JP2021025436A - Control apparatus and control method - Google Patents

Abstract

To effectively secure fuel pressure necessary for an exhaust pipe injection by an exhaust pipe injector.SOLUTION: A control apparatus 100 for an engine 10 that includes an exhaust pipe injector 44 capable of injecting fuel into an exhaust pipe on upstream of a post-exhaust process device 40 and drives a pump 14 by transmitting rotary force thereto, the pump supplying the exhaust pipe injector 44 with fuel, includes: a fuel pressure obtainment part 92 for obtaining fuel pressure of fuel supplied to the exhaust pipe injector from the pump; a recovery control part 140 for performing recovery control in which to recover exhaust process performance of the post-exhaust process device 40 by causing the exhaust pipe injector 44 to perform an exhaust pipe injection; and a revolution speed correction control part 150 for performing revolution speed correction control in which to increase an idling revolution speed of the engine in a case where the fuel pressure obtained by the fuel pressure obtainment part 92 is lower than a given lower limit fuel pressure necessary for the exhaust pipe injection by the exhaust pipe injector 44 when the recovery control is performed.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a control device and a control method, and more particularly to a control device and a control method of an engine having an exhaust pipe injector capable of injecting fuel into an exhaust pipe on the upstream side of the exhaust aftertreatment device.

As an example of this type of exhaust aftertreatment device, one provided with an oxidation catalyst, a particulate filter (hereinafter, a filter) and the like is known. There is a limit to the ability of the filter to collect particulate matter (Particulate Matter: PM). Therefore, when the PM accumulation amount of the filter reaches a predetermined amount, the exhaust pipe injector is made to execute the exhaust pipe injection to supply the unburned fuel (hydrocarbon: HC) to the oxidation catalyst, and the temperature of the exhaust flowing into the filter is adjusted. It is necessary to periodically carry out filter regeneration that raises the temperature to the PM combustion temperature (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2012-127300 Japanese Unexamined Patent Publication No. 2011-256844

By the way, if the pump that supplies fuel to the exhaust pipe injector is configured to be driven by the power of the engine, the fuel discharge pressure of the pump depends on the engine speed. For this reason, for example, if the pump deteriorates over time, the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector cannot be effectively secured at low engine speeds when the fuel discharge pressure of the pump drops. There is a possibility that playback cannot be performed efficiently.

The technique of the present disclosure has been made in view of the above circumstances, and an object of the present invention is to effectively secure the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector.

The apparatus of the present disclosure has an exhaust pipe injector capable of injecting fuel into an exhaust pipe on the upstream side of the exhaust aftertreatment device, and transmits rotational force to a pump that supplies fuel to the exhaust pipe injector to transmit the pump. A control device for an engine to be driven, the fuel pressure acquisition unit that acquires the fuel pressure of the fuel supplied from the pump to the exhaust pipe injector, and the exhaust pipe injector that executes exhaust pipe injection to perform the exhaust post-processing. A regeneration control unit that executes regeneration control for recovering the exhaust processing capacity of the apparatus, and a predetermined fuel pressure acquired by the fuel pressure acquisition unit when the regeneration control is executed are required for the exhaust pipe injection of the exhaust pipe injector. It is characterized by including a rotation speed correction control unit that performs rotation speed correction control for increasing the idling rotation speed of the engine when the fuel pressure is lower than the lower limit fuel pressure of.

Further, when the rotation speed correction control is performed, the rotation speed correction control unit increases the idling speed of the engine so that the fuel pressure acquired by the fuel pressure acquisition unit becomes equal to or higher than the lower limit fuel pressure. It is preferable to increase.

Further, the exhaust aftertreatment device includes an oxidation catalyst and a filter in order from the exhaust upstream side, and the regeneration control unit causes the exhaust pipe injector to perform exhaust pipe injection as the regeneration control. It is preferable to carry out filter regeneration control for burning and removing particulate matter deposited on the filter by supplying unburned fuel to the oxidation catalyst and raising the temperature of the exhaust gas flowing into the filter.

Further, when the idling speed of the engine exceeds a predetermined upper limit threshold speed due to the execution of the rotation speed correction control, the rotation speed limit control unit that limits the increase in the idling speed by the upper limit threshold speed. It is preferable to further provide.

