DK178547B1

DK178547B1 - A valve system for an internal combustion engine

Info

Publication number: DK178547B1
Application number: DKPA201470742A
Authority: DK
Inventors: Erik Due Pedersen
Original assignee: Man Diesel & Turbo Filial Af Man Diesel & Turbo Se Tyskland
Priority date: 2014-11-27
Filing date: 2014-11-27
Publication date: 2016-06-13
Also published as: JP2016102497A; JP6100350B2; DK201470742A1; CN105649706B; CN105649706A; KR101625527B1

Abstract

The present invention relates to a valve system for an internal combustion engine having a pressure source of pressurised fluid, comprising an exhaust or intake valve, an actuator comprising an actuator housing having an axial extension between a first housing end and a second housing end, the first housing end having a first opening fluidly connected with the pressure source, a piston which is slidable within the actuator housing and has a first piston end and a second piston end, the second piston end being connected to the valve through an opening in the second housing end for activating the valve between a closed position and an open position, and a first chamber defined between a first piston face of the first piston end and the first housing end, the first piston face facing the first end of the actuator housing, wherein the piston comprises a second piston face arranged displaced in relation to the first piston face along the axial extension, the second piston face being arranged in a second chamber defined by the actuator housing and the piston, and the piston comprises or defines a fluid channel fluidly connecting the first chamber and the second chamber, so that the pressurised fluid is led from the first chamber to the second chamber to press onto the second piston face and open the valve. The present invention also relates to an internal combustion engine comprising the valve system according to the present invention and to a valve actuation method for moving an intake/exhaust valve of a valve system according to the present invention.

Description

A VALVE SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Field of the invention

The present invention relates to a valve system for an internal combustion engine having a pressure source of pressurised fluid. The present invention also relates to an internal combustion engine comprising the valve system according to the present invention and to a valve actuation method for moving an intake/exhaust valve of a valve system according to the present invention.

Background art

In internal combustion engines as shown in US 5193495, the cylinders are to be emptied for exhaust gas after end of combustion, and new gas is let into the cylinder during a stroke. For that purpose an exhaust valve or intake valve needs to be opened. When opening e.g. the exhaust valve, the pressure in the cylinder is quite high, and once the valve has been slightly opened, the pressure is sufficiently reduced. An electronically operated valve is activated by an actuator applying pressing force on the top of the stem of the valve In order move the valve downwards in order to fully open the valve. To overcome the high pressure in the cylinder, the initial force on the valve needs to be very high, and subsequently the operation force can be sufficiently lower for continuing the movement to fully open the valve.

In known actuators, the actuators have a dual piston operated by pressurised fluid, and once the initial pressure in the cylinder is overcome, movement of an outer piston of the dual piston is stopped, leaving only an inner piston of the dual piston moving for fully opening the valve. In this way, the resulting surface area of the dual piston is substantially decreased after the initial high pressure in the cylinder has been overcome, so that the amount of pressurised fluid is decreased for moving the valve further to a fully open position. When having a dual piston with an inner piston moving within an outer piston, the dual piston is exposed to failure during operation, and such dual piston is also very complicated and expensive to produce. In particular, the moving parts of the dual piston are exposed to bumps, which has resulted in actuator failure, early piston wear and cracks.

Summary of the invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved valve system which is easier to manufacture and less exposed to actuator failure.

The above objects, together with numerous other objects, advantages, and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a valve system for an internal combustion engine having a pressure source of pressurised fluid, comprising: - an exhaust or intake valve, - an actuator comprising: - an actuator housing having an axial extension between a first housing end and a second housing end, the first housing end having a first opening fluidly connected with the pressure source, - a piston which is slidable within the actuator housing and has a first piston end and a second piston end, the second piston end being connected to the valve through an opening in the second housing end for activating the valve between a closed position and an open position, and - a first chamber defined between a first piston face of the first piston end and the first housing end, the first piston face facing the first end of the actuator housing, wherein the piston comprises a second piston face arranged displaced in relation to the first piston face along the axial extension, the second piston face being arranged in a second chamber defined by the actuator housing and the piston, and the piston comprises or defines a fluid channel fluidly connecting the first chamber and the second chamber, so that the pressurised fluid is led from the first chamber to the second chamber to press onto the second piston face and open the valve.

