JP2019007432A - Variable compression device and engine system - Google Patents

Abstract

To secure starting property with liquid fuel in an engine.SOLUTION: A variable compression device has a fluid chamber in which a piston rod is moved in a direction of increasing a compression ratio by being supplied with pressure-raised working fluid. The variable compression device includes: pressure-raised working fluid supply part for supplying pressure-raised working fluid; and a control part for supplying the pressure-raised working fluid to the fluid chamber before start processing of starting supplying fuel to a combustion chamber.SELECTED DRAWING: Figure 1

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 that can be operated with 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 is compatible with both a compression ratio suitable for operation with liquid fuel and a compression ratio suitable for operation with gaseous fuel. Provided.

JP 2014-20375 A

  In such an engine, in order to ensure safety and stability, it is necessary to use liquid fuel when starting the engine. However, since the compression ratio adjusting mechanism is started when the engine is started, the compression ratio is in the lowest state at the stage of starting the engine where fuel is supplied to the combustion chamber. For this reason, a diesel engine with a variable compression ratio has insufficient startability with liquid fuel.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to ensure startability by liquid fuel in an engine.

  The present invention provides a variable chamber having a fluid chamber in which a piston rod is moved in a direction of increasing a compression ratio when a pressurized working fluid is supplied as a first means related to a variable compression device for solving the above-mentioned problems. A pressurizing fluid supply unit that supplies a pressurized working fluid, and a control unit that supplies the pressurized working fluid to the fluid chamber prior to a start process for starting fuel supply to the combustion chamber; The structure of comprising is adopted.

  As a second means related to the variable compression device, in the first means, the pressurization fluid supply section is provided at a plunger pump that pressurizes and supplies the working fluid to the fluid chamber, and at a discharge port of the plunger pump. And a supply pump that pumps fluid to the plunger pump, and the control unit controls the supply pump to supply the working fluid having a pressure higher than a valve opening pressure of the check valve. The structure of supplying to the plunger pump is adopted.

  As a third means related to the variable compression device, in the first means, the pressurized fluid supply unit is provided at a plunger pump for supplying the working fluid to the fluid chamber by increasing the pressure, and at a discharge port of the plunger pump. A check valve, a supply pump for pumping fluid to the plunger pump, and a booster pump provided between the plunger pump and the supply pump, the control unit controls the booster pump, A configuration is adopted in which the working fluid having a pressure higher than the valve opening pressure of the check valve is supplied to the plunger pump.

  As a first means related to the engine system, a configuration is adopted in which the variable compression device of any one of the first to third means is provided.

  According to the present invention, the working fluid pressurized by the control unit is supplied to the fluid chamber before the start process is started. Thereby, it is possible to make a compression ratio into a high state at the time of engine starting process. Therefore, it is possible to ensure the startability of the liquid fuel when starting the engine.

It is sectional drawing of the engine system in one Embodiment of this invention. It is a fragmentary sectional view of the engine system in one embodiment of the present invention. It is a time chart which shows operation | movement of the engine system in one Embodiment of this invention. It is a fragmentary sectional view in the modification of the engine system in one embodiment of the present invention.

  Hereinafter, an embodiment of an engine system 100 according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

  The engine system 100 of this embodiment is mounted on a ship 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 supercharger 200 is regarded as an auxiliary machine and will be described as a separate body from the engine 1 (main machine). However, the supercharger 200 can be configured 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 gaseous fuel such as natural gas is burned together with liquid fuel such as heavy oil, and a diesel operation mode in which liquid fuel such as heavy oil is burned. Yes. In the gas operation mode, only gaseous fuel may be burned. Such an engine 1 includes a frame 2, a cylinder part 3, a piston 4, an exhaust valve unit 5, a piston rod 6, a crosshead 7, a hydraulic part 8, a connecting rod 9, and a crank angle sensor 10. A crankshaft 11, a scavenging reservoir 12, an exhaust reservoir 13, and an air cooler 14. The cylinder portion 3, the piston 4, the exhaust valve unit 5 and the piston rod 6 constitute a cylinder.

