JP6946977B2 - Variable compressor and engine system - Google Patents

Description

The present invention relates to a variable compression device and an engine system.

For example, Patent Document 1 discloses a large reciprocating piston combustion engine having a crosshead. The large reciprocating piston combustion engine of Patent Document 1 is a dual fuel engine capable of operating on both a liquid fuel such as heavy oil and a gaseous fuel such as natural gas. The large reciprocating piston combustion engine of Patent Document 1 changes the compression ratio by moving the piston rod by hydraulic pressure in order to correspond to both the compression ratio suitable for operation with liquid fuel and the compression ratio suitable for operation with gaseous fuel. An adjustment mechanism is provided in the cross head portion.

Japanese Unexamined Patent Publication No. 2014-20375

In an engine system having a compression adjustment device that changes the compression ratio as described above, a part of the working fluid supplied to the adjustment mechanism (hydraulic chamber) may be supplied to the inside of the piston as a cooling fluid via a piston rod. be. In order to supply the cooling fluid to the inside of the piston via the piston rod, it is conceivable to use the working fluid leaking from the hydraulic chamber side or to supply the cooling fluid from the opening formed on the side of the piston rod. However, when a working fluid leaking from the fluid chamber side is used, it is difficult to stably supply the working fluid. Further, when the cooling fluid is supplied to the inside of the piston rod from the opening formed on the side of the piston rod, the relative position between the piston rod and the fluid chamber differs depending on the compression ratio, so that the opening in the piston rod is opened. It is necessary to provide a large size, which limits the movable range of the piston rod.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to be able to stably supply a cooling fluid and to widen the range of motion of the piston rod.

In the present invention, as a first means for solving the above-mentioned problems, a fluid chamber in which the piston rod is moved in a direction of increasing the compression ratio by supplying a pressurized working fluid, and the compression ratio of the piston rod. A variable compression device having a restricting member for restricting movement in a direction of increasing the amount of water, wherein a flange is formed at an end of the piston rod on the fluid chamber side, and the flange and the restricting member are used as the bottom surface. It has a regulating member side fluid chamber formed between the two, a supply flow path for supplying cooling fluid to the regulating member side fluid chamber, and an opening end on the bottom surface, and the cooling fluid in the regulating member side fluid chamber. A configuration is adopted in which the piston rod has a flow path inside the piston rod that guides the inside of the piston rod.

As the second means, in the first means, a configuration is adopted in which an open end of the supply flow path is formed on the surface of the regulating member on the fluid chamber side on the regulating member side.

As a third means, in the first means, a fluid chamber forming member forming a part of the fluid chamber on the regulating member side by inserting the end portion of the piston rod is further provided, and a notch is formed on the bottom surface. The open end of the supply flow path is formed on the surface of the fluid chamber forming member on the fluid chamber side on the regulation member side, and the open end of the flow path in the piston rod is formed in the notch. , Is adopted.

As a fourth means, in any of the first to third means, the flange adopts a configuration in which the groove flow path is provided in a region overlapping the opening end of the flow path in the piston rod.

As a fifth means, a configuration is adopted in which the variable compression device described in any of the first to fourth means is provided.

According to the present invention, the flow path is guided from the flow path opening formed in the flange of the piston rod, which is the bottom surface of the upper fluid chamber, to the flow path in the piston rod. As a result, when supplying the cooling fluid to the piston, it is not necessary to form a radial flow path connected to the flow path in the piston rod from the side of the flange. Therefore, since the thickness of the flange of the piston rod is not limited, it is possible to sufficiently secure the amount of movement of the flange in the fluid chamber, that is, the amount of movement of the piston rod by the variable compression device while stably supplying the cooling fluid. ..

It is sectional drawing of the engine system in one Embodiment of this invention. It is a schematic cross-sectional view which shows a part of the engine system in one Embodiment of this invention. It is a schematic cross-sectional view which shows the flow of the hydraulic oil of the engine system in one Embodiment of this invention. It is a schematic cross-sectional view which shows the flow of hydraulic oil in the modification of the engine system in one Embodiment of this invention.

Hereinafter, an embodiment of the two-stroke engine according to the present invention will be described with reference to the drawings. In the drawings below, the scale of each member is appropriately changed in order to make each member recognizable.

