Intake and exhaust system
The intake and exhaust system addresses the issue of unburned fuel discharge by using a connection flow path and control device to recirculate fuel from the exhaust to the intake path, enhancing thermal efficiency and reducing emissions.
Patent Information
- Application Number
- JP2023115050
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-07-13
- Publication Date
- 2025-01-24
AI Technical Summary
In engines with combustion chambers, the simultaneous opening of intake and exhaust valves can lead to the discharge of unburned fuel through the exhaust port, which affects thermal efficiency and greenhouse gas emissions.
An intake and exhaust system with a connection flow path between the exhaust and intake paths, equipped with a control device that manages gas flow to return unburned fuel from the exhaust port to the intake path during specific valve lift phases.
The system effectively suppresses the emission of unburned fuel, improving thermal efficiency and reducing greenhouse gas emissions by recirculating unburned fuel back into the intake path.
Smart Images
Figure 2025012308000001_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates to an intake and exhaust system. [Background technology]
[0002] There is an engine having a combustion chamber, an intake valve, and an exhaust valve. In such an engine, as disclosed in, for example, Patent Document 1, an intake port communicating with the combustion chamber is opened and closed by the intake valve, and an exhaust port communicating with the combustion chamber is opened and closed by the exhaust valve. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] International Publication No. 2019 / 049878 Summary of the Invention [Problem to be solved by the invention]
[0004] During the intake stroke, the intake valve opens, causing a gas flow from the intake port toward the combustion chamber. During the exhaust stroke, the exhaust valve opens, causing a gas flow from the combustion chamber toward the exhaust port. In the process of exhausting the gas, unburned fuel may be discharged. For example, when switching from the exhaust stroke to the intake stroke, a situation may occur in which both the intake valve and the exhaust valve are open. In a situation in which both the intake valve and the exhaust valve are open, a blow-by may occur in which unburned fuel remaining in the intake port is discharged through the exhaust port. From the viewpoint of improving thermal efficiency or suppressing greenhouse gas emissions, it is desirable to suppress the emission of unburned fuel.
[0005] An object of the present disclosure is to provide an intake and exhaust system capable of suppressing the emission of unburned fuel. [Means for solving the problem]
[0006] In order to solve the above problems, the intake and exhaust system of the present disclosure includes an engine having a combustion chamber, an intake passage communicating with the combustion chamber, an exhaust passage communicating with the combustion chamber, an exhaust port which is a portion of the exhaust passage within the cylinder head, and a connecting passage which connects the intake passage.
[0007] A control device may be provided for effecting the drawing of gases from the exhaust port through a connecting passageway to the intake passageway, the control device being operable when the engine exhaust valve is open.
[0008] The control device may perform a process of sucking gas from the exhaust port via a connecting passage to the intake passage while increasing the lift amount of the exhaust valve.
[0009] The control device may perform a process of sucking out gas from the exhaust port via a connecting passage to the intake passage while the lift amount of the exhaust valve is being reduced.
[0010] The control device may perform the suction of gas from the exhaust port through a connecting passage to the intake passage at a time when both the exhaust valve and the intake valve of the engine are open during the process of reducing the lift amount of the exhaust valve.
[0011] The engine may further include a compressor provided in the intake passage, and the connecting passage may connect the exhaust port to a portion of the intake passage upstream of the compressor.
[0012] The compressor may be provided in the intake passage, and the connection passage may connect the exhaust port to a portion of the intake passage downstream of the compressor, and the connection passage may be provided with a booster. Effect of the Invention
[0013] According to the present disclosure, it is possible to suppress the emission of unburned fuel. [Brief description of the drawings]
[0014] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an intake and exhaust system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of each cylinder of the engine according to the embodiment of the present disclosure. [Diagram 3] FIG. 3 is a graph showing a first example of the transition of each state quantity according to the embodiment of the present disclosure. [Figure 4] FIG. 4 is a graph showing a second example of the transition of each state quantity according to the embodiment of the present disclosure. [Diagram 5] FIG. 5 is a schematic diagram showing the configuration of an intake and exhaust system according to a modified example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present disclosure are not illustrated.