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

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

  The piston 4 has a substantially cylindrical shape, and is connected to a piston rod 6 described later and is disposed inside the cylinder liner 3b. 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 3b is sealed by the piston ring. The piston 4 slides in the cylinder liner 3b with the piston rod 6 due to pressure fluctuations 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 the exhaust port H in the cylinder part 3 is closed by the exhaust valve drive part 5c. The exhaust valve housing 5b is a cylindrical housing that houses 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 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 cross head pin 7a and connected so that the connecting rod 9 can rotate.

  The cross head 7 includes a cross head pin 7a, a guide shoe 7b, and a lid member 7c. The cross head pin 7a is a columnar member that connects the piston rod 6 and the connecting rod 9 so as to be movable. Supply and discharge of hydraulic oil (working fluid) is inserted into an insertion space into which the end of the piston rod 6 is inserted. A hydraulic chamber R3 (fluid chamber) is formed. In the cross head pin 7a, an outlet hole O penetrating along the axial direction of the cross head pin 7a is formed below the center. The outlet hole O is an opening through which cooling oil that has passed through a cooling flow path (not shown) of the piston rod 6 is discharged. The crosshead pin 7a is provided with a supply flow path R4 that connects the hydraulic chamber R3 and a plunger pump 8c, which will be described later, and a relief flow path R5, which connects the hydraulic chamber R3 and a relief valve 8f, which will be described later. Yes. Further, the cross head 7 is formed with an auxiliary flow path R6 that communicates with the cross head pin 7a and the lid member 7c and opens to the circumferential surface of the piston rod 6 and the circumferential surface of the cross head pin 7a.

  The guide shoe 7b is a member that rotatably supports the cross head pin 7a, and moves on a guide rail (not shown) along the stroke direction of the piston 4 along with the cross head pin 7a. When the guide shoe 7b moves along the guide rail, the cross head pin 7a is restricted from rotating and moving in directions other than the linear direction along the stroke direction of the piston 4. The lid member 7c is an annular member that is fixed to the upper part of the cross head pin 7a and into which the end of the piston rod 6 is inserted. Such a crosshead 7 transmits the linear motion of the piston 4 to the connecting rod 9.

  As shown in FIG. 2, the hydraulic section 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. 8f. Moreover, the piston rod 6, the cross head 7, the hydraulic part 8, and the control part 300 function as a variable compression apparatus in the present invention. Furthermore, the supply pump 8a, the swing pipe 8b, the plunger pump 8c, the first check valve 8d, and the second check valve 8e correspond to the pressurized fluid supply unit in the present invention.

  The supply pump 8a is a pump that boosts the hydraulic oil supplied from a hydraulic oil tank (not shown) based on an instruction from the control unit 300 and supplies the pressure to the plunger pump 8c. The supply pump 8a is driven by the power of the battery of the ship and can operate before 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 with the crosshead pin 7a and the fixed supply pump 8a. It is possible.

  The plunger pump 8c is fixed to the cross head pin 7a, and includes a rod-shaped plunger 8c1, a cylindrical cylinder 8c2 that slidably accommodates the plunger 8c1, and a plunger driving unit 8c3. The plunger pump 8c slides in the cylinder 8c2 when the plunger 8c1 is connected to a drive unit (not shown), boosts the operating oil, and supplies it to the hydraulic chamber R3. Further, the cylinder 8c2 is provided with a first check valve 8d at an opening on the discharge side of hydraulic oil provided at an end portion, and a second check valve 8e is provided at an intake side opening provided on the side peripheral surface. 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 is configured to close by energizing the valve body toward the inside of the cylinder 8c2, and prevents hydraulic oil supplied to the hydraulic chamber R3 from flowing back to the cylinder 8c2. doing. Further, the first check valve 8d causes the valve body to be pushed by the hydraulic oil 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. To open the valve. The second check valve 8e is urged 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. The second check valve 8e is configured such that when the pressure of the hydraulic oil supplied from the supply pump 8a becomes equal to or greater than the biasing force (opening pressure) of the biasing member of the second check valve 8e, Opens when pressed. The first check valve 8d has a valve opening pressure higher than the valve opening pressure of the second check valve 8e, and is supplied from the supply pump 8a during steady operation that is operated at a preset compression ratio. The valve will not open due to the pressure of hydraulic oil.

