JP2014238056A - Exhaust emission purification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission purification device capable of continuing the regeneration of a filter even when the regeneration accompanying post injection is interrupted.SOLUTION: An exhaust emission purification device includes an oxidation catalyst 18 and a filter 19 disposed in an exhaust passage 5 of an engine 1, a fuel injection device 13 injecting fuel according to a fuel injection pattern, and a control device (ECU 50) estimating the accumulation amount of particle materials and setting the fuel injection pattern. If the interruption of a first pattern is requested when the first pattern is being set, a second pattern is set in place of the first pattern until the request for interruption is eliminated. The first pattern is the fuel injection pattern including post injection, and the second pattern is the fuel injection pattern in which the total injection amount in a compressing stroke and an expanding stroke is increased.

Description

  The present invention relates to an oxidation catalyst and a filter disposed in an exhaust path of an engine, a fuel injection device that injects fuel according to a set fuel injection pattern, an amount of particulate matter deposited, and the fuel injection The present invention relates to an exhaust gas purification device including a control device configured to set a pattern.

  Conventionally, a diesel particulate filter having an oxidation catalyst and a filter is known. Patent Document 1 also discloses an example of an exhaust gas purifying apparatus including such a diesel particulate filter.

  Such an exhaust gas purification device is configured to activate the oxidation catalyst by increasing the temperature of the exhaust gas. When the oxidation catalyst is activated, nitrogen oxides in the exhaust gas are oxidized to generate nitrogen dioxide. Since nitrogen dioxide has a strong oxidizing action, PM (particulate matter) on the filter is oxidized and removed. In order to increase the temperature of the exhaust gas, an exhaust throttle, an intake throttle, and a delay of the main injection timing are performed. In addition to the above control, the exhaust gas purification device is configured to further increase the temperature of the exhaust gas entering the filter (filter inlet temperature) by supplying fuel to the activated oxidation catalyst using post injection. Has been. When the filter inlet temperature exceeds the combustion temperature of PM (400 ° C.), the PM on the filter is oxidized and removed by oxygen in the exhaust gas. Combustion with oxygen can remove PM more rapidly than oxidation with nitrogen dioxide. For this reason, when the filter is completely regenerated, the temperature of the exhaust gas is increased by using post injection.

  The exhaust gas purification device described in Patent Document 1 limits the maximum duration of filter regeneration in order to prevent engine oil from being diluted by post injection. When the execution time of filter regeneration exceeds the maximum duration, filter regeneration is prohibited (paragraph 0019 of Patent Document 1). In the prohibited period during regeneration, the normal combustion mode (normal operation) is executed instead of the regeneration combustion mode (paragraph 0012 of Patent Document 1).

JP 2010-180852 A

  In the exhaust gas purification apparatus described in Patent Document 1, regeneration of the filter is interrupted when the regeneration execution time with post injection exceeds the maximum duration, and normal operation is performed during the suspension. When normal operation is performed, no filter regeneration is performed. For this reason, the completion of the regeneration of the filter is delayed.

  An object of the present invention is to provide an exhaust gas purifying apparatus capable of continuing the regeneration of a filter even when the regeneration accompanied by the post injection is interrupted.

  An exhaust gas purification apparatus according to the present invention includes an oxidation catalyst and a filter disposed in an exhaust path of an engine, a fuel injection apparatus that injects fuel according to a set fuel injection pattern, and an estimation of a particulate matter accumulation amount And a control device configured to set the fuel injection pattern, and when an interrupt request for the first pattern is generated when the first pattern is set The second pattern is set instead of the first pattern until the interruption request disappears, and the first pattern is the fuel injection pattern for regenerating the filter, and includes post-injection, The second pattern is the fuel injection pattern for regenerating the filter. In the second pattern, the total in the compression stroke and the expansion stroke is Injection amount is increased.

  In the exhaust gas purifying apparatus, the control device is configured to calculate the accumulation amount based on an operating condition of the engine, and to calculate the accumulation amount based on a differential pressure between both sides of the filter. The pressure type estimation method can be executed, and the accumulation amount is estimated based on the calculation formula estimation method while the interruption request is generated.

  The exhaust gas purification device further includes an input device that generates the interruption request by an input operation.

  The exhaust gas purifying apparatus according to the present invention can continue the regeneration of the filter during the interruption when the regeneration accompanied by the post injection is interrupted.

It is a figure which shows the structure of the engine which concerns on this embodiment. It is a figure which shows the structure of the cooling water circuit of an engine. It is a figure which shows an example of a fuel-injection pattern. It is a figure which shows the list of control modes. It is a figure which shows a self reproduction | regeneration area | region, a reproducible area | region, and a nonreproducible area | region. It is a figure which shows an example of the time change of deposition amount. It is a flowchart which shows the transition of a control mode. It is a figure which shows the time change of deposition amount. It is a figure which shows the time change of the presence or absence of an interruption request. It is a figure which shows the time change of control mode. It is a figure which shows the time change of the presence or absence of the differential pressure type estimation method.

  A diesel engine 1 equipped with an exhaust gas purifying apparatus according to the present embodiment will be described with reference to the drawings. A diesel engine (hereinafter, engine) 1 is connected to a drive mechanism 100. The drive mechanism 100 is a traveling device and / or a working device driven by the engine 1. The engine 1 and the drive mechanism 100 are mounted on a work vehicle such as a backhoe or a tractor, for example.

  FIG. 1 is a diagram illustrating a configuration of an engine 1 according to the present embodiment. The engine 1 includes an intake path 2, an intake throttle valve 3, a cylinder block 4, an exhaust path 5, an exhaust throttle valve 6, a filter unit 7, an EGR pipe 8, an EGR throttle valve 9, a supercharger 10, a crankshaft 11, and fuel. An injection device 13 is provided.