[0016] Fig. 1 is a schematic diagram showing the configuration of an intake and exhaust system 1 according to this embodiment. The intake and exhaust system 1 is a system related to the intake and exhaust of an engine 100. As shown in Fig. 1, the intake and exhaust system 1 includes an engine 100, an intake flow path 200, an exhaust flow path 300, a turbocharger 400, a connection flow path 500, and a control device 600. As described later, the configuration in Fig. 1 is merely an example, and various modifications may be made to the example in Fig. 1.
[0017] The engine 100 has multiple cylinders. In the example of Fig. 1, the engine 100 has a first cylinder #1, a second cylinder #2, a third cylinder #3, a fourth cylinder #4, a fifth cylinder #5, and a sixth cylinder #6. However, the number of cylinders of the engine 100 may be other than six.
[0018] Fig. 2 is a schematic diagram showing the configuration of each cylinder of the engine 100 according to this embodiment. In Fig. 2, the intake port 104a, the exhaust port 104b, the fuel injection nozzle 112, and the ignition device 114 are illustrated on the same cross section. However, the intake port 104a, the exhaust port 104b, the fuel injection nozzle 112, and the ignition device 114 do not have to be located on the same cross section.
[0019] 2, the engine 100 includes a cylinder liner 102, a cylinder head 104, and a piston 106. The piston 106 is housed within the cylinder liner 102. A combustion chamber 108 is formed by the cylinder liner 102, the cylinder head 104, and the piston 106.
[0020] An intake port 104a and an exhaust port 104b are formed in the cylinder head 104. The intake port 104a and the exhaust port 104b open to the combustion chamber 108. The intake valve 110a opens and closes the opening of the intake port 104a on the combustion chamber 108 side. The exhaust valve 110b opens and closes the opening of the exhaust port 104b on the combustion chamber 108 side. The intake valve 110a and the exhaust valve 110b open and close in accordance with the rotation of a camshaft (not shown).
[0021] A pipe forming a branch flow passage 202 of the intake flow passage 200 described later is connected to the intake port 104a. An air-fuel mixture flows into the combustion chamber 108 via the intake port 104a. A pipe forming a branch flow passage 302 of the exhaust flow passage 300 described later is connected to the exhaust port 104b. Exhaust gas is discharged from the combustion chamber 108 via the exhaust port 104b. As described later, a branch flow passage 502 of the connection flow passage 500 is connected to the exhaust port 104b.
[0022] The fuel injection nozzle 112 is connected to a fuel supply source via a fuel supply flow path (not shown). The fuel supply source is, for example, a fuel tank (not shown) or a pipeline for city gas or the like. Fuel gas is supplied to the fuel injection nozzle 112 from the fuel supply source via the fuel supply flow path. The fuel injection nozzle 112 is provided in a branch flow path 202 of the intake flow path 200. The tip of the fuel injection nozzle 112 faces the intake port 104a. However, the fuel injection nozzle 112 may be provided in the intake port 104a.
[0023] The fuel injection nozzle 112 injects the fuel gas into the intake port 104a. The fuel gas is generated, for example, by gasifying LNG (liquefied natural gas). The fuel gas is not limited to LNG, and may be, for example, gasified LPG (liquefied petroleum gas), light oil, heavy oil, ammonia, hydrogen, or the like. The engine 100 is a gas engine that uses the fuel gas as fuel. Hereinafter, the fuel gas is also simply referred to as fuel.
[0024] The ignition device 114 is provided in the cylinder head 104. A tip portion of the ignition device 114 protrudes into the combustion chamber .
[0025] The engine 100 is a four-stroke engine. During the intake stroke, fuel is injected from the fuel injection nozzle 112, the intake valve 110a opens, and the exhaust valve 110b closes. The piston 106 moves toward the bottom dead center, and intake air and fuel are drawn into the combustion chamber 108 from the intake port 104a. During the compression stroke, the intake valve 110a and the exhaust valve 110b close. The piston 106 moves toward the top dead center, and the air-fuel mixture in the combustion chamber 108 is compressed. The air-fuel mixture is ignited by the ignition device 114 and combusted, and during the combustion stroke, the piston 106 is pressed toward the bottom dead center. During the exhaust stroke, the intake valve 110a closes, and the exhaust valve 110b opens. The piston 106 moves toward the top dead center, and the exhaust gas after combustion is discharged from the combustion chamber 108 through the exhaust port 104b. Returning to FIG. 1, the description will be continued below.
