WO2019039451A1 - Variable compression device and engine system - Google Patents

Abstract

The invention relates to a variable compression device provided with: a piston rod (6); a connecting member (7a) connected to the piston rod; a fluid chamber (R3) which is disposed between the connecting member and the piston rod and which, when an operating fluid having an increased pressure is supplied thereto, moves the piston rod relative to the connecting element in a direction in which a compression ratio increases; and a restriction member (15) which can contact and move away from the piston rod and which, when the piston rod is moved in the direction in which the compression ratio is increasing, comes into contact with the piston rod to limit the movement of the piston rod so as to maintain the compression ratio.

Description

Variable compressor and engine system

The present disclosure relates to a variable compression device and an engine system.
Priority is claimed on Japanese Patent Application No. 2017-159610, filed Aug. 22, 2017, the content of which is incorporated herein by reference.

For example, Patent Document 1 discloses a large reciprocating piston combustion engine having a crosshead. The large-sized reciprocating piston combustion engine of Patent Document 1 is a dual fuel engine that can be operated with both liquid fuel such as heavy oil and gaseous fuel such as natural gas. In the large reciprocating piston combustion engine of Patent Document 1, an adjustment mechanism capable of changing the compression ratio is used in the crosshead portion to cope with both the compression ratio suitable for operation with liquid fuel and the compression ratio suitable for operation with gaseous fuel. It is provided.

Japan JP 2014-20375

The adjustment mechanism of Patent Document 1 raises the compression ratio by lifting the piston rod in the high compression ratio direction by the hydraulic pressure chamber provided in the crosshead. However, when the piston rod is hydraulically lifted, the combustion pressure transmitted from the combustion chamber is applied to the hydraulic fluid, the hydraulic fluid is elastically compressed, and the compression ratio is instantaneously reduced every cycle. In addition, when the pressure in the combustion chamber does not rise when the piston rod is lowered in the low compression ratio direction, the inertia force of the piston rod may unintentionally increase the compression ratio. Such unintended fluctuation of the compression ratio at the time of high compression operation may reduce the engine performance or the performance of the seal member in the piston rod.

The present disclosure is made in view of the above-described problems, and aims to prevent an unintended change in compression ratio and maintain the compression ratio.

A variable compression device according to an aspect of the present disclosure is a variable compression device that changes a compression ratio in a combustion chamber of an engine, and includes a piston rod, a connection member connected to the piston rod, the connection member, and the piston rod And a fluid chamber that moves the piston rod in a direction to increase the compression ratio with respect to the connection member by being supplied with a pressurized working fluid, and capable of coming into contact with and separating from the piston rod And a restricting member that abuts on the piston rod and restricts the movement of the piston rod so as to maintain the compression ratio when the piston rod is moved in a direction to increase the compression ratio.

In the variable compression device according to the above aspect, the restriction member includes a restriction pin movable toward the piston rod in a cross direction intersecting the extension direction of the piston rod, and the piston rod is The restriction pin may have a recess into which it can be inserted.

In the variable compression device according to the above aspect, the restriction member may be movable along the extension direction of the piston rod, and may have a support that supports the piston rod from below.

In the variable compression device according to the above aspect, the piston rod has an opening into which the restriction member can be inserted, the restriction member is inserted into the opening of the piston rod, and the piston rod is suspended and supported from above May have a supporting portion.

An engine system according to an aspect of the present disclosure includes the variable compression device according to the above aspect.

According to the present disclosure, when the piston rod is moved in the direction of increasing the compression ratio, the restricting member abuts on the piston rod to restrict the movement of the piston rod. Thereby, when the working fluid in the fluid chamber is elastically compressed due to the combustion pressure or when the pressure in the combustion chamber does not rise, the movement of the piston rod is restricted to prevent the reduction or increase of the compression ratio and maintain the compression ratio. can do.