  The engine 1 has four cylinders, and the cylinder block 4 has four combustion chambers 12. The intake path 2 includes an intake pipe 2 a that is open to the outside, and an intake manifold 2 b that connects the intake pipe 2 a to the four combustion chambers 12. Outside air (intake gas) is introduced into the combustion chamber 12 via the intake path 2. The intake throttle valve 3 is disposed on the intake pipe 2a and changes the opening degree of the intake path 2. The exhaust path 5 includes an exhaust pipe 5a that is open to the outside and an exhaust manifold 5b that connects the four combustion chambers 12 to the exhaust pipe 5a. The exhaust gas is discharged from the combustion chamber 12 into the atmosphere via the exhaust path 5. The exhaust throttle valve 6 is provided on the exhaust pipe 5 a and changes the opening degree of the exhaust path 5. An EGR pipe (EGR path) 8 connects the exhaust path 5 to the intake path 2. Part of the exhaust gas is introduced into the intake path 2 via the EGR pipe 8 and merges with the intake gas. The EGR throttle valve 9 is provided on the EGR pipe 8 and changes the opening degree of the EGR pipe 8. A later-described EGR cooler 24 (FIG. 2) is provided on the EGR pipe 8 on the downstream side of the EGR throttle valve 9. The supercharger 10 includes an exhaust turbine 10a disposed on the exhaust pipe 5a and a compressor 10b disposed on the intake pipe 2a. The fuel injection device 13 employs a common rail system, and supplies fuel to each combustion chamber 12 according to a fuel injection pattern.

  The filter unit 7 is provided on the exhaust path 5. The filter unit 7 is a diesel particulate filter and includes an oxidation catalyst 18 and a filter 19. The oxidation catalyst 18 is disposed upstream of the filter 19 in the exhaust path 5. When the exhaust gas is exhausted along the exhaust path 5, the exhaust gas passes through the filter 19 after passing through the oxidation catalyst 18. PM (particulate matter) contained in the exhaust gas is captured by the filter 19.

  In FIG. 1, the engine 1 includes an ECU 50, a rotation speed input device 14, a warning device 15, a stationary regeneration button 16, and an interruption request button 17.

  The ECU (control device) 50 is configured to control various devices related to the operation of the engine 1.

  The rotational speed input device 14 is an operating device for designating a target rotational speed. In the present embodiment, the rotational speed input device 14 represents an accelerator lever group that changes the operating state of the engine 1.

  The warning device 15 executes various warnings to the operator. In the present embodiment, the warning device 15 includes a large number of lamp groups that can display a plurality of different warnings.

  The stationary regeneration button 16 is an input device that generates a command (stationary regeneration mode command) for changing the control mode to the stationary regeneration mode by a manual input operation. The stationary reproduction button 16 is a push button, and can specify a command “present” state and a command “none” state. The contents of the control mode will be described later.

  The interruption request button 17 is an input device that generates an interruption request for the reset regeneration mode by a manual input operation. The interruption request button 17 is a push button, and can specify a state of interruption request “present” and a state of interruption request “none”.

  In FIG. 1, the engine 1 includes an environmental temperature sensor 31, an intake air temperature sensor 32, an initial exhaust gas temperature sensor 33, a catalyst inlet temperature sensor 34, a filter inlet temperature sensor 35, and an EGR temperature sensor 36. The environmental temperature sensor 31 detects the temperature (environmental temperature) of the intake gas in the intake passage 2 on the upstream side of the compressor 10b and the outlet 8b. The intake air temperature sensor 32 detects the temperature (intake air temperature) of the intake gas in the intake passage 2 on the downstream side of the compressor 10 b and the outlet 8 b of the EGR pipe 8. The initial exhaust temperature sensor 33 detects the temperature of the exhaust gas (initial exhaust temperature) in the exhaust path 5 on the upstream side of the exhaust throttle valve 6, the exhaust turbine 10 a, and the inlet 8 a of the EGR pipe 8. The catalyst inlet temperature sensor 34 detects the temperature of exhaust gas (catalyst inlet temperature) in the exhaust path 5 on the downstream side of the exhaust throttle valve 6 and the exhaust turbine 10a and on the upstream side of the oxidation catalyst 18. The filter inlet temperature sensor 35 detects the temperature of the exhaust gas (filter inlet temperature) in the exhaust path 5 on the downstream side of the oxidation catalyst 18 and the upstream side of the filter 19. The EGR temperature sensor 36 detects the temperature (EGR temperature) of the exhaust gas in the EGR pipe 8 on the downstream side of the EGR cooler 24 and the EGR throttle valve 9.

  In FIG. 1, the engine 1 includes a differential pressure sensor 40, an atmospheric pressure sensor 41, an intake pressure sensor 42, and an initial exhaust pressure sensor 43. The differential pressure sensor 40 includes a filter inlet pressure sensor 40a and a filter outlet pressure sensor 40b. The filter inlet pressure sensor 40 a detects the pressure in the exhaust path 5 on the downstream side of the oxidation catalyst 18 and the upstream side of the filter 19. The filter outlet pressure sensor 40 b detects the pressure in the exhaust path 5 on the downstream side of the filter 19. The differential pressure sensor 40 detects a differential pressure between both sides of the filter 19 based on detection information from the filter inlet pressure sensor 40a and the filter outlet pressure sensor 40b. The atmospheric pressure sensor 41 detects a pressure (atmospheric pressure) outside the engine 1. The intake pressure sensor 42 detects the pressure (intake pressure) of the intake gas in the intake path 2 on the downstream side of the compressor 10b and the outlet 8b of the EGR pipe 8. The initial exhaust pressure sensor 43 detects the pressure of the exhaust gas in the exhaust path 5 (initial exhaust pressure) on the upstream side of the exhaust throttle valve 6, the exhaust turbine 10 a, and the inlet 8 a of the EGR pipe 8.

