JP2018123736A - Diesel particulate filter regeneration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diesel engine particulate filter regeneration device which can quickly decrease a power accumulation amount of a battery, and can shorten a time at which the power accumulation amount of the battery becomes smaller than a normal amount.SOLUTION: In a DPF regeneration device 15 in which a DPF 11 is connected to an exhaust system 5 of an engine 1, and which raises an exhaust gas temperature when PMs are accumulated on the DPF 11 while exceeding a set amount, and combusts and removes the PMs in the DPF 11, the DPF regeneration device comprises an alternator 16 driven by the engine 1, and a battery 17 electrically charged by the alternator 16, and also comprises a power generation stop part 18 for sopping the power generation of the alternator 16 when a PM accumulation amount reaches an intermediate set amount before reaching a set amount, and an exhaust gas temperature rise auxiliary part 19 for increasing an engine load by releasing the stop of the power generation of the alternator 16 when the PM accumulation amount reaches the set amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diesel particulate filter regeneration device for regenerating a diesel particulate filter.

  As a technique for forcibly regenerating a diesel particulate filter (hereinafter referred to as DPF), for example, a technique described in Patent Document 1 is known. This technology uses an engine load by an alternator to increase exhaust gas temperature, and burns and removes particulate matter (hereinafter referred to as PM) deposited on the DPF to perform DPF regeneration.

  This technology also reduces the target battery charge before DPF regeneration, then increases the target battery charge during DPF regeneration and increases the power generation load of the alternator. Increase and burn off PM.

JP 2010-180842 A JP 2007-230409 A JP-A-2005-090259 JP 2011-069314 A

  By the way, since the technique reduces the target battery charge amount before the DPF regeneration and performs charging with the reduced target battery charge amount, it takes time to sufficiently reduce the charged amount of the battery. Therefore, there is a possibility that the state in which the amount of electricity stored in the battery is less than usual will continue for a long time.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a diesel particulate filter regeneration device that can quickly reduce the amount of electricity stored in a battery and shorten the time during which the amount of electricity stored in the battery is less than normal.

  In order to achieve the above-mentioned object, according to the present invention, a diesel particulate filter that collects particulate matter in exhaust gas is connected to an exhaust system of an engine, and the particulate matter is accumulated in a set amount or more on the diesel particulate filter. When the exhaust gas temperature is raised to burn and remove particulate matter in the diesel particulate filter, the diesel particulate filter regeneration device is driven by an engine to generate electricity, a battery charged by the alternator, and the particles Power generation stop means for stopping power generation of the alternator when the amount of particulate matter accumulated reaches an intermediate set amount before reaching the set amount, and power generation of the alternator when the amount of particulate matter deposition reaches the set amount. Exhaust gas temperature rising auxiliary means for releasing the stop and increasing the engine load Those were example.

  According to the exhaust gas temperature raising device of the present invention, the amount of electricity stored in the battery can be quickly reduced, and the time during which the amount of electricity stored in the battery is less than normal can be shortened.

It is explanatory drawing of the DPF reproduction | regeneration apparatus which concerns on one embodiment of this invention. It is a schematic flowchart of a DPF regeneration process. It is explanatory drawing explaining DPF regeneration and ACG regenerative power generation in time series. It is explanatory drawing of the electric power generation amount increase / decrease of ACG. It is a diagram which shows an example of the relationship between an alternator rotational speed and output current. It is a diagram which shows an example of the relationship between an alternator rotation speed and a torque.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, the engine 1 is a diesel engine mounted on a vehicle and includes an intake manifold 2 and an exhaust manifold 3. An intake system 4 is connected to the intake manifold 2, and an exhaust system 5 is connected to the exhaust manifold 3.

  The intake system 4 is provided with a compressor 7 of a turbocharger 6. The compressor 7 is driven by a rotational force from a turbine 8 of a turbocharger 6 described later.

  The exhaust system 5 is provided with a turbine 8 of a turbocharger 6 and an exhaust purification device 9. The turbine 8 is rotationally driven by exhaust gas.

  The exhaust purification device 9 is provided in the exhaust system 5 downstream from the turbine 8. The exhaust purification device 9 includes an oxidation catalyst (hereinafter referred to as DOC) 10, a DPF 11 disposed on the downstream side of the DOC 10, and a NOx catalyst 12 disposed on the downstream side of the DPF 11.

