EGR-equipped engine

Abstract

The present invention aims to eliminate malfunctions that occur immediately after startup in engines equipped with an EGR circuit. [Solution] An EGR-equipped engine is characterized in that an EGR circuit 44 is provided in the EGR circuit 44, and a condensation reservoir 51 is provided in the EGR circuit 44 to condense and store water vapor in the exhaust gas.

Description

Technical Field

[0001] The present invention relates to an engine equipped with an EGR (Exhaust Gas Recirculation) device that recirculates and burns a part of the exhaust gas into the combustion chamber of the engine.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2023-96961 describes an engine equipped with an EGR circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the engine equipped with the above EGR circuit, a part of the exhaust gas is sent to the cylinder together with the fresh intake air through the EGR cooler provided in the exhaust gas recirculation circuit and burned. However, immediately after the engine is started, the EGR circuit is cooled, so water vapor condenses in the circuit and the condensed water flows to the EGR valve, which may cause malfunction.

[0005] An object of the present invention is to eliminate the malfunction immediately after startup in an engine equipped with an EGR circuit.

Means for Solving the Problems

[0006] The above problems of the present invention are solved by the following technical means.

[0007] The invention according to claim 1 is an EGR-equipped engine, characterized in that in an engine equipped with an EGR circuit 44, a dew condensation reservoir 51 for condensing and storing water vapor in the exhaust gas is provided in the EGR circuit 44.

[0008] The invention of claim 2 is an EGR-equipped engine according to claim 1, wherein the condensation reservoir 51 is a stepped portion 52 that changes the inner diameter of the exhaust gas pipeline to accumulate condensation.

[0009] The invention of claim 3 is an EGR-equipped engine according to claim 1, characterized in that a connecting pipe 70 having a condensation reservoir 51 consisting of a recessed portion 53 is connected to the exhaust gas pipeline of the EGR circuit 44.

[0010] The invention of claim 4 is an EGR-equipped engine characterized in that an induction port 68 is formed in the gasket 72 of the flange joint connecting the EGR cooler 57 and the EGR valve 43, which guides the exhaust gas to the inner peripheral edge of the EGR cooler 57.

[0011] The invention of claim 5 is an EGR-equipped engine characterized in that a soot collection section 59 for collecting non-combustible materials in exhaust gas is provided in a gasket 72 that joins the components constituting the EGR circuit 44.

[0012] The invention of claim 6 is an EGR-equipped engine according to claim 5, wherein a barrier 60 that rises up into the gas passage is formed in the gasket 72 to form a soot collection section 59.

[0013] The invention of claim 7 is an EGR-equipped engine according to claim 5, in which a small-diameter small gasket 72a and a large-diameter large gasket 72b are stacked, and the inner peripheral edge 61 of the large gasket 72b that does not overlap with the small gasket 72a is used as a soot collection section 59. [Effects of the Invention]

[0014] In the invention of claim 1, water vapor contained in the exhaust gas passing through the EGR circuit 44 condenses into water in the condensation reservoir 51 and remains there, preventing water from entering the EGR valve 43, thus preventing water from causing malfunctions immediately after startup.

[0015] In the invention of claim 2, a simple configuration of a stepped portion 52 provided in the exhaust gas pipeline of the EGR circuit 44 condenses and stores water vapor as a condensation reservoir 51, preventing water from entering the EGR valve 43.

[0016] In the invention of claim 3, by interposing the connecting pipe 70 provided with the recessed portion 53 in the EGR circuit 44, the recessed portion 53 serves as the condensate reservoir 51, and moisture in the exhaust gas can be retained.

[0017] In the invention of claim 4, when the EGR cooler 57 and the EGR valve 43 are connected by the gasket 72, the exhaust gas is guided to the inner periphery side inside the EGR cooler 57 through the induction port 68 of the gasket 72, and the exhaust gas is effectively cooled.

[0018] In the invention of claim 5, dust such as soot in the exhaust gas flowing through the EGR circuit 44 is collected by the soot collection portion 59 of the gasket 72 and does not enter the EGR valve 43.

[0019] In the invention of claim 6, the soot collection portion 59 is formed by the barrier 60 standing up to the passage provided in the gasket 72 to prevent dust such as soot from flowing.