Further, when the idling speed of the engine is limited by the upper limit threshold speed by the rotation speed limit control unit, the regeneration control unit may perform exhaust pipe injection of the exhaust pipe injector and post injection of the engine. It is preferable to carry out the regeneration control by using the above in combination.

The method of the present disclosure has an exhaust pipe injector capable of injecting fuel into an exhaust pipe on the upstream side of the exhaust aftertreatment device, and transmits rotational force to a pump that supplies fuel to the exhaust pipe injector to transmit the pump. It is a control method of the engine to be driven, and is supplied from the pump to the exhaust pipe injector at the time of performing regeneration control in which the exhaust pipe injector is made to execute the exhaust pipe injection to restore the exhaust processing capacity of the exhaust aftertreatment device. The number of revolutions that increases the idling rotation speed of the engine when the fuel pressure of the fuel is acquired and the acquired fuel pressure is lower than the predetermined lower limit fuel pressure required for the exhaust pipe injection of the exhaust pipe injector. It is characterized by executing correction control.

According to the technique of the present disclosure, it is possible to effectively secure the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector.

It is a schematic overall block diagram which shows the fuel injection device of the engine which concerns on this Embodiment, and the exhaust system. It is a schematic functional block diagram which shows the control device which concerns on 1st Embodiment and the related peripheral configuration. It is a flowchart explaining the flow of the process of rotation speed correction control which concerns on 1st Embodiment. It is a figure explaining the operation by the rotation speed correction control which concerns on 1st Embodiment. It is a schematic functional block diagram which shows the control device which concerns on 2nd Embodiment, and the related peripheral configuration. It is a flowchart explaining the process flow of the rotation speed correction control and the rotation speed limit control which concerns on 2nd Embodiment. It is a figure explaining the operation by the rotation speed correction control and the rotation speed limit control which concerns on 2nd Embodiment.

Hereinafter, the control device and the control method according to the present embodiment will be described with reference to the accompanying drawings. The same parts have the same reference numerals, and their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing a fuel injection device and an exhaust system of the engine 10 according to the present embodiment.

As shown in FIG. 1, the cylinder block CB of the engine 10 is provided with a plurality of cylinders C for reciprocating a piston (not shown). The engine 10 is not limited to the in-line multi-cylinder engine shown in the illustrated example, and may be a V-type engine, a horizontally opposed engine, a single-cylinder engine, or the like.

A cylinder head (not shown) above the cylinder block CB is provided with an in-cylinder injector 17 that injects fuel into the cylinder C. The in-cylinder injector 17 is, for example, an injector capable of multi-injection such as pilot injection, pre-injection, main injection, after-injection, and post-injection during one combustion cycle of the engine 10, and the nozzle tip portion is a cylinder C (cylinder C). It is attached to the cylinder head while facing the inside of the combustion chamber). The fuel injection amount and injection timing of the in-cylinder injector 17 are controlled in response to a command from the control device 100.

The fuel injection device includes a fuel tank 11, a suction pipe 12, a fuel filter 13, a feed pump 14 (an example of a pump of the present disclosure), a supply pump 15, a first supply pipe 20, and a second supply pipe 21. A common rail 16, a pressure control valve 18, and a first return pipe 19 are provided. Further, the fuel injection device includes a branch supply pipe 22 for supplying fuel to the exhaust pipe injector 44, a flow rate adjusting valve 23, a relief valve 24, and a second return pipe 25.

The fuel tank 11 stores fuel (for example, light oil). One end of the suction pipe 12 is immersed in the fuel in the fuel tank 11, and the other end is connected to the suction port of the feed pump 14. The fuel filter 13 is interposed in the suction pipe 12 and removes foreign substances in the fuel pumped by the feed pump 14.

Both the feed pump 14 and the supply pump 15 are connected to the crankshaft of the engine 10 via a power transmission mechanism (for example, a gear or a belt pulley) (not shown), and are driven by the power of the engine 10. The feed pump 14 discharges the fuel pumped from the fuel tank 11 through the fuel suction pipe 12 to the first supply pipe 20.

The first supply pipe 20 connects the discharge port of the feed pump 14 and the suction port of the supply pump 15. Further, the upstream end of the branch supply pipe 22 described later is connected to the first supply pipe 20.

