KR20190111771A - Exhaust valve actuation system and large two-stroke internal combustion engine - Google Patents

Abstract

The present invention relates to an exhaust valve actuation system for a large two-stroke internal combustion engine and, more specifically, to a hydraulic exhaust valve actuation system capable of being electronically controlled. According to the present invention, the exhaust valve actuation system comprises: a displacement pump (40) including a first shaft (43) and first and second ports and providing two flowing directions; a hydraulic accumulator (28) fluid-connected to the first port; a motor-generator, such as a variable displacement motor (30), including a second shaft (33) and third and fourth ports, and providing two flowing directions with respect to the rotational direction of one shaft. The second port is fluid-connected to a linear hydraulic actuator (70) actuated on a spindle (23) of an exhaust valve (4) and the first shaft (43) is operatively coupled to the second shaft (33).

Description

EXHAUST VALVE ACTUATION SYSTEM AND LARGE TWO-STROKE INTERNAL COMBUSTION ENGINE}

The present invention relates to an exhaust valve actuation system for a large internal combustion engine, and more particularly to a hydraulically driven exhaust valve actuation system that can be controlled electronically. Hydraulically driven exhaust operation systems are commonly used in large turbocharged two-stroke compression ignition internal combustion engines. The invention also relates to a large two-stroke compression ignition internal combustion engine with an exhaust valve actuation system.

Large turbocharging two-stroke compression ignition internal combustion engines are commonly used as motive power in large marine vessels or power plants such as container ships.

The cylinders of these engines are provided with a cylinder cover, i.e. a single exhaust valve at the top of the cylinder, and a piston controlled scavenging port ring in the lower region of the cylinder liner.

Most modern engines are provided with an electronically controlled, hydraulically actuated exhaust valve actuation system. Compared with the old camshaft operated exhaust valve actuation system, the electronically controlled and hydraulically actuated system offers significantly improved flexibility and adjustment to optimize exhaust and fuel consumption over the full operating conditions of the engine. This allows more efficient control of the combustion process, resulting in more efficient combustion and lower emission values, resulting in lead-free operation, reduced partial load fuel consumption and reduced minimum drive speed at all drive speeds.

The hydraulic actuation system must open the exhaust valve against the pressure of the combustion chamber acting on the valve disk of the exhaust valve and the force of the air spring pushing the exhaust valve towards the seat.

Thus, initially a very large force is needed to open the exhaust valve and a significant amount of hydraulic energy is used for the opening stroke of the exhaust valve.

Most of the energy delivered by the hydraulic actuator in the open stroke of the exhaust valve is stored in the gas spring as potential energy. Instead, the main part of the energy and the stored energy of the exhaust gas acting on the exhaust valve in the closing stroke is wasted because there is no means to capture the energy returning from the hydraulic actuator in the form of hydraulic energy. This hydraulic energy is wasted as return oil (hydraulic liquid) into the tank of the hydraulic system.

The amount of hydraulic energy used to operate the exhaust valves in large two-stroke diesel energy is of considerable importance, and much of the fuel savings gained from increasing combustion control in electronically controlled engines are lost in hydraulically driven exhaust valve actuation systems.

WO01 / 20138 discloses a device for controlling a valve of an internal combustion engine. The device includes a hydraulic circuit with a pump, a control valve designed to control the media flow in the circuit, and a power unit designed to move the engine valve between the open and closed positions. The pump is designed such that the flow of the medium is continually circulated in at least part of the circuit during operation of the internal combustion engine, and the control valve induces the flow of the medium circulated by the pump to the power unit as necessary, so that the power unit may It is designed to move in the desired direction. In this device, this hydraulic energy is wasted as return oil (hydraulic liquid) to the tank of the hydraulic system as detailed above.

It is an object of the present invention to overcome or at least reduce the above mentioned problems in view of the above situation.

The above and other objects are achieved by the features of the independent claims. Further implementations are apparent from the dependent claims, the description and the drawings.