[0020] In the invention of claim 7, by overlapping two sheets of the small gasket 72a and the large gasket 72b, the soot collection portion 59 is formed by the inner peripheral edge 61 of the large gasket 72b that does not overlap with the small gasket 72a, and the flow of dust such as soot can be reduced.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic diagram of the intake and exhaust mechanism of an engine according to an embodiment of the present invention. [Figure 2] It is a plan view of an exhaust manifold. [Figure 3] It is a front sectional view of an exhaust manifold. [Figure 4] It is a partially enlarged side view of an EGR circuit, (A) is an enlarged perspective view of a connecting pipe. [Figure 5] It is a perspective view of a connecting pipe of another embodiment. [Figure 6] It is a perspective view of a gasket provided at a flange joint portion. [Figure 7] It is a perspective view of a gasket of another embodiment. [Figure 8]Furthermore, this is a perspective view of a gasket in another embodiment. [Figure 9] This is a perspective view of the assembly of the small and large gaskets. [Figure 10] This is a perspective view of a small gasket. [Figure 11] This is a perspective view of the gasket. [Figure 12] This is a flowchart of the management system for an unmanned combine harvester. [Figure 13] This is an engine control flowchart. [Figure 14] This is an engine control flowchart. [Figure 15] This is a side view of the connection between the thermostat housing and the outlet pipe. [Figure 16] This is an explanatory diagram of a system to support farmers in harvesting crops. [Figure 17] This is diagram 1 illustrating the mechanism for handling extremely low temperatures in an EGR-equipped engine. [Figure 18] This is diagram 2 illustrating the mechanism for handling extremely low temperatures in an EGR-equipped engine. [Modes for carrying out the invention]

[0022] Hereinafter, embodiments of the present invention will be described with reference to the examples shown in the drawings.

[0023] Figure 1 is a schematic diagram of the intake and exhaust mechanism of a four-stroke diesel engine, which performs intake and exhaust of air into the engine cylinder 5. Air drawn in by the intake turbine 36 of the supercharger TB is sent from the air cleaner 35, through the intake turbine 36 and intercooler 37, to the intake manifold 38 and into the cylinder 5. 39 is an intake valve, and 40 is a piston. 48 is a cam that opens and closes the intake and exhaust valves 39 and 41 via a rocker arm 49.

[0024] The exhaust gas burned in cylinder 5 passes through the exhaust valve 41 and the exhaust manifold 42, and is then discharged by driving the turbocharger TB with the exhaust turbine 45 of the turbocharger TB. The system also has an EGR (exhaust gas recirculation) circuit 44 for mixing a portion of the exhaust gas into the intake side. The EGR circuit 44 connects the exhaust pipe 55 downstream of the aftertreatment device 46 (described later) and the intake pipe 56 upstream of the intake turbine 36 of the turbocharger TB. An EGR cooler 57 is also provided in the middle of the EGR circuit 44. The amount of exhaust gas returned to cylinder 5 changes depending on the opening and closing of the EGR valve 43.

[0025] In this way, by returning a portion of the exhaust gas to the intake side, the combustion temperature is lowered, and the emission of NOx in the exhaust gas is suppressed. Because the exhaust gas contains less oxygen, the amount of fuel injected is reduced accordingly, lowering the combustion temperature in cylinder 5 and reducing the generation of NOx.

[0026] The EGR circuit 44 is configured to reduce the amount of oxygen (O2) by mixing a portion of the exhaust gas into the intake air, thereby reducing the generation of nitrogen oxides (NOx). However, if the EGR (recirculation) rate increases too much, the amount of oxygen in the intake air will decrease, resulting in incomplete combustion. Therefore, it is necessary to adjust the EGR rate depending on the combustion state, and this adjustment is performed by controlling the EGR valve 43 and throttle valve 47 with the ECU 100.

[0027] After passing through the exhaust turbine 45, the exhaust gas passes through the aftertreatment device 46 and is discharged into the atmosphere from the muffler 50. The aftertreatment device 46 consists of an oxidation catalyst (DOC) 46a and a diesel particulate filter (DPF) 46b.