The supply pump 15 includes a plunger that is reciprocated by the rotation of a shaft (not shown), and pressurizes and discharges fuel by the reciprocating motion of the plunger. The discharge port of the supply pump 15 is connected to the common rail 16 via the second supply pipe 21, so that the high-pressure fuel pressurized by the supply pump 15 is supplied from the second supply pipe 21 to the common rail 16. It has become.

The common rail 16 accumulates high-pressure fuel supplied from the supply pump 15 and distributes it to each in-cylinder injector 17. Further, the common rail 16 is provided with a pressure control valve 18, and when the pressure in the common rail 16 reaches a predetermined pressure, the high-pressure fuel is returned to the fuel tank 11 via the first return pipe 19. There is.

The branch supply pipe 22 branches from the first supply pipe 20 and is connected to the exhaust pipe injector 44, and introduces the fuel discharged by the feed pump 14 into the exhaust pipe injector 44. The flow rate adjusting valve 23 is a valve whose opening degree can be linearly adjusted, and is provided in the branch supply pipe 22. The flow rate adjusting valve 23 adjusts the flow rate of fuel supplied from the feed pump 14 to the exhaust pipe injector 44 via the branch supply pipe 22. The operation of the flow rate adjusting valve 23 is controlled in response to a command from the control device 100.

The relief valve 24 is preferably provided in the branch supply pipe 22 on the upstream side of the flow rate adjusting valve 23, and is connected to the first return pipe 19 via the second return pipe 25. The relief valve 24 opens when the pressure of the fuel flowing through the branch supply pipe 22 becomes equal to or higher than a predetermined set pressure. That is, when the pressure of the fuel discharged from the feed pump 14 reaches a predetermined set pressure at the time of high engine rotation or the like, the relief valve 24 is opened, so that the fuel flowing through the branch supply pipe 22 is the second return pipe 25. Is returned to the fuel tank 11 via the first return pipe 19.

The cylinder head of the engine 10 is provided with an exhaust manifold 30 that collects the exhaust gas discharged from each cylinder C. Further, an exhaust pipe 31 for guiding the exhaust gas to the atmosphere is connected to the exhaust manifold 30. The exhaust pipe 31 is provided with a turbine 33 of the supercharger 32, an exhaust pipe injector 44, an exhaust aftertreatment device 40, and the like in this order from the exhaust upstream side. Reference numeral 35 indicates an intake pipe, and reference numeral 34 indicates a compressor of the supercharger 32.

The exhaust gas aftertreatment device 40 includes a pre-stage post-treatment device 41 and a post-stage post-treatment device 50.

The pretreatment device 41 has an oxidation catalyst 42 and a filter 43 in this order from the upstream side of the exhaust gas.

The oxidation catalyst 42 is formed by supporting a catalyst component or the like on the surface of a ceramic carrier such as a cordierite honeycomb structure, and oxidizes HC and CO contained in the exhaust gas. When unburned fuel (HC) is supplied by the exhaust pipe injection of the exhaust pipe injector 44, the oxidation catalyst 42 oxidizes the unburned fuel (HC) to raise the exhaust temperature.

The filter 43 is formed, for example, by arranging a large number of cells partitioned by a porous partition wall along the flow direction of exhaust gas, and alternately sealing the upstream side and the downstream side of these cells. .. The filter 43 collects PM in the exhaust gas in the pores and the surface of the partition wall, and when the PM accumulation amount reaches a predetermined amount, the filter regeneration is performed to burn and remove the PM. Note that the filter regeneration may be performed at predetermined intervals, such as when the cumulative mileage from the previous filter regeneration execution reaches a predetermined threshold distance.

The post-stage post-treatment device 50 has a urea water injection device 51 and a selective catalytic reduction catalyst (hereinafter referred to as SCR catalyst) 57 in this order from the upstream side of the exhaust gas.

The urea water injection device 51 supplies the urea water tank 52 that stores the urea water, the strainer 53 that is immersed in the urea water in the urea water tank 52 to remove foreign matter, and the supply pipe 54 that is connected to the strainer 53. It includes a urea water pump 55 provided in the pipe 54 for pumping urea water from the urea water tank 52, and a urea water injector 56 for injecting the urea water supplied from the supply pipe 54 into the exhaust pipe 31.