  In FIG. 1, the engine 1 includes a rotation speed sensor 51. The rotational speed sensor 51 detects the rotational speed (engine rotational speed) of the crankshaft 11.

  FIG. 2 is a diagram illustrating a configuration of the cooling water circuit 20 of the engine 1. The cooling water circuit 20 includes a water path 21, a water pump 22, a water jacket 23, an EGR cooler 24, and a radiator 25. The water pump 22 causes the cooling water of the engine 1 to flow along the water path 21. The water jacket 23 is formed in the cylinder block 4. Further, the engine 1 includes a water temperature sensor 26. The water temperature sensor 26 detects the temperature (cooling water temperature) of the cooling water flowing through the water path 21 on the downstream side of the water jacket 23 and the upstream side of the radiator 25.

  A method for estimating the deposition amount will be described. The accumulation amount indicates the amount of PM accumulated on the filter 19. The ECU 50 can estimate the accumulation amount based on two estimation methods. The two estimation methods are a calculation formula estimation method and a differential pressure type estimation method.

  The calculation formula estimation method is a method for estimating the accumulation amount based on the operating condition of the engine. In the calculation formula estimation method, the PM emission amount and the PM regeneration amount are estimated based on the operating condition of the engine, and the accumulation amount is estimated based on the obtained PM emission amount and PM regeneration amount. The PM discharge amount indicates the amount of PM discharged from the engine 1 per unit time. The PM regeneration amount indicates the amount of PM removed from the filter 19 by regeneration in a unit time. The accumulation amount is obtained by subtracting the PM regeneration amount from the PM discharge amount. Both the PM emission amount and the PM regeneration amount are estimated based on the engine operating conditions. The PM emission amount is basically estimated based on the engine speed and the total injection amount in one cycle. The PM regeneration amount is estimated based on the flow rate of the exhaust gas and the filter inlet temperature detected by the filter inlet temperature sensor 35. The engine operating conditions are the temperature group detected by the temperature sensors 31-36, the pressure group detected by the pressure sensors 41-45, the engine rotational speed detected by the rotational speed sensor 51, and the fuel injection device 13. It is specified based on the total injection amount.

  The differential pressure type estimation method is a method for estimating the deposition amount based on the differential pressure between both sides of the filter 19. As the amount of deposition increases, clogging of the filter 19 increases, and the differential pressure of the filter 19 increases. On the contrary, the differential pressure of the filter 19 decreases as the accumulation amount decreases. That is, the differential pressure type estimation method estimates the deposition amount using the correlation between the differential pressure and the deposition amount. Strictly speaking, the accumulation amount is obtained by adding a correction based on the flow rate of the exhaust gas to the differential pressure obtained by the differential pressure sensor 40. The flow rate of the exhaust gas is estimated based on the operating conditions of the engine.

  The regeneration of the filter 19 will be described with reference to FIGS. In the following, numerical values of various temperatures (° C.) and deposition amounts (g / L) are listed, but these numerical values are merely exemplary numerical values used in the present embodiment. The unit g / L of the deposition amount indicates the weight of PM per unit volume.

  The regeneration of the filter 19 is performed by combustion of PM with oxygen and oxidation of PM with nitrogen dioxide. PM accumulated on the filter 19 is removed by combustion or oxidation. Combustion of PM by oxygen indicates combustion by self-ignition of PM. Self-ignition occurs when the PM temperature exceeds the PM combustion temperature (400 ° C.). Nitrogen dioxide functions as an oxidizing agent for PM. When the temperature of the oxidation catalyst 18 exceeds a predetermined activation temperature (300 ° C.), the oxidation catalyst 18 is activated, and highly active nitrogen dioxide is generated from nitrogen oxides in the exhaust gas. Since the filter 19 is provided on the downstream side of the oxidation catalyst 18, nitrogen dioxide generated around the oxidation catalyst 18 passes through the filter 19. For this reason, PM deposited on the filter 19 is oxidized and removed. Note that when the catalyst inlet temperature is higher than the high temperature (550 ° C.), nitrogen dioxide is not generated, and regeneration is performed only by combustion with oxygen.

  When the catalyst inlet temperature is lower than the activation temperature, oxidation by nitrogen dioxide and combustion by oxygen do not occur. For this reason, the engine 1 uses the change of the exhaust throttle and the fuel injection pattern in order to increase the catalyst inlet temperature.

  FIG. 3 is a diagram illustrating an example of a fuel injection pattern. In FIG. 3, the horizontal axis indicates the injection timing, and the vertical axis indicates the injection amount. The fuel injection pattern indicates the form of fuel injection defined by the injection timing and the injection amount. The fuel injection pattern shown in FIG. 3 includes pre-injection, main injection, after-injection, and post-injection. The injection period of the main injection includes top dead center (TDC). Pre-injection is performed to ensure ignitability. Main injection is performed for main combustion. After-injection is performed to increase the catalyst inlet temperature and post-injection is performed to increase the filter inlet temperature.

  By causing the intake throttle valve 3 to perform intake throttling, the load applied to the engine 1 increases, so the fuel injection amount (main injection amount) increases. As a result, the catalyst inlet temperature rises. Further, by changing the fuel injection pattern to be executed by the fuel injection device 13, the total fuel injection amount can be increased without increasing the torque. Specifically, the main injection retard and / or after injection is used. As a result, the filter inlet temperature rises. In addition, when the fuel injection pattern is set so as to include post injection, the total fuel injection amount further increases. In this case, the fuel supplied by the post injection is combusted by the oxidation catalyst 18, and the filter inlet temperature rises greatly with respect to the catalyst inlet temperature.

