vehicle

Abstract

To prevent intrusion of foreign matter into an EGR passage.SOLUTION: A vehicle includes an engine, an exhaust manifold which branches exhaust gas discharged from a cylinder of the engine into an exhaust passage and an EGR passage and discharges the exhaust gas, an exhaust gas treatment device which is provided in the exhaust passage and has a filter for collecting particulates in the exhaust gas, and a regeneration control device which performs regeneration of the filter by performing post injection. During the post injection, the regeneration control device stops the post injection of an injector of the cylinder in which a branch portion to the EGR passage exists on the way from an exhaust port to the exhaust passage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a technique for preventing foreign matter, such as soot and hydrocarbon particles, from entering an EGR path. [Background technology]

[0002] After fuel is burned in each cylinder of the engine, the exhaust gas is collected in the exhaust manifold and discharged outside the vehicle via the exhaust pipe. An exhaust gas treatment device is installed in the exhaust pipe to break down and remove particulate matter (PM) and nitrogen oxides (NOx) in the exhaust gas.

[0003] Known exhaust gas treatment devices include a DPD (Diesel Particulate Defuser) with a diesel oxidation catalyst (DOC) and a catalyzed soot filter (CSF), and a SCR (Selective Catalytic Reduction) with a nitrogen oxide reduction catalyst and an ammonia oxidation catalyst. Particulate matter in the exhaust gas is trapped by the soot filter, and nitrogen oxides are reduced and decomposed by the SCR.

[0004] In addition, an exhaust gas recirculation (EGR) device is connected to the exhaust manifold, and part of the exhaust gas is sent to the intake manifold via the EGR device and mixed with the intake air from outside the vehicle. This reduces the oxygen concentration in the intake air, lowers the combustion temperature in the cylinder, and reduces the amount of nitrogen oxides in the exhaust gas.

[0005] As the amount of soot trapped in the soot collection filter increases, it becomes clogged, so a regeneration process is carried out before this occurs. In the regeneration process, unburned fuel is mixed into the exhaust gas by post injection and sent to the DPD, where the unburned fuel is burned in the diesel oxidation catalyst, raising the exhaust gas temperature, and the soot in the soot collection filter is burned by the high-temperature exhaust gas, thereby regenerating the soot collection filter (Patent Document 1, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-282479 A [Patent Document 2] JP 2011-247143 A Summary of the Invention [Problem to be solved by the invention]

[0007] The inventors of the present application have found that repeated regeneration of the soot collection filter may cause soot-containing particles to accumulate in the EGR path. These deposits consist of mixed particles of soot in the exhaust gas and hydrocarbons derived from unburned fuel. The particles that enter the EGR path are cooled, and the hydrocarbons turn into resins and accumulate in the EGR path. If the accumulation of these particles progresses, the flow of the EGR path may be obstructed.

[0008] The present disclosure aims to prevent foreign matter from entering the EGR path. [Means for solving the problem]

[0009] The vehicle disclosed herein comprises an engine, an exhaust manifold that branches exhaust gas discharged from cylinders of the engine into an exhaust path and an EGR path, an exhaust gas treatment device provided in the exhaust path and having a filter that collects particulate matter in the exhaust gas, and a regeneration process control device that performs post-injection to regenerate the filter, and when performing the post-injection, the regeneration process control device stops post-injection of the injector of the cylinder where there is a branch to the EGR path on the way from the exhaust port to the exhaust path. Effect of the Invention

[0010] According to the present disclosure, since unburned fuel is not contained in the flow from the exhaust port of the cylinder toward the EGR path, particles (foreign matter) containing soot and hydrocarbons can be prevented from entering the EGR device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an overall configuration. [Diagram 2] FIG. 2 is a diagram showing the flow of exhaust gas. [Diagram 3] FIG. 2 is a diagram showing the flow of exhaust gas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the embodiments described below are all examples of the present disclosure. Therefore, the components, the arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Also, each figure is a schematic diagram and is not necessarily a precise illustration. Note that in each figure, the same reference numerals are used for substantially the same configurations, and duplicated explanations may be omitted or simplified.

[0013] 1 shows the structure of the engine and its surroundings, including the intake system and exhaust system. A plurality of cylinders 1 (four in the illustrated example) (sometimes referred to as cylinders 1-1 to 1-4 when referring to individual cylinders) are formed in an engine body 100. Each cylinder 1 is provided with an injector 2 (sometimes referred to as injectors 2-1 to 2-4 when referring to individual injectors) that inject fuel, and is configured to be able to inject fuel into the cylinder 1.

[0014] Air taken in from outside the vehicle has foreign matter removed by an air cleaner 21, is pressurized by a compressor 42 of a turbocharger 40, passes through an intake pipe 22, is cooled by an intercooler 23, and is sent to the intake manifold 20 via an intake pipe 24. An intake throttle 25 that adjusts the flow rate of air supplied to the intake manifold 20 is provided in the intake pipe 24. The air sent to the intake manifold 20 is distributed to each cylinder 1.

