of exhaust gas passing through the engine fluctuates (see, for example, Patent Document 1).
JP 2003-254041 A JP 2003-120263 A JP 2001-164959 A JP 2004-52642 A

However, in the method of detecting the differential pressure and the intake air amount between the upstream side and the downstream side of the filter and dividing the detected differential pressure by the detected intake air amount, the detected value of the differential pressure itself is small or in the exhaust passage. Under the operating conditions where the amount of exhaust gas passing through the filter is small due to the significant influence of exhaust pulsation, the differential pressure between the upstream side and downstream side of the filter cannot be accurately detected, and the amount of accumulated PM May not be accurately estimated.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to accurately detect the difference in pressure between the upstream side and the downstream side of the filter, and thereby to determine the amount of PM deposited on the filter. An object of the present invention is to provide an exhaust purification device that can be estimated with high accuracy.

  In order to achieve the above object, an exhaust emission control apparatus according to the present invention includes an internal combustion engine and an electric motor, and outputs one motive power output from the internal combustion engine and motive power output from the electric motor. An exhaust emission control device used in a hybrid system capable of simultaneously outputting from a shaft, the particulate filter being disposed in an exhaust passage of the internal combustion engine and collecting particulates contained in the exhaust, an upstream side and a downstream side of the filter Differential pressure detection means for detecting a difference in the pressure of the exhaust, fine particle accumulation amount estimation means for estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means, and the internal combustion engine includes the filter When the particulate accumulation amount estimation means tries to estimate the amount of particulates deposited on the filter in an operating state in which the amount of exhaust gas passing through the filter fluctuates beyond a predetermined range, The operating state of the internal combustion engine is changed so that the fluctuation of the amount of exhaust gas passing through the engine falls within a predetermined range, and the power output by the internal combustion engine that changes with the change of the operating state of the internal combustion engine is output to the output shaft. Control means for controlling the power output from the electric motor to the output shaft so as to cancel.

  When estimating the amount of particulates accumulated in the filter based on the difference (differential pressure) between the upstream and downstream exhaust pressures detected by the differential pressure detecting means, the amount of exhaust passing through the filter varies greatly. In this case, it is difficult for the differential pressure detection means to accurately detect the differential pressure caused by the fine particles accumulated on the filter, and thus there is a possibility that the amount of fine particles accumulated on the filter cannot be estimated with high accuracy.

  On the other hand, in the exhaust emission control device according to the present invention, the control means includes the particulate accumulation amount estimation means when the internal combustion engine is in an operating state in which the amount of exhaust passing through the filter fluctuates beyond a predetermined range. When trying to estimate the amount of fine particles accumulated on the filter, the operating state of the internal combustion engine is forcibly changed so that the fluctuation of the amount of exhaust gas passing through the filter is within the predetermined range. As a result, the differential pressure detection means can detect the differential pressure more accurately, and hence the amount of fine particles deposited on the filter can be estimated more accurately.

  However, forcibly changing the operating state of the internal combustion engine so that the exhaust gas passing through the filter falls within the predetermined range means that the output of the internal combustion engine also varies only within a certain range. Therefore, in order to meet the output required for the hybrid system, when the power output from the internal combustion engine and the power output from the electric motor are simultaneously output from one output shaft, only the operating state of the internal combustion engine is forcibly limited. If it is changed to, it becomes difficult to output from the output shaft so as to follow the output required for the hybrid system.

  Therefore, the control means changes the operating state of the internal combustion engine, and simultaneously, the power output from the electric motor to the output shaft so as to cancel the power output from the internal combustion engine, which fluctuates with the change in the operating state of the internal combustion engine, to the output shaft. Control. Thereby, it is possible to estimate the amount of fine particles deposited on the filter more accurately while appropriately responding to the output required for the hybrid system.

The exhaust emission control apparatus according to the present invention includes an internal combustion engine, an electric motor, and a generator that generates electric power using power output from the internal combustion engine, and the power output from the internal combustion engine. And exhaust power purifier for use in a hybrid system capable of simultaneously outputting the power output from the motor from one output shaft, the particulates disposed in the exhaust passage of the internal combustion engine and collecting particulates contained in the exhaust A filter, differential pressure detecting means for detecting a difference in pressure between the upstream side and downstream side of the filter, and fine particles for estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detecting means And a deposit amount estimating means for estimating the amount of particulate accumulated on the filter when the internal combustion engine is in an operating state in which the exhaust gas passing through the filter is less than a predetermined amount. In such a case, the operating state of the internal combustion engine is changed so that the exhaust gas passing through the filter becomes equal to or greater than the predetermined amount, and the power that increases with the change in the operating state of the internal combustion engine is used for power generation. And a control means for controlling the generator.