According to a first aspect, there is provided an exhaust valve actuation system for a large two-stroke internal combustion engine, in particular an electronically controllable hydraulically driven exhaust valve actuation system, the exhaust valve actuation system comprising:

A positive displacement pump having a first shaft, a first port and a second port and capable of providing two flow directions, a hydraulic accumulator fluidly connected to the first port, a linear hydraulic actuator acting on the spindle of the exhaust valve And a motor-generator having a second port and a second shaft configured to be fluidly connected to the first shaft, the first shaft being operatively coupled to the second shaft.

By connecting the accumulator to the first port of the variable displacement pump and connecting the hydraulic exhaust valve actuator to the second port of the variable displacement pump, the hydraulic fluid is trapped between the hydraulic accumulator and the hydraulic actuator, and the return means (e.g. gas spring) Mechanical energy supplied to the hydraulic actuator during the closing stroke of the exhaust valve by the exhaust gas acting on the exhaust valve is transmitted to the hydraulic accumulator. In addition, other parts of the hydraulic energy coming from the hydraulic actuators during the return stroke are delivered to a motor generator or variable displacement motor that can act as a brake momentarily. That is, it acts as a hydraulic pump to supply high pressure hydraulic liquid to the hydraulic motor normally. Thus, a very large portion of the energy supplied to the exhaust valve during the closing stroke is recovered there by reducing the amount of net energy for greatly operating the exhaust valve.

According to a possible embodiment of the first aspect, the hydraulic accumulator is connected to the first port to form a first closed hydraulic system.

According to a possible embodiment of the first aspect, a linear hydraulic actuator is connected to the second port to form a second closed hydraulic system.

According to a possible embodiment of the first aspect, the volumetric pump is a variable displacement pump capable of providing two flow directions with respect to one direction of rotation of the first shaft.

According to a possible embodiment of the first aspect, the motor-generator is configured to operate in two directions of rotation of the second shaft.

According to a possible embodiment of the first aspect, the motor-generator is a variable displacement motor having a third port and a fourth port and capable of two directions of rotation of the second shaft with respect to one flow direction.

According to a possible embodiment of the first aspect, the motor-generator is an electric motor-generator.

According to a possible embodiment of the first aspect, the motor-generator is a variable displacement motor having a third port and a fourth port and having two flow directions with respect to one rotational direction of the second shaft.

According to a possible embodiment of the first aspect, the third port is connected to a first source of first high pressure hydraulic fluid, the fourth port is connected to a second source of second high pressure, and the first high pressure is higher than the second high pressure. Higher.

According to a possible embodiment of the first aspect, the exhaust valve actuation system comprises an electronic control device configured to control the rotational speed and the capacity of the variable displacement motor and to control the capacity of the variable displacement pump.

According to a possible embodiment of the first aspect, the exhaust valve actuation system comprises a first sensor indicating the position of the exhaust gas spindle.

According to a possible embodiment of the first aspect, the exhaust valve actuation system comprises a second sensor indicating the rotational speed of the variable displacement motor.

According to a possible embodiment of the first aspect, the variable displacement pump is a radial piston pump and / or the variable displacement hydraulic motor is a radial piston motor.

According to a possible embodiment of the first aspect, the exhaust valve actuation system comprises a first control valve fluidly connected to one or more control ports of the variable displacement pump, thereby controlling the capacity and the directional flow of the first variable displacement pump, The first control valve is electronically controlled by the electronic controller.

According to a possible embodiment of the first aspect the exhaust valve actuation system comprises a second control valve fluidly connected to one or more control ports of the variable displacement hydraulic motor for controlling the capacity and directional flow of the variable displacement hydraulic motor, 2 The control valve is electronically controlled by an electronic controller.

According to a possible embodiment of the first aspect, the electronic controller is configured to maintain the rotational speed of the second shaft at a predetermined rotational speed by controlling the capacity of the variable displacement hydraulic motor.