The urea water injected from the urea water injector 56 is hydrolyzed by exhaust heat and water vapor in the exhaust to produce ammonia (NH3), which is supplied to the SCR catalyst 57 on the downstream side as a reducing agent.

The SCR catalyst 57 is formed by supporting zeolite or the like on, for example, a porous ceramic carrier. The SCR catalyst 57 adsorbs ammonia supplied as a reducing agent from the urea water injector 56, and selectively reduces and purifies nitrogen oxides (NOx) from the exhaust passing through the adsorbed ammonia.

The engine speed sensor 90 acquires the engine speed Ne from the crankshaft of the engine 10. The accelerator opening sensor 91 acquires an accelerator opening Q (injection instruction value to the in-cylinder injector 17) according to the amount of depression of the accelerator pedal (not shown). The fuel pressure sensor 92 (an example of the fuel pressure acquisition unit) is provided in the branch supply pipe 22, and the pressure of the fuel supplied from the feed pump 14 to the exhaust pipe injector 44 via the branch supply pipe 22 (hereinafter, referred to as Fuel pressure FP) is acquired. The first exhaust temperature sensor 93 is provided at the outlet portion of the oxidation catalyst 42, and acquires the temperature of the exhaust gas that has passed through the oxidation catalyst 42 (hereinafter, the oxidation catalyst outlet temperature). The second exhaust temperature sensor 94 is provided at the outlet of the SCR catalyst 57, and acquires the temperature of the exhaust gas that has passed through the SCR catalyst 57 (hereinafter, the SCR catalyst outlet temperature). The differential pressure sensor 95 acquires the front-rear differential pressure ΔP of the filter 43. The sensor values of each of these sensors 90 to 95 are transmitted to the electrically connected control device 100.

[First Embodiment]
FIG. 2 is a schematic functional block diagram showing the control device 100 according to the first embodiment and related peripheral configurations.

The control device 100 is, for example, a device that performs calculations such as a computer, and is a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, and an output port connected to each other by a bus or the like. Etc., and execute the program.

Further, the control device 100 functions as a device including an oxidation catalyst temperature estimation unit 110, an SCR catalyst temperature estimation unit 120, a temperature rise control unit 130, a filter regeneration control unit 140, and a rotation speed correction control unit 150 by executing a program. To do. Each of these functional elements will be described as being included in the control device 100, which is integrated hardware in the present embodiment, but any part of these may be provided in separate hardware.

_{The oxidation catalyst temperature estimation unit 110 estimates the oxidation catalyst temperature T DOC} corresponding to the internal temperature of the oxidation catalyst 42 based on the oxidation catalyst outlet temperature transmitted from the first exhaust temperature sensor 93. The oxidation catalyst temperature _TDOC may be estimated based on the operating state of the engine 10 acquired by the engine speed sensor 90, the accelerator opening sensor 91, the intake air amount sensor (not shown), or the like. _{The oxidation catalyst temperature T DOC} estimated by the oxidation catalyst temperature estimation unit 110 is transmitted to the temperature rise control unit 130 and the filter regeneration control unit 140.

_{The SCR catalyst temperature estimation unit 120 estimates the SCR catalyst temperature T SCR} corresponding to the internal temperature of the SCR catalyst 57 based on the SCR catalyst outlet temperature transmitted from the second exhaust temperature sensor 94. The SCR catalyst temperature _TSCR may be estimated based on the operating state of the engine 10 acquired by the engine rotation speed sensor 90, the accelerator opening sensor 91, the intake air amount sensor (not shown), or the like. _{The SCR catalyst temperature T SCR} estimated by the SCR catalyst temperature estimation unit 120 is transmitted to the temperature rise control unit 130.

_{When the oxidation catalyst temperature T DOC} and the SCR catalyst temperature T _SCR are lower than a predetermined active temperature (for example, about 200 ° C.) at the time of cold start of the engine 10, the temperature rise control unit 130 determines these catalyst temperatures. The temperature rise control is carried out to raise the temperature above the active temperature.