  When estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means, if the amount of exhaust gas passing through the filter is small, the differential pressure detection means is caused by the fine particles accumulated on the filter. Since it is difficult to accurately detect the differential pressure, the amount of fine particles deposited on the filter may not be estimated with high accuracy.

  On the other hand, in the exhaust emission control device according to the present invention, the control unit is configured to have the particulate accumulation amount estimation unit deposited on the filter when the internal combustion engine is in an operation state where the exhaust gas passing through the filter is less than a predetermined amount. When the amount is to be estimated, the operating state of the internal combustion engine is forcibly changed so that the exhaust gas passing through the filter becomes equal to or greater than the predetermined amount. As a result, the differential pressure detection means can detect the differential pressure more accurately, and thus the amount of fine particles deposited on the filter can be estimated with higher accuracy.

  However, forcibly changing the operating state of the internal combustion engine so that the exhaust gas passing through the filter becomes equal to or greater than the predetermined amount means that the power output from the internal combustion engine also increases, and therefore the power required for the internal combustion engine. Power exceeding the limit will be generated. Therefore, in order to meet the output required for the hybrid system, when the power output from the internal combustion engine and the power output from the electric motor are simultaneously output from one output shaft, only the operating state of the internal combustion engine is forcibly limited. Since the power output from the internal combustion engine increases, the output exceeding the required output is output from the output shaft.

  Therefore, the control means controls the generator so as to change the operating state of the internal combustion engine and at the same time use the power increased by the change in the operating state of the internal combustion engine for power generation. Thereby, it is possible to estimate the amount of fine particles deposited on the filter more accurately while appropriately responding to the output required for the hybrid system.

  The electric motor and the generator may be configured as a motor generator having both a function as an electric motor that outputs power and a function as a generator that generates electric power using the power output from the internal combustion engine. .

  An exhaust emission control device according to the present invention is an exhaust emission control device used in a hybrid system including an internal combustion engine and an electric motor capable of rotating a crankshaft of the internal combustion engine. A particulate filter that is disposed in the exhaust passage and collects particulates contained in the exhaust, a differential pressure detecting means that detects a difference in pressure between the upstream side and the downstream side of the filter, and the differential pressure detecting means Particulate deposition amount estimation means for estimating the amount of particulates deposited on the filter based on the differential pressure, and the particulate deposition amount estimation means tries to estimate the amount of particulates deposited on the filter when the internal combustion engine is in a non-combustion state. In this case, it is characterized by comprising control means for controlling the electric motor so as to rotate the crankshaft of the internal combustion engine in a non-combustion state.

When estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means, if the internal combustion engine is in a non-combustion state and the exhaust gas does not pass through the filter, the differential pressure detection means accumulates on the filter. Since the differential pressure due to the fine particles cannot be detected, the amount of fine particles deposited on the filter cannot be estimated.

  On the other hand, in the exhaust emission control device according to the present invention, when the control means tries to estimate the amount of fine particles accumulated on the filter when the internal combustion engine is in a non-combustion state. The electric motor is controlled so as to rotate the crankshaft of the internal combustion engine in the non-combustion state. As a result, the air discharged from the cylinder of the internal combustion engine flows through the exhaust passage, so that the exhaust passes through the filter, and even if the internal combustion engine is in a non-combustion state, the differential pressure detection means is deposited on the filter. The differential pressure caused by the fine particles can be detected, and the amount of fine particles deposited on the filter can be estimated.

  As described above, the control means in the exhaust emission control apparatus according to the present invention provides the operating state of the internal combustion engine or the power output from the electric motor when the fine particle accumulation amount estimation means tries to estimate the fine particle amount accumulated on the filter. Therefore, if the particulate accumulation amount estimation means tries to estimate too frequently, the operating state of the internal combustion engine or the power output from the motor must be changed accordingly, and the hybrid system in which the exhaust emission control device is used From the viewpoint of the usability of the vehicle equipped with the is not preferable.

  Therefore, the image forming apparatus further includes a determining unit that determines whether or not the particle amount accumulated on the filter should be estimated by the particle accumulation amount estimating unit, and the particle accumulation amount estimating unit determines the amount of particles accumulated on the filter by the determining unit. It is preferable to estimate the amount of fine particles accumulated on the filter when it is determined that the estimation should be performed.

  For example, when the amount of fine particles accumulated on the filter estimated by the fine particle accumulation amount estimation means is greater than or equal to a first predetermined amount, the fine particles accumulated on the filter are oxidized and removed to regenerate the fine particle collecting ability of the filter. Regenerating processing means for performing the above, and sub-particle accumulation amount estimation means for estimating whether or not the amount of particles deposited on the filter is equal to or greater than a second predetermined amount that is less than the first predetermined amount, The determining means estimates the amount of fine particles accumulated on the filter by the fine particle accumulated amount estimating means when the sub fine particle accumulated amount estimating means determines that the amount of fine particles accumulated on the filter is not less than the second predetermined amount. It is preferable to determine that it should be.

