JP4040961B2 - Reciprocating piston engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a reciprocating piston engine, in particular a two-cycle large diesel engine, comprising at least one cylinder including a combustion chamber, the cylinder head of which supports an exhaust valve housing, the exhaust valve housing comprising a combustion chamber Including an exhaust port that can be closed with respect to the combustion chamber by a valve that cooperates with a seating portion on the exhaust valve housing side, a guide device and an operation device attached to the valve, and is arranged on the circumferential side in the radial direction A through bolt that penetrates the projection of the cylinder is attached to the cylinder head and engages with the cylinder head. The region including the valve seat and the region including the guide device of the exhaust valve housing can supply cooling water. It is related with the type which each has a cooling passage attached.
[0002]
[Prior art and problems to be solved by the invention]
According to the prior art, this kind of configuration 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 cause very intense 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 be lower than the dew point temperature of the exhaust gas, which is desirable to prevent low temperature corrosion. On the other hand, however, the very intense heating of the exhaust valve housing and in particular the bearing area attached to the through-bolts also leads to the resulting intense thermal expansion, which is an excess of the initial-stressed through-bolts. May lead to a loss of initial stress of the through-bolt and accompanying stress. As a result, the exhaust valve housing can no longer be securely crimped to the cylinder head, and so-called blow-by or burnout can occur in the area of the abutment surface and the sealing surface. Therefore, it has been found that the known configuration is not sufficiently reliable. Even if this point is ignored, in this case, in order to comply with the regulations regarding the maximum surface temperature of the internal combustion engine, it is also necessary to provide strong protective heat insulation on almost the entire exhaust valve housing (for example, Patent Document 1). reference).
[0003]
[Patent Document 1]
EP 0076348 Specification [0004]
Accordingly, an object of the present invention based on the above is to improve the structure of the type described at the beginning while avoiding the drawbacks and maintaining the advantages so as to obtain high reliability.
[0005]
[Means for Solving the Problems]
According to the present invention, the object is that the cooling passages attached to the region engaging the cylinder head and the cooling passages of the exhaust valve housing attached to the region containing the guide device are at least radially close to the exhaust port. This is solved by being connected to each other by at least one connecting pipe provided radially inward of the attached through-bolt in the region of the protrusions.
[0006]
The aforementioned communication passages between the respective cooling passages that circulate in the same way are attached to the through bolts, which lead to excessive extension of the through bolts, at least in the area close to the specially dangerous exhaust port of the exhaust valve housing. It functions as a cooling passage that can release the inflowing heat to such an extent that thermal expansion of the bearing area on the housing side does not occur. In this way, the initial stress of the through-bolts is maintained, and with this it is ensured that a positive seal between the exhaust valve housing and the cylinder head is maintained. At this time, there is an advantage that the cooling water supplied to the cooling system formed by the circulating cooling passages and the communication pipes can have a relatively low temperature that is clearly below 100 ° C., whereby the cooling system The internal vapor lock and the accompanying cooling effect do not occur. Nevertheless, it is possible to avoid the situation where the dew point temperature of the exhaust gas is below the inner surface of the exhaust port, which may occur in the case of a configuration including a cooling passage including the entire exhaust port. Despite the advantages described above, relatively simple manufacturing and relatively low structural weight can be achieved. Furthermore, relatively little protective insulation is required on the surface. Therefore, the advantages achievable by the present invention can be considered to be excellent economics.
[0007]
Advantageous embodiments of the features of the independent claims and developments suitable for the purpose are described in the dependent claims. For example, it is advantageous to provide a connecting pipe in each radial projection area. This leads to exceptionally good heat dissipation in the area of all protrusions, so that all protrusions can be positioned relatively close to the exhaust port, which results in a compact design style.
[0008]
It is often advantageous to attach a plurality of parallel connecting pipes to each of the projections to be cooled. This has the advantage of allowing the cross-sectional area of the connecting pipe to be embodied relatively small, which leads to a relatively high rate of cooling water at a given flow rate, It leads to good heat discharge without excessive cooling water heating.
[0009]
Furthermore, it has proved 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 radial projection. is doing. Thereby, even when the cooling water temperature is relatively low, it can be reliably avoided that the dew point temperature of the surface exhaust gas falls below the exhaust port. On the other hand, the bearing area attached to the through-bolt, which is radially outside the normal wall thickness, is reliably protected against unacceptable heating.
[0010]
Yet another advantageous measure is that at least one coolant supply pipe is attached to only one of both circulating cooling passages and at least one coolant discharge pipe is attached to the other of both circulating cooling passages. It is. This forcibly realizes the circulating movement of the coolant and the associated flow through the connecting pipe.
[0011]
The communication pipe preferably has a hole-like passage extending in parallel with the valve stem and / or in parallel with the attached through bolt, which communicates with the circulating cooling passage. This passage may be perforated or cast. In any case, the configuration described above facilitates simple and accurate manufacturing.