  The DOC 10 is formed by supporting a catalyst component on the surface of a carrier made of, for example, ceramic. The DOC 10 oxidizes HC in the exhaust gas and generates heat of oxidation when the exhaust gas temperature is equal to or higher than the catalyst activation temperature. The exhaust system upstream of the DOC 10 is provided with a temperature sensor 5a for detecting the exhaust gas temperature, and the detected value of the temperature sensor is input to a control device (ECU) 14 described later.

  The DPF 11 has a porous partition wall (not shown) and collects PM in the exhaust gas in the pores and the surface of the partition wall. The DPF 11 is provided with a differential pressure sensor 13 that detects a differential pressure between the inlet and the outlet, and a detected value of the differential pressure sensor 13 is input to the ECU 14.

  The NOx catalyst 12 reduces and purifies NOx in the exhaust gas with a reducing agent (ammonia generated from urea water).

  Further, the engine 1 is provided with a DPF regeneration device 15 for raising the exhaust gas temperature and burning and removing the PM in the DPF 11 when PM accumulates in the DPF 11 over a set amount.

  The DPF regeneration device 15 includes an alternator 16 that is driven by the engine 1 to generate electric power, a battery 17 that is charged by the alternator 16, and an alternator 16 when the PM accumulation amount of the DPF 11 reaches an intermediate set amount before reaching the set amount. A power generation stop unit 18 that stops the power generation of the exhaust gas, and an exhaust gas temperature increase auxiliary unit 19 that releases the power generation stop of the alternator 16 to increase the engine load when the PM accumulation amount reaches a set amount.

  The alternator 16 is connected to the crankshaft 1a of the engine 1 through pulleys 20a and 20b and a belt 20c. The alternator 16 has a stator (not shown) and a rotor (not shown), generates a magnetic field by supplying current to the exciting coil of the rotor, and rectifies the AC voltage generated in the power generating coil of the stator. It comes to take out. The alternator 16 is connected to a power generation adjusting unit 21 for adjusting the amount of power generated by adjusting the current supplied to the exciting coil. Specifically, the power generation adjusting unit 21 is composed of a regulator and adjusts the amount of power generation in response to a signal from the ECU 14.

  The battery 17 is made of a lead storage battery and is formed to be rechargeable. The battery 17 is connected to an electrical component 22 that is an electrical load such as an auxiliary machine, a light, and an air conditioner of the engine 1.

  The power generation stop unit 18 and the exhaust gas temperature increase assist unit 19 are composed of programs stored in the ECU 14. The ECU 14 also includes a PM accumulation amount detection unit 23 that detects the PM accumulation amount of the DPF 11 from the detection value of the differential pressure sensor 13, and a storage amount detection unit 24 that detects the accumulation amount of the battery 17 from the terminal voltage of the battery 17. A discharge limiting unit 25 for releasing the power generation stop by the power generation stop unit 18 when power generation is stopped by the power generation stop unit 18 and the stored amount of the battery 17 is lowered to a lower limit value necessary for driving the engine 1; When the power generation amount of the alternator 16 decreases after the temperature increase assist unit 19 cancels the power generation stop of the alternator 16 and before the inlet temperature of the DOC 10 reaches the catalyst activation temperature of the DOC 10, the exhaust gas temperature increase assist unit 19 increases the exhaust gas. After the midway ending unit 26 for terminating the temperature and the exhaust gas temperature raising auxiliary unit 19 cancel the power generation stop of the alternator 16, the inlet temperature of the DOC 10 is DOC1. When it reaches the catalyst activation temperature, it is further stored as a program and a PM combustion portion 27 for burning the PM in the DPF 11.

  Next, the operation of this embodiment will be described.

  As shown in FIGS. 1 and 2, the ECU 14 determines whether or not the detected value of the PM accumulation amount detection unit 23 has become equal to or greater than the intermediate set amount in step S1, and proceeds to step S2 if Yes. When the DPF regeneration process ends, the process returns to the start.

  When No in step S1, the vehicle travels in the normal travel mode as shown in FIG. At this time, there is no DPF regeneration request, and the alternator (ACG) 16 generates power so as to maintain the battery capacity constant (for example, 90%). At this time, the power generation voltage of the alternator 16 is between 12.5 V (power generation stopped state) and 13.5 V (normal power generation state).