  Here, the first predetermined amount is a limit fine particle that causes clogging of the filter due to accumulation of fine particles on the filter, and this clogging causes an increase in exhaust resistance and a decrease in output of the internal combustion engine. This amount is set slightly less than the amount deposited.

  Therefore, in order not to cause a decrease in the output of the internal combustion engine, it is important to accurately estimate whether or not fine particles are accumulated in the filter over the first predetermined amount. However, since the fine particles are gradually deposited on the filter, it takes a certain period of time to deposit the first predetermined amount of fine particles.

  Therefore, first, the sub-particle accumulation amount estimation means estimates whether or not the amount of particles accumulated on the filter is equal to or larger than a second predetermined amount that is smaller than the first predetermined amount. When it is determined that the amount is greater than or equal to the second predetermined amount, it is preferable that the particle accumulation amount estimation unit estimates the amount of particles accumulated on the filter.

  The sub-particulate deposition amount estimation means is configured such that when the integrated value of the fuel injection amount from the end of the previous regeneration processing by the regeneration processing means is a predetermined amount or more, the amount of particulate deposited on the filter is a second predetermined amount or more. It is possible to exemplify that it is estimated to be.

The sub-particulate deposition amount estimation means estimates that the amount of particulates deposited on the filter is greater than or equal to a second predetermined amount when the differential pressure detected by the differential pressure detection means is greater than or equal to a predetermined pressure. It can be illustrated. However, since the sub-particle deposition amount estimation means estimates whether or not the second predetermined amount is less than the first predetermined amount, the sub-particle deposition amount estimation means tries to estimate the particulate deposition amount. In this case, the control means need not change the operating state of the internal combustion engine or the power output by the electric motor.

  As described above, according to the exhaust gas purification apparatus of the present invention, the difference in pressure between the upstream side and the downstream side of the filter is accurately detected, and the amount of particulate (PM) accumulated on the filter is accurately estimated. be able to.

  Exemplary embodiments of the present invention will be described below in detail with reference to the drawings based on the following examples in which the best mode for carrying out the invention is applied to an in-vehicle hybrid system. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to those unless otherwise specified.

  As shown in FIG. 1, the hybrid system 1 includes an internal combustion engine (engine) 20, a motor generator (hereinafter referred to as "M / G") 30, a power switching mechanism 40, a speed reducer 50, an inverter 60, a battery 70, and the like. Include as a component.

  The engine 20 is a water-cooled four-cycle diesel engine having four cylinders 2. An intake passage 21 is connected to the engine 20, and the intake passage 21 is connected to an air cleaner box (not shown). An air flow meter 21 a that outputs an electrical signal corresponding to the mass of the intake air flowing through the intake passage 21 is attached to the intake passage 21 downstream of the air cleaner box. The intake passage 21 downstream of the air flow meter 21a is provided with an intake throttle valve 21b for controlling the flow rate (intake amount) of intake air.

  On the other hand, an exhaust passage 22 is connected to the engine 20, and the exhaust passage 22 is formed of a porous base material having a plurality of pores in the middle of the exhaust passage 22, and is exhausted when the exhaust passes through the pores. A particulate filter (hereinafter referred to as “filter”) 23 for collecting the fine particles (PM) is provided. A differential pressure sensor 24 that outputs an electrical signal corresponding to the pressure difference between the upstream and downstream exhaust passages of the filter 23 is attached. When the exhaust gas passes through the filter 23, the differential pressure sensor 24 is attached. Thus, the difference in pressure between the upstream side and the downstream side of the filter 23 can be detected. In addition, an air-fuel ratio sensor 25 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing in the exhaust passage 22 is provided in the exhaust passage 22 upstream of the filter 23.

  As shown in FIG. 2, the power switching mechanism 40 includes a double pinion planetary gear 41 including a ring gear 42, a planetary carrier 43, and a sun gear 44, a brake 45 that fixes the ring gear 42, a C1 clutch 46, and a C2 clutch 47. ing. The engine 20 is directly connected to the sun gear 44, and the M / G 30 is directly connected to the planetary carrier 43. Power is transmitted to the speed reducer 50 via the C1 clutch 46 for the planetary carrier 43 and via the C2 clutch 47 for the ring gear 42.

  In the hybrid system 1 according to the present embodiment, the characteristics described below can be obtained by employing the power switching mechanism 40 configured as described above. In the following description, the rotation direction of the M / G 30 is the forward rotation direction of the vehicle on which the hybrid system 1 is mounted.

