JP5760311B2 - DPF regeneration timing determination method and DPF regeneration timing determination device - Google Patents

Description

The present invention relates to a DPF regeneration timing determination method and a DPF regeneration timing determination apparatus that can accurately determine a regeneration timing based on the amount of accumulated PM.

  In a vehicle equipped with an internal combustion engine such as a diesel engine, a diesel particulate filter (hereinafter referred to as DPF) is inserted in the middle of the exhaust pipe from the internal combustion engine to the atmosphere, and SOF, SOOT, etc. contained in the exhaust Particulate matter (hereinafter referred to as PM) is collected. The DPF is a member that temporarily collects PM in a filter having a honeycomb pore shape (which may be a square pore) mainly made of ceramic.

  When a large amount of PM collected in the DPF accumulates, the exhaust gas hardly flows, the exhaust pressure of the internal combustion engine rises, and the characteristics of the internal combustion engine deteriorate. Therefore, it is necessary to remove PM deposited on the DPF by combustion. This operation is called DPF regeneration. During DPF regeneration, the exhaust temperature is raised by fuel injection for raising the exhaust temperature, and the DPF is combusted by raising the temperature of the DPF.

  At this time, if PM accumulates too much in the DPF, the DPF will be damaged by the heat during DPF regeneration. Therefore, it is necessary to regenerate the DPF before PM accumulates too much in the DPF. However, in the past, since the amount of accumulated PM (PM load; indicating the degree of filter clogging) cannot be measured accurately, a large safety factor (margin) is taken, and when the amount of accumulated PM is less than the allowable amount, DPF Is playing. Further, DPF regeneration is performed every time the travel distance of the vehicle reaches a predetermined value regardless of the amount of accumulated PM. For this reason, the time interval for executing the DPF regeneration becomes shorter than the actually required time.

  However, if the DPF regeneration is executed at an interval shorter than necessary, extra fuel will be consumed, and the fuel efficiency will deteriorate. Therefore, it is desirable to accurately detect the PM deposition amount of the DPF and to perform the DPF regeneration at the most appropriate time when the PM deposition amount has approached an actually allowable amount.

JP 2008-180189 A Japanese Patent Laying-Open No. 2005-214084

  Conventionally, the PM accumulation amount of the DPF is detected from the differential pressure between the upstream and downstream of the DPF as in Patent Documents 1 and 2. However, the flow rate and temperature of the exhaust gas that cause the differential pressure are constantly changing as the state of the internal combustion engine changes. For example, the flow rate of exhaust gas from an internal combustion engine is pulsating. For this reason, the differential pressure between the upstream and downstream of the DPF cannot be accurately detected. In addition, when the internal combustion engine has a low load, the flow rate of the exhaust gas is small for accurately detecting the differential pressure, so that the differential pressure cannot be detected accurately. The fact that the volume of the exhaust gas varies depending on the temperature also reduces the accuracy of differential pressure detection. As described above, the conventional DPF differential pressure sensor cannot accurately determine the regeneration time based on the PM accumulation amount because the detected differential pressure is not accurate.

Accordingly, an object of the present invention is to provide a DPF regeneration timing determination method and a DPF regeneration timing determination device capable of solving the above-described problems and accurately determining a regeneration timing based on the amount of accumulated PM.

In order to achieve the above object, the DPF regeneration timing determination method of the present invention is a method for determining the timing of DPF regeneration by detecting the differential pressure of the DPF inserted into the exhaust pipe of the vehicle, wherein the vehicle operates the exhaust brake. During this, air is supplied from the positive pressure pump to the exhaust pipe upstream of the DPF, and the differential pressure of the DPF is detected, and whether or not DPF regeneration is necessary based on the detected differential pressure of the DPF is determined. When it is determined that DPF regeneration is necessary, the determination is stored. During exhaust brake operation, DPF regeneration based on the stored determination is suspended, and the exhaust brake is in operation. While not necessary, air is allowed to flow from the positive pressure pump into the exhaust pipe .

The DPF regeneration timing determination device of the present invention includes a DPF inserted into an exhaust pipe of a vehicle, an air pipe guided from a positive pressure pump and joined to the exhaust pipe upstream of the DPF, and the air pipe An air intake valve that shuts off / opens the air pipe at the junction, a differential pressure sensor that detects a differential pressure between upstream and downstream of the DPF, and the positive pressure applied to the DPF while the vehicle is operating an exhaust brake The air intake valve is controlled so that air flows from the pump. At this time, the differential pressure detected by the differential pressure sensor is read, and it is determined whether or not DPF regeneration is necessary based on the detected differential pressure of the DPF. , storing the determination when it is determined that it is necessary to DPF regeneration, during operation of the exhaust brake to hold the DPF regeneration based on the determination that stores, when it is judged not to be required DPF regeneration the said DPF And a control unit which holds a state of controlling the air intake valve so that the pressure pump air flows, are those having a.

