EP1828555A1

EP1828555A1 - Two-stroke large diesel engine

Info

Publication number: EP1828555A1
Application number: EP05806781A
Authority: EP
Inventors: Harro Andreas Hoeg; Knud Leon Brandt; Jan Gundlach
Original assignee: MAN B&W Diesel AS
Current assignee: MAN B&W Diesel AS
Priority date: 2005-11-10
Filing date: 2005-11-10
Publication date: 2007-09-05
Anticipated expiration: 2025-11-10
Also published as: CN101268256B; WO2007054109A1; NO338690B1; DE502005004913D1; NO20073258L; ATE403069T1; HK1121794A1; EP1828555B1; CN101268256A; PL1828555T3; ES2314729T3; DK1828555T3

Abstract

In a two-stroke reciprocating piston engine having at least one cylinder (1) whose combustion chamber (3) has an outlet opening (4), which can be controlled by an outlet valve (5) which can be actuated by means of an actuating device which comprises a feed device and a return device, and on whose cylinder head (2) is placed a valve housing (9) which comprises an outlet duct (8), which adjoins the outlet opening (4) of the combustion chamber (3), and a guide sleeve (10), which engages through the upper wall of said valve housing (9), for a shank (7), which extends through the outlet duct (8), of the outlet valve (5), wherein the return device has a piston (15), which is attached to the valve shank (7), and a working space (17) which is delimited by said piston (15), is acted on with compressed air and is sealed off from an annular gap (11), which is present between the mutually facing guide faces of the guide sleeve (10) and valve shank (7), communicates with the outlet duct (8) and can be supplied with oil, by a sealing device which is arranged in the region of the upper, outlet-duct-remote end of the annular gap (11) and has at least one sealing ring (22), according to the invention, it is possible to provide a simple design and a service-free mode of operation in that, above the sealing ring (22), which faces towards the outlet duct (8), of the sealing device, an oil reservoir (24 and 31 and 36) is provided which can be filled with oil and is filled with oil at the upper side, which faces away from the outlet duct (8), of said sealing ring (22).

Description

Applicant: MAN B & W Diesel A / S Copenhagen

Two-stroke diesel engine

The invention relates to a two-stroke large diesel engine having at least one cylinder whose combustion chamber has an controllable by a means of a feed device and a return actuator actuated outlet valve controllable outlet and on the cylinder head, a valve housing is placed, which is connected to the outlet opening of the combustion chamber exhaust port and a guide bushing passing through the upper wall thereof for a shaft of the outlet valve passing through the outlet passage, the return device having a piston attached to the valve stem and a working space which can be acted upon with compressed air and which is opposite to a guide bush and valve stem guide surfaces facing one another annular gap communicating with the outlet channel, to which oil can be supplied, by means of an annular gap in the region of the upper, outlet-channel-end of the annular gap eordnete, at least one sealing ring having sealing device is sealed

An arrangement of this kind is known from DE 101 61 438 A1. Applying the annular gap between the guide surfaces of the guide sleeve and valve stem with oil provides reliable protection against combustion residues entering the annular gap from the outlet channel, which in the past led to corrosion of the valve stem and destruction of the sealing ring of the sealing device. In the mentioned from DE 101 61 438 A1 known arrangement of the Ringspait by means of an associated metering device with the of the Auslassventi! associated hydraulic actuator applied branched off oil. The metering device provided in the known arrangement leads to a complex design with high costs of production and maintenance.

On this basis, it is therefore an object of the present invention to improve an arrangement of the type mentioned with simple and inexpensive means so that the dossier previously required is unnecessary and still ensures a reliable oil supply of the annular gap between the valve stem and guide bushing and a reliable function of Air spring trained return device is ensured.

This object is achieved in that above the outlet channel facing sealing ring of the sealing device is provided with an oil reservoir can be acted upon, the Ölfüilung is present at the side facing away from the annular gap top of said sealing ring.