Specifically, the temperature rise control unit 130 raises the intake throttle if at least one of the _{oxidation catalyst temperature T DOC} and the SCR catalyst temperature T _SCR transmitted from the temperature estimation units 110 and 120 is lower than the active temperature. By causing the in-cylinder injector 17 to execute early post injection (injection performed at a timing close to the after injection) and raising the in-cylinder combustion temperature of the engine 10, the oxidation catalyst 42 and the SCR catalyst 57 are brought to the active temperature range. The temperature rises. The temperature rise control ends when the oxidation catalyst temperature T _DOC and the SCR catalyst temperature T _SCR reach the active temperature.

The filter regeneration control unit 140 determines when the front-rear differential pressure ΔP transmitted from the differential pressure sensor 95 reaches a predetermined upper limit differential pressure, or the interval from the previous filter regeneration execution (for example, cumulative mileage or cumulative mileage). ) Reaches a predetermined interval, or when a predetermined execution condition is satisfied, filter regeneration control (an example of the regeneration control of the present disclosure) for burning and removing PM accumulated on the filter 43 is performed.

The filter regeneration control is performed by supplying unburned fuel to the oxidation catalyst 42 by injecting the exhaust pipe of the exhaust pipe injector 44 and raising the temperature of the exhaust gas flowing into the filter 43 to the PM combustion temperature. The exhaust pipe injection amount during filter regeneration control may be feedback-controlled for the operation of the flow rate adjusting valve 23 based on the deviation between the PM combustion temperature (target temperature) and the oxidation catalyst temperature _TDOC. The filter regeneration control is performed when the front-rear differential pressure ΔP transmitted from the differential pressure sensor 95 drops to a predetermined lower limit differential pressure, when the total fuel injection amount reaches a predetermined upper limit injection amount, or from the start of regeneration control. It ends when the elapsed time of is reached the predetermined upper limit time.

The rotation speed correction control unit 150 performs rotation speed correction control for correcting the idling speed of the engine 10 during filter regeneration based on the fuel pressure FP transmitted from the fuel pressure sensor 92.

Specifically, in the memory of the control device 100, the lower limit value of the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector 44 at the time of filter regeneration is stored as a _{predetermined lower limit fuel pressure FP Min.} If the fuel pressure FP transmitted from the fuel pressure sensor 92 during execution of the filter regeneration control is _{less than the lower limit fuel pressure FP Min} (FP <FP _Min ), the rotation speed correction control unit 150 performs idling injection to the in-cylinder injector 17. The fuel discharge pressure of the feed pump 14 is increased by increasing the indicated value and increasing the idling speed of the engine 10.

In this way, when the fuel pressure FP is lower _{than the lower limit fuel pressure FP Min} during filter regeneration, the rotation speed correction control is executed to increase the idling speed of the engine 10 and raise the fuel discharge pressure of the feed pump 14. By doing so, the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector 44 can be reliably secured. How much the idling speed is increased is determined so that the fuel pressure FP becomes equal to or higher than the _{lower limit fuel pressure FP Min} based on the deviation between the fuel pressure FP acquired by the fuel pressure sensor 92 and the lower limit fuel pressure FP _Min. The idling injection instruction value for the in-cylinder injector 17 may be feedback-controlled, or the in-cylinder injector 17 may be created in advance based on a map showing the relationship between the fuel discharge pressure of the feed pump 14 and the engine speed Ne. The idling injection instruction value for is may be feed-forward controlled.

Next, the flow of the rotation speed correction control processing according to the present embodiment will be described with reference to FIG. This routine is preferably started by turning on the ignition switch of the engine 10.

As shown in FIG. 3, in step S100, it is determined whether or not the _{oxidation catalyst temperature T DOC is lower than the active temperature.} If the oxidation catalyst temperature T _DOC is less than the active temperature (Yes), this control proceeds to step S110. On the other hand, when the oxidation catalyst temperature T _DOC is equal to or higher than the active temperature (No), this control proceeds to the determination process in step S130.

In step S110, the temperature rise control for raising the temperature of the oxidation catalyst 42 is performed by increasing the fuel injection amount of the in-cylinder injector 17 to raise the combustion temperature of the engine 10. Next, in step S120, it is determined whether or not _{the oxidation catalyst temperature T DOC has reached the active temperature.} If the oxidation catalyst temperature T _DOC has reached the active temperature (Yes), this control proceeds to the determination process in step S130. On the other hand, when the oxidation catalyst temperature T _DOC has not reached the active temperature (No), this control is returned to the process of step S110 in order to continue the temperature rise control.