[0026] The intake passage 200 communicates with the combustion chamber 108 of the engine 100. In the intake passage 200, intake air, which is air supplied to the combustion chamber 108, flows. An intake port (not shown) through which air is taken in from the outside is provided at the upstream end of the intake passage 200. The intake passage 200 has a plurality of branch passages 202 that communicate with the plurality of combustion chambers 108, respectively. The plurality of branch passages 202 are provided on the downstream side of the intake passage 200. As described above, the pipe that forms the branch passage 202 is connected to the intake port 104a of the engine 100. The intake port 104a corresponds to the downstream end of the branch passage 202. The intake port 104a is included in the intake passage 200. The intake port 104a is a portion of the intake passage 200 inside the cylinder head 104.
[0027] The exhaust flow passage 300 communicates with the combustion chamber 108 of the engine 100. Exhaust gas discharged from the combustion chamber 108 flows through the exhaust flow passage 300. An exhaust port (not shown) is provided at the downstream end of the exhaust flow passage 300, through which the exhaust gas is discharged to the outside. The exhaust flow passage 300 has a plurality of branch flow passages 302 that communicate with the plurality of combustion chambers 108, respectively. The plurality of branch flow passages 302 are provided on the upstream side of the exhaust flow passage 300. As described above, the pipe that forms the branch flow passage 302 is connected to the exhaust port 104b of the engine 100. The exhaust port 104b corresponds to the upstream end of the branch flow passage 302. The exhaust port 104b is included in the exhaust flow passage 300. The exhaust port 104b is a portion of the exhaust flow passage 300 inside the cylinder head 104.
[0028] The turbocharger 400 has a compressor 402 and a turbine 404. The impeller of the compressor 402 and the impeller of the turbine 404 rotate as a unit. The impeller of the compressor 402 and the impeller of the turbine 404 are connected by a shaft.
[0029] The compressor 402 is provided in the intake air flow path 200 upstream of the branch flow path 202. The compressor 402 compresses the intake air taken in from the intake port and sends it downstream. An intercooler C1 is provided in the intake air flow path 200 upstream of the branch flow path 202 and downstream of the compressor 402. The intake air flowing through the intercooler C1 is cooled by heat exchange with air outside the intercooler C1. The intake air that has passed through the intercooler C1 is sent to each combustion chamber 108 via each branch flow path 202. Note that the intercooler C1 may be one that uses cooling water such as engine cooling water or industrial water to cool the intake air.
[0030] The turbine 404 is provided in the exhaust passage 300 downstream of the branch passages 302. The exhaust gas discharged from the engine 100 is sent to the turbine 404 via each branch passage 302. The exhaust gas sent to the turbine 404 passes through the turbine 404 and is discharged from an exhaust port. The turbine 404 generates rotational power by rotating a blade of the turbine 404 by the exhaust gas. The rotational power generated by the turbine 404 is transmitted to the compressor 402 via a shaft.
[0031] The connection flow passage 500 is connected to the intake flow passage 200 on the upstream side of the compressor 402. The connection flow passage 500 branches into a plurality of branch flow passages 502 on the opposite side of the connection point with the intake flow passage 200 on the upstream side of the compressor 402. As shown in FIG. 2, each branch flow passage 502 is connected to the exhaust port 104b of each cylinder. In the example of FIG. 1, branch flow passages 502a, 502b, 502c, 502d, 502e, and 502f are provided as the branch flow passages 502. The branch flow passages 502a, 502b, 502c, 502d, 502e, and 502f are connected to the exhaust ports 104b of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, the fifth cylinder #5, and the sixth cylinder #6, respectively.
[0032] As described above, the connection passage 500 connects the exhaust port 104b and the intake passage 200. The connection passage 500 is provided to return the fuel present in the exhaust port 104b to the intake passage 200.
[0033] An on-off valve 504 is provided in each branch flow path 502. The on-off valve 504 is capable of opening and closing the branch flow path 502. In the example of Fig. 1, on-off valves 504a, 504b, 504c, 504d, 504e, and 504f are provided as the on-off valves 504. The on-off valves 504a, 504b, 504c, 504d, 504e, and 504f are provided in the branch flow paths 502a, 502b, 502c, 502d, 502e, and 502f, respectively.
[0034] The exhaust port 104b is located downstream of the compressor 402. Therefore, the pressure at the exhaust port 104b is higher than the pressure at the upstream side of the compressor 402 in the intake passage 200. Therefore, when the on-off valve 504 is opened, gas is sucked from the exhaust port 104b into the branch passage 502, and the gas is sent via the connecting passage 500 to the intake passage 200 upstream of the compressor 402.