  For example, as shown in FIGS. 4 (a), 4 (b), and 4 (c), when considering a model in which the same electrical load is connected in parallel to simplify the explanation, the electrical load in the connected state is When the resistance value is R and the generated voltage of the alternator 16 is Va, the consumption current I of the electric load is I = Va / R, and the generated current Ia of the alternator 16 is Ia = charging current of the battery 17 + Va / R R. As shown in FIG. 4B, when there are two connected electrical loads, the current consumption I of the electrical load is I = 2 × Va / R, and the generated current Ia of the alternator 16 is Ia = The charging current of the battery 17 increases by 2 × Va / R. Similarly, as shown in FIG. 4C, when there are three connected electrical loads, the current consumption I of the electrical load is I = 3 × Va / R, and the generated current Ia of the alternator 16 is Ia = charging current of the battery 17 + 3 × Va / R and further increases.

  At this time, the drive torque of the alternator 16 varies depending on the engine speed and the generated current. For example, as shown in FIG. 6, even if the engine speed is the same, if the generated current is large, the drive torque of the alternator 16 increases and the engine load increases. The output current of the alternator 16 varies depending on the temperature of the alternator 16 and the ambient temperature. For example, as shown in FIG. 5, when the alternator 16 is cold (cold) and hot (hot), the ambient temperature is low (ambient temperature 25 ° C.) and high (90 ° C.). When the alternator 16 is heated even if the alternator 16 has the same rotational speed, the output current (when hot (ambient temperature 25 ° C.)) decreases, and when the ambient temperature increases further, the output current (thermal (circular temperature 90) ° C)) is even lower.

  As shown in FIGS. 1, 2, and 3, when the ECU 14 proceeds to step S <b> 2, it issues a signal for setting the power generation of the alternator 16 to 0 to the power generation control unit 21 as a DPF regeneration request. The power generation control unit 21 that has received the signal sets the current supplied to the exciting coil of the alternator 16 to zero, and stops the power generation of the alternator 16. Since the power generation of the alternator 16 is completely stopped, the electrical component 22 is driven only by the electricity of the battery 17, and the amount of power stored in the battery 17 can be quickly reduced. From this, the intermediate set amount can be set to a value close to the set amount, and the battery charge amount can be prevented from being reduced for a long time. The amount of battery discharge at this time is determined by the magnitude of the electrical load by the electrical component 22 and time.

  Thereafter, the ECU 14 determines whether or not the stored amount of the battery 17 detected by the stored amount detection unit 24 is larger than a lower limit value required for driving the engine 1 in step S3, and proceeds to step S4 if Yes. When it is No, it progresses to step S5 and cancels | stops an electric power generation. This limits excessive discharge. The ECU 14 that has proceeded to step S4 determines whether or not the PM accumulation amount of the DPF 11 has exceeded a set value. This set value is set to a value that requires forced regeneration of the DPF 11. The ECU 14 continues the power generation stop when the answer is No in Step S4, and proceeds to Step S5 to release the power generation stop when the answer is Yes.

  When the power generation stop is canceled in step S5, normal power generation control is executed. In normal power generation control, the power generation adjustment unit 21 is required to generate power according to the amount of power stored in the battery 17. At this time, since the amount of power stored in the battery 17 is smaller than normal, the amount of power required for the power generation adjusting unit 21 is larger than normal, and regenerative power generation is started. In regenerative power generation, the power generation voltage is 14.8V, for example. Thereby, the engine load by the alternator 16 becomes larger than that before executing the power generation stop in step S2, and the exhaust gas temperature rises. The power generation amount at this time is determined by the magnitude of the electrical load by the electrical component 22 and the battery charge amount (the power generation amount increases as the charge amount decreases).

  After canceling the power generation stop in step S5, the ECU 14 proceeds to step S6. The ECU 14 determines whether or not the power generation amount of the alternator 16 has decreased in step S6, and proceeds to step S7 if No, and ends the DPF regeneration process using the load of the alternator 16 if Yes. This is because when the amount of power stored in the battery 17 is equal to or greater than the upper limit (No in step S6), the power generation of the alternator 16 is suppressed by normal power generation control, and the exhaust gas temperature cannot be increased. Thereafter, since a considerable amount of PM is accumulated in the DPF 11, normal DPF regeneration control is started. The normal DPF regeneration control is performed, for example, by raising the DOC inlet temperature to the catalyst activation temperature by post injection, supplying HC to the DOC 10 to oxidize, and raising the DPF 11 to the PM combustion temperature by the oxidation heat. The HC supply to the DOC 10 may be performed by exhaust pipe injection (fuel injection into the exhaust pipe). Although the exhaust gas temperature does not reach the catalyst activation temperature, it is higher than usual, so that normal DPF regeneration control can be performed efficiently.

