JP7309114B2 - Uniflow scavenging 2-cycle engine - Google Patents

Description

The present disclosure relates to uniflow scavenged two-stroke engines.

A uniflow scavenging two-cycle engine may use gaseous fuel gas as fuel. For example, Patent Literature 1 discloses a configuration in which a fuel injection port is formed closer to the exhaust port than the scavenging port in the cylinder. A plurality of fuel injection ports are provided at intervals in the circumferential direction of the cylinder. The fuel gas injected into the cylinder from the fuel injection port is compressed by the piston together with the scavenging air, and then combusted in the combustion chamber.

Japanese Patent No. 6080224

By the way, when the required output of the engine is small, the amount of fuel gas injected from each fuel injection port is small, and the fuel gas diffuses and becomes too lean, which easily causes misfire.

An object of the present disclosure is to provide a uniflow scavenging two-stroke engine capable of suppressing misfiring under low load.

In order to solve the above problems, the uniflow scavenging two-cycle engine of the present disclosure includes a scavenging chamber having an inlet, a cylinder having a scavenging port inside the scavenging chamber, an inner peripheral surface of the cylinder, a scavenging A plurality of injections including a first injection opening that opens inside the port or radially outward of the cylinder from the scavenging port, and a second injection opening that is spaced further from the inlet than the first injection opening. The nozzle, a fuel injection device that supplies fuel gas to the injection port, and the fuel injection device are controlled, and when the required output is less than the threshold, the supply of the fuel gas to the first injection port is stopped, and the fuel is supplied from the second injection port. and a control unit for injecting gas, wherein the first injection port is located on the inlet side with respect to the central axis of the cylinder, and the second injection port is located on the side away from the inlet with respect to the central axis of the cylinder. Located in

In order to solve the above problems, the uniflow scavenging two-cycle engine of the present disclosure includes a scavenging chamber having an inlet, a cylinder having a scavenging port inside the scavenging chamber, an inner peripheral surface of the cylinder, a scavenging A plurality of injections including a first injection opening that opens inside the port or radially outward of the cylinder from the scavenging port, and a second injection opening that is spaced further from the inlet than the first injection opening. The nozzle, a fuel injection device that supplies fuel gas to the injection port, and the fuel injection device are controlled, and when the required output is less than the threshold, the supply of the fuel gas to the first injection port is stopped, and the fuel is supplied from the second injection port. and a control unit for injecting gas, wherein the control unit retards the injection timing when stopping the supply of the fuel gas to the first injection port, compared to when the fuel gas is injected from all the injection ports. be .

In order to solve the above problems, the uniflow scavenging two-cycle engine of the present disclosure includes a scavenging chamber having an inlet, a cylinder having a scavenging port inside the scavenging chamber, an inner peripheral surface of the cylinder, a scavenging A plurality of injections including a first injection opening that opens inside the port or radially outward of the cylinder from the scavenging port, and a second injection opening that is spaced further from the inlet than the first injection opening. The nozzle, a fuel injection device that supplies fuel gas to the injection port, and the fuel injection device are controlled, and when the required output is less than the threshold, the supply of the fuel gas to the first injection port is stopped, and the fuel is supplied from the second injection port. a control unit for injecting gas, wherein the control unit reduces the amount of fuel gas supplied to the first injection port to be less than the amount of fuel gas supplied to the second injection port, The injection timing of the second injection port is retarded from the injection timing.

When the required output decreases across the threshold value, the control unit stops the supply of the fuel gas to the first injection port, and the second injection is performed by an amount smaller than the decrement that is no longer supplied from the first injection port. The amount of fuel supplied to the mouth may be increased.

According to the uniflow scavenging two-cycle engine of the present disclosure, it is possible to suppress misfiring at low load.

FIG. 1 is an explanatory diagram showing the overall configuration of a uniflow scavenging two-cycle engine. FIG. 2 is a diagram for explaining the arrangement of fuel injection ports. FIG. 3 is a block diagram showing the control system of the uniflow scavenging two-cycle engine. FIG. 4 is a first diagram for explaining the processing of the fuel control unit. FIG. 5 is a second diagram for explaining the processing of the fuel control unit. FIG. 6 is a third diagram for explaining the processing of the fuel control unit. FIG. 7 is a fourth diagram for explaining the processing of the fuel control unit. FIG. 8 is a diagram showing simulation results of the diffusion state of fuel gas in the vicinity of the crown surface of the piston in the combustion chamber. FIG. 9 is a diagram for explaining a modification. FIG. 10 is a diagram for explaining the arrangement of fuel pipes.

An embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In this specification and the drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals, thereby omitting redundant description. Illustrations of elements that are not directly related to the present disclosure are omitted.

FIG. 1 is an explanatory diagram showing the overall configuration of a uniflow scavenging two-stroke engine 100. As shown in FIG. The uniflow scavenging two-cycle engine 100 is used, for example, in ships and the like. A cylinder head 112 is provided on one end side of the cylinder 110 . A cylinder jacket 114 is provided on the other end side of the cylinder 110 . A piston 116 is arranged within the cylinder 110 .

The piston 116 reciprocates in the cylinder 110 in the central axis direction of the cylinder 110 (the stroke direction of the piston 116, hereinafter simply referred to as the stroke direction). Exhaust, intake, compression, combustion, and expansion occur during the two strokes of piston 116, the upward stroke and the downward stroke. One end of a piston rod 118 is attached to the piston 116 . A crosshead 120 is connected to the other end of the piston rod 118 .

The crosshead 120 reciprocates in the stroke direction integrally with the piston 116 . The crosshead shoe 122 restricts movement of the crosshead 120 in a direction perpendicular to the stroke direction (horizontal direction in FIG. 1). Connecting rod 124 is connected to crosshead 120 and crankshaft 126 . The movement of the connecting rod 124 accompanying the reciprocating movement of the crosshead 120 causes the crankshaft 126 to rotate.

An exhaust valve box 128 is attached to the cylinder head 112 . Combustion chamber 130 is formed inside cylinder 110 surrounded by cylinder head 112, exhaust valve box 128, and piston 116 when piston 116 is on the top dead center side.

An exhaust port 132 is formed in the exhaust valve box 128 . The exhaust port 132 is positioned vertically above the top dead center of the piston 116 . The exhaust valve box 128 is provided with an exhaust valve driving device (not shown). The exhaust valve 134 is moved in the stroke direction by an exhaust valve driving device. Movement of the exhaust valve 134 opens and closes the exhaust port 132 .

When exhaust valve 134 is open, exhaust gas is exhausted from combustion chamber 130 through exhaust port 132 . The exhaust gas rotates turbine T of supercharger 138 through exhaust pipe 136 . This rotational power causes the compressor C of the supercharger 138 to compress the active gas and send it to the cooler 140 . Active gases include oxygen, oxidants such as ozone, or mixtures thereof (eg, air). Cooler 140 is disposed in a scavenge sump 144 formed within casing 142 . Cooler 140 cools the compressed active gas. The cooled active gas is delivered to scavenge sump 144 .

Casing 142 abuts on cylinder jacket 114 . The casing 142 is located outside the cylinder jacket 114 in the radial direction (hereinafter referred to as radial direction) of the cylinder 110 . A scavenging chamber 146 is formed inside the cylinder jacket 114 . The scavenging reservoir 144 is located radially outside the scavenging chamber 146 .

A through hole 142 a is formed in the wall portion of the casing 142 on the cylinder jacket 114 side. The through-hole 142a penetrates the wall portion of the casing 142 on the cylinder jacket 114 side in the direction in which the casing 142 and the cylinder jacket 114 face each other.

A through hole 114 a is formed in a portion of the cylinder jacket 114 that faces the through hole 142 a of the casing 142 . Through hole 114 a of cylinder jacket 114 penetrates the wall of cylinder jacket 114 in the same direction as through hole 142 a of casing 142 .

The scavenging reservoir 144 and the scavenging chamber 146 communicate with each other through the through holes 114a and 142a. In the scavenging chamber 146, the opening of the through hole 114a serves as an inflow port 146a into which the active gas compressed from the scavenging reservoir 144 flows.