  FIG. 4 is a diagram showing a list of control modes. The engine 1 has six possible control modes. The six control modes are a self-regeneration mode, an assist regeneration mode, a reset regeneration mode, a stationary standby mode, a stationary regeneration mode, and a maintenance standby mode. When the engine 1 is activated, any one of the six control modes is selected, and the ECU 50 controls the engine 1 based on the selected control mode. Control conditions, start conditions, and end conditions are set for each of these control modes. The control conditions include a fuel injection pattern configuration, an intake throttle amount, and a target rotational speed configuration. The configuration of the fuel injection pattern indicates the presence / absence of pre-injection, main injection, after-injection, and post-injection, and the injection amount and injection timing of these injections. The configuration of the target rotational speed indicates the presence / absence and the magnitude of the target rotational speed.

  The self-regeneration mode is a control mode in which no special control for regenerating the filter 19 is performed. In the self-regeneration mode, normal operation is executed. As shown in FIG. 3, the fuel injection pattern in the self-regeneration mode includes pre-injection and main injection. If the catalyst inlet temperature becomes higher than the activation temperature during normal operation (self-regeneration mode), the filter 19 is automatically regenerated.

  The assist regeneration mode is a control mode for regenerating the filter 19 without using post injection. In the assist regeneration mode, the fuel injection pattern is set so as to increase the catalyst inlet temperature, and the intake throttle is used. As shown in FIG. 3, the fuel injection pattern in the assist regeneration mode includes pre-injection, main injection, and after-injection. Further, the injection timing of the main injection in the assist regeneration mode is delayed from the injection timing of the main injection in the self regeneration mode. The delay in the injection timing of the main injection and the use of after-injection reduce the proportion of the fuel amount that contributes to torque generation and increase the proportion of the fuel amount that contributes to the temperature increase. Further, the intake air throttle increases the load applied to the engine 1, so the main injection amount is increased. As shown in FIG. 3, the main injection is executed in the compression stroke and the expansion stroke. That is, in the assist regeneration mode, the total injection amount in the compression stroke and the expansion stroke is increased. For this reason, the catalyst inlet temperature rises.

  The assist regeneration mode is intended to reach the catalyst inlet temperature at an assist target temperature (350 ° C.) that is higher than the activation temperature and lower than the combustion temperature. When the catalyst inlet temperature reaches the activation temperature, the filter 19 is gradually regenerated. However, the execution of work is permitted in the assist playback mode, and fluctuations in the rotational speed are assumed. When the rotational speed varies, the main injection amount also varies, and the catalyst inlet temperature also varies. For this reason, when the rotational speed is kept low, the catalyst inlet temperature does not reach the assist target temperature.

  The reset regeneration mode is a control mode for rapidly regenerating the filter 19 using post injection. In the reset regeneration mode, the fuel injection pattern is set so as to increase the filter inlet temperature, and the intake throttle is used. As shown in FIG. 3, the fuel injection pattern in the reset regeneration mode includes pre-injection, main injection, after-injection, and post-injection. That is, the control condition in the reset regeneration mode includes the use of post injection in addition to the control condition in the assist regeneration mode. If post-injection is executed when the catalyst inlet temperature exceeds the activation temperature, the fuel burns in the oxidation catalyst 18. As a result, the exhaust gas is further heated, and the filter inlet temperature further increases.

  The reset regeneration mode is intended to reach the filter inlet temperature to a reset target temperature (600 ° C.) higher than the combustion temperature so that the accumulation amount becomes almost zero. When the filter inlet temperature reaches the reset target temperature (600 ° C.), the filter 19 is regenerated in a relatively short time. However, the execution of work is permitted even in the reset regeneration mode, and fluctuations in the rotational speed are assumed. For this reason, when the rotation speed is kept low, the filter inlet temperature does not reach the reset target temperature.

  In the self regeneration mode, the assist regeneration mode, and the reset regeneration mode, since the rotational speed is not fixed as described above, the catalyst inlet temperature or the filter inlet temperature may not be favorably increased. In such a case, the regeneration of the filter 19 is not performed well. Therefore, a stationary regeneration mode is provided so that the filter 19 is reliably regenerated.

  The stationary regeneration mode is a control mode for rapidly regenerating the filter 19 while maintaining the rotational speed at a predetermined rotational speed and using post injection. In the stationary regeneration mode, the fuel injection pattern is set so as to increase the filter inlet temperature, the intake throttle is used, and the target rotational speed is maintained at a predetermined rotational speed. That is, in the stationary regeneration mode, the rotational speed is fixed in addition to the control executed in the reset regeneration mode. The predetermined rotation speed is 2200 rpm in this embodiment. The control conditions in the stationary regeneration mode are set so that the filter inlet temperature reaches a stationary target temperature (600 ° C.) higher than the combustion temperature (400 ° C.). In the present embodiment, the stationary target temperature is equal to the reset target temperature.

  As the filter inlet temperature increases, the rate at which the amount of deposition decreases increases. However, if the filter inlet temperature becomes too high, the filter 19 may be melted or cracked. For this reason, the stationary target temperature (600 ° C.) is set so that the execution time of the stationary regeneration mode is a predetermined time H5a (30 minutes), which is a short time. Similarly, the height of the reset target temperature is also set so that the execution time of the reset regeneration mode is also a predetermined time H3a (30 minutes), which is a short time.

  The stationary standby mode is a control mode for waiting for execution of the stationary regeneration mode. When the regeneration of the filter 19 is not performed well in the self regeneration mode, the assist regeneration mode, and the reset regeneration mode, it is necessary to execute the stationary regeneration mode as described above. However, in the stationary regeneration mode, the rotation speed is maintained at a predetermined rotation speed. It is not preferable that the stationary regeneration mode is suddenly executed during the work because it causes a sudden change in the rotational speed. For this reason, a stationary standby mode is provided in order to wait for a command from the operator. In the stationary standby mode, the ECU 50 operates the warning device 15 so as to issue a stationary warning. The stationary warning is a warning that prompts the operator to execute the stationary regeneration mode. Specifically, the ECU 50 turns on a warning lamp. Upon receiving the stationary warning, the operator stops the work and moves the work vehicle equipped with the engine 1 from the work place to another place as necessary. Thereafter, the operator inputs a stationary regeneration instruction via the stationary regeneration button 16. When a stationary regeneration instruction is input, the stationary regeneration mode is started.

