JP2003184550A - Reciprocating piston engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To strongly protect substantially the whole of an exhaust valve housing in order to keep a stipulation concerning the maximum surface temperature of an internal combustion engine. <P>SOLUTION: In a reciprocating piston engine, a cooling path (17) attached to a region which engages with a cylinder head (4) and a cooling path (21) of the exhaust valve housing (7) attached to a region which contains a guide means (19) are connected to each other by at least one connecting pipe (23) provided on a radially inner side of an attached through bolt (9) in a region of a radially extending protrusion (22) at least adjacent to an exhaust port, to thereby obtain high reliability and compact structure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating piston engine, particularly a two-stroke large diesel engine,
It comprises at least one cylinder containing a combustion chamber, the cylinder head of the cylinder supporting an exhaust valve housing, the exhaust valve housing being connected to the combustion chamber by a valve cooperating with a seat on the exhaust valve housing side. A through bolt, which is arranged on the circumferential side and penetrates a radial projection, is attached to the cylinder head and includes an exhaust port that can be closed with respect to the valve, a guide device attached to the valve, and an operating device. The present invention relates to a type in which a cooling passage capable of supplying cooling water, in particular, a circulating cooling passage is respectively provided in a region including a valve seat and a region including a guide device in an exhaust valve housing.

[0002]

2. Description of the Prior Art According to the prior art, this kind of arrangement is known. In this known arrangement, no additional cooling device associated with the exhaust port is provided in the region between the respective circulating cooling passages associated with the valve seat region or the valve guide region. This can result in very heavy heating of the entire exhaust valve housing. Therefore, in this case, the wall surface temperature of the inner surface of the exhaust port is not expected to fall below the dew point temperature of the exhaust gas, which is desirable for preventing low temperature corrosion. On the other hand, however, the very intense heating of the exhaust valve housing and in particular the bearing area associated with the through-bolt also leads to the resulting severe thermal expansion, which leads to an overstress of the pre-stressed through-bolt. Of the through bolt and the loss of initial stress of the through bolt. As a result, so-called blow-by or burnout can occur in the area of the abutment surface and the sealing surface, since the exhaust valve housing is no longer reliably pressed onto the cylinder head. Therefore, it has been found that the known configuration is not sufficiently reliable. Even if this point is disregarded, in this case, in order to comply with the regulation regarding the maximum surface temperature of the internal combustion engine, it is also necessary to provide strong protective heat insulation to almost the entire exhaust valve housing (for example, Patent Document 1). reference).

[0003]

[Patent Document 1] European Patent No. 0076348

Therefore, the object of the present invention, which is based on the above, is to improve the structure of the kind mentioned at the outset while avoiding its drawbacks and maintaining its advantages, so as to obtain high reliability. Is.

[0005]

SUMMARY OF THE INVENTION According to the invention, the object is to provide a cooling passage associated with the area for engaging the cylinder head and an exhaust valve housing cooling passage associated with the area containing the guide device. At least in the region of the radial projections near the exhaust port, they are connected to each other by at least one connecting pipe provided radially inside the associated through bolt.

The previously mentioned connecting passages between the respective cooling passages, which are likewise per se, lead to excessive extension of the through bolts, at least in the region of the exhaust valve housing close to the particularly dangerous exhaust port. It functions as a cooling passage that allows the inflowing heat to escape to the extent that thermal expansion does not occur in the bearing side region of the housing attached to the bolt. In this way it is ensured that the initial stress of the through-bolts is maintained and thus the positive seal between the exhaust valve housing and the cylinder head. At this time, the cooling water supplied to the cooling system formed by the circulating cooling passage and the connecting pipe is 100
The advantage is that it is possible to have a relatively low temperature well below ° C, so that vapor locks inside the cooling system and the consequent loss of cooling effect do not occur. Nevertheless, it is possible to avoid a situation where the inside surface of the exhaust port is below the dew point temperature of the exhaust gas, which may occur in the case of a configuration with a cooling passage that encompasses the entire exhaust port. Despite the advantages mentioned above, a relatively simple manufacture and a comparatively low structural weight can be realized. In addition, the surface may require relatively little protective insulation. Therefore, the advantages achievable by the present invention can also be considered to be outstanding economics.

An advantageous embodiment of the features of the independent claim,
And suitable developments are described in the dependent claims. For example, it is convenient to provide a connecting pipe in each radial projection area. This is
All projections may be positioned relatively close to the exhaust port, as this leads to exceptionally good heat dissipation in the area of all projections, which results in a compact design style.

It is often advantageous to attach a plurality of parallel connecting pipes to each projection to be cooled.
This has the advantage that it makes it possible to embody the cross-sectional area of the connecting pipe to be relatively small, which leads to a relatively high velocity of the cooling water at a given flow rate,
Along with that, it leads to good heat discharge without excessive heating of the cooling water.