  The present invention exhibits the following excellent effects.

  (1) It is possible to accurately determine the regeneration time based on the PM accumulation amount.

It is a block diagram of the DPF regeneration time determination apparatus which shows one Embodiment of this invention. Is a flowchart controller showing an algorithm for determining DPF regeneration timing to perform the DPF regeneration timing determining device of the present invention. It is a diagram illustrating a state in which not performed determination DPF regeneration timing in DPF regeneration timing determination device of FIG. It is a figure which shows a state when performing DPF regeneration time determination in the DPF regeneration time determination apparatus of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a DPF regeneration timing determination device 1 according to the present invention is joined to a DPF 3 inserted into an exhaust pipe 2 of a vehicle and an exhaust pipe 2 guided by a positive pressure pump 4 and upstream of the DPF 3. The air pipe 5, the air intake valve 6 that shuts off / opens the air pipe 5 at the confluence of the air pipe 5, the differential pressure sensor 7 that detects the differential pressure between the upstream and downstream of the DPF 3, and the vehicle performs the exhaust brake. The air intake valve 6 is controlled so that air flows from the positive pressure pump 4 to the DPF 3 during operation, and a control unit 8 that reads the differential pressure detected by the differential pressure sensor 7 is provided.

  The exhaust pipe 2 and the DPF 3 are conventionally known and will not be described.

  The positive pressure pump 4 is conventionally provided for brakes, and is particularly used for large vehicles. The positive pressure pump 4 can temporarily store air at a desired pressure higher than atmospheric pressure.

  The air pipe 5 connects the outlet of the positive pressure pump 4 to the exhaust pipe 2 upstream of the DPF 3.

  The air intake valve 6 is a valve that can selectively control a state where the air pipe 5 is shut off and a state where the air pipe 5 is opened, and is controlled by the control unit 8.

  The differential pressure sensor 7 is a conventionally known one and will not be described.

  The exhaust brake is a conventionally known one, and is used particularly in a large vehicle. An exhaust brake valve 10 is attached to the outlet of the exhaust manifold of the internal combustion engine 9. While the exhaust brake is not in operation, the exhaust brake valve 10 is opened and exhaust flows from the outlet of the exhaust manifold to the exhaust pipe 2. However, during operation of the exhaust brake, the exhaust brake valve 10 is shut off and the exhaust manifold Exhaust gas does not flow from the outlet to the exhaust pipe 2, and the vehicle is braked by the pumping loss of the internal combustion engine 9.

  The control unit 8 is a programmed digital arithmetic circuit realized by, for example, an ECU (Engine Control Unit).

  The control unit 8 has a function of controlling the air intake valve 6. Specifically, by controlling the air intake valve 6 so that the air pipe 5 is opened, air can flow from the positive pressure pump 4 to the DPF 3. On the other hand, by controlling the air intake valve 6 so that the air pipe 5 is blocked, it is possible to prevent air from flowing from the positive pressure pump 4 to the DPF 3.

  The control unit 8 has a function of reading the differential pressure between the upstream and downstream of the DPF 3 detected by the differential pressure sensor 7. Further, the control unit 8 detects the PM deposition amount of the DPF 3 from the relationship between the known differential pressure and the PM deposition amount based on the differential pressure, and when the PM deposition amount of the DPF 3 reaches the threshold value. Has a function of determining that it is the DPF regeneration time. Alternatively, it may be determined that it is the regeneration time when the differential pressure reaches a threshold value.

Hereinafter, the operation of the DPF regeneration time determination device 1 according to the present invention will be described.

  In the present invention, the differential pressure sensor 7 detects the differential pressure between the upstream and downstream of the DPF 3. At this time, in the past, an accurate differential pressure (or PM deposition amount) could not be detected due to the influence of the magnitude of the flow rate, the difference in temperature, and the pulsation of the flow rate. However, in the present invention, during operation of the exhaust brake in which the exhaust from the internal combustion engine 9 does not flow into the DPF 3, air from the positive pressure pump 4 is flowed into the DPF 3 to detect the differential pressure. The air flowing from the positive pressure pump 4 is stable regardless of the flow rate or temperature of the internal combustion engine 9 and has no pulsation. Therefore, the differential pressure sensor 7 accurately detects the differential pressure having a correlation with the PM accumulation amount of the DPF 3.