[First Embodiment]
The engine system 100 of the present embodiment is mounted on a ship such as a large tanker, and has an engine 1, a supercharger 200, and a control unit 300 as shown in FIG. In the present embodiment, the supercharger 200 will be regarded as an auxiliary machine, and will be described as a separate body from the engine 1 (main engine). However, it is also possible to configure the supercharger 200 as a part of the engine 1.

The engine 1 is a multi-cylinder uniflow scavenging diesel engine, and has a gas operation mode in which a gaseous fuel such as natural gas is burned together with a liquid fuel such as heavy oil, and a diesel operation mode in which the liquid fuel such as heavy oil is burned. There is. In the gas operation mode, only the gas fuel may be burned. Such an engine 1 includes a frame 2, a cylinder portion 3, a piston 4, an exhaust valve unit 5, a piston rod 6, a crosshead 7, a hydraulic portion 8 (boosting mechanism), and a connecting rod 9. It has a crank angle sensor 10, a crankshaft 11, a scavenging reservoir 12, an exhaust reservoir 13, and an air cooler 14. Further, the cylinder is composed of the cylinder portion 3, the piston 4, the exhaust valve unit 5, and the piston rod 6.

The frame 2 is a strength member that supports the entire engine 1, and houses a crosshead 7, a hydraulic unit 8, and a connecting rod 9. Further, inside the frame 2, the crosshead pin 7a, which will be described later, of the crosshead 7 can reciprocate.

The cylinder portion 3 has a cylindrical cylinder liner 3a, a cylinder head 3b, and a cylinder jacket 3c. The cylinder liner 3a is a cylindrical member, and a sliding surface with the piston 4 is formed inside. The space surrounded by the inner peripheral surface of the cylinder liner 3a and the piston 4 is defined as the combustion chamber R1. Further, a plurality of scavenging ports S are formed in the lower part of the cylinder liner 3a. The scavenging port S is an opening arranged along the peripheral surface of the cylinder liner 3a, and communicates the scavenging chamber R2 inside the cylinder jacket 3c with the inside of the cylinder liner 3a. The cylinder head 3b is a lid member provided at the upper end of the cylinder liner 3a. The cylinder head 3b is connected to the exhaust reservoir 13 by forming an exhaust port H at the center in a plan view. Further, the cylinder head 3b is provided with a fuel injection valve (not shown). Further, an in-cylinder pressure sensor (not shown) is provided in the vicinity of the fuel injection valve of the cylinder head 3b. The in-cylinder pressure sensor detects the pressure in the combustion chamber R1 and transmits it to the control unit 300. The cylinder jacket 3c is a cylindrical member provided between the frame 2 and the cylinder liner 3a and into which the lower end of the cylinder liner 3a is inserted, and a scavenging chamber R2 is formed therein. Further, the scavenging chamber R2 of the cylinder jacket 3c is connected to the scavenging reservoir 12.

The piston 4 has a substantially cylindrical shape, is connected to a piston rod 6 described later, and is arranged inside the cylinder liner 3a. Further, a piston ring (not shown) is provided on the outer peripheral surface of the piston 4, and the gap between the piston 4 and the cylinder liner 3a is sealed by the piston ring. The piston 4 slides in the cylinder liner 3a together with the piston rod 6 due to the fluctuation of the pressure in the combustion chamber R1. Further, the inside of the piston 4 is hollow, and the ejection port 4a of the outer flow path R8, which will be described later, is formed on the lower surface side of the inside.

The exhaust valve unit 5 includes an exhaust valve 5a, an exhaust valve housing 5b, and an exhaust valve drive unit 5c. The exhaust valve 5a is provided inside the cylinder head 3b, and the exhaust valve driving portion 5c closes the exhaust port H in the cylinder portion 3. The exhaust valve housing 5b is a cylindrical housing that accommodates an end portion of the exhaust valve 5a. The exhaust valve drive unit 5c is an actuator that moves the exhaust valve 5a in the direction along the stroke direction of the piston 4.