1 is a cross-sectional view of an engine system in accordance with an embodiment of the present disclosure. 1 is a partial cross-sectional view of an engine system in accordance with an embodiment of the present disclosure. FIG. 7 is a partial cross-sectional view of a portion of a variable compression device in accordance with an embodiment of the present disclosure. It is a fragmentary sectional view showing the modification of the variable compression device in one embodiment of this indication. It is a fragmentary sectional view showing the modification of the variable compression device in one embodiment of this indication. It is a fragmentary sectional view showing the modification of the variable compression device in one embodiment of this indication.

Hereinafter, an embodiment of an engine system 100 in the present disclosure will be described with reference to the drawings.

The engine system 100 according to the present embodiment is mounted on a vessel such as a large tanker, for example, and includes an engine 1, a supercharger 200, and a control unit 300, as shown in FIG. In the present embodiment, the turbocharger 200 will be described as an accessory and will be described separately from the engine 1 (main engine). However, it is also possible to configure the turbocharger 200 as a part of the engine 1.

The engine 1 is a multi-cylinder uniflow scavenged diesel engine. The engine 1 has a gas operation mode in which a gaseous fuel such as natural gas is burned with a liquid fuel such as heavy oil, and a diesel operation mode in which a liquid fuel such as heavy oil is burned. In the gas operation mode, only gaseous fuel may be burned. As shown in FIGS. 1 and 2, the engine 1 includes a frame 2, a cylinder 3, a piston 4, an exhaust valve unit 5, a piston rod 6, a crosshead 7, a hydraulic unit 8, and a connecting rod. A crank angle sensor 10, a crank shaft 11, a scavenging air reservoir 12, an exhaust reservoir 13, an air cooler 14, and a movement restricting portion 15 (regulating member) are provided. Further, a cylinder is constituted by 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 the crosshead 7, the hydraulic unit 8, and the connecting rod 9 are accommodated. Further, in the inside of the frame 2, a cross head pin 7 a described later of the cross head 7 can be reciprocated.

The cylinder portion 3 includes a cylindrical cylinder cover 3a, a cylinder liner 3b, a cylinder head 3c and a cylinder jacket 3d. The cylinder liner 3b is a cylindrical member accommodated in the cylinder cover 3a. A sliding surface with the piston 4 is formed on the inner side (inner peripheral surface) of the cylinder liner 3b. A space surrounded by the inner circumferential surface of the cylinder liner 3b and the piston 4 is taken as a combustion chamber R1. Further, a plurality of scavenging ports S are formed in the lower portion of the cylinder liner 3b. The scavenging port S is an opening arranged along the circumferential surface of the cylinder liner 3b, and communicates the scavenging chamber R2 inside the cylinder jacket 3d with the inside of the cylinder liner 3b. The cylinder head 3c is a lid member provided on the upper end portion of the cylinder cover 3a. An exhaust port H is formed at a central portion of the cylinder head 3 c in a plan view, and is connected to the exhaust reservoir 13. Further, the cylinder head 3c is provided with a fuel injection valve (not shown). The cylinder jacket 3d is a cylindrical member provided between the frame 2 and the cylinder cover 3a and into which the lower end of the cylinder liner 3b is inserted. A scavenging chamber R2 is formed inside the cylinder jacket 3d. The scavenging chamber R2 of the cylinder jacket 3d is connected to the scavenging air reservoir 12.

The piston 4 has a substantially cylindrical shape, is connected to a piston rod 6 described later, and is disposed inside the cylinder liner 3b. Further, a piston ring (not shown) is provided on the outer peripheral surface of the piston 4, and the piston ring seals the gap between the piston 4 and the cylinder liner 3b. The piston 4 slides in the cylinder liner 3b with the piston rod 6 due to the pressure fluctuation in the combustion chamber R1.

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

The piston rod 6 is an elongated 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 the connecting rod 9 is connected so as to be rotatable. A part of an end of the piston rod 6 on the cross head pin 7 a side has a large diameter portion whose diameter is formed to be large. In addition, a seal member is provided on an outer periphery of a portion of the piston rod 6 which is disposed in a hydraulic pressure chamber R3 described later.