In step S130, the execution condition of either the front-rear differential pressure ΔP transmitted from the differential pressure sensor 95 reaches a predetermined upper limit differential pressure, or the interval from the previous filter regeneration execution reaches a predetermined interval. Is determined whether or not is satisfied. When the execution condition of the filter reproduction is satisfied (Yes), this control proceeds to the determination process of step S140. On the other hand, if the execution condition is not satisfied (No), this control is returned.

In step S140, it is determined whether or not the fuel pressure FP transmitted from the fuel pressure sensor 92 is _{less than the lower limit fuel pressure FP Min} (FP <FP _Min). When the fuel pressure FP is _{less than the lower limit fuel pressure FP Min} (Yes), this control proceeds to step S150 and increases the idling speed of the engine 10 in parallel with the filter regeneration control by the exhaust pipe injection of the exhaust pipe injector 44. Execute rotation speed correction control. On the other hand, when the fuel pressure FP is equal to _{or higher than the lower limit fuel pressure FP Min} (No), this control proceeds to step S160, and only the filter regeneration control by the exhaust pipe injection is executed without executing the rotation speed correction control.

In step S170, the front-rear differential pressure ΔP transmitted from the differential pressure sensor 95 drops to a predetermined lower limit differential pressure, the total fuel injection amount reaches a predetermined upper limit injection amount, or the elapsed time from the start of regeneration control. It is determined whether or not any of the end conditions for reaching the upper limit time is satisfied. If the end condition is not satisfied (No), this control is returned to the determination process in step S140 in order to continue the filter reproduction control. That is, until the filter regeneration is completed, each process of step S150 or step S160 is appropriately performed based on the relationship between the fuel pressure FP and the lower limit fuel pressure FP _Min.

On the other hand, if the end condition is satisfied in step S170 (Yes), this control proceeds to step S180, ends the filter reproduction control, and then returns.

According to the first embodiment described in detail above, when the fuel pressure FP of the fuel supplied from the feed pump 14 to the exhaust pipe injector 44 is lower than the _{predetermined lower limit fuel pressure FP Min when the filter regeneration control is performed.} Is configured to appropriately perform rotation speed correction control for increasing the idling speed of the engine 10. Specifically, as shown in FIG. 4, when the discharge capacity of the feed pump 14 changes (decreases) from the solid line L1 to the broken line L2 due to aged deterioration or the like, the idling speed during filter regeneration is indicated by the arrow X in the figure. By increasing and correcting in the direction, the fuel discharge pressure of the feed pump 14 is maintained above the _{lower limit fuel pressure FP Min.} As a result, even if the discharge capacity of the feed pump 14 is reduced due to aged deterioration or the like, the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector 44 can be reliably secured during filter regeneration, and the execution efficiency of filter regeneration can be ensured. Can be maintained effectively.

[Second Embodiment]
FIG. 5 is a schematic functional block diagram showing the control device 100 according to the second embodiment and related peripheral configurations. The control device 100 according to the second embodiment is obtained by adding the rotation speed limit control unit 160 as a part of the functional elements to the control device 100 of the first embodiment. The same configurations as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the rotation speed limit control unit 160, for example, when the fuel pressure FP is _{significantly lower than the lower limit fuel pressure FP Min} during filter regeneration, the rotation speed correction control unit 150 causes the idling speed to be set to a predetermined upper limit threshold rotation speed. when it is corrected exceeds the number Ne _Max performs the rotational speed limiting control for limiting the increase in the engine speed Ne by the correction in the upper threshold speed Ne _Max. In this way, by setting the upper limit value (limit value) for the correction for increasing the idling speed, an excessive increase in the idling speed can be effectively suppressed.