These measures ensure that the sealing ring facing the outlet channel of the sealing device provided at the upper "cold" end of the annular gap is permanently flooded from above with the oil present in the oil reservoir, due to the pressure in the working space of the pneumatic restoring device and the movement of the oil Valve stem is forced into the sealing gap of the sealing device and passed therethrough, resulting in an advantageous manner not only to a gas-tight seal the working space of the return device and a good lubrication of the contact surfaces of the sealing ring, but at the same time to a controlled supply of below the sealing ring located Accordingly, the oil reservoir provided above the sealing ring also serves as an oil source for supplying said annular gap with oil, which can reliably prevent the penetration of combustion residues into the annular gap The oil is transported by the pressure in the working space and by the movement of the valve stem, also results in a very simple and maintenance-free construction. The oil consumption can be within the given using the geometry of the sealing ring Keep limits, so that despite a simple design also a reliable dosage and low oil consumption are guaranteed. The measures according to the invention accordingly give an overall excellent economy.

Advantageous embodiments and expedient developments of the higher-level measures are specified in the subclaims.

Advantageously, the oil reservoir is at least partially supplied with leaking oil from a hydraulic feed device associated with the outlet valve. This results in a particularly simple and inexpensive construction.

As a rule, the exhaust valve is associated with a hydraulic feed device and a return device arranged below it, which is designed as an air spring which has a valve shaft attached to the piston of a limited, thereby acted upon by air working space. The leaking from the hydraulic actuator leak oil can drip on the piston of the air spring and then passes to the circumferential guide surfaces of the piston over into the working space. Appropriately, while allowing the oil to collect easily in the bottom of the working space, resulting in the desired oil reservoir, which expediently provided by this oil reservoir oil return line is provided in which a safety valve to relieve the working space is arranged. By adjusting the opening pressure of the safety valve, a desired oil level in the oil reservoir can be maintained here.

According to a particularly advantageous development, the safety valve may be preceded by an overflow pipe protruding into the oil reservoir, the overflow edge of which is positioned higher than the oil ring flooded with oil. This facilitates the adjustment of the safety valve, since the oil level is specified by the overflow pipe, whose upper edge acts as an overflow edge.

Where the leakage oil should not be sufficient, the working space of the air spring can simply be supplied with oil and / or oil mist via an external oil source. to Production of oil mist can be simply assigned to the compressed air supply of the working space provided compressed air line a Ölbeimischeinrichtung.

A further advantageous measure may consist in that a sealing cap which engages over the sealing device has, above the sealing channel facing the outlet channel, at least one radial recess communicating with the oil reservoir and leading to its bore associated with the valve stem. This makes it possible to achieve a particularly reliable flooding of the sealing channel of the sealing device facing the outlet channel.

According to another advantageous embodiment of the higher-level measures, the above-mentioned cap above the outlet channel facing the sealing ring having an inner, the oil reservoir containing annular groove, which is acted upon via a supply line with oil. This results in a particularly space-saving design with a very compact oil reservoir, which can be filled by a comparatively small amount of oil.

Suitably, the annular groove may extend to the upper edge of the cap. In this case, this upper edge acts as an overflow edge, which is achieved in a simple manner, the desired oil level in the oil reservoir.

When using leakage oil to supply the annular groove with oil, the associated supply line can be easily connected to a trained in the working drip under cross gutter. The working space itself contains no bottom-side oil reservoir, which offers freedom of design with regard to the arrangement of the safety valve.

A further preferred embodiment of the higher-level measures may consist in that the sealing device has two sealing rings arranged one above the other and that the ring palmar region provided between these sealing rings is connected to a supply line and a disposal line to form the Qlroservoirε. This results in a particularly compact design. Since the oil reservoir is flowed through here permanently, still results in a reliable oil supply. Further advantageous embodiments and expedient developments of the parent measures are specified in the remaining subclaims and from the following description of the example with reference to the drawing closer.

In the drawing described below:

1 shows a first embodiment of the invention with reference to a vertical section through the upper region of a cylinder with associated exhaust valve arrangement of a two-stroke large diesel engine,

FIG. 2 shows a second exemplary embodiment of the invention with reference to a section of a vertical section according to FIG. 1, which section contains the upper end region of the guide bushing assigned to the valve shaft.