Furthermore, it is advantageous if at least the lower region of the connecting pipe extends at a distance from the inner surface of the exhaust port, which corresponds approximately to the wall thickness of the exhaust port provided outside the range of the radial projections. It turns out. Thereby, even when the temperature of the cooling water is relatively low, it is possible to surely avoid falling below the dew point temperature of the surface exhaust gas inside the exhaust port. On the other hand, the bearing area, which is radially outside the normal wall thickness and is associated with the through bolt, is reliably protected against unacceptable heating.

Yet another advantageous measure is that only one of the two circulating cooling passages is provided with at least one coolant supply pipe and the other of the two circulating cooling passages is provided with at least one coolant discharge pipe. It is to be attached. As a result, the circulating movement of the coolant and the reliable flow-through of the connecting pipe are thereby forcibly realized.

The connecting pipe preferably has a hole-shaped passage communicating with the circulating cooling passage and extending parallel to the valve rod and / or parallel to the attached through bolt. This passage may be perforated or cast. In either case, the arrangement described above facilitates simple and accurate manufacture.

Further advantageous embodiments of the features of the independent claim, as well as suitable developments, are described in the remaining dependent claims, and are explained in more detail in the following description of the embodiments with reference to the drawings. explain.

[0013]

The basic construction and the mode of operation of a two-stroke large diesel engine are known per se and therefore need not be explained in detail in the context of the present invention. An engine of this kind usually comprises a plurality of cylinders 1 of the type shown in FIG. 1, which cylinders are
The pistons, which delimit the combustion chambers, are not shown in detail here, respectively, which are connected to a crosshead via a piston rod, which crosshead cooperates with a crankshaft via a connecting rod.

The cylinder 1 comprises a cylinder liner 3, which receives at least one injection valve 5 and is provided with a stepped central notch 6 for accommodating an exhaust valve housing 7. The exhaust valve housing 7 engages with the notch 6 in its lower region, and rests on a bearing surface 8 on the cylinder head side, which is a flange-shaped support surface and is formed by a stepped portion of the notch 6. . In order to obtain a sufficient crimping force which is effective in the area of the bearing surface 8, there is provided a through bolt 9 which is provided radially outside the notch 6 of the cylinder head 4 and which can be screwed into the cylinder head at the lower end. These through bolts pass through the respective insertion passages 10 of the exhaust valve housing 7, and the upper end portions of the through bolts are mounted on the auxiliary support surface 11 of the exhaust valve housing 7. Accept 12 each.

The exhaust valve housing 7 includes an exhaust port 13 extending from the combustion chamber 2 as a starting point, the exhaust port 13 being movable up and down by an operating device 20 received on the exhaust valve housing 7. By means of a valve 14 cooperating with a valve seat provided in the inlet region, the combustion chamber 2
Can be closed against. In order to receive the aforementioned valve seat, the exhaust valve housing 7 is provided here with a lower seat 15 made of a suitable material, which seat comprises a support flange which rests on a bearing surface on the cylinder head side. Including. The seat 15 continues by means of a circumferential groove to the housing part 16 of the exhaust valve housing, generally designated 7, including the upper support surface 11 associated with the through bolt 9.

The seat 15 comprises, above the flange associated with the support surface 8, a cooling passage 17 formed by a corresponding expansion of the cutout 6 of the cylinder head 4, which cooling passage is provided on the upper housing. It is closed upwards by means of a flange which is provided at the lower end of the part 16 and which engages in the notch 6 of the cylinder head 4.

The valve 14 has a valve rod 18 standing upward from its valve body, which valve rod has an exhaust port 13 and an exhaust port 1 of an upper housing part 16.
3 and a guide bush 19 arranged in a region surrounding the guide bush 19.
Collaborate with. The region of the upper housing part 16 of the exhaust valve housing 7, including the guide bush 19, is also provided with a circulating cooling passage 21.

To receive the through bolt 9, the upper housing part 16 has a rib-like projection 22 attached to the through bolt 9, which projects radially from the edge region of the cylinder head 4 including the notch 6. And each of these protrusions includes a vertical insertion passage 10. The upper surface of the protrusion 22 forms a support surface 11 attached to the nut 12 of the through bolt 9. The lower surface of the protrusion 22 is the upper housing portion 1
Since it extends obliquely inwardly to the lower end region of 6, the console-like support of the projection 22 is thereby created.