The cross head 7 includes a cross head pin 7a (connection member), a guide shoe 7b, and a lid member 7c. The cross head pin 7 a is a cylindrical member that movably connects the piston rod 6 and the connecting rod 9. A hydraulic chamber R3 (fluid chamber) is formed in the insertion space where the end of the piston rod 6 of the crosshead pin 7a is inserted, in which supply and discharge of hydraulic fluid (working fluid) are performed. Below the center of the crosshead pin 7a, an outlet hole O is formed to extend along the axial direction of the crosshead pin 7a. The outlet hole O is an opening through which the cooling oil having passed through a cooling flow passage (not shown) of the piston rod 6 is discharged. Further, the crosshead pin 7a is provided with a supply flow passage R4 connecting the hydraulic pressure chamber R3 and the plunger pump 8c described later, and a relief flow passage R5 connecting the hydraulic pressure chamber R3 and the relief valve 8f described later . Further, in the cross head 7, an auxiliary flow passage R6 is formed which communicates the cross head pin 7a with the lid member 7c and opens in the circumferential surface of the lid member 7c and the circumferential surface of the cross head pin 7a.

The guide shoe 7b rotatably supports the crosshead pin 7a. The guide shoe 7b moves on a guide rail (not shown) along the stroke direction of the piston 4 along with the cross head pin 7a. By the movement of the guide shoe 7b along the guide rail, the crosshead pin 7a is restricted from rotational movement and movement other than linear movement along the stroke direction of the piston 4. The lid member 7c is an annular member fixed to the upper portion of the crosshead pin 7a and into which the end of the piston rod 6 is inserted. The 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 rocking pipe 8b, a plunger pump 8c, a first check valve 8d and a second check valve 8e which the plunger pump 8c has, and a relief valve. It is equipped with 8f. Further, the piston rod 6, the crosshead 7, the hydraulic unit 8, the movement restricting unit 15, and the control unit 300 function as a variable compression device in the present disclosure. Furthermore, the supply pump 8a, the rocking pipe 8b, the plunger pump 8c, the first check valve 8d, and the second check valve 8e correspond to the pressurizing fluid supply unit in the present disclosure.

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

The plunger pump 8c is fixed to the crosshead pin 7a. The plunger pump 8c includes a rod-like plunger 8c1, a cylindrical cylinder 8c2 slidably accommodating the plunger 8c1, and a plunger driving unit 8c3. The plunger pump 8c slides in the cylinder 8c2 by connecting the plunger 8c1 to a drive unit (not shown), and pressurizes the hydraulic oil and supplies it to the hydraulic chamber R3. A first check valve 8d is provided at the discharge side opening of the hydraulic oil provided at the end of the cylinder 8c2, and a suction side opening of the hydraulic oil provided at the side circumferential surface of the cylinder 8c2 is provided first. 2 A check valve 8e is provided. The plunger driving 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 is closed by urging the valve toward the inside of the cylinder 8c2, and prevents the hydraulic oil supplied to the hydraulic chamber R3 from flowing back to the cylinder 8c2 doing. In the first check valve 8d, when the pressure of the hydraulic oil in the cylinder 8c2 becomes equal to or greater than the biasing force (opening pressure) of the biasing member of the first check valve 8d, the valve body is pushed by the hydraulic oil. Open the valve. The second check valve 8e is biased toward the outside of the cylinder 8c2, and prevents the hydraulic oil supplied to the cylinder 8c2 from flowing back to the supply pump 8a. In the second check valve 8e, when the pressure of the hydraulic oil supplied from the supply pump 8a is equal to or greater than the biasing force (opening pressure) of the biasing member of the second check valve 8e, the valve body becomes hydraulic fluid. It opens by being pushed. Note that the valve opening pressure of the first check valve 8d is higher than the valve opening pressure of the second check valve 8e, and in the steady-state operation operated with the compression ratio set in advance, the first check valve 8d is The valve does not open due to the pressure of the hydraulic oil supplied from the supply pump 8a.