[0015] Meanwhile, exhaust gas generated by burning fuel in the cylinder 1 is collected in the exhaust manifold 10 and discharged from the exhaust pipe branching portion 15 through an exhaust pipe 45 to the outside of the vehicle. A turbine 41 of a turbocharger 40 is provided in the exhaust pipe 45 and rotated by the pressure of the exhaust gas, and this rotational force rotates the compressor 42. The exhaust pipe 45 is also provided with an exhaust valve 43 that adjusts the flow rate of the exhaust gas. Furthermore, the exhaust pipe 45 is provided with an exhaust gas treatment device 50 for removing soot (particulate matter, PM) and nitrogen oxides (NOx) from the exhaust gas.

[0016] The exhaust valve 43 is configured so that throttling it increases the internal exhaust pressure and increases the exhaust resistance from the cylinder 1. This increases the rotational resistance of the engine, making it possible to strengthen the engine braking effect.

[0017] The exhaust gas treatment device 50 has a DPD 51 that collects and burns off soot in the exhaust gas, and an SCR 60 that decomposes nitrogen oxides in the exhaust gas. The DPD 51 has a diesel oxidation catalyst 52, a soot collection filter 53, a temperature sensor 54, and a collection filter differential pressure sensor 55, and soot in the exhaust gas is collected by the soot collection filter 53. The DPD 51 may be provided in the engine room to improve mounting ease, etc.

[0018] As the vehicle continues to travel, the soot trapping filter 53 becomes clogged with trapped soot. This clogging is detected by measuring the pressure difference between the upstream and downstream sides of the soot trapping filter 53 with the differential pressure sensor 55.

[0019] The SCR 60 has a nitrogen oxide reduction catalyst 61, an ammonia oxidation catalyst 62, and a urea injector 63. When urea water is supplied from the urea injector 63 into the exhaust gas, the urea water is hydrolyzed to produce ammonia. When this ammonia and the nitrogen oxides in the exhaust gas are sent to the nitrogen oxide reduction catalyst 61, the nitrogen oxides are reduced to produce nitrogen and water. The remaining ammonia is oxidized by the ammonia oxidation catalyst 62 provided downstream to produce nitrogen and water.

[0020] In addition, EGR devices 30, 70 are provided for the purpose of improving the fuel efficiency of the engine and reducing nitrogen oxides in the exhaust gas. It is known that nitrogen oxides are generated when nitrogen and oxygen in the air react at high temperatures. The EGR devices 30, 70 mix the exhaust gas with the engine intake air to lower the oxygen concentration in the cylinder 1, thereby lowering the combustion temperature and reducing the amount of nitrogen oxides generated.

[0021] The EGR devices 30, 70 include a high-pressure EGR device 30 and a low-pressure EGR device 70. In the high-pressure EGR device 30, a high-pressure EGR pipe 31 (upstream pipe) branches off from the exhaust manifold 10, and sends exhaust gas to the intake manifold 20 via a high-pressure EGR cooler 33, a high-pressure EGR pipe 35 (downstream pipe), and a high-pressure EGR valve 37. On the other hand, in the low-pressure EGR device 70, a low-pressure EGR pipe 71 branches off from the exhaust gas processing device 50, and sends exhaust gas to the intake pipe 22 via a low-pressure EGR cooler 73, a low-pressure EGR pipe 75, and a low-pressure EGR valve 77.

[0022] When the soot trapping filter 53 becomes clogged and the pressure difference detected by the differential pressure sensor 55 exceeds a predetermined value, a regeneration process is performed for the soot trapping filter 53. There are two types of regeneration process: automatic regeneration performed while the vehicle is running, and manual regeneration performed by the driver while the vehicle is stopped. In the regeneration process, unburned fuel from post injection is sent to the DPD 51 together with the exhaust gas, and the unburned fuel is burned by the diesel oxidation catalyst 52 to heat the exhaust gas, and the soot trapped in the soot trapping filter 53 is burned by this heated exhaust gas.

[0023] 2 shows an outline of the intake and exhaust system of the cylinder 1. An intake manifold 20 and an exhaust manifold 10 are connected to the cylinder 1. Air for combustion is introduced from the intake manifold 20, and exhaust gas after combustion is discharged to the exhaust manifold 10 through an exhaust port 3 (which may be expressed as exhaust ports 3-1 to 3-4 when showing individual exhaust ports). An exhaust pipe branching section 15 is formed in the exhaust manifold 10, and an exhaust pipe 45 is connected to the exhaust pipe branching section 15. A turbine 41 and an exhaust valve 43 of a turbocharger 40 are provided in the exhaust pipe 45, and the downstream side of the exhaust pipe 45 is connected to an exhaust gas processing device 50.