[0035] The control device 600 includes a central processing unit (CPU), a ROM in which programs and the like are stored, a RAM as a work area, etc. The control device 600 controls the operation of each device in the intake and exhaust system 1.
[0036] For example, the control device 600 controls the operation of the engine 100 .
[0037] For example, the control device 600 controls the operation of each on-off valve 504. This allows the control device 600 to execute suction of gas from the exhaust port 104b through the connecting flow path 500 to the intake flow path 200. Hereinafter, suction of gas through the connecting flow path 500 is also simply referred to as suction of gas. The control device 600 can control the operation of each on-off valve 504 to control the timing of suction of gas.
[0038] The transition of each state quantity for one of the multiple cylinders will be described below with reference to Figures 3 and 4. However, the transition of each state quantity for the other cylinders is similar. As will be described later, the transitions in Figures 3 and 4 are merely examples, and various modifications may be made to the example of Figure 3 and the example of Figure 4.
[0039] Fig. 3 is a graph showing a first example of the transition of each state quantity according to this embodiment. In Fig. 3, the horizontal axis represents the crank angle, and the vertical axis represents the lift amount of the intake valve 110a and the exhaust valve 110b, and the timing of gas suction, as state quantities. In Fig. 3, when suction is ON, gas suction is being performed, and when suction is OFF, gas suction is not being performed.
[0040] 3 shows the change in the lift amount LAa of the intake valve 110a and the change in the lift amount LAb of the exhaust valve 110b. In the example of FIG. 3, at the crank angle CA1, the lift amount LAb of the exhaust valve 110b starts to increase, and the exhaust valve 110b starts to open. At the crank angle CA3 after the crank angle CA1, the decrease in the lift amount LAb of the exhaust valve 110b ends, and the exhaust valve 110b finishes closing. At the crank angle CA2 after the crank angle CA1 and before the crank angle CA3, the lift amount LAa of the intake valve 110a starts to increase, and the intake valve 110a starts to open. At the crank angle CA4 after the crank angle CA3, the decrease in the lift amount LAa of the intake valve 110a ends, and the intake valve 110a finishes closing.
[0041] In the combustion in the combustion chamber 108, some fuel may remain unburned in the gap between the piston 106 and the cylinder liner 102, or in the gap between the cylinder liner 102 and the cylinder head 104. The unburned fuel remaining in the combustion chamber 108 is discharged from the combustion chamber 108 to the exhaust port 104b when the exhaust valve 110b is open. As described above, in the example of FIG. 3, a situation occurs in which both the intake valve 110a and the exhaust valve 110b are open. In this situation, a blow-by may occur in which the unburned fuel remaining in the intake port 104a is discharged through the exhaust port 104b. The control device 600 controls the timing of gas suction so that the discharge of the unburned fuel is effectively suppressed.
[0042] In the example of Fig. 3, the control device 600 performs gas suction when the exhaust valve 110b is open. For example, as shown in Fig. 3, the control device 600 performs gas suction between crank angles CA1 and CA3 when the exhaust valve 110b is open. On the other hand, the control device 600 prohibits and does not perform gas suction before crank angle CA1 and after crank angle CA3 when the exhaust valve 110b is closed.
[0043] In the example of FIG. 3, the control device 600 performs the suction of gas over a period from when the exhaust valve 110b starts to open to when it finishes closing. However, the control device 600 may prohibit and not perform the suction of gas during a part of the above-mentioned periods. That is, the control device 600 may perform the suction of gas during at least a part of the period when the exhaust valve 110b is open. As a result, the fuel present in the exhaust port 104b can be sucked by the connection flow path 500 and returned to the intake flow path 200 via the connection flow path 500. In addition, by prohibiting the suction of gas during the period when the exhaust valve 110b is closed, it is possible to suppress unnecessary suction of gas under a situation where there is a low possibility that fuel is present in the exhaust port 104b. However, the control device 600 may additionally perform the suction of gas during a part of the period when the exhaust valve 110b is closed.
[0044] Fig. 4 is a graph showing a second example of the transition of each state quantity according to this embodiment. In Fig. 4, similar to Fig. 3, the horizontal axis represents the crank angle, and the vertical axis represents the lift amount of the intake valve 110a and the exhaust valve 110b, and the timing of the gas suction, as state quantities. In the example of Fig. 4, the timing of the gas suction is different from the example of Fig. 3.