According to a possible embodiment of the first aspect, the electronic control device is configured to control the flow to and from the second port in accordance with a signal indicating a desired position of the exhaust valve.

According to a possible embodiment of the first aspect, the exhaust valve actuation system comprises a flywheel connected to the first shaft or the second shaft.

According to a possible embodiment of the first aspect, the first shaft is coupled to and rotates in concert with the second shaft.

According to a possible embodiment of the first aspect, the variable displacement pump and variable displacement motor consist of a single unit having a single common shaft.

According to a possible embodiment of the first aspect, the variable displacement hydraulic motor is configured to temporarily serve as a pump and / or the variable displacement pump is configured to temporarily operate as a motor.

According to a second aspect, there is provided a large turbocharging two-stroke self-ignition internal combustion engine, the internal combustion engine comprising:

A plurality of cylinders with a scavenging port in the lower region and an exhaust valve at the top, movable in the opposite direction between a closed position in which the valve disc rests on the valve seat and an open position allowing gas discharge in the cylinder, An exhaust valve having a valve, a single-acting fluid actuated means operatively connected to the valve stem to press the exhaust valve toward the closed position, a linear hydraulic actuator operatively connected to the valve stem and an open position when the linear hydraulic actuator is pressurized A hydraulic actuator configured to pressurize toward the side, and an exhaust valve actuation system according to the first aspect and possibly one embodiment thereof.

According to a possible embodiment of the second aspect, the electronic control device 50 compares the signal of the first sensor 62 with the desired position with respect to the exhaust valve 4 by the position and / or velocity of the exhaust valve in a closed loop manner. It is configured to control.

According to a possible embodiment of the second aspect, the conduit connecting the first port to the accumulator is connected to the first high voltage source in the case of an orifice.

Other and different aspects of the invention will become apparent from the embodiment (s) described below.

In the following detailed description of the disclosure, the invention is described in more detail with reference to the embodiments shown in the drawings.
1 is an elevational view showing the front end and one side of a large two-stroke self-ignition turbocharging engine according to an embodiment of the present invention.
FIG. 2 is an elevational view showing the rear end and the other side of the engine of FIG. 1. FIG.
3 is a schematic representation of the engine according to FIG. 1 with an intake and exhaust system.
4 is a diagram illustrating a first embodiment of an electrohydraulic exhaust valve actuation system of the FIG. 1 engine.
4A is a diagram illustrating another embodiment of an electrohydraulic exhaust valve actuation system of the FIG. 1 engine.
5 is a graph showing an opening movement of the exhaust valve.
6 is a graph showing the torque of the motor and the speed of the motor.

In the following detailed description, a large two-stroke engine is described as an exemplary embodiment. 1-3 show a large low speed turbocharging two stroke diesel engine comprising a crankshaft 42 and a crosshead 44. 3 shows a schematic representation of a large low speed turbocharging two stroke diesel engine with an intake and exhaust system. In this exemplary embodiment, there are six cylinders 1 of heat in the engine. Large turbocharged two-stroke diesel engines generally have five to sixteen cylinders in a line supported by engine frame 45. This engine can be used, for example, as the main engine of a marine transport vessel or as a stationary engine for generator operation of a power plant. The total power of the engine may be in the range of 5,000 to 110,000 kW, for example.

The engine is a two-stroke uniflow type diesel (self-ignition) with a scavenging port 22 in the form of a piston control port ring in the lower region of the cylinder 1 and an exhaust valve 4 on top of the cylinder 1. A) engine. Thus, since the flow in the combustion chamber is always from bottom to top, the engine is so-called uniflow. The scavenging air passes from the scavenging receiver 2 to the scavenging receiver 22 of the individual cylinder 1. The piston 7 reciprocating in the cylinder 1 compresses scavenging, fuel is injected, combustion proceeds, and exhaust gas is generated. When the exhaust valve 4 is opened, the exhaust gas flows through the exhaust duct 35 associated with the associated cylinder 1 into the exhaust gas receiver 3, and then passes through the first exhaust conduit 18 to turbo Flowing into the turbine 6 of the charger 5, where the exhaust gas flows out through the second exhaust conduit 7. Through the shaft 8 the turbine 6 drives the compressor 9 which is fed through the air inlet 10.