[0028] The oxidation catalyst (DOC) burns the non-combustible material in the chamber, while the diesel particulate filter (DPF) collects particulate matter (PM). The aftertreatment device 46 may consist only of the diesel particulate filter (DPF) 46b. By including the oxidation catalyst (DOC), the non-combustible material is burned, resulting in cleaner exhaust gas.

[0029] Figures 2 and 3 show the exhaust manifold 42, which collects exhaust gas from each cylinder 5 at exhaust ports 6a, 6b, 6c, and 6d, sends it to the aftertreatment device 46 from the main exhaust port 7, and sends some of the exhaust gas to the EGR inlet pipe 8 of the EGR circuit 44. The section connecting the exhaust manifold 42 to the EGR inlet pipe 8 is a stepped section 52 with different inner diameters, where water vapor contained in the exhaust gas condenses and accumulates. Eventually, it evaporates due to overheating of the exhaust manifold 42 and is discharged from the main exhaust port 7.

[0030] Figures 4 and 5 show a connecting pipe 70 that connects the EGR cooler 57 and the EGR inlet pipe 8. The connecting pipe 70 has a recessed section 53 at its inner bottom to collect condensed water. The recessed section 53 in Figure 4 is a groove that slopes toward the EGR cooler 57, while the recessed section 53 in Figure 5 is a rectangular groove in plan view.

[0031] Figure 6 shows a gasket 72 provided at the flange joint connecting the EGR cooler 57 and the EGR circuit 44. An induction port 68, consisting of small holes, is provided along the inner peripheral edge 69 of the flange contact surface, allowing the passing exhaust gas to flow to the inner peripheral edge of the EGR cooler 57 and effectively cool the exhaust gas. The gasket 72 provided in Figure 7 has an L-shaped hole 67 on the inner peripheral edge 69 of the flange contact surface, allowing the passing exhaust gas to flow to the inner peripheral edge of the EGR cooler 57 and effectively cool the exhaust gas.

[0032] The gasket 58 shown in Figure 8 has an upright edge on the inner peripheral edge 69 of the flange contact surface that rises up into the passage, forming a barrier 60 to prevent soot and other dust in the exhaust gas from flowing through.

[0033] Figures 9 and 10 show that a small gasket 73a with a small inner diameter and a large gasket 73b with a large inner diameter are stacked on top of each other, and the inner peripheral edge 69 of the small gasket 73a acts as a barrier 60 to prevent soot and other dust in the exhaust gas from flowing through.

[0034] The gasket 74 in Figure 11 has a bulge 74b in the center and a small-diameter opening 74c on its side.

[0035] Figure 12 shows the management system for an unmanned combine harvester, specifically the control system in case of engine DPF overfilling. In step S1, if overfilling occurs, the combine harvester will exit the field at a low speed. The support center, which received the notification in step S1, will contact the farmer user. In step S3, the user can choose to stop the combine harvester or return to the base. If they choose to return to the base, the combine harvester will automatically return to the base using GPS. Then, in step S4, after returning to the base, the DPF will be replaced and the combine harvester will restart. After restarting, the combine harvester will use GPS to return to its original position to resume work.

[0036] Figure 13 is an engine control flowchart. In an agricultural machine equipped with an aftertreatment device, the engine controls the intake throttle opening to increase the exhaust temperature in the low-load range in order to activate the catalyst of the aftertreatment device, or to increase the amount of EGR. When it is determined that there is a large change in the accelerator opening in the intake throttle limiting region, the intake throttle opening is temporarily opened. Outside the intake throttle limiting region, when it is determined that there is a large change in the accelerator opening, the fuel injection pressure is increased to correct the pressure.

[0037] In engines that use a control system to reduce the intake throttle opening in order to increase exhaust temperature or increase EGR volume, when the accelerator opening changes significantly, such as during acceleration, the engine speed increases and the fuel injection amount increases, leading to a tendency for insufficient air supply. In such cases, soot emissions can be reduced by momentarily opening the intake throttle opening. Similarly, outside the intake throttle restriction region, soot emissions can be reduced by increasing the fuel injection pressure in response to changes in accelerator opening. As a result, the amount of soot accumulating in the DPF can be suppressed, and the regeneration interval can be extended.