[0045] In the example of Fig. 4, the control device 600 performs the suction of gas when the exhaust valve 110b is open, similarly to the example of Fig. 3. In the example of Fig. 4, unlike the example of Fig. 3, the control device 600 prohibits and does not perform the suction of gas during a part of the period from when the exhaust valve 110b starts to open to when it finishes closing.
[0046] For example, the control device 600 performs the suction of gas during the increase process of the lift amount LAb of the exhaust valve 110b. The increase process of the lift amount LAb of the exhaust valve 110b means a process from the time when the increase of the lift amount LAb starts to the time when the lift amount LAb reaches the maximum value. For example, as shown in FIG. 4, the control device 600 performs the suction of gas from the crank angle CA1 at which the exhaust valve 110b starts to open to the crank angle CA5 at which the lift amount LAb is increasing. Then, the control device 600 prohibits and does not perform the suction of gas from the crank angle CA5 to the crank angle CA2. As described above, in the example of FIG. 4, the control device 600 performs the suction of gas during a part of the increase process of the lift amount LAb of the exhaust valve 110b. However, the control device 600 may perform the suction of gas over the entire period of the increase process of the lift amount LAb of the exhaust valve 110b.
[0047] During the process of increasing the lift amount LAb of the exhaust valve 110b, unburned fuel remaining in the gap between the cylinder liner 102 and the cylinder head 104 is likely to be discharged from the combustion chamber 108 to the exhaust port 104b. Therefore, by performing the gas suction during the process of increasing the lift amount LAb of the exhaust valve 110b, the gas suction can be performed at a timing when the fuel concentration in the exhaust port 104b is high. Therefore, the fuel present in the exhaust port 104b is effectively sucked by the connecting passage 500 and returned to the intake passage 200 via the connecting passage 500.
[0048] For example, the control device 600 performs the suction of gas during the process of decreasing the lift amount LAb of the exhaust valve 110b. The process of decreasing the lift amount LAb of the exhaust valve 110b means the process from the time when the lift amount LAb reaches the maximum value to the time when the decrease in the lift amount LAb ends. For example, as shown in FIG. 4, the control device 600 performs the suction of gas during the period from the crank angle CA2 at which the lift amount LAb is decreasing to the crank angle CA3 at which the exhaust valve 110b ends closing. Then, the control device 600 prohibits and does not perform the suction of gas after the crank angle CA3. As described above, in the example of FIG. 4, the control device 600 performs the suction of gas during a part of the process of decreasing the lift amount LAb of the exhaust valve 110b. However, the control device 600 may perform the suction of gas throughout the entire process of decreasing the lift amount LAb of the exhaust valve 110b.
[0049] During the process of decreasing the lift amount LAb of the exhaust valve 110b, unburned fuel remaining in the gap between the piston 106 and the cylinder liner 102 is likely to be discharged from the combustion chamber 108 to the exhaust port 104b. Therefore, by performing the gas suction during the process of decreasing the lift amount LAb of the exhaust valve 110b, the gas suction can be performed at a timing when the fuel concentration in the exhaust port 104b is high. Therefore, the fuel present in the exhaust port 104b is effectively sucked by the connecting passage 500 and returned to the intake passage 200 via the connecting passage 500.
[0050] In particular, in the example of FIG. 4, the control device 600 performs the suction of gas during the period when both the intake valve 110a and the exhaust valve 110b are open during the process of decreasing the lift amount LAb of the exhaust valve 110b. In the example of FIG. 4, the control device 600 performs the suction of gas throughout the entire period. However, the control device 600 may perform the suction of gas during some of the periods. During the above period, in addition to the unburned fuel remaining in the gap between the piston 106 and the cylinder liner 102 being discharged to the exhaust port 104b, there may be a blow-through in which the unburned fuel remaining in the intake port 104a is discharged through the exhaust port 104b. Therefore, by performing the suction of gas during the above period, the suction of gas can be performed at a timing when the fuel concentration in the exhaust port 104b is higher. Therefore, the fuel present in the exhaust port 104b is more effectively sucked by the connecting passage 500 and returned to the intake passage 200 via the connecting passage 500.