_{When the fuel pressure FP reaches the lower limit fuel pressure FP Min} at the time of filter regeneration, the filter regeneration control unit 140 completes the filter regeneration control only by the exhaust pipe injection by the exhaust pipe injector 44. Further, the filter regeneration control unit 140 controls _{the rotation speed correction when the fuel pressure FP is lower than the lower limit fuel pressure FP Min} and the rotation speed limit control unit 160 does not perform the rotation speed limit control during filter regeneration. In parallel with this, the filter regeneration control is completed by injecting the exhaust pipe by the exhaust pipe injector 44. Further, the filter regeneration control unit 140 controls _{the rotation speed limit when the fuel pressure FP is lower than the lower limit fuel pressure FP Min} at the time of filter regeneration and the rotation speed limit control unit 160 performs the rotation speed limit control. In parallel with this, the filter regeneration control is completed by using the exhaust pipe injection of the exhaust pipe injector 44 and the post injection of the engine 10 together. In this way, when the idling speed is _{limited by the upper limit threshold speed Ne Max} by the rotation speed limit control and the fuel discharge pressure of the feed pump 14 is lower _{than the lower limit fuel pressure FP Min} , post injection is performed in the exhaust pipe injection. By using the above in combination, the shortage of the exhaust pipe injection amount can be effectively compensated.

Next, the flow of the rotation speed correction control and the rotation speed limit control according to the second embodiment will be described with reference to FIG. Since the processes in steps S200 to S240 have the same contents as the processes in steps S100 to S140 of the first embodiment shown in FIG. 3, these description will be omitted.

In step S240, when the fuel pressure FP transmitted from the fuel pressure sensor 92 is equal to _{or higher than the lower limit fuel pressure FP Min} (No), this control proceeds to step S260, and the filter executes only the exhaust pipe injection of the exhaust pipe injector 44. Perform playback control. On the other hand, in step S240, when the fuel pressure FP transmitted from the fuel pressure sensor 92 is _{less than the lower limit fuel pressure FP Min} (Yes), this control proceeds to the determination process in step S245.

In step S245, it is determined whether or not the idling speed of the engine 10 is _{increased and corrected by exceeding the predetermined upper limit threshold speed Ne Max by the rotation speed correction control.} When the idling speed does not exceed the upper limit threshold speed Ne _Max (No), this control proceeds to step S250, and in parallel with the speed correction control for increasing the idling speed of the engine 10, the exhaust pipe injector 44 is exhausted. Filter regeneration control that executes only tube injection is performed.

On the other hand, if it is determined in step S245 that the idling speed exceeds the upper limit threshold speed Ne _Max (Yes), this control proceeds to step S255, and the idling speed is limited by the upper threshold speed Ne _Max. In parallel with the limit control, filter regeneration control is performed in which the exhaust pipe injection of the exhaust pipe injector 44 and the post injection of the engine 10 are used in combination.

In step S270, the front-rear differential pressure ΔP transmitted from the differential pressure sensor 95 drops to a predetermined lower limit differential pressure, the total fuel injection amount reaches a predetermined upper limit injection amount, or the elapsed time from the start of regeneration control. It is determined whether or not any of the end conditions for reaching the upper limit time is satisfied. If the end condition is not satisfied (No), this control is returned to the determination process in step S240 in order to continue the filter reproduction control. On the other hand, when the end condition is satisfied (Yes), this control proceeds to step S280, ends the filter reproduction control, and returns.

According to the second embodiment described in detail above, when the fuel pressure FP is lower _{than the predetermined lower limit fuel pressure FP Min} during filter regeneration, the rotation speed correction control for increasing the idling speed of the engine 10 is performed. It is configured. As a result, as in the first embodiment, even when the discharge capacity of the feed pump 14 is reduced due to aged deterioration or the like, the fuel pressure required for the exhaust pipe injection of the exhaust pipe injector 44 can be reliably secured during filter regeneration. It will be possible.

Further, as shown in FIG. 7, the discharge capacity of the feed pump 14 is significantly reduced from the solid line L1 to the one-point chain line L3 due to deterioration over time, and the idling speed exceeds the upper limit threshold speed Ne _{Max by the rotation speed correction control.} When the correction is made, the engine speed limit control is configured to limit the increase in the engine speed Ne by the upper limit threshold speed Ne _Max. This makes it possible to effectively prevent the idling speed of the engine 10 from being excessively increased during filter regeneration.