The compressor 9 delivers pressurized boost air to the boost air conduit 11 leading to the boost air receiver 2. The scavenge in conduit 13 passes through intercooler 12 to cool the charge air. The cooled boost air travels to the boost air receiver 2 through an auxiliary blower 16 driven by an electric motor 17 which pressurizes the boost air flow under low or partial load conditions. At higher loads, the turbocharger compressor 9 delivers sufficiently compressed scavenges, and then the auxiliary blower 16 is bypassed via the non-return valve 15.

The cylinder is formed in the cylinder liner 52. The cylinder liner 52 is supported by a cylinder frame supported by the engine frame 45.

As shown in the first embodiment of FIG. 4, the exhaust valve 4 comprises a valve spindle 23 with a valve disc 25 at one end. The valve spindle 23 is slidably and sealingly received in the bore of the valve housing. The valve housing defines at its lower end the circumferential valve seat 26 on which the valve disc 25 is placed when the exhaust valve 4 is in the closed position.

The air spring 67 including the plunger 61 is configured to elastically press the exhaust valve 4 to the closed position. The plunger 61 is fixed to the valve stem 23 and is slidably and sealably received in the bore of the housing. The spring chamber 66 is positioned below the plunger 61, and pressurizes the plunger 61 upward when pressed. The spring chamber 66 is connected to the pneumatic source 63 via a non-return valve to ensure accurate pressurization of the spring chamber 66.

Alternatively, the air spring is a liquid based return-biased system filled with pressurized liquid which is allowed to exit from the spring chamber 66 but is given a pressure, preferably a constant pressure, by the connection of the pressure source. Can be replaced by

The upper end of the valve spindle 23 is connected to a plunger 61 slidably and sealingly received in the bore of the valve housing. The pressure chamber 60 is formed in a bore above the plunger 61 and the chamber 60 is in fluid communication with the port connected to the second hydraulic conduit 35.

The pressure chamber 60 and the plunger 61 are housed in the housing and are part of the linear exhaust valve actuator 70. When the pressure chamber 60 is pressurized, the plunger 61 presses the exhaust valve 4 in an open position, that is, in a downward direction (downward as in the direction of FIG. 4). The exhaust valve 4 is then hydraulically opened against the force of the air spring 67 and the force of the combustion pressure in the combustion chamber acting on the valve disc 25. The air spring 67 includes a spring chamber 66 connected to the high pressure air source 63 via a non-return valve.

The valve actuation system is provided with a variable displacement pump 40 having a first shaft 43 of the type capable of transmitting two flow directions without reversing the direction of rotation of the first shaft 43. The variable displacement pump 40 is a pressure chamber of the linear actuator of the exhaust valve 4 via the first port and the second hydraulic conduit 35 connected to the hydraulic accumulator 28 via the first hydraulic conduit 34. 60) connected to the second port. The first hydraulic conduit 34 is connected to a first high pressure first source through an orifice 36 to compensate for the leakage loss in the variable displacement pump 40 and the linear hydraulic exhaust valve actuator 70. 28) continues to pressurize at the first high pressure to store a significant amount of hydraulic energy. However, only a small amount of hydraulic liquid flow through the orifice 36 is possible to compensate for the leakage loss for longer. Thus, the hydraulic liquid flowing through the orifice 36 is insufficient to affect the dynamic pressure change in the first hydraulic conduit 34 that occurs during the opening and closing strokes of the exhaust valve 4. That is, hydraulic accumulator 28 is connected to the first port to form a first closed hydraulic system.

The variable displacement pump 40 is a radial piston pump in the embodiment. In an embodiment, the radial piston pump has a radial piston in the cylinder block operating against the stroke ring, the position of the stroke ring relative to the cylinder block being adjustable to adjust the capacity of the variable displacement pump. The eccentric position of the stroke ring is controlled by two control pistons and compensators opposite each other (the capacity is zero when the position of the stroke ring is centered).