  EGR (exhaust gas recirculation) can be used in the self-regeneration mode. On the other hand, EGR is not used in the assist regeneration mode, the reset regeneration mode, and the stationary regeneration mode. In these control modes, the total injection amount is increased, and the amount of unburned hydrocarbons generated is also increased. That is, EGR is not used in these control modes in order to prevent unburned hydrocarbons from adhering to the EGR pipe 8.

  FIG. 5 is a diagram showing a self-reproducing area, a reproducible area, and a non-reproducible area. In FIG. 5, the horizontal axis indicates the rotational speed of the engine 1, and the vertical axis indicates the load (torque). FIG. 5 shows an output characteristic curve of the engine 1, and an area within the output characteristic curve is divided into a self-reproducing area, a reproducible area, and a non-reproducible area. The first boundary line L1 indicates the boundary between the self-reproducing area and the reproducible area. The second boundary line L2 indicates the boundary between the reproducible area and the non-reproducible area. The first boundary line L1 shows the rotational speed-torque curve when the catalyst inlet temperature in normal operation is the activation temperature (300 ° C.). That is, the self-regeneration region indicates a region where the catalyst inlet temperature is equal to or higher than the activation temperature. When the rotation speed and torque are within the self-regeneration region, the filter 19 is regenerated without performing special control. That is, the self-reproducing area indicates an area where the filter 19 is necessarily reproduced in the self-reproducing mode. The second boundary line L2 indicates the rotational speed-torque curve when the catalyst inlet temperature in the normal operation is at the regeneration limit temperature. The catalyst inlet temperature rises by executing the reset regeneration mode. However, if the catalyst inlet temperature in normal operation is too low, the catalyst inlet temperature does not reach the activation temperature even if the reset regeneration mode is executed. The regeneration limit temperature indicates the lower limit value of the catalyst inlet temperature at which the activation temperature can be reached. The reproducible region indicates a region where the catalyst inlet temperature is lower than the activation temperature and is equal to or higher than the regeneration limit temperature. If the assist regeneration mode or the reset regeneration mode is executed when the rotation speed and torque are within the reproducible region, the filter 19 can be regenerated. The non-renewable region indicates a region where the catalyst inlet temperature is lower than the regeneration limit temperature. When the rotation speed and the torque are within the non-recoverable region, the filter 19 cannot be regenerated regardless of whether the assist regeneration mode or the reset regeneration mode is executed.

  In the stationary regeneration mode, the rotational speed is maintained at a predetermined rotational speed R0. In FIG. 5, when the rotation speed is equal to or higher than the predetermined rotation speed R0, there is no non-reproducible area. For this reason, in the stationary regeneration mode, the catalyst inlet temperature always reaches the activation temperature, and the filter 19 is necessarily regenerated. The predetermined rotational speed R0 is specified based on an experimentally obtained output characteristic curve as shown in FIG.

  With reference to FIG. 6, an example of the temporal change of the deposition amount according to the change of the control mode will be described. FIG. 6 is a diagram illustrating an example of a temporal change in the deposition amount. In FIG. 6, the horizontal axis represents the continuous operation time (hr) of the engine 1, and the vertical axis represents the accumulation amount (g / L). Note that the time difference due to the control delay is ignored for convenience of explanation.

  From time T0 to time T1, the self-regeneration mode (normal operation) is executed, and the amount of deposition is increasing. At time T1, the accumulation amount reaches the assist threshold value A2 (8 g / L), and the control mode is changed from the self regeneration mode to the assist regeneration mode. One of the conditions for starting the assist regeneration mode is that the deposition amount is equal to or greater than the assist threshold value A2. From time T1 to time T2, the accumulation amount is decreased by the control of the assist regeneration mode. At time T2, the deposition amount reaches the allowable threshold value A1 (6 g / L), and the control mode is changed from the assist regeneration mode to the self regeneration mode. One of the conditions for starting the self-regeneration mode is that the deposition amount is smaller than the allowable threshold value A1. The self-regeneration mode is executed from time T2 to time T3, and the deposition amount increases. Further, the assist regeneration mode is executed from the time T3 to the time T4, and the deposition amount decreases. In this way, basically, the self-regeneration mode and the assist regeneration mode are repeatedly executed alternately. As a result, an increase in the deposition amount is suppressed.

  Time T5 indicates a time later than time T4. The self-regeneration mode is executed from time T5 to time T6, and the deposition amount increases. At time T6, the continuous operation time has reached the allowable continuous time Hd (100 hours), and the control mode is changed from the self-regeneration mode to the reset regeneration mode. The continuous operation time exceeding the allowable continuous time Hd is one of the conditions for starting the reset regeneration mode. The reset regeneration mode is executed from time T6 to time T7, and the amount of deposition is greatly reduced to almost zero. When the reset regeneration mode ends, the continuous operation time is reset to 0 hour. Time T0 and time T6 indicate times when the continuous operation time is 0 hour.