Figure 3 shows a third embodiment of the invention in Figure 2 corresponding representation and

FIG. 4 shows a radial section through a sealing device of the sealing device provided in the upper end region of the guide bush.

Main field of application of the invention are two-stroke large diesel engines as they are used, for example, for marine propulsion. The structure and operation of such arrangements is known per se.

As a rule, such motors have a plurality of cylinders 1 arranged next to one another in series. In FIG. 1, the upper region of such a cylinder 1 is indicated. This consists of a not shown in Figure 1 cylinder liner and. in the cylinder is a combustion chamber 3, which is provided with an upper, coaxial outlet opening 4, which is controllable by means of an associated exhaust valve 5. The outlet valve 5 has a valve seat 6 which cooperates with a valve seat provided in the region of the outlet opening 4 and which is attached to the lower end of a spindle-shaped valve stem 7. An outlet channel 8 adjoins the outlet opening 4 and is open with respect to the combustion chamber 3 when the outlet valve is lifted from the associated seat and vice versa. The exhaust valve 5 is associated with a mounted on the cylinder head 2 exhaust valve housing 9, which contains the exhaust passage 8. Attached to the valve housing 9 is a seat ring 9a which engages in the cylinder head 2 and which contains the valve seat which delimits the outlet opening 4. The valve housing 9 further includes a shaft 10 of the outlet valve 5 associated with the guide bushing 10. This is coaxial with the outlet opening 4 and extends from the puncture of the valve stem 7 through the upper wall portion of the outlet channel 8 to the upper portion of the valve housing 9. The guide bush 10 passes through the upper wall region of the outlet channel 8, so that the annular gap 11 between the mutually facing guide surfaces of the guide bushing 10 and the shaft 7 of the exhaust valve 5 is accessible from the outlet channel 8 ago.

The valve stem 7 passes through the guide bushing 10 and protrudes with its guide sleeve 10 projecting portion into a received on the valve housing 9 structure 12, which includes an outlet valve 5 associated actuator for effecting the opening and closing movement. The actuating device contains a feed device designed as a hydraulic unit and a resetting device designed as an air spring. The structure 12 has a two-part housing, the upper part 12a of which the hydraulic unit forming the feed device and the lower part 12b of which contain the air spring forming the return device.

The hydraulic unit forming the feed device comprises a piston 13 attached to the upper end of the valve stem 7 and a pressure chamber 14 limited by the latter and arranged in the upper part 12a, which by means of a pressure source, not shown in detail, expediently designed as a pump driven by the motor, having a high pressure Hydraulic oil can be acted upon. The provided below the hydraulic unit, acting as a return spring air spring comprises a penetrated by the valve stem 7, on this fixed piston 15, which encompasses a work space 17 enclosed by a collar 16 integrally formed on the lower part 12b and which can be acted on with compressed air via a compressed air line 18 connected to a compressed air source. To reduce excess pressure in the working space 17, this is provided with an outlet, to which an adjustable safety valve 19 is assigned, which opens at a set pressure.

The working space 17 delimiting, as the piston 15 associated cylinder acting collar 16 protrudes with axial and radial play in an associated, frontal recess of the upper part 12a in, resulting in a free space 20 between the upper part 12a and lower part 12b. The leakage oil escaping from the hydraulic unit located above the intermediate space 20 enters the intermediate space 20, from which an unpressurized return line 21 can exit. This expediently adjoins the bottom of the region of the intermediate space 20 that surrounds the collar 16.

The acted upon by compressed air working chamber 17 is sealed relative to the annular gap 11 between the facing guide surfaces of the valve stem 7 and guide bush 10 by a sealing ring 22 at least one sealing device. The sealing device may be formed as a stuffing box containing at least one sealing ring 22. In the embodiment according to Figures 1 and 2, a sealing ring 22 is provided. In the embodiment according to FIG. 3, sealing rings 22, 23 arranged one above the other are provided.