The piston rod 6 is a long member having one end connected to the piston 4 and the other end connected to the crosshead pin 7a. The end of the piston rod 6 is inserted into the crosshead pin 7a and is connected so that the connecting rod 9 can rotate. Further, the piston rod 6 has a flange formed with a large diameter at a part of the end portion on the side of the cross head pin 7a. Further, as shown in FIG. 3, the piston rod 6 has a double pipe structure, and is composed of an outer pipe 6a and an inner pipe 6b. The piston rod 6 is bent downward (toward the lower surface of the flange) from the upper surface of the flange (the surface facing the lid member 7c described later) toward the inner pipe 6b on the inner side in the radial direction, and further bent toward the inner pipe 6b in the radial direction. An outer flow path R8 (a flow path inside the piston rod) passing between the inner pipe 6b and the inner pipe 6b is formed. That is, the flange of the piston rod 6 is formed with a flow path opening on the upper surface. Further, the inner pipe 6b is formed with an inner flow path R9 that communicates with the inner cavity of the piston 4 and extends to the lower end (end of the crosshead 7 side) of the piston rod 6.

The crosshead 7 has a crosshead pin 7a (fluid chamber forming member), a guide shoe 7b, and a lid member 7c (regulatory member). The cross head pin 7a is a columnar member that movably connects the piston rod 6 and the connecting rod 9, and the end portion of the piston rod 6 and the flange are inserted into the cross head pin 7a. A fluid chamber R3 (fluid chamber) is formed in which the fluid) is supplied and discharged. The cross head pin 7a is formed with an discharge port O penetrating along the axial direction of the cross head pin 7a below the center. The discharge port O is an opening through which the hydraulic oil (cooling fluid) that has passed through the inner flow path R9 of the piston rod 6 is discharged. Further, the crosshead pin 7a is provided with a supply flow path R4 for connecting the fluid chamber R3 and the plunger pump 8c described later, and a relief flow path R5 for connecting the fluid chamber R3 and the relief valve 8f described later. ..

The guide shoe 7b is a member that rotatably supports the cross head pin 7a, and moves along the stroke direction of the piston 4 along the stroke direction of the piston 4 along with the cross head pin 7a on a guide rail (not shown). When the guide shoe 7b moves along the guide rail, the cross head pin 7a is restricted from rotating and moving in a direction other than the linear direction along the stroke direction of the piston 4. The lid member 7c is an annular member fixed to the upper portion of the cross head pin 7a and into which the end portion of the piston rod 6 is inserted. Further, the lid member 7c is provided with a seal ring on the sliding surface with the piston rod 6. As a result, the upper hydraulic chamber R7 (regulatory member side fluid chamber) surrounded by the cross head pin 7a, the lid member 7c, and the flange of the piston rod 6 is formed. Further, the lid member 7c is formed with a part of a cooling oil supply flow path R6 (supply flow path) for guiding the hydraulic oil supplied to the upper hydraulic chamber R7. The cooling oil supply flow path R6 is two flow paths that guide a part of the hydraulic oil pumped by the supply pump 8a from the cross head pin 7a to the upper hydraulic chamber R7 via the lid member 7c. Each of the two cooling oil supply flow paths R6 has a supply opening (open end) formed on the surface of the lid member 7c on the upper hydraulic chamber R7 side. Further, such a crosshead 7 transmits the linear motion of the piston 4 to the connecting rod 9.

As shown in FIG. 2, the hydraulic unit 8 includes a supply pump 8a, a swing pipe 8b, a plunger pump 8c, a first check valve 8d and a second check valve 8e included in the plunger pump 8c, and a relief valve. It has 8f. Further, the piston rod 6, the crosshead 7, the hydraulic unit 8, and the control unit 300 function as the variable compression device in the present invention.

The supply pump 8a is a pump that boosts the hydraulic oil supplied from the hydraulic oil tank (not shown) and supplies it to the plunger pump 8c based on the instruction from the control unit 300. The supply pump 8a is driven by the electric power of the battery of the ship and can be operated before the liquid fuel is supplied to the combustion chamber R1. The swing pipe 8b is a pipe that connects the supply pump 8a and the plunger pump 8c of each cylinder, and swings between the plunger pump 8c that moves along with the crosshead pin 7a and the fixed supply pump 8a. It is possible.