The capacity of the variable displacement pump 40 is controlled by the first control valve 41 which is a solenoid proportional control valve in this embodiment. The first control valve 41 is operably connected to the variable displacement pump 40 to hydraulically adjust the capacity of the variable displacement pump 40. For example, it is controlled by controlling the oil pressure transmitted by the first control valve 41 to the radially opposed control piston. The first control valve 41 is electronically controlled by the electronic controller 50.

The first shaft 43 of the variable displacement pump 40 is in this embodiment the first of the motor-generator 30 through a coupling 53 which rotates the first shaft 43 and the second shaft 33 together. 2 Engage with the shaft. However, in the embodiment, the first shaft 43 and the second shaft 33 are joined by gears having a ratio of one to one or a ratio different from one to one.

The pressure relief valve 39 connects a second hydraulic conduit 35 to the tank T to protect the system from excessive pressure. Thus, the linear hydraulic actuator 70 is connected to the second port to form a second closed hydraulic system.

The motor-generator is an electric-motor generator in the embodiment, and in the illustrated embodiment a variable displacement hydraulic motor 30 which can supply the flow of hydraulic fluid in two flow directions without changing the direction of rotation of the second shaft 33. )to be. The variable displacement hydraulic motor 30 has a third port and a fourth port. The third port is connected to the first source of high pressure 29 and the fourth port is connected to the second source of high pressure 19. The second high pressure is lower than the first high pressure, preferably considerably lower, but much higher than zero or normal technical pressure.

The variable displacement motor 30 is a radial piston motor in the embodiment. In an embodiment, the radial piston motor is a radial piston in a cylinder block operating against a stroke ring, the position of the stroke ring relative to the cylinder block being adjustable to adjust the capacity of the variable displacement pump. The eccentric position of the stroke ring is controlled by two control pistons and compensators opposite to each other (the capacity is zero if the position of the stroke ring is not eccentric).

The capacity of the variable displacement motor 30 is controlled by the second control valve 31 which is a solenoid proportional control valve in this embodiment. The second control valve 31 is operatively connected to the variable displacement motor 30 for hydraulically adjusting the capacity of the variable displacement motor 30. For example, it is controlled by controlling the oil pressure transmitted to the control piston opposed in the radial direction by the first control valve 41. The second control valve 31 is electronically controlled by the electronic controller 50.

The rotational speed of the motor 30, that is, the rotational speed of the second shaft 33, is captured by the second sensor 32. The signal of the second sensor 32 is transmitted to the electronic controller 50 by, for example, a signal cable.

The electronic controller 50 sends a signal to the second control valve 31 via a signal cable to control the rotational speed of the first shaft / hydraulic motor 30. The first control valve controls the capacity and flow direction of the variable displacement pump 40.

The exhaust valve 4 is provided with a first sensor 62 for measuring the position and speed of the exhaust valve 4. The first sensor 62 generates a signal indicative of the position and / or speed of the exhaust valve 4. The sensor 62 is connected to the electronic controller 50 via, for example, a signal cable so that the electronic controller 50 is informed of the position and speed of the exhaust valve 4.

The electronic controller 50 controls the speed of the exhaust valve 4 by sending a signal to the first control valve via a signal cable to control the capacity of the variable displacement pump 40.

The electronic controller 50 monitors the speed of the exhaust valve 4. The electronic control device 50 is configured in this embodiment to determine the appropriate speed / profile that the exhaust valve 4 will follow. This profile is applied continuously according to the engine operating conditions in the embodiment.

The electronic controller 50 is informed about the crank angle of the engine, and controls the operation of the valve 4 so that the profile of the exhaust valve operation is synchronized with the engine cycle.