The through bolt 9 and the insert passage 10 attached thereto are arranged so as to be distributed on a partial circle concentric with the valve shaft, as best shown in FIG.
In the example shown, there are provided four through bolts 9 or insertion passages 10 which are arranged opposite to each other in pairs with respect to the plane of symmetry S defined by the valve shaft and the center line of the exhaust port 13. There is. The same applies to the protrusions 22, the number and the angular spacing of which depend on the through bolts 9.
It corresponds to the number and the angular interval. Therefore, in the illustrated example, four protrusions 22 are provided so as to face each other so as to form a set with respect to the plane of symmetry S. At this time, the angular intervals of the protrusions 22 arranged on the same side of the plane of symmetry S that are adjacent to each other are shorter than the angular intervals of the protrusions 22 that face each other with respect to the plane of symmetry S. In this way, two sets of protrusions are formed, which are substantially arranged on both sides of the exhaust port 13.

The projections 22 are formed from the exhaust gas to the exhaust port 13
Exhaust port 13 that receives the load of heat released to the wall of the
It also functions as a cooling rib attached to the. To prevent the projections 22 from being heated too strongly, the resulting thermal expansion leads to excessive extension of the through bolt 9 which is prestressed by a corresponding tightening of the nut 12, , A cooling passage 17 on the lower seating portion side that circulates, inside the attached insertion passage 10 in the radial direction,
The cooling device is provided as a connecting pipe 23 that connects the circulating upper guide bush side cooling passage 22. The coolant is supplied through the supply pipe 24 attached to the circulating lower cooling passage 17 as shown by the flow arrow, and as shown by the flow arrow as well, the cooling upper The cooling water discharged through the processing pipe 25 attached to the cooling passage 21 is used. In this way, a cooling system formed by the cooling passages 17 and 21 and the connecting pipe 23, which flow through in substantially one direction, is obtained.

As shown in FIG. 1, the connecting pipe 23 includes a hole-shaped passage parallel to the valve shaft or the through bolt shaft that bridges the height distances of the cooling passages 17 and 21 and connects them. . This hole-shaped passage may already be provided during the casting of the upper housing part 16 which is constructed as a casting, or may be produced by drilling in the cutting process.
As shown in FIG. 2, the hole-shaped passage of the connecting pipe 23 is located on a partial circle located inside the partial circle concentric to the valve shaft, which is attached to the through bolt 9 or the insertion notch 10. The radius of the latter partial circle is arranged in a ratio of 2: 3 with respect to the radius of the partial circle attached to the insertion passage 10. At this time, in the hole-shaped passage of the communication pipe 23 that functions as a cooling passage, the radial projection 22 is substantially
3 in the area added to the center of the upper housing part 16 including 3. The radial positioning of the above-mentioned axially parallel passages of the connecting pipe 23 is, as can be seen from FIG. 1, in the lower region of the upper housing part 16 which has an inner wall substantially parallel to the valve axis, in the exhaust port. Conveniently, there is a spacing a slightly smaller than the wall thickness d between the inner surface of 13 and the aforementioned axially parallel passages of the connecting pipe 23.

The lower end of the axially parallel passage of the connecting pipe 23 is located radially below the circulating lower cooling passage 17 and is accessible from the cooling passage 17. For this purpose, the axially parallel passages may be connected to a circulating groove which opens towards the circulating lower cooling passage 17. In the illustrated example, the lower end of the axis-parallel passage of the communication pipe 23 is
As can be seen in FIG. 1, it is connected to the cooling passages 17 by radial branch holes 26 attached thereto. Instead of the branch hole, a slit-shaped milling part may be provided. As shown in FIG. 2, the upper axially parallel end of the connecting pipe 23 communicates with this cooling passage in the circumferential edge region of the bottom surface of the circulating upper cooling passage 21.

In the example shown, each radial projection 22 is provided with two parallel connecting pipes 23. However, the protrusion 22 located closest to the exhaust port 13, ie, normally located near the outflow cross section of the exhaust port 13, subject to a particularly high heat load, FIG.
In many cases, it is sufficient to attach the connecting pipe 23 functioning as a cooling device only to the protrusion 22 facing downward. Similarly, it is often sufficient to provide only one connecting pipe 23 rather than a plurality of protrusions.

The cross-sectional area of the connecting pipe 23 is smaller than the cross-sectional area of the protrusion 22 attached thereto. The number and cross-sectional area of the connecting pipes 23 are such that the wall surface temperature generated on the inner surface of the exhaust port 13 is higher than the dew point temperature of the exhaust gas.
Moreover, it is expedient to choose such that the temperature of the cooling water flowing through the connecting pipe 23 is kept clearly below the vaporization temperature.

Although an advantageous embodiment has been described above, this embodiment is not intended to be limiting. For example, the measures of the present invention are not, of course, bound to a particular number of through bolts or projections associated therewith. Of course,
More or less through bolts or associated projections may be provided than in the illustrated example. The drawings are as follows:

[Brief description of drawings]

1 is a vertical cross-sectional view showing the upper region of a cylinder of a two-stroke large diesel engine.