  For example, when the engine 20 is stopped, the brake 45 is engaged to fix the ring gear 42, and the M / G 30 is rotated in the reverse direction to rotate the crankshaft 20a of the engine 20 in the non-combustion state. Can start. It is mainly used to start the engine when starting a hybrid system with an ignition key switch.

  Further, by engaging the brake 45 and fixing the ring gear 42 and operating the internal combustion engine 20, the M / G 30 can be driven by the power output from the internal combustion engine 20 to generate electric power. It is mainly used when the battery capacity is low when the vehicle is stopped (parking range).

  Further, for example, by engaging the C1 clutch 46 and rotating the M / G 30 forward, the power output from the M / G 30 is transmitted to the rotating shafts 9 a and 10 a of the drive wheels 9 and 10 via the speed reducer 50. Thus, the vehicle can be advanced with the engine 20 stopped. It is mainly used when the vehicle starts and when it is lightly loaded.

  Further, for example, by operating the engine 20 by engaging the C1 clutch 46 and the C2 clutch 47, the vehicle can be advanced only by the power output from the engine 20 (engine running). Mainly used for medium loads over low vehicle speeds.

  Further, by engaging the C1 clutch 46 and the C2 clutch 47 to drive the engine 20 and to rotate the M / G 30 in the forward direction, the torque of the M / G 30 is also added to the above-described engine travel, thereby accelerating the vehicle. The performance can be improved. It is mainly used at high loads over low vehicle speeds (engine + motor travel).

  Further, by engaging the C1 clutch 46 and the C2 clutch 47 and operating the engine 20, the vehicle is advanced with a part of the power output from the engine 20, and the M / G 30 is driven with the remaining power to generate power. Can do. It is mainly used when the battery capacity is lower than the low vehicle speed.

  Further, by engaging the C1 clutch 46 and the C2 clutch 47 and rotating the M / G 30 in the forward direction to bring the engine 20 into a non-combustion state (no fuel supply into the cylinder), the power output by the M / G 30 is increased. In addition, the vehicle is advanced by being transmitted to the rotating shafts 9a and 10a of the drive wheels 9 and 10 through the speed reducer 50, and the crankshaft 20a of the engine 20 in the non-combustion state is rotated in the forward direction (idle) while being in the non-combustion state. ).

  Electric energy for driving the M / G 30 is supplied from the battery 70. This battery is a rechargeable secondary battery, and can be charged with surplus power in the regeneration mode in which the M / G 30 is operated as a generator.

  The hybrid system 1 configured as described above is provided with an electronic control unit (ECU) 80 which is a means for controlling the hybrid system 1. The ECU 80 includes a hybrid control computer (hereinafter referred to as “HVCC”) and an engine control computer (hereinafter referred to as “ECC”), each of which includes arithmetic logic operations including a CPU, ROM, RAM, backup RAM, and the like. Circuit.

  The HVCC obtains necessary engine output, motor torque, and the like based on detection values of various sensors such as an accelerator position sensor and a shift position sensor, outputs a required value to the ECC, and controls the driving force.

  ECC is a basic routine that should be executed at regular intervals. Input of output signals from various sensors such as the air flow meter 21a, calculation of engine speed, calculation of fuel injection amount in accordance with an engine output request value from HVCC, fuel The injection timing is calculated. Various signals input by the ECC in the basic routine and various control values obtained by calculating the ECC are temporarily stored in the ECC RAM.

  The ECC in the ECU 80 reads various control values from the RAM in an interrupt process triggered by the input of signals from various sensors and switches, the passage of a fixed time, or the input of a pulse signal from the crank position sensor. Then, the fuel injection valve and the like are controlled according to these control values.

  In addition, the remaining battery level is input to the ECU 80 from a battery computer that is attached to the battery 70 and monitors the state of charge of the battery 70.

[PM regeneration processing]
As PM accumulates on the filter 23, the exhaust flow path in the filter becomes narrow, and the exhaust resistance increases. If PM accumulates excessively on the filter 23, the exhaust pressure rises, causing a reduction in the output of the internal combustion engine. For this reason, it is necessary to execute PM regeneration processing for regenerating the collection ability of the filter by oxidizing and removing PM deposited on the filter 23 at an appropriate timing. Therefore, the ECU 80 executes PM regeneration processing control as described below.

  As an outline, the ECU 80 executes PM accumulation amount estimation control as described below to estimate the PM accumulation amount. Then, when the estimated PM accumulation amount is equal to or greater than the first predetermined amount, the PM regeneration process is executed. The first predetermined amount is higher than the limit PM accumulation amount that causes clogging of the filter due to PM accumulating on the filter, and this clogging causes an increase in exhaust resistance and a decrease in engine output. This is a slightly smaller amount.