The electronic controller 50 may be provided with a lookup table based on equations using the data corrected from the engine operation test or the data corrected from the engine operation test to determine the appropriate profile desired for the exhaust valve 4. have. The desired profile for the exhaust valve 4 is chosen such that the system is optimized for exhaust gas, power and / or fuel efficiency, and these factors are taken into account depending on the situation.

As described above, sufficient pressure of the hydraulic liquid in the pressure chamber 60 causes the exhaust valve 4 to open against the pressure in the combustion chamber and the force of the air spring 67. When the electronic controller 50 determines that the exhaust valve 4 needs to be opened, the electronic controller 50 thus adjusts the capacity and flow direction of the variable displacement pump 40 to the first control valve 41. Give a command to Hydraulic fluid is then pumped from the hydraulic actuator 28 to the pressure chamber 60 of the exhaust valve actuator 70 to open the exhaust valve against the pressure of the air spring 67 and the pressure in the combustion chamber. The pumping operation is substantially assisted by the high pressure of the hydraulic liquid stored in the hydraulic accumulator 28, so that the variable displacement pump 40 does not need to supply power to support this flow. In the embodiment the pressure of the hydraulic actuator 28 is high enough to cause the variable displacement pump 40 to be operated by a hydraulic motor and at the same time force the variable displacement motor 30 to be operated by the pump. Here, the electronic controller 50 thus controls the capacity and flow direction of the variable displacement hydraulic motor 30 in order to maintain the desired rotational speed of the second shaft 33. When the exhaust valve 4 reaches the open stroke, the electronic controller 50 instructs the first control valve 41 to adjust the capacity of the variable displacement pump 40 to zero to stop the movement of the exhaust valve 4. Instruct.

If the electronic controller 50 determines that the exhaust valve needs to be closed, the process is reversed, and the electronic controller 50 controls the first control valve 41 to adjust the displacement flow direction of the variable displacement pump 40. And thus flows from the second conduit 35 to the first hydraulic conduit 34 and to the hydraulic accumulator 28. This flow is assisted by the exhaust gas acting on the exhaust valve and by the air spring 67 and counteracts the pressure in the hydraulic accumulator 28. Accordingly, the variable displacement pump 40 needs to be driven by the variable displacement motor 30 in accordance with the pressure of the accumulator 28 and the assistance in the pressure chamber 60. Here, the electronic controller 50 adjusts the capacity and flow direction of the variable displacement motor 30 to maintain a constant speed of the second shaft 33. Accurate control of the electronic control device 50 to the capacity of the variable displacement pump 40 allows for a “soft-close” of the exhaust valve disc 25 on its seat 26, so that the exhaust valve actuator may be closed. Can be configured without damper.

5 is a graph showing the opening movement of the exhaust valve 4 with time. The illustrated profile is merely an example, and the shape of the profile and the size of the open stroke can be freely controlled by the electronic controller 50. The electronic controller 50 determines the profile for opening the exhaust valve 4 and thus controls the capacity of the variable displacement pump 40. The electronic controller 50 is notified of the position of the exhaust valve 4 by the signal of the position sensor 62. As a result, the electronic controller 50 can determine the position of the exhaust valve according to any desired profile.

6 is a graph showing the torque and the rotational speed of the first shaft of the motor 30. The graph shows that the motor torque is negative. That is, the motor 30 acts as a brake / pump during the initial stage of the open stroke of the exhaust valve 4. At the same time, the speed of the second shaft 33 of the hydraulic motor 30 increases slightly and returns to the set speed. Negative torque is generated because the pressure of the hydraulic accumulator 28 is higher than the pressure of the linear hydraulic actuator 70 of the exhaust valve, so that the flow from the hydraulic actuator 28 to the linear hydraulic actuator 70 is variable displacement pump 40. ). That is, the variable displacement pump 40 operates at this stage like a motor. The situation is reversed when the exhaust valve 4 returns to the seat 26. During the initial phase of the return stroke, the electronic controller changes the capacity of the variable displacement pump 40 to pump hydraulic liquid from the linear hydraulic actuator 70 to the hydraulic actuator 28. This pumping action requires separating torque from the variable displacement motor 30 to the variable displacement pump 40 and at a positive torque relative to the variable displacement motor 30 and the rotational speed of the second shaft 33 of the motor. The graph shows a slight decrease in. The electronic controller 50 is configured to maintain the rotational speed of the second shaft 33 at a desired constant level, thereby adjusting the capacity of the variable displacement motor 30.