The other end side of the cylinder 110 is located inside the scavenging chamber 146 . A scavenging port 148 is formed in a portion of the cylinder 110 located inside the scavenging chamber 146 . The scavenging port 148 opens into the scavenging chamber 146 .

The scavenging port 148 penetrates from the inner peripheral surface to the outer peripheral surface of the cylinder 110 . A plurality of scavenging ports 148 are provided at intervals in the circumferential direction of cylinder 110 (hereinafter simply referred to as the circumferential direction). The scavenging port 148 is positioned closer to the top dead center than the bottom dead center of the piston 116 in the cylinder 110 .

When the crown surface of the piston 116 moves to the bottom dead center side of the scavenging port 148, active gas is sucked into the internal space S of the cylinder 110 from the scavenging port 148 due to the pressure difference between the internal pressure of the scavenging chamber 146 and the cylinder 110. be done.

A fuel injection port 150 is formed in the cylinder 110 vertically above the cylinder jacket 114 (on the top dead center side of the piston 116). The fuel injection port 150 penetrates from the inner peripheral surface of the cylinder 110 to the outer peripheral surface thereof. Two fuel injection ports 150 are provided. Each fuel injection port 150 is provided with a fuel injection device 152 .

Here, the case where two fuel injection devices 152 are provided has been described. However, three or more fuel injection devices 152 may be provided at intervals in the circumferential direction. In this case, the same number of fuel injection ports 150 as the fuel injection devices 152 are formed in the cylinder 110 .

The fuel injection device 152 injects fuel gas supplied from a fuel pipe (not shown). The injected fuel gas is sprayed through the fuel injection port 150 onto the active gas sucked into the internal space S of the cylinder 110 . Fuel gas shall be generated by gasifying LNG (liquefied natural gas), for example. The fuel gas is not limited to LNG, and gasified LPG (liquefied petroleum gas), light oil, heavy oil, or the like, for example, may be used.

Since the fuel injection port 150 is provided closer to the scavenging port 148 than the combustion chamber 130, the injection pressure of the fuel gas is kept low. The injected fuel gas is mixed with the active gas and compressed while flowing toward the combustion chamber 130 as the piston 116 rises. The cylinder head 112 is provided with a pilot injection valve (not shown). Fuel oil is injected into the combustion chamber 130 from the pilot injection valve. The fuel oil is vaporized by the heat of the gas within combustion chamber 130 . The fuel oil vaporizes and spontaneously ignites, increasing the temperature of the combustion chamber 130 . The mixture of fuel gas and active gas is then combusted. Piston 116 reciprocates due to expansion pressure due to combustion of fuel gas.

FIG. 2 is a diagram for explaining the arrangement of fuel injection ports 150. As shown in FIG. FIG. 2 shows a cross section of the cylinder jacket 114 taken along a plane perpendicular to the central axis of the cylinder 110 (hereinafter referred to as a vertical plane) at a position including the through hole 114a. Regarding cylinder 110 , a cross section taken along a vertical plane is shown at a position including fuel injection port 150 . Also, the outer shape of the fuel injection device 152 as seen from the vertical upper side is shown.

As shown in FIG. 2, the two fuel injection ports 150 are arranged with the central axis O of the cylinder 110 interposed therebetween. An opening of the fuel injection port 150 on the inner peripheral surface side of the cylinder 110 serves as an injection port 154 through which fuel gas flows into the cylinder 110 . Of the two injection ports 154, the injection port 154 positioned closer to the inlet 146a of the scavenging chamber 146 is referred to as a first outlet 154a, and the outlet 154 positioned away from the inlet 146a is referred to as a second outlet 154b.

The first injection port 154a is located on the side of the inlet port 146a with respect to the central axis O of the cylinder 110 (the right side of the dashed line in FIG. 2). The first injection port 154a is circumferentially displaced from the front of the inlet 146a. The second injection port 154b is located on the side of the center axis O of the cylinder 110 that is separated from the inflow port 146a (the left side of the dashed line in FIG. 2).