2 shows an exhaust valve housing having the configuration of FIG. 1,
FIG. 2 is a horizontal sectional view taken along the line II / II in FIG. 1.

[Explanation of symbols]

1 cylinder 2 combustion chamber 4 cylinder head 7 Exhaust valve housing 9 through bolts 13 Exhaust port 14 valves 17,21 Cooling passage 19 Guide bush (guide device) 20 Operating device 22 Radial protrusion (exhaust valve housing protrusion) 23 Communication piping 24 Supply Pipe (Coolant Supply Pipe) 25 Processing pipe (coolant processing pipe) 26 Branch holes (radial piping members)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02F 1/38 F02F 1/38 AF term (reference) 3G016 CA14 CA16 CA36 CA57 DA06 DA22 GA00 3G024 AA11 AA16 CA05 DA12 EA10 GA27 GA28

Claims (11)

[Claims] 1. A reciprocating piston engine, in particular a two-cycle large diesel engine, comprising at least one cylinder (1) containing a combustion chamber (2), the cylinder head (4) of the cylinder having an exhaust valve housing (7). ), The exhaust valve housing leading to the combustion chamber (2),
A valve that cooperates with the valve seat on the exhaust valve housing side (1
4) Exhaust port (1 that can be closed to the combustion chamber by
3), a guide device (19) attached to the valve (14)
And a through bolt (9), which includes the operating device (20) and which is arranged on the circumferential side and penetrates the radial projection (22), is attached to the cylinder head (4). A cooling passage (1), which is capable of supplying cooling water, to the region of engagement, which includes the valve seat, and the region of the exhaust valve housing (7), which includes the guide device (19), in particular.
7) or (21) respectively, the exhaust valve housing having a cooling passage (17) attached to an area engaging with the cylinder head (4) and an area including a guiding device (19) The cooling passage (21) of (7) is provided with a radial projection (2) near at least the exhaust port.
Reciprocating piston engine, characterized in that in the region of 2) they are connected to each other by at least one connecting pipe (23) provided radially inside the associated through bolt (9). 2. Reciprocating piston engine according to claim 1, wherein each projection (22) is associated with at least one connecting pipe (23). 3. A plurality of, in particular two, parallel connecting pipes (23) are attached to each projection (22) at least near the exhaust port, and in particular to every projection (22). The reciprocating piston engine according to Item 2. 4. Cooling passages (17, 2) in which the connecting pipe (23) extends parallel to the valve stem and / or the through bolt.
The reciprocating piston engine according to any one of claims 1 to 3, having a region communicating with 1). 5. The wall of the exhaust port (13) outside the range of the protrusion (22), even if the radial distance from the inner surface of the exhaust port (13) to the lower region of the communication pipe (23) is long. The reciprocating piston engine according to any one of claims 1 to 4, which matches the thickness. 6. The reciprocating piston engine according to claim 1, wherein the cross-sectional area of the connecting pipe (23) is relatively small as compared with the cross-sectional area of the attached protrusion (22). 7. The number and cross-sectional area of the connecting pipes (23) are such that the temperature of the cooling water flowing therethrough is clearly below 100 ° C., and the wall temperature of the inner surface of the exhaust port (13) is such that the exhaust gas Claims 1 to 6 selected to remain well above the dew point temperature of
The reciprocating piston engine according to any one of items 1 to 7. 8. The reciprocating piston engine according to claim 1, wherein a region parallel to the axis of the connecting pipe (23) is configured as a hole-shaped passage. 9. A radial pipe member (26) is provided in the region of the end of the connecting pipe (23) which is parallel to the axis and which is located radially inward of the adjacent cooling passage (17). Any one of claims 4 to 8 which communicates with the adjacent cooling passages (17) via and penetrates the peripheral edge region of the bottom surface of the adjacent cooling passages (21) at the upper end. The reciprocating piston engine according to item 1. 10. At least one coolant supply pipe (24) is attached to only one of the two circulating cooling passages (17) or (21), whereby both of the circulating cooling passages (17) or (21) are connected. Reciprocating piston engine according to any one of claims 1 to 9, wherein the other is associated with at least one coolant treatment pipe (25). 11. Four projections (22) are provided, each of which is attached to one through bolt (9), these projections being symmetrical with respect to the valve shaft and the center line of the exhaust port (13). The protrusions (22), which are arranged opposite to each other in pairs with respect to the surface S and are adjacent to each other, are
Reciprocating piston engine according to any one of claims 1 to 10, having mutual angular spacings that are shorter than the projections (22) facing each other.