[0012]
Other advantageous embodiments of the constituent elements of the independent claims and developments suitable for the purpose are described in the remaining dependent claims and are explained in detail in the following description of the embodiments with reference to the drawings.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The basic structure and mode of operation of a two-cycle large diesel engine are known per se and therefore need not be described in detail in the context of the present invention. This type of engine typically includes a plurality of cylinders 1 of the type shown in FIG. 1, each of which is accompanied by a piston, not shown in detail, that delimits the combustion chamber. The piston is connected to the crosshead via a piston rod, and the crosshead cooperates with the crankshaft via a connecting rod.
[0014]
The cylinder 1 includes a cylinder liner 3, which receives at least one injection valve 5 and is provided with a stepped central notch 6 for receiving an exhaust valve housing 7. The exhaust valve housing 7 engages with the notch 6 in the lower region thereof, and rests on the support surface 8 on the cylinder head side formed by the stepped portion of the notch 6 with a flange-like support surface. . In order to obtain a sufficient crimping force effective in the region of the bearing surface 8, a through bolt 9 provided on the radially outer side of the notch 6 of the cylinder head 4 and screwed into the cylinder head at the lower end is provided. These through bolts pass through the respective insertion passages 10 attached to the exhaust valve housing 7, and the upper ends of the through bolts are nuts mounted on the attached support surface 11 of the exhaust valve housing 7. Accept 12 each.
[0015]
The exhaust valve housing 7 includes an exhaust port 13 extending from the combustion chamber 2, and this exhaust port is located in an inlet region of the exhaust port 13 that can be moved up and down by an operating device 20 received on the exhaust valve housing 7. The combustion chamber 2 can be closed by a valve 14 that cooperates with the provided valve seat. In order to receive the aforementioned valve seat, the exhaust valve housing 7 is here provided with a lower seating part 15 made of a suitable material, this seating part having a support flange resting on the support surface on the cylinder head side. Including. The seating part 15 continues with a housing part 16 of the exhaust valve housing, generally designated 7, including an upper support surface 11 attached to the through-bolt 9 by a circumferential groove.
[0016]
The seat 15 includes a cooling passage 17 formed by a corresponding expansion of the notch 6 of the cylinder head 4 on the upper side of the flange attached to the support surface 8, which cooling passage is formed in the upper housing part 16. It is closed upward by a flange which is provided at the lower end and engages with the notch 6 of the cylinder head 4.
[0017]
The valve 14 has a valve stem 18 that rises upward from the valve body, and this valve stem is a guide disposed in a region surrounding the exhaust port 13 and the exhaust port 13 of the upper housing portion 16. It penetrates the bush 19 and cooperates with the attached operating device 20 above the guide bush 19. The region of the housing part 16 on the upper side of the exhaust valve housing 7, including the guide bush 19, also comprises a cooling passage 21 that circulates.
[0018]
In order to receive the through-bolt 9, the upper housing part 16 is provided with rib-like projections 22 which are attached to the through-bolt 9 and project radially from the edge region of the cylinder head 4 including the notches 6. Each of the projections 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 extends obliquely inwardly to the lower end region of the upper housing portion 16, thereby forming a console-like support for the protrusion 22.
[0019]
The through-bolt 9 and the insertion 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 illustrated example, four through bolts 9 or insertion passages 10 are provided so as to be opposed to each other so as to form a set with respect to a plane of symmetry S defined by the valve shaft and the center line of the exhaust port 13. Yes. The same is true for the protrusions 22, and the number and angular interval thereof correspond to the number of through-bolts 9 and the angular interval. Accordingly, 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 symmetry plane S. At this time, the angular intervals of the projections 22 arranged on the same side of the symmetry plane S adjacent to each other are shorter than the angular intervals of the projections 22 facing each other with respect to the symmetry plane S. In this way, two sets of protrusions substantially arranged on both sides of the exhaust port 13 are formed.
[0020]
The protrusion 22 also functions as a cooling rib attached to the exhaust port 13 that receives a load of heat released from the exhaust gas to the wall portion of the exhaust port 13. In order to prevent the protrusion 22 from being heated so strongly that the resulting thermal expansion leads to excessive stretching of the through-bolt 9 which is initially stressed by the corresponding tightening of the nut 12, the protrusion 22 is Cooling configured as a connecting pipe 23 that connects the cooling passage 17 on the lower seating portion that circulates and the cooling passage 22 on the upper guide bush side that circulates inside the attached insertion passage 10 in the radial direction. Equipment. The coolant is supplied through the supply pipe 24 attached to the lower cooling passage 17 that circulates as shown by the flow arrow, and the upper circuit that circulates also as shown by the flow arrow. 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 that flows substantially in one direction is obtained.
[0021]
As shown in FIG. 1, the connecting pipe 23 includes a hole-like passage parallel to the valve shaft or the through bolt shaft that bridges the height distances of the cooling passages 17 and 21 to communicate with each other. This hole-shaped passage may already be provided when casting the upper housing part 16 configured as a cast product, or it may be produced by drilling in a cutting process. As shown in FIG. 2, the hole-like passage of the connecting pipe 23 is on a partial circle that is attached to the through bolt 9 or the insertion notch 10 and that is located inside the partial circle concentric with the valve shaft. The radius of the latter partial circle is 2: 3 with respect to the radius of the partial circle attached to the insertion passage 10. At this time, the hole-shaped passage of the connecting pipe 23 functioning as a cooling passage is substantially in a region where the radial protrusion 22 is added to the center portion of the upper housing portion 16 including the exhaust port 13. As can be seen from FIG. 1, the radial positioning of the aforementioned axially parallel passage of the connecting pipe 23 is carried out in the lower region of the upper housing part 16 having an inner wall substantially parallel to the valve shaft. It is expedient to carry out an interval a slightly shorter than the wall thickness d between the inner surface of 13 and the aforementioned axis-parallel passage of the connecting pipe 23.