The relief valve 8 f is provided on the cross head pin 7 a. The relief valve 8 f includes a main body 8 f 1 and a relief valve drive 8 f 2. The main body 8f1 is a valve connected to the hydraulic pressure 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. The relief valve 8f is opened by the relief valve drive unit 8f2, whereby the hydraulic oil stored in the hydraulic pressure chamber R3 is returned to the hydraulic oil tank.

As shown in FIG. 1, the connecting rod 9 is an elongated member connected to the crosshead pin 7 a and connected to the crankshaft 11. The connecting rod 9 converts the linear motion of the piston 4 transmitted to the crosshead pin 7a into rotational 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 an elongated member connected to a connecting rod 9 provided in a cylinder, and transmits power to, for example, a screw or the like by being rotated by rotational motion transmitted by the connecting rod 9. The scavenging air reservoir 12 is provided between the cylinder jacket 3 d and the supercharger 200, and the air pressurized by the supercharger 200 flows in. Further, an air cooler 14 is provided inside the scavenging air reservoir 12. 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 thus supplied to the turbocharger 200 in a state where pulsation is suppressed. The air cooler 14 cools the air inside the scavenging air reservoir 12.

As shown in FIG. 3, the movement restricting portion 15 is provided on the cross head pin 7 a. The movement restricting unit 15 includes a drive unit 15a, a worm wheel unit 15b, and a worm 15c (support unit). The drive unit 15a is connected to the worm wheel unit 15b via a ratchet gear. The drive unit 15 a rotates the worm wheel unit 15 b around a rotation axis intersecting the stroke direction of the piston 4 based on an instruction from the control unit 300. The ratchet gear is provided with a switching mechanism for switching the rotational direction of the worm wheel portion 15b, and the rotational direction of the worm wheel portion 15b is switched clockwise or counterclockwise with respect to the rotational axis. Can. Further, the switching mechanism is configured of two locking members that can be locked in contact with the teeth of the ratchet gear, and a cam that switches contact and non-contact with each of the two locking members. The worm wheel portion 15b is rotated about the rotation axis by the drive portion 15a. A tooth that meshes with the worm 15c is provided at an end of the worm wheel portion 15b on the hydraulic pressure chamber R3 side. The worm 15 c is a cylindrical member in which the piston rod 6 is disposed at the center. Thread-like teeth are provided on the outer peripheral surface of the worm 15c. The worm 15c is accommodated at the bottom of the hydraulic chamber R3. The worm 15c is moved toward the top dead center (in the direction to increase the compression ratio) by meshing with the teeth of the worm wheel portion 15b. The worm 15 c contacts the lower surface of the large diameter portion of the piston rod 6 in a state of being moved in the top dead center direction, and supports the piston rod 6 from below.

The turbocharger 200 pressurizes air taken in from an intake port (not shown) by the turbine rotated by the gas discharged from the exhaust port H, and supplies it to the combustion chamber R1.

The control unit 300 is a computer that controls the amount of supplied fuel and the like based on an operation and the like by the operator of the ship. The control unit 300 also controls the hydraulic unit 8 to change the compression ratio in the combustion chamber R1. 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 hydraulic pressure chamber R3 to change the position of the piston rod 6, thereby reducing the compression ratio. Change The control unit 300 also raises the worm 15 c in the top dead center direction by controlling the drive unit 15 a of the movement restricting unit 15.

The engine system 100 causes the piston 4 to slide in the cylinder liner 3 b by igniting and detonating the fuel injected from the fuel injection valve (not shown) into the combustion chamber R 1, and rotates the crankshaft 11. 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 movement of the piston 4 toward the top dead center to raise the temperature, resulting in natural Ignite. In the case of liquid fuel, it is vaporized by temperature rise in the combustion chamber R1 and spontaneously ignited.

Then, the fuel in the combustion chamber R1 is rapidly ignited by natural ignition, and the pressure is applied to the piston 4 in the direction of the bottom dead center. As a result, the piston 4 moves in the bottom dead center direction, the piston rod 6 is moved along with the piston 4, and the crankshaft 11 is rotated via the connecting rod 9. Further, as the piston 4 is moved to the bottom dead center, pressurized air flows from the scavenging port S into the combustion chamber R1. The exhaust port H is opened by driving the exhaust valve unit 5, and the exhaust gas in the combustion chamber R1 is pushed out to the exhaust reservoir 13 by the pressurized air.