  Time T8 indicates a time later than time T7. From time T8 to time T9, the control mode is maintained in the self-regeneration mode, and the deposition amount increases. At time T9, the accumulation amount reaches the assist threshold value A2 (8 g / L), and the control mode is changed from the self regeneration mode to the assist regeneration mode. From time T9 to time T10, the control mode is maintained in the assist playback mode. However, although the assist regeneration mode is being executed, the deposition amount is increasing. As described above, such a situation occurs when the rotational speed is low, for example. For this reason, at time T10, the accumulation amount reaches the stationary threshold A3 (10 g / L), and the control mode is changed from the assist regeneration mode to the stationary standby mode. In the stationary standby mode, a stationary warning is issued. In response to the stationary warning, the operator decides, for example, to stop the operation in order to execute the stationary regeneration mode. At time T11, a stationary regeneration mode command is manually input, and the control mode is changed from the stationary standby mode to the stationary regeneration mode. The stationary regeneration mode is executed from the time T11 to the time T12, the accumulation amount is greatly reduced, and is smaller than the allowable threshold value A1 (6 g / L).

  Next, the maintenance standby mode will be described. If the control mode is changed to the stationary regeneration mode, the filter 19 is normally reliably regenerated. However, the change to the stationary regeneration mode is performed manually. For this reason, if the driving of the engine 1 is continued without the stationary regeneration mode being executed, the accumulation amount becomes excessive. If the reset regeneration mode or the stationary regeneration mode is executed when the accumulation amount is excessive, the PM on the filter 19 may burn in a chain. Hereinafter, this chain combustion is called rapid regeneration. Since high heat is generated with rapid regeneration, the high heat may cause the filter 19 to melt or break. Therefore, a maintenance standby mode is provided as a control mode for prohibiting regeneration of the filter 19 when excessive deposition occurs.

  When the accumulation amount exceeds the maintenance threshold value, the control mode is changed to the maintenance standby mode. The maintenance threshold A4 (12 g / L) is larger than the assist threshold A2 (8 g / L) and the stationary threshold A3 (10 g / L). Similar to the stationary standby mode, a maintenance standby mode is provided to wait for a command from the operator. In the maintenance standby mode, the ECU 50 operates the warning device 15 so as to issue a maintenance warning. The maintenance warning is a warning that prompts the operator to perform maintenance of the engine 1. Specifically, the ECU 50 turns on a warning lamp. When receiving the maintenance warning, the operator moves the work vehicle equipped with the engine 1 from the work place to another place as necessary, and stops the driving of the engine 1.

  FIG. 7 is a flowchart showing the transition of the control mode. In FIG. 7, the ECU 50 selects any one of a self-regeneration mode M1, an assist regeneration mode M2, a reset regeneration mode M3, a stationary standby mode M4, a stationary regeneration mode M5, and a maintenance standby mode M6 as a control mode. Each control mode starts when a predetermined start condition is satisfied, ends when a predetermined end condition is satisfied, and shifts to another control mode. Basically, a transition of the control mode occurs as the deposition amount increases or decreases.

  In FIG. 7, the conditions indicated by the solid and dashed arrows include the deposition amount determination conditions. As described above, the accumulation amount is estimated based on the calculation formula estimation method and the differential pressure type estimation method. Since the accuracy of estimation by the differential pressure type estimation method decreases as the deposition amount increases, the differential pressure type estimation method is not used when the deposition amount is relatively large. On the other hand, when the accumulation amount is relatively small, both the calculation formula estimation method and the differential pressure type estimation method are used. A solid line arrow indicates a case where both the calculation formula estimation method and the differential pressure type estimation method are used. A broken arrow indicates a case where only the calculation formula estimation method is used. Further, the conditions indicated by the two-dot chain line arrows indicate determination conditions other than the deposition amount.

  When the engine 1 is started, first, the self-regeneration mode M1 is selected as the control mode.

  When the condition C1 is satisfied in the self regeneration mode M1, the control mode is changed from the self regeneration mode M1 to the assist regeneration mode M2. Condition C1 is “deposition amount ≧ assist threshold value A2 (8 g / L)”. When the condition C2 or the condition C3 is satisfied in the assist regeneration mode M2, the control mode is changed from the assist regeneration mode M2 to the self regeneration mode M1. Condition C2 is “execution time of assist regeneration mode M2 ≧ predetermined time H2a (30 minutes)”. The condition C3 is “deposition amount <allowable threshold A1 (6 g / L)”.

  When the condition C4 is satisfied in the self regeneration mode M1, the control mode is changed from the self regeneration mode M1 to the reset regeneration mode M3. Condition C4 is “continuous operation time ≧ allowable continuous time Hd (100 hours)”. When the condition C5 or the condition C6 is satisfied in the assist regeneration mode M2, the control mode is changed from the assist regeneration mode M2 to the reset regeneration mode M3. Condition C5 is “continuous operation time ≧ allowable continuous time Hd (100 hours)”. Condition C6 is “deposition amount ≧ assist threshold A2 (8 g / L) and execution time of assist regeneration mode M2 ≧ predetermined time H2c (10 minutes)”. When the condition C7 or the condition C8 is satisfied in the reset regeneration mode M3, the control mode is changed from the reset regeneration mode M3 to the self regeneration mode M1. Condition C7 is “effective time of reset regeneration mode ≧ predetermined time H3b (25 minutes)”. The valid time of the reset regeneration mode M3 indicates a time during which the filter inlet temperature is maintained at the reset target temperature (600 ° C.) or higher during the execution of the reset regeneration mode M3. The ECU 50 measures the valid time based on the detection information of the filter inlet temperature sensor 35. Condition C8 is “reset regeneration mode execution time ≧ predetermined time H3a (30 minutes)”.

  When the condition C9 is satisfied in the assist regeneration mode M2, the control mode is changed from the assist regeneration mode M2 to the stationary standby mode M4. Condition C9 is “deposition amount ≧ stationary threshold A3 (10 g / L)”. When the condition C10 or the condition C11 is satisfied in the reset regeneration mode M3, the control mode is changed from the reset regeneration mode M3 to the stationary standby mode M4. The condition C10 is “deposition amount ≧ stationary threshold A3 (10 g / L)”. The condition C11 is “deposition amount ≧ assist threshold A2 (8 g / L) and execution time of the reset regeneration mode ≧ predetermined time H3c (10 minutes)”.