[0024] An EGR branch portion 17 is formed in the exhaust manifold 10, and an upstream high-pressure EGR pipe 31 is connected to the EGR branch portion 17. A high-pressure EGR cooler 33 that cools the exhaust gas flowing through the high-pressure EGR pipe 31 is provided in the high-pressure EGR pipe 31, and a downstream high-pressure EGR pipe 35 is connected to the downstream side of the high-pressure EGR cooler 33. A high-pressure EGR valve 37 is provided in the downstream high-pressure EGR pipe 35, making it possible to control the flow rate of exhaust gas passing through the high-pressure EGR device 30. The high-pressure EGR pipe 35 is connected to the intake manifold 20.

[0025] 3 shows the flow of exhaust gas discharged from cylinder 1. The exhaust gas discharged from exhaust ports 3-1 to 3-4 of each of cylinders 1-1 to 1-4 is collected in exhaust manifold 10 and separated into a flow discharged from exhaust pipe branching portion 15 to exhaust pipe 45 and a flow sent from EGR branching portion 17 to high-pressure EGR device 30 (see the arrows in the figure).

[0026] Although it depends on the opening degree of the high-pressure EGR valve 37, mainly exhaust gas discharged from the exhaust port 3-4 of the rightmost cylinder 1-4 in Fig. 3 flows into the high-pressure EGR device 30. On the other hand, exhaust gas discharged from each of the exhaust ports 3-1 to 3-3 of the three left-hand cylinders 1-1 to 1-3 in Fig. 3 is discharged from the exhaust pipe branching portion 15 to the exhaust pipe 45.

[0027] Next, an operation when performing regeneration processing of the soot trapping filter 53 will be described. When clogging of the soot trapping filter 53 progresses, a running regeneration processing at low speed and low load or a manual regeneration processing when the vehicle is stopped is performed. During the regeneration processing, the high pressure EGR valve 37 is closed and the exhaust valve 43 is throttled. In this state, the engine is operated at low speed or idling. Then, the injectors 2-1 to 2-3 of the cylinders 1-1 to 1-3 perform post-injection after combustion, and the injected fuel is sent to the DPD 51 in an unburned state. At this time, the injector 2-4 of the cylinder 1-4, in which the EGR branch portion 17 exists between the exhaust port 3-4 and the exhaust pipe branch portion 15, stops post-injection.

[0028] In this way, by stopping the post-injection of the injector 2-4 of the cylinder 1-4 in which the EGR branch section 17 is located between the exhaust port 3-4 and the exhaust pipe branch section 15 during the regeneration process, unburned fuel is prevented from flowing into the high-pressure EGR pipe 31, and the accumulation of soot and hydrocarbon particles in the high-pressure EGR device 30 can be prevented.

[0029] Although the engine in the above embodiment has been described as having four cylinders, the number of cylinders may be any number. The number of cylinders for which the injector is stopped during post injection is determined by the arrangement of the exhaust port, exhaust pipe branching portion, and EGR branching portion of each cylinder. In short, if an EGR branching portion is present between the exhaust port and exhaust pipe branching portion of a cylinder, the post injection of the injector of that cylinder can be stopped to achieve the desired effect of preventing foreign matter from entering the EGR path.

[0030] Foreign matter tends to get into the EGR path more often during manual regeneration processing than during automatic regeneration processing, and the regeneration processing according to the present disclosure is more effective in the case of manual regeneration processing. [Industrial Applicability]

[0031] This can effectively prevent foreign matter from entering the EGR. [Explanation of symbols]

[0032] 1 cylinder 2 Injectors 3. Exhaust port 10 Exhaust manifold 15 Exhaust pipe branch 17 EGR branch section 20 Intake manifold 30 High pressure EGR device 31 High pressure EGR piping (upstream side) 33 High pressure EGR cooler 35 High pressure EGR piping (downstream side) 37 High pressure EGR valve 40 Turbocharger 41 Turbine 42 Compressor 43 Exhaust valve 45 Exhaust pipe 50 Exhaust gas treatment device 51 DPD 52 Diesel Oxidation Catalyst 53 Soot collection filter 60 SCR 61 Nitrogen oxide reduction catalyst 62 Ammonia oxidation catalyst 63 Urea Injector

Claims

1. The engine, an exhaust manifold that branches exhaust gas discharged from a cylinder of the engine into an exhaust path and an EGR path; an exhaust gas treatment device provided in the exhaust path and having a filter that collects particulates in the exhaust gas; a regeneration process control device that performs a post-injection to perform a regeneration process of the filter; Equipped with The regeneration processing control device includes: When performing the post injection, the post injection of the injector of the cylinder where a branch portion to the EGR path exists on the way from the exhaust port to the exhaust path is stopped. vehicle.

2. The regeneration process is a manual regeneration process performed with the engine idling while the vehicle is stopped.

2. The vehicle of claim 1.

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