  In the PM regeneration process, the ECU 80 performs a temperature raising process for raising the temperature of the filter 23 to a high temperature range of about 500 ° C. to 700 ° C., and makes the exhaust gas flowing into the filter 23 an oxygen-excess atmosphere. The air-fuel ratio process is performed.

  As a method of executing the temperature raising process, in addition to the normal main fuel injection by the fuel injection valve near the compression top dead center of the engine 20, fuel is injected into the cylinder during the exhaust stroke or the expansion stroke. Post-injection to be performed, or sub-injection such as bi-rubber injection for injecting fuel into the cylinder in the vicinity of the top dead center of the intake stroke or exhaust stroke, and oxidizing the unburned fuel component in a catalyst having oxidation ability provided in the vicinity of the filter The temperature of the filter 23 is increased by heat generated during oxidation.

  In addition to the above-described sub-injection or together with the sub-injection, by adding fuel as a reducing agent into the exhaust gas flowing through the exhaust passage 22, these unburned fuel components are oxidized in the vicinity of the filter 23. The temperature of the filter 23 may be increased by heat generated during the oxidation in a catalyst having a function.

  In the air-fuel ratio process, when the method of performing the temperature increase process described above is adopted, a method in which the fuel injection valve performs sub-injection into the cylinder or a method in which fuel is added to the exhaust gas is employed. In this control, the amount of fuel sub-injected from the fuel injection valve or the amount of fuel added to the exhaust gas is adjusted so that the output signal value becomes a value corresponding to the lean air-fuel ratio.

When the PM regeneration process is executed in this way, the PM accumulated on the filter 23 is oxidized and the PM is removed from the filter 23. When the PM regeneration process end condition is satisfied, the PM regeneration process is terminated.

  The PM regeneration process end condition is that the execution time of the PM regeneration process has exceeded a predetermined time or the upstream side and downstream side of the filter 23 calculated based on the detection value of the differential pressure sensor 24. It can be exemplified that the difference in the pressure of the exhaust passage (exhaust pressure) is not more than a predetermined pressure. The predetermined time is, for example, a time determined according to the PM collection capacity of the filter, and is a time set longer as the PM collection capacity of the filter increases. The predetermined pressure is a pressure corresponding to a differential pressure when PM is not deposited on the filter.

[PM deposition amount estimation control]
When the difference (differential pressure) between the upstream and downstream exhaust pressures of the filter 23 calculated based on the detection value of the differential pressure sensor 24 is equal to or higher than a certain pressure, the PM accumulation amount is the first predetermined amount. It can be estimated that this is the case.

  However, when estimating the PM accumulation amount based on the detection value of the differential pressure sensor 24, when the operating state of the engine 20 is in a transient state such as acceleration / deceleration operation, the differential pressure between the upstream side and the downstream side of the filter 23. Is difficult to detect accurately. In addition, it is difficult to detect accurately even in an operating state where the amount of exhaust discharged from the engine and passing through the filter 23 is small because the detection value of the differential pressure itself is small or the influence of exhaust pulsation in the exhaust passage appears remarkably. Become. If the differential pressure between the upstream side and the downstream side of the filter 23 cannot be accurately detected, an error may occur in the estimated PM accumulation amount.

  Then, if an error occurs in the estimated amount of PM deposition, PM regeneration processing is not performed even though PM is actually deposited in excess of the first predetermined amount, PM is excessively deposited, Engine output will decrease. Further, if the PM regeneration process is performed in a state where PM is accumulated in excess of the first predetermined amount, a large amount of PM may be oxidized and removed, so that the filter may be overheated and damaged. In addition, as described above, when the PM regeneration process is terminated for a predetermined time, the PM regeneration process may be terminated, but all the PM may remain deposited without being oxidized even though the PM regeneration process is performed.

  Therefore, in order to accurately detect the differential pressure between the upstream side and the downstream side of the filter 23, the operating state of the engine 20 is an operating state in which the amount of exhaust gas passing through the filter does not vary, such as during steady operation, It is preferable that the engine is in an operating state in which the amount of exhaust gas passing through the engine 23 is somewhat large.

  Therefore, in this embodiment, the ECU 80 executes the PM accumulation amount estimation control as described below to estimate the PM accumulation amount.

  Hereinafter, the PM accumulation amount estimation control according to the present embodiment will be specifically described with reference to the flowchart shown in FIG. This control routine is a routine stored in advance in the ROM of the ECU 80, and is a routine executed by the ECU 80 in a predetermined case described later.