FIG. 3 is a block diagram showing the control system of the uniflow scavenging two-cycle engine 100. As shown in FIG. FIG. 3 mainly shows a configuration related to control of the fuel injection device 152 . As shown in FIG. 3 , the uniflow scavenging two-cycle engine 100 includes a control device 200 . The control device 200 is configured by, for example, an ECU (Engine Control Unit). The control device 200 includes a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like, and controls the uniflow scavenging two-cycle engine 100 as a whole. The control device 200 also functions as a fuel control section 202 (control section).

The fuel control unit 202 controls the fuel injection device 152 to control the injection amount and injection timing of the fuel gas. A crank angle sensor 204 is provided on the crankshaft 126 , and a crank angle signal indicating the crank angle is output from the crank angle sensor 204 to the fuel control section 202 . Based on the crank angle signal, the fuel control unit 202 controls the fuel injection device 152 so that the fuel gas injection amount and injection timing are determined according to the operating conditions.

FIG. 4 is a first diagram for explaining the processing of the fuel control unit 202. FIG. The diagram on the left side in FIG. 4 shows the amount of fuel supplied to the first injection port 154a, and the diagram on the right side shows the amount of fuel supply to the second injection port 154b. In the figures below, the threshold M indicates 100% of the requested power. In the range where the required output is greater than the threshold value A, the fuel supply amount increases or decreases in proportion to the amount of increase or decrease in the required output for both the first injection port 154a and the second injection port 154b.

When the required output is equal to or less than the threshold A, the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 154a.

Specifically, it is assumed that the required output straddles the threshold A and decreases. At this time, the fuel control unit 202 stops the supply of fuel gas to the first injection port 154a. Further, the fuel control unit 202 increases the amount of fuel supplied to the second injection port 154b by an amount smaller than the decrement (fuel supply amount Q) that is no longer supplied from the first injection port 154a. That is, the fuel supply amount Q′ when the fuel gas is injected only from the second injection port 154b is smaller than the fuel supply amount 2Q when the fuel gas is injected from the two injection ports 154b.

Further, the fuel control unit 202 may perform the processes shown in FIGS. 5, 6, and 7 instead of the above process shown in FIG.

FIG. 5 is a second diagram for explaining the processing of the fuel control section 202. As shown in FIG. The diagram on the left side in FIG. 5 shows the amount of fuel supplied to the first injection port 154a, and the diagram on the right side shows the amount of fuel supply to the second injection port 154b. In the range where the required output is greater than the threshold value B, the fuel supply amount increases or decreases in proportion to the amount of increase or decrease in the required output for both the first injection port 154a and the second injection port 154b. Here, threshold B is greater than threshold A.

When the required output is equal to or less than the threshold A, the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 154a.

Specifically, it is assumed that the required output straddles the threshold B and the threshold A and decreases. As the required output moves from the threshold B to the threshold A, the fuel control unit 202 reduces the supply of fuel gas to the first injection port 154a, and makes the fuel supply amount zero when the threshold A is reached.

Further, as the required output moves from the threshold value B to the threshold value A, the fuel control unit 202 supplies fuel to the second injection port 154b by an amount smaller than the decrement (fuel supply amount Q) that is no longer supplied from the first injection port 154a. increase the amount of fuel supplied to That is, the fuel supply amount Q′ when the fuel gas is injected only from the second injection port 154b is smaller than the fuel supply amount 2Q when the fuel gas is injected from the two injection ports 154b.

FIG. 6 is a third diagram for explaining the processing of the fuel control unit 202. FIG. The diagram on the left side in FIG. 6 shows the amount of fuel supplied to the first injection port 154a, and the diagram on the right side shows the amount of fuel supply to the second injection port 154b. In the range where the required output is greater than the threshold value B, the fuel supply amount increases or decreases in proportion to the amount of increase or decrease in the required output for both the first injection port 154a and the second injection port 154b.

When the required output is equal to or less than the threshold A', the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 154a. Here, the threshold A' is smaller than the threshold A, for example.

Specifically, it is assumed that the required output decreases across the threshold B and the threshold A'. As the required output moves from the threshold B to the threshold A', the fuel control unit 202 reduces the supply of fuel gas to the first injection port 154a, and reduces the fuel supply amount to 0 when the threshold A' is reached.