  The relief valve 8f is provided on the cross head pin 7a and includes a main body portion 8f1 and a relief valve drive portion 8f2. The main body 8f1 is a valve connected to the hydraulic 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 unit 8f1, and opens and closes the main body unit 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 hydraulic 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 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 cross head 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 a long member connected to a connecting rod 9 provided in the cylinder, and transmits power to, for example, a screw or the like by being rotated by a rotational motion transmitted by each connecting rod 9. The scavenging reservoir 12 is provided between the cylinder jacket 3d and the supercharger 200, and air pressurized by the supercharger 200 flows in. The scavenging reservoir 12 is provided with an air cooler 14 therein. The exhaust reservoir 13 is a tubular member that is connected to the exhaust port H of each cylinder and to the supercharger 200. The gas discharged from the exhaust port H is temporarily stored in the exhaust reservoir 13 and supplied to the supercharger 200 with pulsation 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 air sucked from an unillustrated intake port and supplies it to the combustion chamber R <b> 1 by a turbine rotated by the gas discharged from the exhaust port H.

  The control unit 300 is a computer that controls a fuel supply amount and the like based on an operation by a ship operator. Further, the control unit 300 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 chamber R3, thereby changing the position of the piston rod 6 to reduce the compression ratio. To change. The control unit 300 is activated by turning on the power switch. As a result, the control unit 300 starts before the engine start switch is operated by the operator, controls the supply pump 8a to supply hydraulic oil to the hydraulic chamber R3, and has a high compression ratio when the engine is started. Let me.

  Such an engine system 100 is a device that rotates the crankshaft 11 by causing the piston 4 to slide in the cylinder liner 3b by igniting and exploding fuel injected into the combustion chamber R1 from a fuel injection valve (not shown). is there. 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 as the piston 4 moves in the direction of the top dead center. Ignite. In the case of liquid fuel, it is vaporized and spontaneously ignited as the temperature rises in the combustion chamber R1.

  Then, the fuel in the combustion chamber R1 is suddenly expanded by spontaneous ignition, and the piston 4 is subjected to pressure directed toward the bottom dead center. As a result, the piston 4 moves in the direction of 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. Furthermore, when the piston 4 is moved to the bottom dead center, the pressurized air flows from the scavenging port S into the combustion chamber R1. 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 increasing the compression ratio, the supply pump 8a is driven by the controller 300, and hydraulic oil is supplied to the plunger pump 8c. And the control part 300 drives the plunger pump 8c, pressurizes hydraulic oil until it becomes the pressure which can lift the piston rod 6, and supplies hydraulic oil to hydraulic chamber R3. Due to the pressure of the hydraulic oil in the hydraulic chamber R3, the end of the piston rod 6 is lifted, and accordingly, the top dead center position of the piston 4 is moved upward (exhaust port H side).

  In order to reduce the compression ratio, the relief valve 8f is driven by the controller 300, and the hydraulic chamber R3 and a 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 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 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.

  Further, when the engine system 100 is started, as shown in FIG. 3, the power switch is first turned ON by the operator. Thereby, the control part 300 starts and a compression ratio setting process is started. Specifically, the control unit 300 controls the supply pump 8a to pressurize the hydraulic oil and supply it to the plunger pump 8c. At this time, the controller 300 pressurizes and supplies the pressure to a pressure at which the piston rod 6 can be lifted by the supply pump 8a. Then, the hydraulic oil supplied to the plunger pump 8c opens the first check valve 8d and is supplied to the hydraulic chamber R3. The control unit 300 lifts the piston rod 6 with the hydraulic oil supplied to the hydraulic chamber R3, and increases the compression ratio of the cylinder. Next, the start switch of the engine 1 is turned ON by the operator, whereby the start process of the engine 1 is started, and liquid fuel is supplied to the combustion chamber R1. As a result, when the engine 1 is started, the compression ratio can be made higher than usual.

  According to the engine system 100 in the present embodiment, the hydraulic oil is supplied to the hydraulic chamber R3 by the compression ratio setting process being performed by the control unit 300 before the start process is started. Thereby, it is possible to make a compression ratio into a high state at the time of fuel supply by moving the position of the piston rod 6 upward. Therefore, when the engine 1 is started, startability can be ensured and the engine 1 can be started stably in the diesel operation mode.