By having the fluid channel in the piston, the pressurised fluid presses onto the first piston face and the second piston face simultaneously, and thus at the initial pressurising on the piston, a larger area is used than just the first piston face, and thus a larger force to overcome the overpressure in the cylinder of the engine is obtained.

The piston may be one part, or parts in a non-movable relationship.

Also, the first chamber may be separated from the second chamber.

Furthermore, the actuator housing may comprise an annular groove defining the second chamber.

Moreover, the second piston face may have a distance in the axial extension to the annular groove in the closed position of the valve.

In addition, the piston may comprise an annular projection providing the second piston face.

Further, the second chamber may have a chamber face being closest to the first piston face, the chamber face having a distance in the axial extension to the second piston face in the closed position of the valve.

Said second chamber may be annular.

Also, the chamber face may end in abutment with the piston.

Moreover, the second chamber may have a second chamber face ending in abutment with the piston.

The fluid channel may have a first channel opening and a second channel opening, the second channel opening being opposite the second chamber in the closed position, the second channel opening being arranged perpendicularly to the axial extension, so that upon movement of the piston opening the valve, the second channel opening is moved past the second chamber to disconnect the fluid communication between the first chamber and the second chamber.

Furthermore, the first channel opening may be arranged in the first piston face or in a circumferential face of the piston.

The piston may further comprise a plurality of first channel openings opposite the first chamber.

Moreover, the piston may further comprise a plurality of second channel openings opposite the second chamber.

Additionally, the valve system may further comprise a damping device arranged in the first piston end.

Such damping device may comprise a damping piston slidably arranged in a bore in the first piston end, and a piston may be arranged in the bore and compressed by the pressurised fluid pressing onto the damping piston.

Also, the piston may comprise an annular protrusion corresponding to an annular space defined by the actuator housing and the piston, so that the protrusion during movement of the piston for opening the valve can confine the annular space.

When the protrusion, during movement of the piston in order to open the valve, can confine the annular space, fluid Is entrapped in the space and the movement of the piston is decelerated in order to dampen oscillation of the piston. In this wav, the stopping movement of the piston is damped significantly.

Further, the first piston face may be arranged at a distance from the first end of the actuator housing along the axial extension.

Moreover, the annular space may be part of the first chamber.

In addition, the annular space may be arranged in a third chamber.

The second chamber may be arranged between the first chamber and the third chamber aiong the axiai extension.

Furthermore, the actuator housing may comprise a third opening arranged at a distance from the second chamber aiong the axial extension, the third opening being closer to the second end of the actuator housing than to the first end of the actuator housing.

Also, the third opening may be a relief opening for receiving the pressurised fluid from the fluid channel when the second channel opening is opposite the third opening.

Additionally, the third opening may be fluidly connected to the third chamber.

The present invention also relates to an internal combustion engine comprising the valve system as described above.

Further, the present invention relates to a vessel comprising an internal combustion engine as described above.

Finally, the present invention relates to a valve actuation method for moving an Intake/exhaust valve of a valve system as described above between an open position and a dosed position, comprising the steps of: - pressurising fluid, - leading the pressurised fluid past the first opening in the actuator housing, - leading the fluid into the fluid channel in the piston, - pressing on the first piston face and second piston face simultaneously by means of the pressurised fluid, - moving the piston towards the second end of the actuator housing in order to open the valve, - dosing the fluid connection to the second chamber, and - moving the piston further to fully open the valve.

This valve actuation method may further comprise the step of entrapping fluid in a space by moving the protrusion during movement of the piston to confine the space.

The step of entrapping fluid in the space may decelerate the movement of the piston until the piston movement stops In order to dampen oscillation of the piston.

Also, the valve actuation method as described above may further comprise the step of compressing the spring by pressing on the damping piston.