  In step S7, the ECU 14 estimates the DOC inlet temperature from the detected value of the temperature sensor 5a, and determines whether or not the DOC inlet temperature is equal to or higher than the catalyst activation temperature. The ECU 14 returns to step S6 when No in step S7 and continues normal power generation control, and proceeds to step S8 when Yes.

  In step S8, the ECU 14 performs PM combustion control to burn and remove PM in the DPF 11. In PM combustion control, HC is supplied to the DOC 10 by performing post injection or exhaust pipe injection, and PM is burned by the oxidation heat.

  Thus, the alternator 16, the battery 17, the power generation stop unit 18 that stops the power generation of the alternator 16 when the PM accumulation amount of the DPF 11 reaches the set amount before reaching the set amount, and the PM accumulation amount is the set amount. Since the exhaust gas temperature increase assisting unit 19 that releases the power generation stop of the alternator 16 and increases the engine load when it reaches the value, the battery charge amount can be quickly reduced, and the battery charge amount is small for a long time. Can be prevented.

  A DOC 10 connected to the exhaust system 5 upstream of the DPF 11 and a PM combustion unit 27 for supplying HC to the DOC 10 and burning PM in the DPF 11 when the inlet temperature of the DOC 10 reaches the catalyst activation temperature of the DOC 10. Since it was provided, PM deposited on the DPF 11 can be efficiently burned and removed.

  When the power generation amount of the alternator 16 decreases after the exhaust gas temperature increase auxiliary unit 19 cancels the power generation stop of the alternator 16 and before the inlet temperature of the DOC 10 reaches the catalyst activation temperature of the DOC 10, the exhaust gas generated by the exhaust gas temperature increase auxiliary unit 19 Since the midway termination unit 26 for terminating the temperature rise is provided, the normal DPF regeneration control can be performed while the exhaust gas temperature is high, and the PM deposited on the DPF 11 can be efficiently burned and removed.

  Since power generation is stopped by the power generation stop unit 18 and the discharge limit unit 25 is released to release the power generation stop by the power generation stop unit 18 when the amount of power stored in the battery 17 is lowered to the lower limit value necessary for driving the engine 1. In addition, it is possible to prevent the amount of power stored in the battery 17 from being reduced excessively and to prevent the battery 17 from being overloaded.

1 Engine 5 Exhaust system 10 DOC (oxidation catalyst)
11 DPF (diesel particulate filter)
15 DPF regeneration device (diesel particulate filter regeneration device)
16 Alternator 17 Battery 18 Power generation stop section (Power generation stop means)
19 Exhaust gas temperature rising auxiliary part (exhaust gas temperature rising auxiliary means)
24 charged amount detection unit (charged amount detection means)
25 Discharge limiting part (discharge limiting means)
26 Midway termination section (midway termination means)
27 PM combustion section (PM combustion means)

Claims (4)

A diesel particulate filter that collects particulate matter in the exhaust gas is connected to the exhaust system of the engine, and when the particulate matter accumulates on the diesel particulate filter over a set amount, the exhaust gas temperature is raised and the diesel particulate filter In a diesel particulate filter regeneration device that burns and removes particulate matter of
An alternator driven by an engine to generate power, a battery charged by the alternator, and a power generation stop that stops power generation of the alternator when the amount of accumulated particulate matter reaches an intermediate set amount before reaching the set amount. And a diesel particulate filter regeneration comprising: an exhaust gas temperature raising assisting means for releasing the power generation stop of the alternator and increasing the engine load when the amount of particulate matter accumulated reaches the set amount apparatus.   An oxidation catalyst connected to an exhaust system upstream of the diesel particulate filter, and a diesel particulate filter by supplying HC to the oxidation catalyst when an inlet temperature of the oxidation catalyst reaches a catalyst activation temperature of the oxidation catalyst The diesel particulate filter regeneration device according to claim 1, further comprising particulate matter burning means for burning particulate matter in the inside.   When the power generation amount of the alternator decreases after the exhaust gas temperature increase auxiliary means cancels the power generation stop of the alternator and before the inlet temperature of the oxidation catalyst reaches the catalyst activation temperature of the oxidation catalyst, the exhaust gas temperature increase The diesel particulate filter regeneration device according to claim 2, further comprising a midway termination means for terminating the temperature rise of the exhaust gas by the auxiliary means.   When the power generation is stopped by the power storage stop means for detecting the power storage amount of the battery and when the power storage amount of the battery is reduced to a lower limit required for driving the engine, the power generation by the power generation stop means The diesel particulate filter regeneration device according to any one of claims 1 to 3, further comprising discharge limiting means for releasing the stop.

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