  When the condition C12 is satisfied in the stationary standby mode M4, the control mode is changed from the stationary standby mode M4 to the stationary regeneration mode M5. Condition C12 is “stationary regeneration mode command: yes”, which indicates that the operator inputs a stationary regeneration instruction via the stationary regeneration button 16.

  When the condition C13 or the condition C14 is satisfied in the stationary regeneration mode M5, the control mode is changed from the stationary regeneration mode M5 to the self regeneration mode M1. Condition C13 is “effective time of stationary regeneration mode M5 ≧ predetermined time H5b (25 minutes)”. The effective time of the stationary regeneration mode M5 indicates a time during which the filter inlet temperature is maintained at the stationary target temperature (600 ° C.) or higher in the stationary regeneration mode M5. The condition C14 is “stationary regeneration mode M5 execution time ≧ predetermined time H5a (30 minutes)”. In the stationary regeneration mode M5, since the rotation speed is maintained at a predetermined rotation speed (2200 rpm), the condition C13 is satisfied except when the outside air temperature is particularly low.

  When the condition C15 or the condition C16 is satisfied in the stationary standby mode M4, the control mode is changed from the stationary standby mode M4 to the maintenance standby mode M6. Condition C15 is “stationary standby mode M4 execution time ≧ predetermined time H4a (10 hours)”. Condition C16 is “deposition amount ≧ recovery threshold A4 (12 g / L)”. When the condition C17 is satisfied in the stationary regeneration mode M5, the control mode is changed from the stationary regeneration mode M5 to the maintenance standby mode M6. Condition C17 is “deposition amount ≧ assist threshold A2 (8 g / L) and execution time of stationary regeneration mode ≧ predetermined time H5a (30 minutes)”.

  Next, the interruption of the reset playback mode will be described. The interruption request button 17 described above is provided to generate an interruption request for interrupting the reset reproduction mode.

The operator generates an interruption request in the following case, for example.
(A) When exhaust of high-temperature exhaust gas is not preferable When the reset regeneration mode is executed, high-temperature exhaust gas is exhausted from the engine 1. When there is an article that is thermally damaged by high-temperature exhaust gas around the engine 1 or the work vehicle on which the engine 1 is mounted, the execution of the reset regeneration mode is not preferable. In such a case, the operator temporarily suspends the reset regeneration mode, moves the engine 1 or the work vehicle equipped with the engine 1 to another place, and then restarts the reset regeneration mode.
(B) When the continuous execution time of the reset regeneration mode becomes long Since post injection is executed in the reset regeneration mode, the engine oil in the engine 1 is diluted by the fuel of the post injection. For this reason, it is not preferable that the continuous execution time of the reset regeneration mode becomes long. In such a case, the operator temporarily suspends the reset regeneration mode, and resumes the reset regeneration mode after a predetermined time has elapsed.

  If an interruption request is generated during execution of the reset reproduction mode, the reset reproduction mode is interrupted and the assist reproduction mode is executed. When the interruption request disappears, the reset reproduction mode once interrupted is executed again. In addition, when an interruption request is generated other than during execution of the reset reproduction mode, the interruption request is ignored. As described above, the end condition of the reset playback mode includes the execution time and the valid time of the reset playback mode. However, the time during which the reset regeneration mode is interrupted is not measured as the execution time and valid time of the reset regeneration mode.

  An example of control mode transition will be described with reference to FIGS. In FIG. 8-11, the horizontal axis indicates the passage of time. FIG. 8 is a diagram showing the temporal change in the deposition amount. In FIG. 8, the vertical axis indicates the amount of PM deposition. The horizontal axis indicates time. FIG. 9 is a diagram illustrating a change over time in the presence / absence of an interruption request. In FIG. 9, the vertical axis indicates the presence / absence of an interruption request (ON, OFF). FIG. 10 is a diagram illustrating a change over time in the control mode. In FIG. 10, the vertical axis represents the control mode. FIG. 11 is a diagram showing a temporal change in the presence / absence of the differential pressure type estimation method. In FIG. 11, the vertical axis indicates the presence / absence (ON, OFF) of the differential pressure type estimation method. Note that the time difference due to the control delay is ignored for convenience of explanation.

  As shown in FIGS. 8 and 10, the self-regeneration mode and the assist regeneration mode are executed alternately until time T23, and the deposition amount is kept between the allowable threshold value and the assist threshold value. The assist regeneration mode is executed from time T21 to time T22, and the self-regeneration mode is executed from time T22 to time T23. At time T23, the continuous operation time reaches the allowable continuous time Hd (100 hours), and the control mode is changed to the reset regeneration mode.

  As shown in FIGS. 8 and 10, the reset regeneration mode is executed from time T23 to time T24, and the amount of deposition is rapidly decreased. At time T24, the valid time of the reset playback mode has reached a predetermined time H3b (25 minutes), and the reset playback mode ends. By the time T24, the deposition amount has become almost zero. At time T24, the control mode is changed from the reset regeneration mode to the self regeneration mode.

  Time T25 is a time later than time T24, and there is a large time difference between times T24 and T25. As shown in FIGS. 8 and 10, the self-regeneration mode and the assist regeneration mode are executed alternately until time T26, and the deposition amount is kept between the allowable threshold value and the assist threshold value. At time T26, the continuous operation time reaches the allowable continuous time Hd (100 hours) again, and the control mode is changed to the reset regeneration mode.