Further, as the required output goes from 0 to the threshold A', the fuel control unit 202 increases the amount of fuel supplied to the second injection port 154b. At this time, the amount of fuel supplied to the second injection port 154b is smaller than when fuel is injected from both the first injection port 154a and the second injection port 154b. For example, when the required output is the threshold value A', the fuel supply amount Q' when the fuel gas is injected only from the second injection port 154b is the fuel supply amount Q' when the fuel gas is injected from the two injection ports 154. Less than 2Q.

When the required output rises from the threshold A', the fuel supply amount to the second injection port 154b increases to the fuel supply amount 2Q and remains constant until the required output reaches the threshold B.

FIG. 7 is a third diagram for explaining the processing of the fuel control unit 202. FIG. The diagram on the left side in FIG. 7 shows the amount of fuel supplied to the first injection port 154a, and the diagram on the right side shows the amount of fuel supply to the second injection port 154b. In the range where the required output is greater than the threshold value B, the fuel supply amount increases or decreases in proportion to the amount of increase or decrease in the required output for both the first injection port 154a and the second injection port 154b.

When the required output is equal to or less than the threshold value A'', the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 154a. Here, the threshold A'' is smaller than the threshold A', for example.

Specifically, it is assumed that the required output decreases across threshold B and threshold A''. The fuel control unit 202 reduces the supply of fuel gas to the first injection port 154a as the required output moves from the threshold value B to the threshold value A'', and reduces the fuel supply amount to 0 when the threshold value A'' is reached. Let

Further, the fuel control unit 202 increases the amount of fuel supplied to the second injection port 154b as the required output goes from 0 to the threshold value A''. At this time, the amount of fuel supplied to the second injection port 154b is smaller than when fuel is injected from both the first injection port 154a and the second injection port 154b. For example, when the required output is the threshold value A″, the fuel supply amount Q′ when the fuel gas is injected only from the second injection port 154b is the fuel supply amount Q′ when the fuel gas is injected from the two injection ports 154. less than quantity 2Q.

The amount of fuel supplied to the second injection port 154b increases at a substantially constant rate until the required output reaches the threshold value B from the threshold value A''.

Further, the above control of the fuel supply amount by the fuel control unit 202 may change linearly or curvilinearly with respect to the required output.

FIG. 8 is a diagram showing simulation results of the diffusion state of fuel gas in the vicinity of the crown surface of piston 116 in combustion chamber 130. As shown in FIG. The left side diagram in FIG. 8 shows the case where the fuel gas is supplied only from the first injection port 154a. The diagram on the right side of FIG. 8 shows the case where the fuel gas is supplied only from the second injection port 154b. In each diagram of FIG. 8, the horizontal axis indicates the Kelvin temperature, and the vertical axis indicates the excess air ratio λ.

In FIG. 8, the fact that the percentage of plots where the excess air ratio λ is small indicates that the fuel gas is not diffused and is locally accumulated. The fuel gas is less diffused when the fuel gas is injected only from the second injection port 154b than when the fuel gas is injected only from the first injection port 154a. When the load is low, misfires are less likely to occur if the fuel gas does not diffuse and is locally accumulated.

As described above, when the required output is equal to or less than the threshold A, the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 154a. Fuel gas is injected only from the second injection port 154b. The second injection port 154b side is farther from the inflow port 146a than the first injection port 154a side, and the flow velocity of the active gas is suppressed. Therefore, misfires are suppressed because the fuel gas does not diffuse but accumulates locally as described above.

4 to 7, the fuel control unit 202 stops supplying the fuel gas to the first injection port 154a more than when injecting the fuel gas from all the injection ports 154. Also, the injection timing may be retarded. When the injection timing is retarded, the mixing time of fuel gas and active gas is shortened. Therefore, the diffusion of the fuel gas becomes more difficult, and misfires at low load are further suppressed. 5 to 7, when the amount of fuel gas supplied to the first injection port 154a is made smaller than the amount of fuel supplied to the second injection port 154b, the first injection port The injection timing of the second injection port 154b may be retarded with respect to the injection timing of 154a. By delaying the injection timing of the second injection port 154b, which supplies a large amount of fuel, the diffusion of the fuel gas becomes more difficult.