  In this routine, the ECU 80 first determines in step (hereinafter simply referred to as “S”) 101 whether or not the engine is stopped, that is, in a non-combustion state. If a negative determination is made, the process proceeds to S102 because the engine is in a combustion state, and the PM accumulation amount estimation control during engine operation described later is executed to estimate the PM accumulation amount.

On the other hand, if an affirmative determination is made in S101, the process proceeds to S103 to determine whether or not the remaining battery capacity is sufficient. If a negative determination is made, the remaining battery level is not sufficient, so the process proceeds to S104 to drive the engine, and then the process proceeds to S102 to execute the engine operation PM accumulation amount estimation control to estimate the PM accumulation amount.

  If an affirmative determination is made in S103, the process proceeds to S105, where the vehicle is in an idle state, that is, the M / G 30 is operating but the C1 clutch 46 and the C2 clutch 47 are not engaged, so that the torque is applied to the speed reducer 50. It is determined whether the vehicle is stopped without being transmitted to the rotating shafts 9a, 10a of the drive wheels 9, 10.

  If an affirmative determination is made, the process proceeds to S106, and the brake 45 is engaged to fix the ring gear 42 and the M / G 30 is rotated in the reverse direction in order to rotate the crankshaft 20a of the engine in the forward direction. At that time, the fuel is not supplied into the cylinders of the engine and remains in a non-combustion state. Further, the rotational speed of the M / G 30 is set so that the rotational speed of the engine becomes a predetermined rotational speed that can be accurately detected by the differential pressure sensor 24 between the upstream side and the downstream side of the filter 23. To control.

  On the other hand, if a negative determination is made in S105, the vehicle is advanced by the power output from the M / G 30 while the engine 20 is stopped, that is, only the C1 clutch 46 is engaged and the M / G 30 rotates forward. ing. Therefore, the process proceeds to S107, and further, the C2 clutch 47 is also engaged, and the crankshaft 20a of the engine 20 is rotated forward (idle) while being in a non-combustion state. At that time, the rotational speed of the M / G 30 is controlled so that the rotational speed of the engine becomes the predetermined rotational speed.

  Thereafter, the process proceeds to S108, and the differential pressure sensor 24 detects the differential pressure between the upstream side and the downstream side of the filter 23. Thereafter, the process proceeds to S109, and the PM deposition amount is estimated based on the differential pressure detected in S108. This is estimated by preliminarily storing the correlation between the differential pressure and the amount of PM deposited on the filter 23 in a ROM in the ECU 80 as a map, and substituting the differential pressure detected in S108 into the map. Is. In this way, S109 functions as a PM (fine particle) accumulation amount estimation means.

  Next, the engine operating PM accumulation amount estimation control executed in S102 will be described using the flowchart shown in FIG. This control routine is a routine stored in the ROM of the ECU 80 in advance. Since S208 and S209 are the same as S108 and S109 in the flowchart shown in FIG. 3, detailed description thereof is omitted.

  In this routine, first, in S201, the ECU 80 determines whether or not the engine 20 is in a transient operation state in which the fluctuation of the amount of exhaust gas passing through the filter 23 such as the acceleration / deceleration operation state fluctuates beyond a predetermined range. Determine. Since the amount of exhaust gas passing through the filter 23 and the intake air amount (Ga) are in a proportional relationship, it is determined whether or not this operation state is in effect based on fluctuations in the intake air amount (Ga). That is, it is determined based on the detection value of the air flow meter 21a that is input in a basic routine executed by the ECC in the ECU 80 and stored in the RAM. If the detected value of the air flow meter 21a is large, that is, if the variation of the intake air amount (Ga) is within the reference range corresponding to the predetermined range of the variation of the amount of exhaust gas passing through the filter 23, a negative determination is made. , Go to S202. On the other hand, if it is determined that the fluctuation has exceeded the reference range, the process proceeds to S203.

  In S203, the driving force is optimally controlled. If an affirmative determination is made in S201, it is considered that the engine output request value output from the HVCC to the ECC in the ECU 80 is fluctuating, so the HVCC outputs the request value to the ECC so that the engine output becomes constant. Then, the excess / deficiency is corrected by the power output by the M / G 30. That is, the torque of the M / G 30 is increased or decreased so as to follow the required vehicle driving torque, and the engine 20 is controlled so as to be in steady operation.

  Thereafter, the process proceeds to S204, in which it is determined whether or not the variation in the intake air amount (Ga) has become small, that is, whether or not the variation in the intake air amount has fallen within the reference range. This is to determine whether or not the variation in the intake air amount is within the reference range based on the detection value of the air flow meter 21a, as in S201. And when negative determination is carried out, the process after S203 is performed again until the fluctuation | variation of intake air amount becomes in the said reference range. On the other hand, if a positive determination is made, the process proceeds to S208 to detect a differential pressure.