The step of dosing the fluid connection to the second chamber may be performed by moving the second opening past the second chamber.

Brief description of the drawings

The invention and its many advantages wii! be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

Fig. 1 shows a partly cross-sectional view of a valve system of an internal combustion engine, the valve being shown in its dosed position,

Fig. 2 shows a partly cross-sectional view of another valve system having a damping device and an air spring,

Fig. 3 shows a partly cross-sectional view of another vaive system having a damping space and a relief opening, the vaive being shown in its slightly open position, and

Fig. 4 shows a partly cross-sectional view of another valve system of an internal combustion engine.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Detailed description of the invention

Fig. 1 shows a vaive system 1 for operating an exhaust or intake vaive 2 of an interna! combustion engine 100 by means of pressurised fluid from a pressure source P. Once the combustion has ended in a cylinder 3 of the engine 100, the exhaust gas is discharged through the exhaust vaive 2 before new diesel fuel is entered into the cylinder 3. The valve system 1 comprises the exhaust or intake vaive 2, which needs to be opened, and an actuator 4 for opening the vaive. The actuator 4 comprises an actuator housing 5 having an axial extension 6 between a first housing end 7 and a second housing end 8. The first housing end 7 has a first opening 9 fluidly connected with the pressure source P, so that the pressurised fluid, also called high pressure fluid, is led into the actuator housing 5. A piston 10 is slidably arranged within the actuator housing 5 and has a first piston end 11 and a second piston end 12. The second piston end 12 is connected to a stem 14 of the exhaust valve 2 through an opening 15 in the second housing end 8 for activating the valve 2 between a closed position and an open position. The valve 2 is in Fig, 1 shown in its closed position. The actuator 4 has a first chamber 16 defined between a first piston face 17 of the first piston end 11 and the first housing end 7. The first piston face faces the first end 7 of the actuator housing 5, The piston 10 comprises a second piston face 18 arranged displaced in relation to the first piston face 17 along the axial extension 6. The second piston face 18 is arranged in a second chamber 19 defined by the actuator housing 5 and the piston 10. The piston 10 comprises or defines a fluid channei 20 fluidly connecting the first and the second chambers 16, 19, so that the pressurised fiuid is led from the first chamber 16 to the second chamber 19 to press onto the second piston face 18 to open the valve 2, thus bringing the valve 2 from the dosed position to the open position,

By having the fiuid channel 20 in the piston 10, the pressurised fluid presses onto the first piston face 17 and the second piston face 18 simultaneously, creating a common larger area than just the first piston face 17. Thus, the fluid for opening the valve 2 presses onto a larger area, creating a larger force for overcoming the initial overpressure in the combustion cylinder 3. The initial larger area onto which the pressurised fluid presses is obtained in a one-piece piston 10 In that the fluid channei 20 in the piston 10 distributes the fluid to the second chamber 19, and thus the known, more complicated design of an inner piston slidably arranged inside an outer piston is avoided. The piston 10 of the present invention is thus one part or fixedly mounted parts in a non-movable relationship,

Only one fluid pressure source is used for feeding pressurised fluid into the first chamber 16, and the fiuid channel 20 in the piston 10 leads the fluid from the first chamber 16 to the separated second chamber 19. The second chamber 19 is annular and is formed by the actuator housing 5 comprising an annular groove 21 defining the second chamber 19 together with the piston 10. The fluid channei 20 is formed by axially extending bore 2.0a fluidly connected with a radially extending bore 20b. The axially extending bore 20a is arranged displaced in relation to the first opening 9 in the actuator housing 5 in the radial direction, so that the pressurised fluid Is led to apply a pressure on the first piston face 17, and not directly into the fluid channel 20. The first piston face 17 is arranged at. a distance from the first end 7 of the actuator housing 5 along the axial extension 6.

The second chamber 19 is designed so that the second piston face 18 has a distance d in the axial extension 6 to the annular groove 21 in the closed position of the valve 2, In this way, the pressurised fluid can press against the second piston face 18 In order to move the piston 10 downwards in Fig, 1. When the piston 10, which is connected to the stem 15 of the valve 2, moves downwards, a disc part 31 of the valve 2 leaves a seat 32 in the cylinder 3, so that exhaust gas can pass the disc part 31 of the valve 2 and out through an exhaust channel 30.