[0038] Figure 14 is a flowchart of an engine equipped with an airflow sensor for agricultural machinery that has a post-treatment device. The flowchart constantly monitors the airflow volume, calculates the difference △ between the current airflow volume and the steady-state air volume (target air volume), and corrects the rail pressure by increasing it according to the amount of △.

[0039] During transients, a delay occurs in the intake air volume compared to steady-state conditions, which contributes to increased smoke. By constantly measuring the extent of this delay and correcting the rail pressure accordingly, the amount of smoke generated can be suppressed. As a result, the amount of soot accumulating in the DPF can be reduced, and the regeneration interval can be extended.

[0040] Figure 15 shows the processing of the thermostat housing 91 and outlet pipe 90' ​​to prevent engine coolant leakage. A small annular projection 90a is machined on the mating surface of the outlet pipe 90', and an annular groove 91a is machined on the housing 91 side to match the annular projection 90a. This configuration prevents coolant leakage and makes it easier to position the outlet pipe 90' ​​and housing 91.

[0041] Figure 16 shows the crop harvesting support system for farmers at the support center.

[0042] As harvest time approaches, the system uses a smartphone (93) to photograph rice stalks (90) to identify the variety, measures the moisture content of the rice stalks (90) with a moisture meter (92), and statistically and meteorologically analyzes and calculates the optimal harvesting time for each variety in each region, providing this information to farmers.

[0043] Figure 17 is an explanatory diagram of a mechanism for countermeasures against extremely low temperatures in an EGR-equipped engine, in which the urea water tank 75 is separated from the engine 10, a solenoid valve 76 is installed in the urea water supply path, and the opening and closing of the solenoid valve 76 is controlled by the ECU 100 according to the ambient temperature. At extremely low temperatures, the EGR valve 43 is not driven, so coolant circulation is unnecessary, and coolant is circulated to the urea water tank 75 to promote the dissolution of the urea water.

[0044] Figure 18 shows a measure to counter extremely low temperatures in an EGR-equipped engine. The ECU 100 is equipped with a calendar function, which measures the ambient temperature at regular intervals during periods when low temperatures are expected (December to February). If the ambient temperature is below a threshold (-8 degrees Celsius), the supply module 76 is activated for a certain period of time to circulate urea solution and suppress freezing. [Explanation of symbols]

[0045] 43 EGR valve 44 EGR circuit 51 Condensation buildup 52 Stepped section 53 Recessed area 57 EGR cooler 59. Soot Collection Unit 60 barriers 61 Inner periphery 68 Exit 72 Gasket 72a Small gasket 72b Large Gasket

Claims

1. An EGR-equipped engine characterized in that an EGR circuit (44) is provided in the EGR circuit (44) for condensing and accumulating water vapor in the exhaust gas, and is further characterized in that an EGR-equipped engine is provided in the EGR circuit (44).

2. The EGR-equipped engine according to claim 1, wherein the condensation reservoir (51) is a stepped portion (52) that changes the inner diameter of the exhaust gas pipeline to accumulate condensation.

3. The EGR-equipped engine according to claim 1, characterized in that a connecting pipe (70) having a recessed portion (53) is connected to the exhaust gas line of the EGR circuit (44).

4. An EGR-equipped engine characterized by having an induction port (68) formed in the gasket (72) of the flange joint connecting the EGR cooler (57) and the EGR valve (43) to guide exhaust gas to the inner periphery of the EGR cooler (57).

5. An EGR-equipped engine characterized by having a soot collection section (59) for collecting non-combustible materials in the exhaust gas in a gasket (72) that joins the components constituting the EGR circuit (44).

6. An EGR-equipped engine according to claim 5, wherein a barrier (60) that rises up into the gas passage is formed in the gasket (72) to form a soot collection section (59).

7. An EGR-equipped engine according to claim 5, wherein a small-diameter gasket (72a) and a large-diameter gasket (72b) are stacked, and the inner peripheral edge (61) of the large gasket (72b) that does not overlap with the small gasket (72a) is used as a soot collection section (59).

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