  On the other hand, if a negative determination is made in S201, that is, if the intake air amount is determined to be within the reference range, the process proceeds to S202, but in this step, the amount of exhaust gas passing through the filter 23 is less than a predetermined amount. Whether the intake air amount is less than a reference amount corresponding to the predetermined amount of the exhaust gas passing through the filter 23. This is determined based on the detection value of the air flow meter 21a. The reference amount is determined in advance as an intake air amount with which the differential pressure sensor 24 can accurately detect the differential pressure. If an affirmative determination is made, the process proceeds to S205. If a negative determination is made, the process proceeds to S208 because the intake air amount is greater than or equal to the reference amount, and a differential pressure is detected.

  In S205, the engine speed is increased so that the engine speed becomes the predetermined speed. Thereafter, the process proceeds to S206, where the engine speed is increased, and the power increased with respect to the required vehicle drive torque is generated by the M / G 30 and absorbed.

  Thereafter, the process proceeds to S207, in which it is determined whether or not the intake air amount has exceeded the reference amount. This is determined based on the detection value of the air flow meter 21a as described in S202. And when negative determination is carried out, the process after S205 is performed again until the amount of intake air becomes more than a reference amount. On the other hand, if a positive determination is made, the process proceeds to S208 to detect a differential pressure.

  In this way, by executing the PM accumulation amount estimation control, the M / G 30 is appropriately controlled even when the engine 20 is in a transient operation state or an operation state in which the amount of exhaust gas passing through the filter 23 is small. This makes it possible to maintain the engine in an operating state that is steady and has a large amount of exhaust gas that passes through the filter 23, so that the differential pressure can be accurately detected, and the PM accumulation amount is accurately estimated. be able to. Moreover, since the differential pressure can be accurately detected regardless of the operating state of the engine, the area for detecting the differential pressure can be expanded.

  Even if the engine 20 is in a non-combustion state, the differential pressure can be accurately detected by driving the engine 20 with the M / G 30 and feeding an appropriate amount of air into the filter 23. In addition, since the differential pressure can be accurately detected regardless of whether the engine 20 is in the combustion state, the region for detecting the differential pressure can be expanded. Further, since it is not necessary to operate the engine 20 for estimating the PM accumulation amount, fuel consumption deterioration can be suppressed.

  Next, the PM regeneration processing control according to the present embodiment will be specifically described with reference to the flowchart shown in FIG. This control routine is a routine that is stored in advance in the ROM of the ECU 80, and is executed by the ECU 80 as an interrupt process triggered by the passage of a fixed time or the input of a pulse signal from the crank position sensor.

  Finally, the PM accumulation amount is accurately estimated by executing the above-described PM accumulation amount estimation control. However, when the differential pressure is detected by the differential pressure sensor 24, the torque of the M / G 30 and the output of the engine 20 are determined. Since this may be increased, frequent execution of this control is not preferable from the viewpoint of usability such as an increase in vehicle vibration.

  Therefore, in this routine, first, in S301, it is determined whether or not the conditions for executing the PM accumulation amount estimation control described above are satisfied. As a condition for executing the PM accumulation amount estimation control, the differential pressure between the upstream side and the downstream side of the filter 23 detected by the differential pressure sensor 24 is equal to or higher than a predetermined pressure, or since the end of the previous PM regeneration process. For example, the integrated value of the fuel injection amount is not less than a predetermined amount. The predetermined amount of the predetermined pressure of the differential pressure and the integrated value of the fuel injection amount are determined in advance so that the PM accumulation amount becomes a value corresponding to a second predetermined amount smaller than the first predetermined amount. is there. Thus, this step functions as a determination unit. If an affirmative determination is made in this step, the process proceeds to S302, and the above-described PM accumulation amount estimation control is executed. On the other hand, if a negative determination is made, the execution of this routine is terminated.

  When the condition for executing the PM accumulation amount estimation control is that the differential pressure between the upstream side and the downstream side of the filter 23 detected by the differential pressure sensor 24 is equal to or higher than a predetermined pressure, the ECU 80 Depending on whether or not the differential pressure upstream and downstream of the filter 23 detected by the differential pressure sensor 24 is greater than or equal to a predetermined pressure, the PM accumulation amount is greater than or equal to a second predetermined amount that is less than the first predetermined amount. Sub PM deposition amount estimation means for estimating whether or not is provided. Then, when the sub PM accumulation amount estimation means determines that it is greater than or equal to the second predetermined amount, an affirmative determination is made in S301.