In Fig. 1, the piston 10 comprises an annular projection 22 providing the second piston face 18. The projection 22 projects as an annular ring into the second chamber 19 for defining the same. A first part of the piston 10 facing the first housing end 7 has a first diameter matching an inner diameter of the actuator housing 5, and a second part of the piston 10 has a second diameter which is larger than the first diameter and matches a second inner diameter of the actuator housing 5. Opposite the second chamber 19, the actuator housing 5 has a third inner diameter which is larger than both the first and the second inner diameters of the actuator housing 5. The piston 10 is fixedly connected to the stem 14 of the valve 2.

The second chamber 19 has a chamber face 23 being closest to the first piston face 17 and ending in abutment with the piston 10. The chamber face 23 has the distance d in the axial extension 6 to the second piston face 18 in the closed position of the valve 2. Opposite the chamber face 23, the second chamber 19 has a second chamber face 24 which also ends in abutment with the piston 10.

As can be seen in Fig. 1, the fluid channel 20 has a first channel opening 25 and a second channel opening 26, the second channel opening 26 being opposite the second chamber 19 in the closed position, where the second channel opening 26 is arranged perpendicularly to the axial extension 6, so that upon movement, of the piston 10 and thus the second channel opening 26, the second channel opening 26 is moved past the second chamber 19, disconnecting the fluid communication between the first chamber 16 and the second chamber 19. The first channel opening 2.5 is arranged in the first piston face 17.

The downwards movement of the piston 10 for opening the valve 2 is provided by the high pressure fluid from the pump P, and the movement, is stopped by stopping means, such as a coiled spring 46 shown in Fig. 1, an air or gas spring shown in Fig. 2, a compressible resilient element 44 shown in Fig. 3 or similar stopping means. Once the valve 2 opens, the spring or resilient element 44 is compressed, which induces an inherent force in the spring or element, said force being used to return the valve to Its dosed position and thus to provide an upwards movement. During the returning movement of the valve, the high pressure fluid is returned out through the first opening 9 and to tank T controlled by a valve 46.

In Fig, 2, the actuator 4 of the valve system 1 has a damping device 27 arranged in the first piston end 11 in order that dosing of the valve 2 is damped and undesired vibrations are avoided. The damping device 27 comprises a damping piston 28 slidably arranged in a bore 33 In the first piston end 11, wherein a spring 29 is compressed by the pressurised fluid pressing onto the damping piston 28, whereby the damping device 27 becomes spring-loaded and ready to absorb the bumps when the valve 2 closes. In order to dose the valve 2 once opened, the valve system 1 comprises an air spring 40 having an air spring piston 41 arranged around the stem 14 comprising air within the space 42 when the stem 14 moves downwards. The piston 10 comprises a plurality of second channel openings 26 opposite the second chamber 19. As can be seen, the first part of the fluid channel 20 is a groove 20c in the piston 10 and is continued by an angular part ending in the radially extending bore 20b.

In Fig. 3, the valve 2 is in a slightly open position. The piston 10 comprises a plurality of first channel openings 25 opposite the first chamber 16, and the fluid channel 20 thus starts as a plurality of channels at the first piston face 17 and converges into one central bore in the piston 10 for ending in the bore 20b extending in an angle towards the annular groove 21. Furthermore, the piston 10 comprises an annular protrusion 34 corresponding to an annular space 35 defined by the actuator housing 5 and the piston 10, so that the protrusion 34, during movement of the piston 10 for opening the valve 2, can confine the annular space 35 and compress the fluid therein. When the protrusion 34, during movement of the piston 10 for opening the valve 2, confines the annular space 35, fluid is entrapped in the space 35 and the piston 10 is decelerated in order to dampen oscillation of the piston. In this way, the stopping movement of the piston 10 is damped significantly and undesired vibrations are thus avoided. In Fig. 3, the annular space 35 is part of the first chamber 16, and in Fig. 4, the annular space 35 is arranged in a third chamber 36. The second chamber 19 is arranged between the first chamber 16 and the third chamber 36 along the axial extension 6.