Since the annular gap 11 between the mutually facing guide surfaces of the valve stem 7 and guide bush 10 is open to the outlet channel 8, there is a risk that combustion residues penetrate into the annular gap 11, which leads to damage of Führungsfiächen and in particular the sealing ring 22 and the lower that is, the sealing channel 22 facing the outlet channel 8 can lead to the sealing device. To prevent this, the annular gap 11 is pressurized with oil from above. This can emerge at the lower end of the annular gap 11 in the outlet channel 8, where it can burn. To act on the annular gap 11 with oil above the sealing ring 22 of the oil sealable oil reservoir 24 is provided, which flooded at the side facing away from the annular gap 11 top of said sealing ring 22 oil filling said sealing ring 22 and thereby as the annular gap 11 from above with Oil supplying and the sealing ring 22 lubricating oil source is used.

In the embodiment according to FIG. 1, the leakage oil escaping from the pressure chamber 14 of the hydraulic unit primarily serves to feed the oil reservoir 24. The same applies to FIG. 2. The aforementioned leak oil drips, as already mentioned above, into the intermediate space 20 and at least reaches it partially on the top of the piston 15 of the air spring assembly. From here, the leakage oil reaches the working space 17 in the region of the circumferential piston surface, where it can collect on the bottom side and form the oil reservoir 24, as can be clearly seen in FIG.

As a rule, enough leak oil leaked from the hydraulic unit passes into the pressure chamber 17 in order to ensure adequate supply of the oil reservoir 24. Where this is not the case, of course, additional oil can be introduced into the pressure chamber 17. This is indicated in FIG. 1 by a supply line 25 which opens into the lower region of the pressure chamber 17. The supply line 25 may be associated with an external oil source. But it would also be possible to simply divert the oil supplied via the supply line 25 from the oil supplied to the pressure chamber 14 of the hydraulic unit. Alternatively or additionally, the working space 17 can also be charged with oil mist. For this purpose, the compressed air line 18 may be associated with an oil mixing device 26. The entrained by the compressed air oil is sprayed in the form of an oil mist in the working space 17. The oil mist precipitates on the walls and drips off into the oil reservoir 24.

When the piston 15 is moved downward, the already compressed air present in the working space 17 is further compressed. The higher the oil level in the reservoir 24, the stronger the air is compressed. From a certain pressure opens the safety valve 19 The oil level in the oil reservoir 24 can therefore be kept at a desired level by appropriate adjustment of the safety valve 19. As already mentioned above, the safety valve 19 controls a flow path leading from the oil reservoir 24 to an oil return line 21.

In the embodiment shown in Figure 1, the safety valve 19 is associated with a projecting into the oil reservoir 24 overflow pipe 27, the upper end forms an overflow edge and accordingly sets the height of the oil level in the oil reservoir 24. The safety valve 19 can be set in this embodiment, regardless of the height of the oil level in the oil reservoir 24 to a fixed pressure, which facilitates the setting. Nevertheless, the oil reservoir 24 results in a constant oil level. The overflow edge formed by the upper end of the overflow pipe 27 is of course higher than the sealing ring 22 so that it is reliably flooded with oil.

The sealing ring 22 receiving the guide bushing 10 is supported with an upper flange 10 a on the valve housing 9. The sealing ring 22 is inserted into an upwardly open annular groove of the flange 10 a, which is overlapped by a cap 28. This is provided in a below the oil level of the oil reservoir 24 and above the sealing ring 22 located area with radial Durchgangsausnehmungen 29, which accordingly lead from the oil reservoir 24 to above the sealing ring 22 located portion of the annular gap 11, whereby a flooding of the sealing ring 22nd is favored with oil. The radial recesses 29 may be formed as bores or cutouts, etc.

In the embodiment underlying the figure 2, the attacked by the valve stem 7 bore of the above-mentioned cap 28 relative to the diameter of the valve stem 7 radial excess, so that the valve stem 7 surrounding annular groove 31 results, which can accommodate an oil reservoir 32, which has a to the annular groove '31 connected supply line 33 can be acted upon with oil. The supply line 33, like the supply line 25 of the embodiment according to FIG. 1, can be connected to an external supply Oil source etc. may be connected, again in the example shown is leak oil, as already mentioned, for feeding the oil reservoir 32 use.