[0051] In the example of Fig. 4, the control device 600 performs the suction of gas only when the fuel concentration in the exhaust port 104b is assumed to be high, as compared to the example of Fig. 3. This makes it possible to more effectively prevent unnecessary suction of gas under circumstances in which the possibility of fuel being present in the exhaust port 104b is low.
[0052] As described above, the intake and exhaust system 1 includes the engine 100 having the combustion chamber 108, the intake passage 200 communicating with the combustion chamber 108, the exhaust passage 300 communicating with the combustion chamber 108, and the connection passage 500 connecting the exhaust port 104b, which is a portion of the exhaust passage 300 inside the cylinder head 104, and the intake passage 200. As a result, the fuel present in the exhaust port 104b can be sucked by the connection passage 500 and returned to the intake passage 200 via the connection passage 500. Therefore, the fuel present in the exhaust port 104b is prevented from being discharged through the exhaust passage 300. Thus, the discharge of unburned fuel is prevented. Therefore, the thermal efficiency is improved and the discharge of greenhouse gases is prevented.
[0053] In particular, the intake and exhaust system 1 includes a compressor 402 provided in the intake flow path 200, and the connection flow path 500 connects the exhaust port 104b to the intake flow path 200 on the upstream side of the compressor 402. This eliminates the need to provide a booster unit 506 described later, unlike the case where the connection flow path 500 is connected to the intake flow path 200 on the downstream side of the compressor 402, as in the intake and exhaust system 1A according to a modified example of FIG.
[0054] The intake and exhaust system 1 has been described above with reference to Figures 1 to 4. However, various modifications may be made to the example described above.
[0055] For example, in the above description, the connection flow path 500 is connected to the intake air flow path 200 on the upstream side of the compressor 402. However, the connection flow path 500 may be connected to the intake air flow path 200 on the downstream side of the compressor 402. This example will be described later with reference to FIG.
[0056] For example, in the above example, the compressor 402 and the intercooler C1 are provided in the intake passage 200, and the turbine 404 is provided in the exhaust passage 300. However, the turbocharger 400 may be omitted, or one of the compressor 402 and the turbine 404 may be omitted. The intercooler C1 may be omitted.
[0057] For example, examples of the transition of each state quantity have been described above with reference to Figures 3 and 4. However, the transition of each state quantity is not limited to the example of Figures 3 and 4. For example, the time when the intake valve 110a is open and the time when the exhaust valve 110b is open do not have to overlap. In other words, the timing when the intake valve 110a starts to open may be after the timing when the exhaust valve 110b finishes closing.
[0058] The timing at which the gas suction starts may be earlier or later than the example in Fig. 3. The timing at which the gas suction ends may be earlier or later than the example in Fig. 3.
[0059] In the example of FIG. 4, one of the first gas suction from crank angle CA1 to crank angle CA5 and the second gas suction from crank angle CA2 to crank angle CA3 may be omitted. However, from the viewpoint of returning more fuel from inside the exhaust port 104b to the intake passage 200, it is preferable that both the first gas suction and the second gas suction are performed. In other words, it is preferable that the control device 600 executes the gas suction during each of the increase and decrease processes of the lift amount LAb of the exhaust valve 110b. The amount of unburned fuel sent into the exhaust port 104b at the timing of the second gas suction is greater than the amount of unburned fuel sent into the exhaust port 104b at the timing of the first gas suction. Therefore, it is preferable that at least the second gas suction is performed.
[0060] The timing at which the first gas suction is started may be earlier or later than the example in Fig. 4. The timing at which the first gas suction is ended may be earlier or later than the example in Fig. 4. The timing at which the second gas suction is started may be earlier or later than the example in Fig. 4. The timing at which the second gas suction is ended may be earlier or later than the example in Fig. 4.
[0061] As described above, the connection flow path 500 may be connected to the intake flow path 200 downstream of the compressor 402. This example will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing the configuration of an intake and exhaust system 1A according to a modified example. In the intake and exhaust system 1A, the connection position of the connection flow path 500 is different from that of the intake and exhaust system 1 described above.
[0062] 5, in the intake and exhaust system 1A, the connection passage 500 has branch passages 502a, 502b, 502c, 502d, 502e, and 502f, similar to the intake and exhaust system 1 described above. The branch passages 502a, 502b, 502c, 502d, 502e, and 502f are connected to the exhaust ports 104b of the first cylinder #1, the second cylinder #2, the third cylinder #3, the fourth cylinder #4, the fifth cylinder #5, and the sixth cylinder #6, respectively. The connection passage 500 is provided to return the fuel present in the exhaust port 104b to the intake passage 200.