In Fig. 3, the actuator housing comprises a third opening 37 arranged at a distance from the second chamber 19 along the axial extension 6 further away from the first chamber 16. The third opening 37 is thus closer to the second end 8 of the actuator housing 5 than to the first end 7 of the actuator housing 5. The third opening 37 functions as a relief opening for receiving the pressurised fluid from the fluid channel 20 when the second channel opening 26 is opposite the third opening 37. During operation, it is crucial that the disc part 31 of the valve 2 is stopped before the disc part 31 hits against the combustion piston in the combustion cylinder 3 in the event that the air spring 40, the compressible element 44 or similar stopping means fails. By having the third opening 37, the downward movement of the piston 10 is stopped at the third opening 37, as the pressurised fluid is then led from the source P and out of the third opening 37. The third opening 37 therefore functions as a safety precaution in the event of failure of other stopping means. When having the third opening 37 functioning as a safety precaution, the first opening 9 in the actuator housing 5 has a cross-sectional area which is smaller than the cross-sectional area of the fluid channel 20, the first channel opening 25, the second channel opening 26 and the third opening 37.

During movement of the valve 2 for opening the same, the bore 20b moves past the annular groove 19, and as the piston 10 moves further to open the valve 2 further, the pressure within the annular groove 19 decreases as the space between the piston 10 and the groove 19 increases. In order to avoid that the pressure becomes too low in the annular groove 19, the annular groove is connected with a low pressure fluid supply 45, having a pressure of substantially 3 bar, to avoid that the fluid inside the annular groove vaporises.

As can be seen in Fig. 4, the first channel opening 2.5 is arranged in a circumferential face 38 of the piston 10 and not in the first, piston face 17. In another embodiment, the first channel openings 25 are arranged both in the circumferential face 38 of the piston 10 and in the first piston face 17. In Fig. 4, the third opening 37 is fluidly connected to the third chamber 36.

The exhaust or intake valve 2 is actuated by the actuator 4 for moving between an open position and a closed position by firstly pressurising fluid and then leading the pressurised fluid past the first opening 9 in the actuator housing 5. The fluid is led further into the fluid channel 20 in the piston 10 and out into the second chamber 19, pressing on the first piston face 17 and the second piston face 18 simultaneously by means of the pressurised fluid. In this way, the piston 10 is moved towards the second end 8 of the actuator housing 5 in order to open the valve 2. The pressurised fluid presses onto both the first and the second piston faces 17, 18 simultaneously until the second channel opening 26 moves past the second chamber 19, closing the fluid connection to the second chamber 19. After closing the fluid communication of the second chamber 19, the piston 10 moves further to fully open the valve 2 by the pressurised fluid pressing only on the first piston face 17. In this way, the consumption of pressurised fluid is minimised in that pressurised fluid acting on the second piston face 18 is only used in the initial phase of the opening of the valve 2, during which the overpressure in the cylinder 3 is high, and subsequently the pressurised fluid is merely used for pressing onto the first piston face 17, filling up the first chamber 16 and not also the second chamber 19.

In order to prevent osciliation or vibrations during the stopping movement of the piston 10, fluid is entrapped in a space 35, either arranged in the first chamber 16 or in the third chamber 36, by moving the protrusion of the piston 10 to confine the space 35 and compress the fluid entrapped therein. Thus, entrapping fluid in the space 35 decelerates the movement of the piston 10 in order to dampen oscillation of the piston. To further avoid vibrations in the valve system 1 when closing the valve 2 again, the spring 29 in the damping piston 28 is compressed during the initial pressuring and leading the fluid through the first opening 9.