  As shown in FIGS. 8 and 10, the reset regeneration mode is executed from time T26 to time T27, and the amount of deposition is drastically reduced. At time T27, the effective time of the reset playback mode has not reached the predetermined time H3b (25 minutes). However, as shown in FIG. 9, an interruption request is generated at time T27. For this reason, the reset playback mode is interrupted at time T27, and the assist playback mode is started. From the time T27 to the time T28, the accumulation amount decreases due to the execution of the assist regeneration mode. The decrease rate of the accumulation amount in the assist regeneration mode is smaller than the decrease rate of the accumulation amount in the reset regeneration mode. However, the decrease in the deposition amount continues without interruption. At time T28, the interruption request has disappeared, the assist reproduction mode ends, and the reset reproduction mode starts again. The reset reproduction mode is executed from time T28 to time T29. At time T29, the effective time of the reset playback mode has reached a predetermined time H3b (25 minutes), and the reset playback mode ends. Here, when the reset playback mode is interrupted, the measurement of the valid time is also interrupted. For this reason, the time measured as the valid time is a time obtained by combining the time from time T26 to time T27 and the time from time T28 to time T29. At time T29, the control mode is changed from the reset regeneration mode to the self regeneration mode.

  As shown in FIG. 11, when the assist regeneration mode or the reset regeneration mode is executed, the differential pressure type estimation method is not used. The differential pressure estimation method is used only when the self-regeneration mode is executed. The calculation estimation method is always used.

  When the filter 19 is being regenerated, the accuracy of the differential pressure type deposition amount decreases for the following reason. During regeneration, PM is removed from a region where the flow rate of the exhaust gas is relatively large on the surface of the filter 19. Specifically, PM is removed from the central portion, and PM is locally removed on the filter 19 to form holes. Then, although the PM is not removed much, the differential pressure is greatly reduced due to the presence of holes. In this case, the differential pressure does not correspond to the accumulated amount of PM. That is, during the regeneration of the filter 19, the accuracy of the differential pressure type deposition amount is greatly reduced. For this reason, the differential pressure type estimation method is not used during the regeneration of the filter 19.

  The exhaust gas purification apparatus according to this embodiment has the following effects due to the following configuration.

(1) The exhaust gas purifying apparatus according to the present embodiment includes an oxidation catalyst 18 and a filter 19 disposed in the exhaust path 5 of the engine 1, and a fuel injection device 13 that injects fuel according to a set fuel injection pattern. And a control device (ECU 50) configured to estimate the amount of particulate matter deposited and to set the fuel injection pattern. If a reset reproduction mode interruption request is generated while the reset reproduction mode is being executed, the assist reproduction mode is executed instead of the reset reproduction mode until the interruption request disappears.

  When the reset regeneration mode is being executed, a fuel injection pattern (first pattern) including post injection is set as the fuel injection pattern. When the assist regeneration mode is being executed, a fuel injection pattern (second pattern) in which the total injection amount in the compression stroke and the expansion stroke is increased is set as the fuel injection pattern. When the first pattern or the second pattern is set, the filter 19 is reproduced.

  For this reason, the exhaust gas purification apparatus according to the present embodiment can continue the regeneration of the filter 19 during the interruption when the regeneration accompanied by the post injection is interrupted.

(2) The control device (ECU 50) estimates the accumulation amount based on the calculation formula estimation method for estimating the accumulation amount based on the operating condition of the engine 1 and the differential pressure between both sides of the filter 19. The differential pressure type estimation method can be executed. While the interruption request is generated, the accumulation amount is estimated based on the calculation formula estimation method.

  For this reason, the exhaust gas purifying apparatus according to the present embodiment can estimate the amount of deposition without reducing the accuracy.

(3) The exhaust gas purifying apparatus according to the present embodiment includes an input device (interrupt request button 17) that generates the interrupt request by an input operation.

  The operator can determine whether or not to perform regeneration with post injection based on his / her own judgment. For this reason, the exhaust gas purification apparatus according to the present embodiment can cope with the case where it is necessary to interrupt the regeneration with post injection.

  The engine 1 according to the present embodiment can employ the following modifications.

  In the engine 1, the supercharger 10 and the EGR device (EGR pipe 8, EGR throttle valve 9, EGR cooler 24) are not essential components. The engine 1 may not include the supercharger 10 and / or the EGR device. When the engine 1 does not include the supercharger 10 and / or the EGR device, the intake air temperature is approximately equal to the environmental temperature, and the initial exhaust temperature is approximately equal to the catalyst inlet temperature.

  In the present embodiment, the intake throttle and the fuel injection pattern are changed in order to increase the temperature of the exhaust gas. Exhaust throttling may be performed instead of or in addition to the intake throttling. Exhaust throttling is performed by the exhaust throttle valve 6.

DESCRIPTION OF SYMBOLS 1 Engine 5 Exhaust path 13 Fuel injection apparatus 18 Oxidation catalyst 19 Filter 50 ECU (control apparatus)

Claims (3)

An oxidation catalyst and a filter disposed in the exhaust path of the engine;
A fuel injection device for injecting fuel in accordance with a set fuel injection pattern;
An exhaust gas purification device comprising: a control device configured to estimate a deposition amount of particulate matter and set the fuel injection pattern;
When the first pattern interruption request occurs when the first pattern is set, the second pattern is set instead of the first pattern until the interruption request disappears,
The first pattern is the fuel injection pattern for regenerating the filter, and includes post injection,
The exhaust gas purification apparatus, wherein the second pattern is the fuel injection pattern for regenerating the filter, and the total injection amount in the compression stroke and the expansion stroke is increased in the second pattern. The control device executes a calculation formula estimation method for estimating the accumulation amount based on an operating condition of the engine and a differential pressure type estimation method for estimating the accumulation amount based on a differential pressure between both sides of the filter. Configured to be able to
The exhaust gas purification device according to claim 1, wherein the accumulation amount is estimated based on the calculation formula estimation method while the interruption request is generated.   The exhaust gas purification device according to claim 1, further comprising an input device that generates the interruption request by an input operation.

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