[0063] In the intake and exhaust system 1A, unlike the above-described intake and exhaust system 1, a portion of the connection flow path 500 downstream of the multiple branch flow paths 502 in the gas flow direction is connected to the intake flow path 200 downstream of the compressor 402. In the example of Fig. 5, the above portion of the connection flow path 500 is connected to the intake flow path 200 downstream of the compressor 402 and upstream of the intercooler C1. However, the above portion of the connection flow path 500 may be connected to the intake flow path 200 downstream of the intercooler C1.
[0064] In the intake and exhaust system 1A, unlike the intake and exhaust system 1 described above, a booster 506 is provided in the connection flow path 500. The booster 506 increases the pressure of the gas sent from the exhaust port 104b to the connection flow path 500. Examples of the booster 506 include an electric fan or an electric compressor. The booster 506 makes the pressure in the connection flow path 500 higher than the pressure in the intake flow path 200 downstream of the compressor 402 and upstream of the intercooler C1. Therefore, when the on-off valve 504 is opened, gas is sucked from the exhaust port 104b to the branch flow path 502, and the gas is sent to the intake flow path 200 downstream of the compressor 402 through the connection flow path 500.
[0065] As described above, the intake and exhaust system 1A includes the compressor 402 provided in the intake flow path 200, and the connection flow path 500 connects the exhaust port 104b to the intake flow path 200 downstream of the compressor 402, and the booster 506 is provided in the connection flow path 500. This allows the fuel present in the exhaust port 104b to be sucked by the connection flow path 500 and returned to the intake flow path 200 via the connection flow path 500. Furthermore, unlike the case where the connection flow path 500 is connected to the intake flow path 200 upstream of the compressor 402 as in the above-mentioned intake and exhaust system 1, the gas containing fuel is prevented from being sent to the compressor 402.
[0066] The above describes the intake and exhaust system 1A with reference to Fig. 5. However, the intake and exhaust system 1A may be modified in the same manner as the various modifications that may be made to the intake and exhaust system 1 described above.
[0067] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.
[0068] The present disclosure can reduce unburned fuel emissions and, therefore, can contribute to, for example, Sustainable Development Goal (SDG) 7, "Ensure access to affordable, reliable, sustainable and modern energy." [Explanation of symbols]
[0069] 1. Intake and exhaust system 1A Intake and exhaust system 100 Engine 104 Cylinder head 104b Exhaust port 108 Combustion chamber 110a Intake valve 110b Exhaust valve 200 Intake passage 300 Exhaust passage 402 Compressor 500 Connection channel 506 Booster 600 Control device LAb Lift Amount
Claims
1. an engine having a combustion chamber; an intake passage communicating with the combustion chamber; an exhaust passage communicating with the combustion chamber; a connecting passage that connects an exhaust port, which is a portion of the exhaust passage within a cylinder head, to the intake passage; Equipped with Intake and exhaust system.
2. a control device that performs suction of gas from the exhaust port to the intake passage through the connecting passage, The control device executes the control when the exhaust valve of the engine is open. The intake and exhaust system according to claim 1 .
3. The control device performs the suction of gas from the exhaust port to the intake passage via the connecting passage during a process of increasing the lift amount of the exhaust valve. The intake and exhaust system according to claim 2 .
4. The control device performs suction of gas from the exhaust port to the intake passage via the connecting passage during a process of reducing a lift amount of the exhaust valve. The intake and exhaust system according to claim 2 or 3.
5. the control device performs the suction of gas from the exhaust port to the intake passage via the connecting passage when both the exhaust valve and the intake valve of the engine are open during a process of reducing the lift amount of the exhaust valve. The intake and exhaust system according to claim 4.
6. A compressor is provided in the intake passage, The connection passage connects the exhaust port and a portion of the intake passage upstream of the compressor.
3. The intake and exhaust system according to claim 1 or 2.
7. A compressor is provided in the intake passage, the connection passage connects the exhaust port to a downstream side of the intake passage relative to the compressor, The connection flow path is provided with a pressure increasing section.
3. The intake and exhaust system according to claim 1 or 2.
Citation Information
Patent Citations
Engine control system
WO2019049878A1