By an internal combustion engine Is meant an internal combustion engine having cylinders with a piston diameter of at least 20 cm, e.g. for an ocean-going vessel or stationary engines operating a generator on a power station. The engine may be a two-stroke or four-stroke engine and typically has 4 to 15 cylinders. The internal combustion engine is a low speed engine typically used as a main propulsion engine having a speed in the range from 50 to 200 rpm. The engine may be powered by a fuel, such as marine diesel or heavy fuel having a sulphur content of at least 0.05%, or gas fuel, such as methane, ethane, methanol, natural gas or petroleum gas or liquefied fuel gas.

Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

A valve system (1) for an internal combustion engine (100) having a pressure source (P) imprinted fluid, said valve system comprising: - an exhaust or intake valve (2), - an actuator (4) comprising: - an actuator housing ( 5) having an axial extension (6) between a first housing (7) and a second housing (8), the first housing (7) having a first opening (9) in fluid communication with the pressure source (P), a piston (10) which can slide within the actuator housing (5) and has a first piston end (11) and a second piston end (12), characterized in that the second piston end (12) is connected to the valve (2) through an opening ( 15) In the second housing (8) for actuating the valve (2), a closed position and an open position, and in that the actuator further comprises a first chamber (16), a first defined piston surface (17) of the first piston end (17) 11) and the first housing (8), the first piston surface (17) having a front against the first end (7) of the actuator the housing (5), wherein the piston (10) comprises a second piston surface (18) arranged displaced relative to the first piston surface (17) along the axial extension (6), where the second piston surface (18) is arranged in a second chamber ( 19) defined by the actuator housing (5) and piston (10), and the piston (10) comprises or defines a fluid channel (20) which brings the first chamber and the second chamber (16, 19) into fluid connection so that the pressurized fluid is passed from the first chamber (16) to the second chamber (19) so that pressure is applied to the second piston surface (18) and the valve is opened (2).

Valve system according to claim 1, wherein the actuator housing (5) comprises an annular groove (21) defining the second chamber (19).

Valve system according to claim 2, wherein the second piston surface (18) has a distance (d) in the axial extent (6) of the annular groove (21) in the closed position of the valve (2).

Valve system according to claim 1 or 2, wherein the piston (10) comprises an annular projection (22) providing the second piston surface (18).

5. Valve system According to a. any of the preceding claims, wherein the second chamber (19) has a chamber surface (23), seams closest to the first piston surface (17), the chamber surface (23) having a distance (d) in the axial extent (6). ) to the second piston surface (18) in the closed position of the valve (2).

Ventilation system according to any of the preceding claims, wherein the fluid passage (20) has a first passage (25) and a second passage (26), the second passage (26) being arranged opposite the second chamber (19). in the closed position where the second channel opening (26) is arranged perpendicular to the axial extension (6) so that when the piston (10) is moved to open the valve (2), the second channel opening (26) is moved past the second chamber (19) for interrupting the fluid connection between the first chamber (16) and the second chamber (19),

Valve system according to any one of the preceding claims, wherein the piston (10) comprises an annular projection (34) corresponding to an annular space (35) defined by the actuator housing (5) and the piston (10), thus that the projection (34), by moving the piston (10) to open the valve (2), can narrow the annular space (35).

Vent system according to any of the preceding claims, wherein the actuator housing (5) comprises a third opening (37) arranged at a distance from the second chamber (19) along the axial extension (6), wherein the third opening (37) ) is closer to the other end (8) of the actuator housing (5) than the first end (7) of the actuator housing (5),

Internal internal combustion engine (100) comprising the valve system (1) according to any one of claims 1-8.

Valve actuation method for moving an intake / exhaust valve (2) of the valve system (1) according to one. any of claims 1-8 between an open position and a closed position, the valve actuation method comprising the steps of: - pressurizing fluid, - passing the pressurized fluid past the first opening (9) of the actuator housing (5), - guiding - applying pressure to the first piston surface (17) and the second piston surface (18) simultaneously by means of the pressurized fluid, - movement of the piston (10) towards the second end (8) of the actuator housing (5) to open the valve (2), - closure of the fluid connection to the second chamber (19), and - further movement of the piston (10) to open the valve completely (2).