The plunger pump 8c is fixed to a cross head pin 7a, and has a rod-shaped plunger 8c1, a cylindrical cylinder 8c2 that slidably accommodates the plunger 8c1, and a plunger drive unit 8c3. When the plunger 8c1 is connected to a drive unit (not shown), the plunger pump 8c slides in the cylinder 8c2 to boost the hydraulic oil and supply it to the fluid chamber R3. Further, the cylinder 8c2 is provided with a first check valve 8d at the opening on the discharge side of the hydraulic oil provided at the end, and a second check valve 8e is provided at the opening on the suction side provided on the side peripheral surface. It is provided. The plunger drive unit 8c3 is connected to the plunger 8c1 and reciprocates the plunger 8c1 based on an instruction from the control unit 300.

The first check valve 8d has a structure in which the valve body is urged toward the inside of the cylinder 8c2 to close the valve, and prevents the hydraulic oil supplied to the fluid chamber R3 from flowing back into the cylinder 8c2. doing. Further, in the first check valve 8d, the valve body is pushed by the hydraulic oil when the pressure of the hydraulic oil in the cylinder 8c2 becomes equal to or higher than the urging force (valve opening pressure) of the urging member of the first check valve 8d. To open the valve. The second check valve 8e is urged toward the outside of the cylinder 8c2 to prevent the hydraulic oil supplied to the cylinder 8c2 from flowing back to the supply pump 8a. Further, in the second check valve 8e, when the pressure of the hydraulic oil supplied from the supply pump 8a becomes equal to or higher than the urging force (valve opening pressure) of the urging member of the second check valve 8e, the valve body becomes the hydraulic oil. The valve is opened by being pushed. The first check valve 8d is supplied from the supply pump 8a during steady operation in which the valve opening pressure is higher than the valve opening pressure of the second check valve 8e and is operated at a preset compression ratio. The valve does not open due to the pressure of the hydraulic oil.

The relief valve 8f is provided on the cross head pin 7a and has a main body portion 8f1 and a relief valve driving portion 8f2. The main body 8f1 is a valve connected to the fluid chamber R3 and a hydraulic oil tank (not shown). The relief valve drive unit 8f2 is connected to the valve body of the main body 8f1 and opens and closes the main body 8f1 based on an instruction from the control unit 300. When the relief valve 8f is opened by the relief valve drive unit 8f2, the hydraulic oil stored in the fluid chamber R3 is returned to the hydraulic oil tank.

As shown in FIG. 1, the connecting rod 9 is a long member that is connected to the cross head pin 7a and also to the crankshaft 11. The connecting rod 9 converts the linear motion of the piston 4 transmitted to the crosshead pin 7a into a rotary motion. The crank angle sensor 10 is a sensor for measuring the crank angle of the crankshaft 11, and transmits a crank pulse signal for calculating the crank angle to the control unit 300.

The crankshaft 11 is a long member connected to a connecting rod 9 provided in a cylinder, and is rotated by a rotational motion transmitted by each connecting rod 9, thereby transmitting power to, for example, a screw or the like. The scavenging reservoir 12 is provided between the cylinder jacket 3c and the supercharger 200, and the air pressurized by the supercharger 200 flows into the scavenging reservoir 12. Further, the scavenging reservoir 12 is provided with an air cooler 14 inside. The exhaust reservoir 13 is a tubular member connected to the exhaust port H of each cylinder and connected to the turbocharger 200. The gas discharged from the exhaust port H is temporarily stored in the exhaust reservoir 13 and is supplied to the supercharger 200 in a state where pulsation is suppressed. The air cooler 14 is a device that cools the air inside the scavenging reservoir 12.

The supercharger 200 is a device that pressurizes the air sucked from the intake port (not shown) by a turbine rotated by the gas discharged from the exhaust port H and supplies the air to the combustion chamber R1.

The control unit 300 is a computer that controls the fuel supply amount and the like based on the operation and the like by the operator of the ship. Further, the control unit 300 changes the compression ratio in the combustion chamber R1 by controlling the hydraulic unit 8. Specifically, the control unit 300 controls the plunger pump 8c, the supply pump 8a, and the relief valve 8f, and adjusts the amount of hydraulic oil in the fluid chamber R3 to change the position of the piston rod 6 and reduce the compression ratio. To change.

Such an engine system 100 is a device that ignites and explodes the fuel injected into the combustion chamber R1 from a fuel injection valve (not shown) to slide the piston 4 in the cylinder liner 3a and rotate the crankshaft 11. be. More specifically, the fuel supplied to the combustion chamber R1 is mixed with the air flowing in from the scavenging port S, and then compressed by the piston 4 moving toward the top dead center, and the temperature rises naturally. Ignite. Further, in the case of liquid fuel, the temperature rises in the combustion chamber R1 to vaporize and spontaneously ignite.