  Thus, it is necessary to regenerate the DPF at a time when the PM deposition amount is smaller than the actually allowable amount by taking a large safety factor as in the prior art by being able to accurately detect the differential pressure correlated with the PM deposition amount. As a result, fuel consumption for DPF regeneration is reduced and fuel efficiency is improved.

  Further, since the positive pressure pump 4 and the exhaust brake valve 10 are members that are conventionally provided in a vehicle, it is not necessary to newly provide them, and an increase in cost for carrying out the present invention can be suppressed.

Hereinafter, the flow of control for determining the DPF regeneration time will be described.

As shown in FIG. 2, in step S1, the control unit 8 determines whether the exhaust brake is operating. If No, the DPF regeneration time determination is not performed, and the process proceeds to step S2.

  In step S2, the control unit 8 controls the air intake valve 6 so that the air pipe 5 is blocked as shown in FIG. Thereby, the exhaust from the internal combustion engine 9 becomes a normal exhaust flow passing through the DPF 3.

If the determination in step S1 is Yes, the DPF regeneration timing determination is performed, and the process proceeds to step S3. In step S3, the control unit 8 controls the air intake valve 6 so that the air pipe 5 is opened as shown in FIG. Since the exhaust brake is operating, the exhaust brake valve 10 is shut off. As a result, only the air from the positive pressure pump 4 flows through the DPF 3. When the pressure of the positive pressure pump 4 and V _0, the pressure upstream of the DPF 3 (inlet pressure) is V _0, the difference between the inlet pressure V ₀ and DPF 3 downstream pressure of (outlet pressure) V ₁ It is detected by the differential pressure sensor 7.

  In step S4, the control unit 8 reads the differential pressure between the upstream and downstream sides of the DPF 3 detected by the differential pressure sensor 7. As described above, this differential pressure is different from the exhaust from the internal combustion engine 9 and is an accurate differential pressure detected using air from the positive pressure pump 4 having no flow rate, temperature difference, and flow rate pulsation. It has become.

  In step S5, the control unit 8 determines whether or not the differential pressure exceeds a threshold value. If No, it is not the time for DPF regeneration and the process ends. If Yes, the process proceeds to step S6.

  In step S <b> 6, the control unit 8 returns the air intake valve 6 to a state when the DPF differential pressure detection is not performed. Subsequently, in step S7, the control unit 8 stores a determination that it is time for DPF regeneration. Based on this determination, DPF regeneration is executed after the operation of the exhaust brake is completed.

1 DPF regeneration timing determination device 2 Exhaust pipe 3 DPF
DESCRIPTION OF SYMBOLS 4 Positive pressure pump 5 Air pipe 6 Air intake valve 7 Differential pressure sensor 8 Control part 9 Internal combustion engine 10 Exhaust brake valve

Claims (2)

In a method for determining a DPF regeneration timing by detecting a differential pressure of a DPF inserted in an exhaust pipe of a vehicle,
While the vehicle is operating an exhaust brake, air is supplied from a positive pressure pump to the exhaust pipe upstream of the DPF, and a differential pressure of the DPF is detected.
Determining whether DPF regeneration is necessary based on the detected differential pressure of the DPF;
When it is determined that DPF regeneration is necessary, the determination is stored,
During the operation of the exhaust brake, the DPF regeneration based on the stored judgment is suspended ,
A DPF regeneration timing determination method , wherein the exhaust pipe is kept in a state where air is supplied from the positive pressure pump while the exhaust brake is in operation and DPF regeneration is not necessary . A DPF inserted in the exhaust pipe of the vehicle;
An air pipe led from a positive pressure pump and joined to the exhaust pipe upstream from the DPF;
An air intake valve that shuts off / opens the air pipe at the confluence of the air pipe;
A differential pressure sensor for detecting a differential pressure between upstream and downstream of the DPF;
While the vehicle is operating an exhaust brake, the air intake valve is controlled so that air flows from the positive pressure pump to the DPF. At this time, the differential pressure detected by the differential pressure sensor is read, and the detected difference in the DPF is detected. It is determined whether or not DPF regeneration is necessary based on the pressure, and the determination is stored when it is determined that DPF regeneration is necessary. During operation of the exhaust brake, DPF regeneration based on the stored determination is suspended. And a control unit that maintains a state in which the air intake valve is controlled so that air flows from the positive pressure pump to the DPF when it is determined that DPF regeneration is not necessary ,
A DPF regeneration time determination device comprising:

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