The leakage oil entering into the working space 17 in the area of the guide surfaces of the piston 15 drips off at the lower edge of the cylindrical running surface assigned to the piston 15. This drip edge 34 is here underlined by a collecting channel 35, from which the supply line 33 goes off. The oil groove 32 containing annular groove 31 extends to the top of the cap 28, the upper side accordingly forms an overflow edge, through which a constant oil level in the oil reservoir 32 is ensured. The overflowing oil enters the region of the bottom of the working space 17, from where the controlled by the safety valve 19 flow path, can be removed via the excess oil. The safety valve 19 can be adjusted without regard to the oil level in the oil reservoir 32, which simplifies the setting. An overflow pipe upstream of the safety valve 19 is not required in this embodiment, which is often advantageous for reasons of space.

In the embodiment according to FIG. 3, as already mentioned above, two sealing rings 22, 23 arranged at a distance from one another are provided. The limited by these two sealing rings 22, 23 portion of the annular gap 11 is applied to form an oil reservoir 36 with oil. In the example shown, the oil is applied in continuous operation. The said annular gap section is accordingly connected to a supply line 37 and a disposal line 38. The supply line 37 may be connected to an external oil source. The disposal line 38 can open into a non-pressurized oil return line. In this embodiment too, the sealing ring facing the outlet channel 8, in this case the lower sealing ring 22, ie the lower sealing ring of the sealing ring arrangement, is reliably flooded with oil, whereby the annular gap 11 is reliably supplied with oil. The Zwangssbeaufschiagung the oil reservoir 36 results in a particularly high reliability.

In general, the application of the annular gap 11 to the oil entering via the sealing ring 22 prevents a reliable penetration of combustion residues into the annular gap 11. In order to support this effect, the Ringspalti 1 are additionally acted upon with compressed air, which is suitably fed below the sealing ring 22, as indicated in Figure 1 by a positioned below the sealing ring 22, the annular gap 11 leading line 39 is indicated. It would also be conceivable to supply oil mist and / or additional oil via such a line.

The oil flow through the annular gap 11 may be comparatively low and may be about one liter per day in a two-stroke large diesel engine. The escaping from the hydraulic unit leak oil is about 10 liters per day in such an engine and therefore can easily cover the oil consumption to supply the annular gap 11 of the.

The oil supply to the annular gap 11 takes place on the sealing ring 22 and can be influenced by its geometry. It can be assumed that between the sealing ring 22 and the valve stem 7, a hydrodynamic lubricating film is formed, the thickness of which depends essentially on the geometry of the sealing ring 22 and other fixed parameters such as the relative speed. A wedge-shaped inlet of the gap between the relatively moving surfaces favors the formation of a lubricating film. Likewise, the width of the contact surface adjoining the inlet influences the thickness of the lubricating film.

In the example underlying the Figure 4, the sealing ring 22 has a symmetrical to a horizontal plane of symmetry cross section with wedge-shaped inlet 41 on both sides and a broad contact surface 40. The wedge shape of the inlet has a comparatively large wedge angle. The contact surface 40 is wide and extends over almost the entire height of the sealing ring 22. With such a geometry of the sealing ring 22, an oil throughput of the above-mentioned order of magnitude can be achieved in a two-stroke large diesel engine.

Claims

1. Two-stroke large diesel engine with at least one cylinder (1), the combustion chamber (3) by an actuatable by means of a feed device and a return actuator actuated outlet valve (5) controllable outlet (4) and on the cylinder head (2) a Ventiigehäuse (9), which has an outlet channel (9) adjoining the outlet opening (4) of the combustion chamber (3) and a guide bushing (10) extending through the upper wall thereof for a shaft (7) of the outlet valve (5) passing through the outlet channel (8) ), wherein the restoring device has a piston (15) attached to the valve stem (7) and a working chamber (17) which can be acted upon with compressed air and which is located opposite one another between the facing guide surfaces of guide bushing (10) and valve stem (7) , with the outlet channel (8) communicating annular gap (11), the oil is supplied, by a in Ber characterized in that at least one sealing ring (22) has sealing means, characterized in that above the outlet channel (8) facing sealing ring (22) of the sealing means an oil reservoir (24 resp 32 or 36) is provided, whose oil filling is present at the top of said sealing ring (22) facing away from the outlet channel (8).