Then, the fuel in the combustion chamber R1 spontaneously ignites and rapidly expands, and pressure is applied to the piston 4 toward the bottom dead center. As a result, the piston 4 moves toward the bottom dead center, the piston rod 6 is moved along with the piston 4, and the crankshaft 11 is rotated via the connecting rod 9. Further, when the piston 4 is moved to the bottom dead center, pressurized air flows into the combustion chamber R1 from the scavenging port S. When the exhaust valve unit 5 is driven, the exhaust port H is opened, and the exhaust gas in the combustion chamber R1 is pushed out to the exhaust reservoir 13 by the pressurized air.

When the compression ratio is increased, the supply pump 8a is driven by the control unit 300, and hydraulic oil is supplied to the plunger pump 8c. Then, the control unit 300 drives the plunger pump 8c to pressurize the hydraulic oil until the pressure is such that the piston rod 6 can be lifted, and supplies the hydraulic oil to the fluid chamber R3. The pressure of the hydraulic oil in the fluid chamber R3 lifts the flange of the piston rod 6, and the top dead center position of the piston 4 is moved upward (exhaust port H side) accordingly.

When the compression ratio is reduced, the relief valve 8f is driven by the control unit 300, and the fluid chamber R3 and the hydraulic oil tank (not shown) are in communication with each other. Then, the load of the piston rod 6 is applied to the hydraulic oil in the fluid chamber R3, and the hydraulic oil in the fluid chamber R3 is pushed out to the hydraulic oil tank via the relief valve 8f. As a result, the hydraulic oil in the fluid chamber R3 is reduced, the piston rod 6 is moved downward (crankshaft 11 side), and the top dead center position of the piston 4 is moved downward accordingly.

Next, the flow of the hydraulic oil on the piston rod 6 side will be described.
As shown in FIG. 3, a part of the hydraulic oil supplied from the supply pump 8a passes through the cooling oil supply flow path R6 and is supplied from the lid member 7c to the upper hydraulic chamber R7. As a result, the upper hydraulic chamber R7 is filled with hydraulic oil. Then, the hydraulic oil in the upper hydraulic chamber R7 flows into the outer flow path R8 from the flow path opening formed on the upper surface of the flange of the piston rod 6 (the bottom surface of the upper hydraulic chamber R7), and flows upward along the piston rod 6. It is guided in the (compression direction) and is discharged from the ejection port 4a to the inside of the piston 4. Further, the hydraulic oil discharged to the inside of the piston 4 is guided to the inner flow path R9, discharged from the lower end of the piston rod 6, and discharged to the outside from the discharge port O.

According to this embodiment, hydraulic oil is supplied from above the upper hydraulic chamber R7 and guided to the outer flow path R8 from the flow path opening formed in the flange of the piston rod 6 which is the bottom surface of the upper hydraulic chamber R7. do. As a result, when supplying hydraulic oil (cooling oil) to the piston 4, it is not necessary to form an opening on the peripheral surface (sliding surface with the crosshead pin 7a) of the flange. Therefore, since the thickness of the flange is not limited, the amount of movement of the flange in the crosshead pin 7a, that is, the amount of movement of the piston rod 6 by the variable compression mechanism can be sufficiently secured.

Further, according to the present embodiment, hydraulic oil is supplied toward the upper hydraulic chamber R7 below the opening of the cooling oil supply flow path R6 formed in the lid member 7c. As a result, the hydraulic oil can be supplied regardless of the position of the piston rod 6 with respect to the cross head pin 7a due to the change in the compression ratio.

[Second Embodiment]
A modified example of the first embodiment will be described as a second embodiment with reference to FIG. It should be noted that the configuration common to the first embodiment has the same reference numerals, and the description thereof will be omitted. Further, in FIG. 4, the configuration of the hydraulic unit 8 is not shown.