In order to increase the compression ratio, the control unit 300 drives the supply pump 8a to supply hydraulic oil to the plunger pump 8c. Then, the control unit 300 drives the plunger pump 8 c to press the hydraulic oil to a pressure capable of lifting the piston rod 6, and supplies the hydraulic oil to the hydraulic chamber R 3. The end of the piston rod 6 is lifted by the pressure of the hydraulic fluid in the hydraulic chamber R3, and the top dead center position of the piston 4 is moved upward (exhaust port H side) accordingly. Then, the control unit 300 controls the drive unit 15a to raise the worm 15c until it abuts on the piston rod 6, at the same time as the piston rod 6 is moved by the hydraulic fluid in the high compression ratio direction. Thereby, when the piston rod 6 is moved to the position of high compression ratio, the worm 15 c supports a part of the load of the piston rod 6.

When the compression ratio is reduced, the relief valve 8f is driven by the control unit 300, and the hydraulic pressure chamber R3 and a hydraulic oil tank (not shown) are in communication. Then, the load of the piston rod 6 is applied to the hydraulic oil in the hydraulic chamber R3, and the hydraulic oil in the hydraulic chamber R3 is pushed out to the hydraulic oil tank via the relief valve 8f. As a result, the hydraulic oil in the hydraulic chamber R3 decreases, and the piston rod 6 is moved downward (toward the crankshaft 11), and the top dead center position of the piston 4 is moved downward accordingly. Then, at the same time as the piston rod 6 is moved in the low compression ratio direction by the hydraulic fluid, the control unit 300 controls the drive unit 15a to separate the worm 15c from the piston rod 6 and complete the bottom of the hydraulic chamber R3 completely. Lower it until it is contained.

According to the variable compression device in the present embodiment, the movement restricting portion 15 supports the piston rod 6 from below at the time of operation with a high compression ratio, thereby restricting the movement of the piston rod 6 in the low compression ratio direction (downward). It is possible to prevent an unintended decrease in compression ratio and maintain the compression ratio. Therefore, according to the variable compression device in the present embodiment, it is possible to prevent the performance of the engine 1 from being degraded and to prevent the performance of the seal member provided on the piston rod 6 from being degraded.

The preferred embodiments of the present disclosure have been described above with reference to the drawings, but the present disclosure is not limited to the above-described embodiments. The shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and various changes can be made based on design requirements and the like without departing from the spirit of the present disclosure.

As shown in FIG. 4, the movement restriction unit 15 may include a drive unit 15 a, a worm wheel unit 15 b, and a worm 15 d (support unit). The worm 15d is a cylindrical member provided below the end of the piston rod 6 disposed below the hydraulic pressure chamber R3. Similar to the worm 15c of the above-described embodiment, the worm 15d can be brought into contact with and separated from the piston rod 6 by meshing with the teeth of the worm wheel portion 15b. Also in such a configuration, as in the above embodiment, the piston rod 6 is supported from below by the worm 15 d to restrict movement of the piston rod 6 in the low compression ratio direction (downward), and the compression ratio Can be prevented.

Further, as shown in FIG. 5, the movement restricting portion 15 may include a drive portion 15a, a ratchet gear 15e, and a support rod 15f (supporting portion, restricting pin). Further, in this case, a groove 6 a (recess) extending in the circumferential direction is formed on the circumferential surface of the large diameter portion of the piston rod 6. The ratchet gear 15e is provided between the drive unit 15a and the support rod 15f, and transmits the power of the drive unit 15a to the support rod 15f. A thread groove is formed on the circumferential surface of the support rod 15f. The support rod 15f is arranged such that the tip of the support rod 15f engages with the groove 6a of the piston rod 6 in the high compression operation. The support rod 15 f is movable by the drive portion 15 a in a direction intersecting with the stroke direction of the piston 4, and can be brought into contact with and separated from the piston rod 6. In the case of such a configuration, the piston rod 6 is supported from the side by the support rod 15f to restrict movement of the piston rod 6 in the low compression ratio direction (downward) and the high compression ratio direction (upward). Unintended reduction and increase in compression ratio can be prevented.