2. Two-stroke large diesel engine according to claim 1, characterized in that the outlet valve (5) by means of a shaft (7) acting, hydraulic feed device against the force of the return device can be brought into the open position and that the oil reservoir (24 or 32) is at least partially supplied with leaking from the hydraulic actuator leaking oil.

3. Two-stroke large diesel engine according to one of the preceding claims, characterized in that the oil level in the oil reservoir (24 or 32) is limited by an overflow edge.

4. Two-stroke large diesel engine according to one of the anticipated claims, characterized in that the restoring device is arranged below the hydraulic actuator and that the piston (15) opposite the bottom portion of the working space (17) of the pneumatic return device containing the oil reservoir (24) and via a Relief valve (19) is relieved, which is arranged in a from the oil reservoir (24) outgoing oil return line (21).

5. Two-stroke large diesel engine according to claim 4, characterized in that the safety valve (19) into the oil reservoir (24) projecting into the overflow pipe (27) is arranged, whose overflow edge forming, upper end higher than the oil-flooded sealing ring (22) is positioned.

6. Two-stroke large diesel engine according to one of the preceding claims, characterized in that the working space (17) is at least partially acted upon via an associated supply line (25) from the outside with oil.

7. Two-stroke large diesel engine according to one of the preceding claims, characterized in that the working space (17) is at least partially acted upon via an associated supply line with an oil mist.

8. Two-stroke large diesel engine according to claim 7, characterized in that the working space (17) via a compressed air line (18) can be supplied with compressed air and that the compressed air line (18) is associated with a Ölbeimischeinrichtung (26).

9. Two-stroke large diesel engine according to one of the preceding claims, characterized in that the guide bush (10) with a the Sealing device has overarching cap (28) is provided, which above the oil-flooded sealing ring (22) at least one with the oil reservoir (24) communicating and leading to its from the valve shaft (7) through bore leading radial recess (29).

10. Two-stroke large diesel engine according to one of the preceding claims 1- 3, characterized in that the guide bush (10) is provided with a sealing device cross-cap (28) above the oil-flooded sealing ring (22) an inner, the oil reservoir

(32) containing annular groove (31), which via a supply line

(33) is beaufschiagbar with oil.

11. Two-stroke large diesel engine according to claim 10, characterized in that the restoring device is formed as arranged below the hydraulic actuator air spring having a piston on the valve stem (7) mounted piston (15) and a limited, can be acted upon with air working space (17) in which an oil drip edge

(34) is formed, which is underlined by a gutter (35) from which the supply line (33) goes off.

12. Two-stroke large diesel engine according to claim 10 or 11, characterized in that the annular groove (31) extends to the upper, an overflow edge forming edge of the cap (28).

13. Two-stroke large diesel engine according to claim 10, characterized in that the sealing device (2) has superposed sealing rings (22, 23) and that between the sealing rings (22, 23) provided annular gap area for forming the oil reservoir (36) to a supply line (37) and a disposal line (38) is connected.

14. Two-stroke large diesel engine according to claim 13, characterized in that the supply line (37) is connected to an outside of the working space (17) located oil source.

15. Two-stroke large diesel engine according to one of the preceding claims, characterized in that at least the outlet channel (8) facing sealing ring (22) of the sealing device has a symmetrical to a horizontal plane cross section with wedge-shaped inlet (41) and wide contact surface (40).

16. Two-stroke large diesel engine according to one of the preceding claims, characterized in that the of the mutually facing guide surfaces of guide bush (10) and valve stem (7) limited annular gap (11) below the outlet channel (8) facing the sealing ring (22) via a Supply line (39) can be acted upon with air and / or oil mist.