Since the variable displacement pump 40 has zero capacity, the energy consumption for the exhaust valve operation is low unless the exhaust valve is moved. The hydraulic energy of the hydraulic actuator 28 during the open stroke drives the linear exhaust valve actuator 70 and actually "drives" the variable displacement pump 40. The energy entering the variable displacement pump 40 is partially recovered during this step by the variable displacement motor 30 which acts as a pump and delivers hydraulic energy back to the hydraulic system of the engine. During the closing stroke, forces acting on the exhaust valve disc 25 and gas in the combustion chamber acting on the shaft 23 to the linear exhaust valve actuator 70, gas spring and plunger 61 are exerted in the pressure chamber 60. Pressurize hydraulic fluid. This pressure assists the variable displacement pump 40 when recharging the hydraulic actuator 28 for the next stroke. Therefore, the energy of the exhaust gas and the air spring is recovered by transferring this energy to the hydraulic accumulator 28 and storing it during the return stroke.

4A shows another embodiment of an exhaust valve actuation system that is essentially the same as the first embodiment shown in FIG. 4 except that the hydraulic pump 40 is a fixed displacement pump instead of a variable displacement pump. The fixed displacement pump 40 is configured to operate in two directions of rotation to provide flow in two directions.

Accordingly, the motor generator in the form of the variable displacement hydraulic motor 30 in this embodiment needs to operate the drive shaft 33 (second shaft) in different directions to control the flow pump 40 in the opposite direction. have. Thus, in this embodiment, the displacement pump 40 and the variable displacement motor 30 each shaft for pressurizing the linear hydraulic actuator 70 to discharge the hydraulic accumulator 28 and open the exhaust valve 4. (33, 43) are operated in one rotational direction, and the variable displacement pump 40 and variable displacement motor 30 empty the linear hydraulic actuator 70 to replenish the hydraulic accumulator 28 (especially the pressure chamber ( 60) is operated in the opposite direction of rotation of each shaft 33, 43 to close the exhaust valve 4.

The control of the exhaust valve operating system by the electronic controller 50 is made through the first control valve 31 to control the operation of the variable displacement motor 30. Since the fixed displacement pump 40 itself does not have any hydraulic control input, the hydraulic and control system according to the embodiment of FIG. 4A is less complicated than the embodiment of FIG. 4.

In an embodiment, the variable displacement motor 30 and the variable displacement pump 40 consist of a single unit comprising a common shaft. This single unit is directly attached to the exhaust valve housing in the embodiment.

The present invention has been described in connection with various embodiments herein. However, other variations to the disclosed embodiments can be understood and practiced by those skilled in the art having practiced the invention as claimed from the drawings, the disclosure and the study of the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. The simple fact that certain measures are cited in different subclaims does not indicate that a combination of them used as a measure cannot be used to advantage. The computer program may be stored / distributed on suitable media, such as optical storage media or solid state media, provided with or as part of other hardware, but may be distributed in other forms, such as the Internet or other wired or wireless communication systems. have. The electronic control unit is represented as a single unit but can be realized by combining a plurality of connected electronic control units.

Reference signs used in the claims should not be construed as limiting the scope.