Further, as shown in FIG. 6, the movement restricting portion 15 may include a drive portion 15a, a ratchet gear 15g, a worm 15h, a worm wheel 15i, and a suspending rod 15j (supporting portion). Further, in this case, a screw hole is formed in the upper surface portion of the large diameter portion of the piston rod 6. The worm 15h is rotated by the ratchet gear 15g and transmits rotational motion to the worm wheel 15i. The worm wheel 15i is provided between the lid 7c and the piston rod 6. A hanging rod 15j is inserted and fixed inside the worm wheel 15i. A thread groove is formed on the circumferential surface of the suspension rod 15j. The hanging rod 15j is arranged such that the screw groove of the hanging rod 15j is screwed into the screw hole of the piston rod 6 at the time of high compression ratio operation. The suspension rod 15 j is movable in the stroke direction of the piston 4 by the drive unit 15 a, and can be abutted on and separated from the piston rod 6. In the case of such a configuration, the piston rod 6 is supported from above by the suspension rod 15j, thereby restricting the movement of the piston rod 6 in the low compression ratio direction (downward) and the high compression ratio direction (upward). And a decrease in compression ratio can be prevented.

According to the present disclosure, it is possible to prevent an unintended change in compression ratio and maintain the compression ratio.

DESCRIPTION OF SYMBOLS 1 engine 2 frame structure 3 cylinder portion 3a cylinder cover 3b cylinder liner 3c cylinder head 3d cylinder jacket 4 piston 5 exhaust valve unit 5a exhaust valve 5b exhaust valve housing 5c exhaust valve drive portion 6 piston rod 6a groove 7 cross head 7a cross head pin (connection Element)
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 First check valve 8e Second check valve 8f Relief valve 8f1 Body part 8f2 Relief valve drive part 8 g Boost pump 9 Connecting rod 10 Crank angle sensor 11 Crankshaft 12 Scavenging reservoir 13 Exhaust reservoir 14 Air cooler 15 Movement restriction part (Regulation member)
15a Drive part 15b Worm wheel part 15c Worm (support part)
15d worm (support part)
15e Ratchet gear 15f Support bar (support part)
15g Ratchet gear 15h Worm 15i Worm wheel 15j Suspension rod (support part)
100 engine system 200 supercharger 300 control unit H exhaust port O outlet hole R1 combustion chamber R2 scavenging chamber R3 hydraulic chamber (fluid chamber)
R4 Supply channel R5 Relief channel R6 Auxiliary channel S Scavenging port

Claims (5)

A variable compression device for changing a compression ratio in a combustion chamber of an engine, comprising:
Piston rod,
A connecting member connected to the piston rod;
A fluid chamber which is provided between the connecting member and the piston rod and is supplied with a pressurized working fluid to move the piston rod in a direction to increase the compression ratio with respect to the connecting member;
The piston rod can be in contact with and separated from the piston rod, and when the piston rod is moved in a direction to increase the compression ratio, the piston rod abuts on the piston rod and regulates movement of the piston rod to maintain the compression ratio. And a restricting member. The restricting member has a restricting pin movable toward the piston rod in a cross direction crossing the extending direction of the piston rod,
The variable compression device according to claim 1, wherein the piston rod has a recess in which the restriction pin can be inserted. The variable compression device according to claim 1, wherein the restriction member is movable along the extension direction of the piston rod and has a support portion for supporting the piston rod from below. The piston rod has an opening through which the restriction member can be inserted.
The variable compression device according to claim 1, wherein the restriction member has a support portion inserted into the opening of the piston rod and suspending and supporting the piston rod from above. An engine system comprising the variable compression device according to any one of claims 1 to 4.

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