Further, when the rotation speed limit control is performed at the time of filter regeneration, the filter regeneration control is completed by using the exhaust pipe injection of the exhaust pipe injector 44 and the post injection of the engine 10 in combination. _{As a result, even in a state where the idling speed is limited by the upper limit threshold speed Ne Max} by the speed limit control and the fuel discharge pressure of the feed pump 14 is insufficient, the shortage of the exhaust pipe injection amount is effective by the post injection. It becomes possible to effectively maintain the execution efficiency of filter reproduction.

[Other]
It should be noted that the present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, in the above embodiment, the rotation speed correction control and the rotation speed limit control have been described as being applied to the filter regeneration control, but the SOx purge control for recovering the SCR catalyst 57 from SOx poisoning (regeneration control of the present disclosure). It may be applied to (1 example).

Further, in the first embodiment, the filter regeneration control has been described as being performed only by the exhaust pipe injection, but the post injection may be used in combination if necessary.

10 Engine 11 Fuel tank 12 Suction pipe 13 Fuel filter 14 Feed pump (pump)
15 Supply pump 16 Common rail 17 In-cylinder injector 20 1st supply pipe 21 2nd supply pipe 22 Branch supply pipe 23 Flow control valve 40 Exhaust post-treatment device 41 Pre-stage post-treatment device 42 Oxidation catalyst 43 Filter 44 Exhaust pipe injector 50 Post-stage post-treatment Equipment 57 SCR catalyst 92 Fuel pressure sensor (fuel pressure acquisition unit)
100 Control device 140 Filter regeneration control unit (regeneration control unit)
150 rpm correction control unit 160 rpm limit control unit

Claims (6)

An engine control device that has an exhaust pipe injector capable of injecting fuel into an exhaust pipe on the upstream side of the exhaust aftertreatment device and transmits rotational force to a pump that supplies fuel to the exhaust pipe injector to drive the pump. And
A fuel pressure acquisition unit that acquires the fuel pressure of the fuel supplied from the pump to the exhaust pipe injector, and
A regeneration control unit that executes regeneration control by causing the exhaust pipe injector to inject an exhaust pipe to restore the exhaust processing capacity of the exhaust aftertreatment device.
When the regeneration control is performed, the idling speed of the engine is increased when the fuel pressure acquired by the fuel pressure acquisition unit is lower than a predetermined lower limit fuel pressure required for exhaust pipe injection of the exhaust pipe injector. A control device including a rotation speed correction control unit that performs rotation speed correction control. The rotation speed correction control unit increases the idling speed of the engine so that the fuel pressure acquired by the fuel pressure acquisition unit becomes equal to or higher than the lower limit fuel pressure when the rotation speed correction control is performed. The control device according to claim 1. The exhaust gas aftertreatment device includes an oxidation catalyst and a filter in this order from the upstream side of the exhaust gas.
As the regeneration control, the regeneration control unit causes the exhaust pipe injector to inject an exhaust pipe to supply unburned fuel to the oxidation catalyst, and raises the temperature of the exhaust gas flowing into the filter to raise the filter. The control device according to claim 1 or 2, wherein the filter regeneration control for burning and removing the particulate matter accumulated in the above is performed. When the idling speed of the engine exceeds a predetermined upper limit threshold speed by executing the rotation speed correction control, a rotation speed limit control unit that limits the increase in the idling speed by the upper limit threshold speed is further added. The control device according to any one of claims 1 to 3. When the idling speed of the engine is limited by the upper limit threshold speed by the speed limit control unit, the regeneration control unit uses both the exhaust pipe injection of the exhaust pipe injector and the post injection of the engine. The control device according to claim 4, wherein the reproduction control is performed by the operation. An engine control method that has an exhaust pipe injector capable of injecting fuel into an exhaust pipe on the upstream side of the exhaust aftertreatment device, and transmits rotational force to a pump that supplies fuel to the exhaust pipe injector to drive the pump. And
At the time of performing regeneration control in which the exhaust pipe injector is made to inject the exhaust pipe to restore the exhaust processing capacity of the exhaust aftertreatment device, the fuel pressure of the fuel supplied from the pump to the exhaust pipe injector is acquired and the fuel pressure is acquired. When the acquired fuel pressure is lower than a predetermined lower limit fuel pressure required for the exhaust pipe injection of the exhaust pipe injector, the rotation speed correction control for increasing the idling rotation speed of the engine is executed. Control method.

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