  Further, according to the engine system 100 in the present embodiment, the control unit 300 controls the supply pump 8a to increase the operating oil so as to be higher than the valve opening pressure of the first check valve 8d. Thereby, the control part 300 can open the 1st check valve 8d with hydraulic fluid in the state which the plunger pump 8c is not driving, and can supply hydraulic fluid to hydraulic chamber R3.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

In the embodiment described above, the control unit 300 employs a configuration in which the hydraulic oil is boosted and supplied to a pressure higher than normal by the supply pump 8a in the compression ratio setting process. However, the present invention is not limited to this, and as shown in FIG. 4, the hydraulic unit 8 may further include a booster pump 8 g. The booster pump 8g is provided between the supply pump 8a and the plunger pump 8c, and the hydraulic oil supplied from the supply pump 8a is supplied to the piston rod 6 based on an instruction from the control unit 300 during the compression ratio setting process. The pressure is increased to a pressure that can be lifted. Further, during steady operation, the hydraulic oil is supplied directly from the supply pump 8a to the plunger pump 8c by switching a valve (not shown).
In this case, even during the compression ratio setting process, the supply pump 8a can pump hydraulic oil at the same pressure as during steady operation. Therefore, when the supply pump 8a is connected to another hydraulic device or the like, the compression ratio setting process does not affect the other hydraulic device.

  The control unit 300 may perform the compression ratio setting process when the engine is stopped. In this case, the control unit 300 can increase the compression ratio when the engine 1 is stopped, and can start the engine with the compression ratio being high at the next engine start. Therefore, even when there is no time lag between the power supply of the electric system and the start of the engine 1, the compression ratio setting process can be performed.

  Moreover, in the said embodiment, although the control part 300 shall perform the compression ratio setting process by controlling the supply pump 8a, it can also be set as the structure which provides a booster separately from the supply pump 8a. is there.

  In the said embodiment, the structure which moves the piston rod 6 using oil_pressure | hydraulic and changes a compression ratio was employ | adopted. However, this invention is not limited to this, The structure which moves the piston rod 6 with the pressure of fluids other than hydraulic oil is included.

DESCRIPTION OF SYMBOLS 1 Engine 2 Frame 3 Cylinder part 3a Cylinder cover 3b Cylinder liner 3c Cylinder head 3d Cylinder jacket 4 Piston 5 Exhaust valve unit 5a Exhaust valve housing 5c Exhaust valve drive part 6 Piston rod 7 Crosshead 7a Crosshead pin 7b Guide shoe 7c Lid member 8 Hydraulic part 8a Supply pump 8b Oscillating 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 8g Booster pump 9 Connecting rod 10 Crank angle sensor 11 Crankshaft 12 Scavenging reservoir 13 Exhaust reservoir 14 Air cooler 100 Engine system 200 Supercharger 300 Control unit H Exhaust port O Exit hole R1 Combustion chamber R2 Scavenging chamber R3 Hydraulic chamber R4 Supply flow path R5 Relief Flow Path R6 Auxiliary flow path S Scavenging port

Claims (4)

A variable compression device having a fluid chamber in which a piston rod is moved in a direction to increase a compression ratio by supplying a pressurized working fluid,
A pressurized fluid supply section for supplying a pressurized working fluid;
A variable compression device comprising: a control unit configured to supply the working fluid whose pressure has been increased to the fluid chamber prior to a start process for starting fuel supply to the combustion chamber. The pressurizing fluid supply unit includes a plunger pump that pressurizes and supplies the working fluid to the fluid chamber, a check valve provided at a discharge port of the plunger pump, and a supply pump that pumps fluid to the plunger pump. Prepared,
The variable compression device according to claim 1, wherein the control unit controls the supply pump to supply the working fluid having a pressure higher than a valve opening pressure of the check valve to the plunger pump. The pressurizing fluid supply unit includes a plunger pump that pressurizes and supplies the working fluid to the fluid chamber, a check valve provided at a discharge port of the plunger pump, a supply pump that pumps fluid to the plunger pump, A booster pump provided between the plunger pump and the supply pump;
2. The variable compression device according to claim 1, wherein the control unit controls the booster pump to supply the working fluid having a pressure higher than a valve opening pressure of the check valve to the plunger pump.   An engine system comprising the variable compression device according to any one of claims 1 to 3.

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