In the present embodiment, the flange of the piston rod 6 is formed with a stepped notch on the surface facing the lid member 7c (the bottom surface of the upper hydraulic chamber R7). An opening of the outer flow path R8 is formed in the notch formed in the flange of the piston rod 6. The cooling oil supply flow path R6 is a linear flow path from the radial outside to the inside of the piston rod 6 at the cross head pin 7a, and is a supply opening on the side peripheral surface (inside of the cross head pin 7a) of the upper hydraulic chamber R7. (Open end) is formed. The supply opening is formed on the upper side (near the lid member 7c of the cross head pin 7a) in the vertical direction. As a result, even when the piston rod 6 is moved in the high compression ratio direction and the flange is in contact with the lid member 7c, the supply opening faces the notch of the flange and passes through the upper hydraulic chamber R7. Can communicate with the outer flow path R8. In this case, it is not necessary to form the cooling oil supply flow path R6 in the lid member 7c, and it is easy to form the flow path of the cooling oil supply flow path R6.

Although the preferred embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiment. The various shapes and combinations of the constituent members shown in the above-described embodiment are examples, and can be variously changed based on design requirements and the like without departing from the spirit of the present invention.

In the above embodiment, the flange of the piston rod 6 may be formed with a groove flow path passing through a position overlapping the flow path opening of the outer flow path R8. In this case, the groove flow path can efficiently guide the hydraulic oil flowing into the upper hydraulic chamber R7 to the flow path opening.

Further, in the second embodiment, the notch formed in the flange is stepped, but the present invention is not limited to this. For example, the edge of the surface of the flange facing the lid member 7c may be cut out in a tapered shape, and a flow path opening of the outer flow path R8 may be formed on the tapered surface. Even in this case, it is possible to obtain the same effect as that of the second embodiment.

Further, in the above embodiment, the hydraulic oil is supplied to the upper hydraulic chamber R7 as cooling oil, but the present invention is not limited to this. For example, the cooling oil pump may be provided as a separate body from the supply pump 8a, and the cooling oil may be supplied as a separate system from the hydraulic oil.

1 Engine 2 Frame 3 Cylinder 3a Cylinder liner 3b Cylinder head 3c Cylinder jacket 4 Piston 4a Ejection 5 Exhaust valve unit 5a Exhaust valve 5b Exhaust valve housing 5c Exhaust valve drive 6 Piston rod 6a Outer pipe 6b Inner pipe 7 Cross head 7a Cross head pin 7b Guide shoe 7c Lid member 8 Hydraulic part 8a Supply pump 8b Swing pipe 8c Plunger pump 8c1 Plunger 8c2 Cylinder 8c3 Plunger drive part 8d 1st check valve 8e 2nd check valve 8f Relief valve 8f1 Main body 8f2 Relief valve Drive unit 9 Connecting rod 10 Cylinder angle sensor 11 Cylinder shaft 12 Sweeping air reservoir 13 Exhaust reservoir 14 Air cooler 100 Engine system 200 Supercharger 300 Control unit H Exhaust port O Exhaust port R1 Combustion chamber R2 Sweeping chamber R3 Fluid chamber R4 Supply flow Road R5 Relief flow path R6 Cooling oil supply flow path R7 Upper hydraulic chamber R8 Outer flow path R9 Inner flow path S Sweep port

Claims (4)

A variable compression device having a fluid chamber in which the piston rod is moved in a direction of increasing the compression ratio by supplying a pressurized working fluid, and a regulating member for restricting the movement of the piston rod in a direction of increasing the compression ratio. And
In the piston rod, a flange is formed at the end on the fluid chamber side.
A fluid chamber on the regulation member side formed between the flange and the regulation member with the flange as the bottom surface,
A supply flow path for supplying the cooling fluid to the fluid chamber on the regulating member side and a flow path in the piston rod having an opening end on the bottom surface and guiding the cooling fluid in the fluid chamber on the regulating member side to the inside of the piston rod. A variable compression device characterized by having. The variable compression device according to claim 1, wherein an open end of the supply flow path is formed on the surface of the regulating member on the fluid chamber side on the regulating member side. A fluid chamber forming member that forms a part of the fluid chamber on the regulation member side by inserting the end portion of the piston rod is further provided.
A notch is formed on the bottom surface,
An open end of the supply flow path is formed on the surface of the fluid chamber forming member on the regulation member side and the fluid chamber side.
The variable compression device according to claim 1, wherein an open end of the flow path in the piston rod is formed in the notch. An engine system comprising the variable compression device according to any one of claims 1 to 3.

Images