28: hydraulic accumulator
30: capacity motor
31: second control valve
33: second shaft
40: capacity pump
41: first control valve
43: first shaft
50: electronic control device
70: hydraulic actuator

Claims (20)

In exhaust valve actuation systems for large two-stroke internal combustion engines, in particular hydraulically actuated exhaust valve actuation systems,
A displacement pump 40 having a first shaft 43, a first port and a second port, capable of providing two flow directions,
A hydraulic accumulator 28 fluidly connected to the first port,
The second port configured to be fluidly connected to a linear hydraulic actuator 70 acting on the spindle 23 of the exhaust valve 4 and
A motor-generator having a second shaft (33),
And the first shaft (43) is operably connected to the second shaft (33). The method of claim 1,
The hydraulic accumulator (28) is connected to the first port to form a first closed hydraulic system. The method according to claim 1 or 2,
The linear hydraulic actuator (70) is connected to the second port to form a second closed hydraulic system. The method according to any one of claims 1 to 3,
Said displacement pump is a variable displacement pump (40) capable of providing two flow directions with respect to one rotational direction of said first shaft. The method of claim 1,
The motor-generator is configured to operate in two directions of rotation of the second shaft (33). The method of claim 5,
The motor-generator is a variable displacement motor (30) having a third port and a fourth port and capable of two directions of rotation of the second shaft (33) with respect to one flow direction. The method of claim 1,
And the motor-generator is an electric motor-generator. The method of claim 1,
The motor-generator is a variable displacement motor (30) having a third port and a fourth port and capable of two flow directions with respect to one rotational direction of the second shaft (33). The method of claim 8,
The third port is connected to a first source of first high pressure, the fourth port is connected to a second source of second high pressure, and the first high pressure is higher than the second high pressure. The method according to claim 8 or 9,
And an electronic control device (50) configured to control the rotational speed and capacity of the variable displacement motor (30) and to control the capacity of the variable displacement pump (40). The method of claim 1,
Exhaust valve actuation system comprising a first sensor (62) indicating the position of the spindle (23). The method of claim 1,
And a second sensor (32) indicative of the rotational speed of the motor-generator. The method of claim 8,
The variable displacement pump (40) is a radial piston pump and / or the variable displacement motor (30) is a radial piston motor. The method of claim 10,
A first control valve 41 fluidly connected to one or more control ports of the variable displacement pump 40 for controlling the volumetric and directional flow of the variable displacement pump 40, the first control valve 41 ) Is an electronically controlled exhaust valve operating system by the electronic control device (50). The method of claim 10,
A second control valve (31) fluidly connected to one or more control ports of the variable displacement hydraulic motor (30) for controlling the capacity and directional flow of the variable displacement hydraulic motor (30); (31) is an exhaust valve operating system that is electronically controlled by the electronic control device (50). The method of claim 10,
The electronic control device (50) is configured to maintain the rotational speed of the second shaft (33) at a predetermined rotational speed by controlling the capacity of the variable displacement hydraulic motor (30). The method of claim 10,
The electronic control device (50) is configured to control the flow to and from the second port in accordance with a signal indicative of a desired position of the exhaust valve (4). In a large turbocharging two-stroke self-ignition internal combustion engine,
A plurality of cylinders 1 having a scavenging port 22 in the lower region of the cylinder and an exhaust valve 4 at the top of the cylinder,
Said exhaust valve (4) having a valve stem (23) and a valve disc (25) and movable in an opposite direction between a closed position and an open position in which the valve disc (25) is placed on the valve seat (26),
Single-acting fluid actuated means operably connected to the valve stem 23 to press the exhaust valve 4 toward the closed position,
A linear hydraulic actuator 70 operatively connected to the valve stem 23 and configured to pressurize the exhaust valve to the open position when the linear hydraulic actuator 70 is pressurized;
A large turbocharging two-stroke self-ignition internal combustion engine comprising an exhaust valve actuation system according to claim 1. The method of claim 18,
A large size comprising an electronic control device 50 configured to control the position and / or speed of the exhaust valve in a closed loop manner by comparing the signal of the first sensor 62 with a desired position with respect to the exhaust valve 4. Turbocharged two-stroke self-ignition internal combustion engine. The method of claim 18,
And a first conduit connecting said first port to said accumulator (28) is connected to said first high pressure source via an orifice (36).

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