  However, since the sub PM accumulation amount estimation means estimates whether or not the second predetermined amount is less than the first predetermined amount, the sub PM accumulation amount estimation means tries to estimate the PM accumulation amount. In this case, it is not necessary to execute the PM accumulation amount estimation control described above.

  In S303, it is determined whether the PM accumulation amount estimated by executing the PM accumulation amount estimation control is equal to or greater than the first predetermined amount. If a positive determination is made, the process proceeds to S304, and the above-described PM regeneration process is executed. On the other hand, if a negative determination is made, the execution of this routine is terminated.

  In S305, it is determined whether or not the above-described PM regeneration process end condition is satisfied. And when negative determination is carried out, the process after S304 is performed again. On the other hand, if a positive determination is made, the process proceeds to S306 and the PM regeneration process is terminated.

  By executing such PM regeneration process control, it is determined whether or not the PM regeneration process should be executed without executing the PM accumulation amount estimation control described above until the PM accumulation amount reaches the second predetermined amount. can do. Thereby, it can suppress that usability deteriorates resulting from performing PM deposition amount estimation control.

It is a figure which shows schematic structure of the hybrid system which concerns on an Example, and the intake / exhaust system of the engine. It is the schematic of the power switching mechanism which concerns on an Example. It is a flowchart figure of PM deposition amount estimation control which concerns on an Example. It is a flowchart figure of PM accumulation amount estimation control at the time of engine operation concerning an example. It is a flowchart figure of PM reproduction | regeneration processing control which concerns on an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid system 9,10 Drive wheel 9a, 9a Rotating shaft 20 Engine 20a Crankshaft 21 Intake passage 21a Air flow meter 21b Intake throttle valve 22 Exhaust passage 23 Particulate filter 24 Differential pressure sensor 25 Air-fuel ratio sensor 30 Motor generator 40 Power switching mechanism 50 Reducer 60 Inverter 70 Battery 80 ECU

Claims (4)

An exhaust emission control device used in a hybrid system having an internal combustion engine and an electric motor and capable of simultaneously outputting power output from the internal combustion engine and power output from the electric motor from one output shaft,
A particulate filter disposed in the exhaust passage of the internal combustion engine for collecting particulates contained in the exhaust;
Differential pressure detection means for detecting a difference in pressure between the upstream side and the downstream side of the filter;
Fine particle accumulation amount estimation means for estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means;
When the internal combustion engine is in an operating state in which the amount of exhaust gas that passes through the filter fluctuates beyond a predetermined range, the particulate matter accumulation amount estimation means tries to estimate the amount of particulate matter that has accumulated on the filter. The operating state of the internal combustion engine is changed so that the fluctuation of the amount of exhaust gas to be within a predetermined range, and the power output from the internal combustion engine that fluctuates with the change of the operating state of the internal combustion engine is canceled out Control means for controlling the power output by the electric motor to the output shaft;
An exhaust emission control device comprising: An internal combustion engine, an electric motor, and a generator that generates electric power using the power output from the internal combustion engine. The power output from the internal combustion engine and the power output from the motor are output from one output shaft. An exhaust purification device used in a hybrid system capable of outputting simultaneously,
A particulate filter disposed in the exhaust passage of the internal combustion engine for collecting particulates contained in the exhaust;
Differential pressure detection means for detecting a difference in pressure between the upstream side and the downstream side of the filter;
Fine particle accumulation amount estimation means for estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means;
When the internal combustion engine is in an operation state in which the exhaust gas passing through the filter is less than a predetermined amount, the exhaust gas passing through the filter is the place where the exhaust gas passing through the filter is Control means for controlling the generator to change the operating state of the internal combustion engine to be equal to or more than a fixed amount, and to use the power for the power generation that increases with the change of the operating state of the internal combustion engine;
An exhaust emission control device comprising:   The electric motor and the generator are configured as a motor generator that has both a function as an electric motor that outputs power and a function as a generator that generates electric power using the power output from the internal combustion engine. The exhaust emission control device according to claim 2. An exhaust purification device used in a hybrid system comprising an internal combustion engine and an electric motor capable of rotating a crankshaft of the internal combustion engine,
A particulate filter disposed in the exhaust passage of the internal combustion engine for collecting particulates contained in the exhaust;
Differential pressure detection means for detecting a difference in pressure between the upstream side and the downstream side of the filter;
Fine particle accumulation amount estimation means for estimating the amount of fine particles accumulated on the filter based on the differential pressure detected by the differential pressure detection means;
When the internal combustion engine is in a non-combustion state and the particulate accumulation amount estimation means tries to estimate the amount of particulates deposited on the filter, the electric motor is rotated so as to rotate the crankshaft of the internal combustion engine in the non-combustion state. Control means for controlling;
An exhaust emission control device comprising:

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