FIG. 9 is a diagram for explaining a modification. FIG. 9 shows an extracted vertically lower portion of a uniflow scavenging two-cycle engine 100A of a modified example. As shown in FIG. 9, the fuel injection port 150 is not provided in the uniflow scavenging two-cycle engine 100A. Instead, a fuel tube 360 is disposed radially outward of the scavenge ports 148 .

A plurality of fuel pipes 360 are arranged at intervals in the circumferential direction. For example, one fuel tube 360 is provided for each of the plurality of scavenging ports 148 . An injection port 354 is formed in the fuel pipe 360 . A main pipe 364 is connected to the fuel pipe 360 via a fuel injection valve 362 . A plurality of fuel injection valves 362 are arranged at intervals in the circumferential direction. A plurality of fuel pipes 360 are connected to one fuel injection valve 362 . When the fuel injection valve 362 is opened, fuel gas is injected from the injection ports 354 of the plurality of connected fuel pipes 360 .

The injected fuel gas joins the active gas flow sucked into the scavenging port 148 . The fuel gas is sucked into the cylinder 110 through the scavenging port 148 together with the active gas. The fuel gas is mixed with the active gas and directed to the combustion chamber 130 where it is combusted in the same manner as in the above embodiments.

FIG. 10 is a diagram for explaining the arrangement of the fuel pipe 360. As shown in FIG. FIG. 10 shows a cross section of the cylinder jacket 114 taken along a vertical plane at a position including the through hole 114a. The outer shape of the fuel pipe 360 is shown as viewed vertically from above.

As shown in FIG. 10, the fuel pipe 360 is arranged with the central axis O of the cylinder 110 interposed therebetween. In FIG. 10, among the fuel pipes 360, the fuel pipe 360 located on the side of the inlet 146a of the scavenging chamber 146 is blacked out. The injection port 354 of the fuel pipe 360 located on the side of the inlet 146a is called a first injection port 354a, and the injection port 354 of the fuel pipe 360 located on the side away from the inlet 146a is called a second injection port 354b.

The first injection port 354a is located on the side of the inlet 146a with respect to the central axis O of the cylinder 110 (the right side of the dashed line in FIG. 10). The second injection port 354b is located on the side of the central axis O of the cylinder 110 that is separated from the inlet port 146a (the left side of the dashed line in FIG. 10).

Also in the modified example, the same control as in the embodiment described above is performed. For example, when the required output is equal to or less than the threshold A, the fuel control unit 202 controls the fuel injection device 152 to stop the supply of fuel gas to the first injection port 354a. Fuel gas is injected only from the second injection port 354b. The second injection port 354b side is farther from the inflow port 146a than the first injection port 354a side, and the flow velocity of the active gas is suppressed. Therefore, misfire is suppressed.

An embodiment of the present disclosure has been described above with reference to the accompanying drawings, but it goes without saying that the present disclosure is not limited to this embodiment. It is clear that a person skilled in the art can conceive of various modifications or modifications within the scope of the claims, and it is understood that these also belong to the technical scope of the present disclosure. be done.

For example, in the modified example described above, the case where the injection port 354 opens radially outward of the cylinder 110 from the scavenging port 148 has been described. However, the injection port 354 may open inside the scavenging port 148 .

In addition, in the above-described embodiment and modification, the first injection ports 154a and 354a are located on the inlet port 146a side with respect to the central axis O of the cylinder 110, and the second injection ports 154b and 354b are located at the center of the cylinder 110. The case where it is located on the side of the axis O separated from the inlet 146a has been described. In this case, on the side of the second injection ports 154b and 354b, the flow velocity of the active gas is slow, the diffusion of the fuel gas is suppressed, and the misfire suppression effect is high. However, at least the second injection ports 154b, 354b should be arranged farther from the inlet 146a than the first injection ports 154a, 354a. Here, the separation distance from the inflow port 146a may be a linear distance or the path length of the channel. Further, both the first injection ports 154a, 354a and the second injection ports 154b, 354b may be positioned on the inlet 146a side with respect to the central axis O of the cylinder 110. Both the first injection ports 154a, 354a and the second injection ports 154b, 354b may be located on the side of the central axis O of the cylinder 110 that is separated from the inlet 146a.

In addition, in the above-described embodiment and modification, the fuel control unit 202, when stopping the supply of fuel gas to the first injection ports 154a, 354a, causes the fuel gas to be injected from all the injection ports 154, 354. Also, the case of retarding the injection timing has been described. However, such retardation control is not an essential process.

Further, in the above-described embodiment and modified example, when the required output decreases across the threshold value A, the fuel control unit 202 reduces the second A case of increasing the amount of fuel supplied to the injection ports 154b and 354b has been described. When the load is low, fuel is injected only from the second injection ports 154b and 354b, so diffusion of the fuel gas is suppressed as described above. Therefore, compared to the case where the fuel gas is also injected from the first injection ports 154a and 354a, combustion is maintained even if the total amount of fuel gas supplied is small. Such control makes it possible to improve fuel efficiency. However, when the required output decreases across the threshold value A, the fuel control unit 202 supplies fuel to the second injection ports 154b and 354b in an amount equivalent to the amount of decrease that is no longer supplied from the first injection ports 154a and 354a. You can increase the amount.

INDUSTRIAL APPLICABILITY The present disclosure can be utilized in uniflow scavenged two-stroke engines.

100 uniflow scavenging two-cycle engine 100A uniflow scavenging two-cycle engine 110 cylinder 146 scavenging chamber 146a inlet 148 scavenging port 152 fuel injection device 154 injection port 154a first injection port 154b second injection port 202 fuel control unit (control unit)
354 injection port 354a first injection port 354b second injection port A threshold value O central axis

Claims (4)

a scavenging chamber having an inflow port;
a cylinder in which a scavenging port is arranged inside the scavenging chamber;
It opens radially outward of the cylinder from the inner peripheral surface of the cylinder, the inside of the scavenging port, or the scavenging port, and is separated from the first injection port and from the inflow port more than the first injection port. a plurality of injection ports including a second injection port arranged in a row;
a fuel injection device that supplies fuel gas to the injection port;
a control unit that controls the fuel injection device, stops supplying the fuel gas to the first injection port and injects the fuel gas from the second injection port when the required output is equal to or less than a threshold;
with
The first injection port is positioned on the inflow port side with respect to the central axis of the cylinder, and the second injection port is positioned on the side away from the inflow port with respect to the central axis of the cylinder. Niflow scavenging 2-cycle engine. a scavenging chamber having an inflow port;
a cylinder in which a scavenging port is arranged inside the scavenging chamber;
It opens radially outward of the cylinder from the inner peripheral surface of the cylinder, the inside of the scavenging port, or the scavenging port, and is separated from the first injection port and from the inflow port more than the first injection port. a plurality of injection ports including a second injection port arranged in a row;
a fuel injection device that supplies fuel gas to the injection port;
a control unit that controls the fuel injection device, stops supplying the fuel gas to the first injection port and injects the fuel gas from the second injection port when the required output is equal to or less than a threshold;
with
The control unit, when stopping the supply of the fuel gas to the first injection port, delays the injection timing more than when injecting the fuel gas from all the injection ports. . a scavenging chamber having an inflow port;
a cylinder in which a scavenging port is arranged inside the scavenging chamber;
It opens radially outward of the cylinder from the inner peripheral surface of the cylinder, the inside of the scavenging port, or the scavenging port, and is separated from the first injection port and from the inflow port more than the first injection port. a plurality of injection ports including a second injection port arranged in a row;
a fuel injection device that supplies fuel gas to the injection port;
a control unit that controls the fuel injection device, stops supplying the fuel gas to the first injection port and injects the fuel gas from the second injection port when the required output is equal to or less than a threshold;
with
When the amount of fuel gas supplied to the first injection port is reduced below the amount of fuel gas supplied to the second injection port, the control unit reduces the injection timing of the first injection port before the injection timing of the first injection port. A uniflow scavenging 2-cycle engine that retards the injection timing of two injection ports. The control unit stops supply of fuel gas to the first injection port when the required output decreases across the threshold value, and an amount smaller than the decrement that is no longer supplied from the first injection port. A uniflow scavenging two-cycle engine according to any one of claims 1 to 3 , wherein the amount of fuel supplied to said second injection port is increased by only .

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