[0022]
The lower end portion of the passage parallel to the axis of the connecting pipe 23 is located on the lower side in the radial direction of the lower cooling passage 17 that circulates and is accessible from the cooling passage 17. For this purpose, the axially parallel passage may be connected to a circulating groove that opens towards the lower cooling passage 17 that rotates. In the illustrated example, the lower end portion of the passage parallel to the axis of the connecting pipe 23 is connected to the cooling passage 17 by a radial branch hole 26 attached thereto, as can be seen from FIG. You may provide a slit-shaped milling part instead of a branch hole. As shown in FIG. 2, the upper end of the connecting pipe 23 that is parallel to the axis communicates with the cooling passage in the circumferential edge region of the bottom surface of the circulating upper cooling passage 21.
[0023]
In the illustrated example, two parallel connecting pipes 23 are attached to each radial protrusion 22. However, only the protrusion 22 located closest to the exhaust port 13 that is exposed to a particularly strong heat load, ie normally the protrusion 22 that is located near the outflow cross section of the exhaust port 13 and faces downward in FIG. In many cases, it is sufficient to attach the connecting pipe 23 functioning as a cooling device. Similarly, it is often sufficient to provide only one connecting pipe 23 rather than a plurality of protrusions.
[0024]
The cross-sectional area of the connecting pipe 23 is smaller than the cross-sectional area of the attached protrusion 22. The number and cross-sectional area of the connecting pipe 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, and the temperature of the cooling water flowing through the connecting pipe 23 is higher than the vaporization temperature. Choosing to keep it clearly low is suitable for the purpose.
[0025]
Although an advantageous embodiment has been described above, it is not intended that the embodiment be limited. For example, the measures of the present invention are not, of course, constrained to a specific number of through bolts or protrusions attached thereto. Of course, more or fewer through bolts, or protrusions attached thereto, may be provided than in the illustrated example. The drawings are as follows.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing an upper region of a cylinder of a two-cycle large diesel engine.
2 is a horizontal cross-sectional view taken along the line II / II of FIG. 1, showing the exhaust valve housing having the configuration of FIG. 1;
[Explanation of symbols]
1 Cylinder 2 Combustion chamber 4 Cylinder head 7 Exhaust valve housing 9 Through bolt 13 Exhaust port 14 Valves 17 and 21 Cooling passage 19 Guide bush (guide device)
20 Operating device 22 Radial protrusion (exhaust valve housing protrusion)
23 Connecting piping 24 Supply piping (coolant supply piping)
25 Processing piping (coolant processing piping)
26 Branch hole (radial piping member)

Claims (11)

A reciprocating piston engine, in particular a two-cycle large diesel engine, comprising at least one cylinder (1) including a combustion chamber (2), the cylinder head (4) of the cylinder carrying an exhaust valve housing (7); The exhaust valve housing is connected to the exhaust port (13), which can be closed to the combustion chamber by a valve (14) that cooperates with the valve seat on the exhaust valve housing side, following the combustion chamber (2). A through bolt (9) including an attached guide device (19) and an operation device (20), arranged on the circumferential side and penetrating the radial projection (22), is attached to the cylinder head (4). The cooling water can be supplied to the region including the valve seat, which engages with the cylinder head (4), and the region including the guide device (19) of the exhaust valve housing (7). Cooling passages (17) or (21) in those of the type included respectively that,
The cooling passage (17) attached to the region engaging with the cylinder head (4) and the cooling passage (21) of the exhaust valve housing (7) attached to the region including the guide device (19) are at least an exhaust port. The reciprocating piston engine is characterized in that it is connected to each other by at least one connecting pipe (23) provided radially inward of the attached through-bolt (9) in the area of the radial protrusion (22) close to. The reciprocating piston engine according to claim 1, wherein at least one connecting pipe (23) is attached to each projection (22). 3. A plurality of, in particular two parallel connecting pipes (23), each attached to each projection (22) at least close to the exhaust port, in particular to all projections (22), respectively. Reciprocating piston engine. 4. The communication pipe (23) according to any one of claims 1 to 3, wherein the communication pipe (23) has a region communicating with the cooling passage (17, 21) extending parallel to the valve shaft and / or the through bolt. Reciprocating piston engine. The radial distance from the inner surface of the exhaust port (13) to the lower region of the connecting pipe (23) matches the wall thickness of the exhaust port (13) outside the range of the protrusion (22) at the longest. The reciprocating piston engine according to any one of claims 1 to 4. The reciprocating piston engine according to any one of claims 1 to 5, wherein a cross-sectional area of the communication pipe (23) is relatively smaller than a cross-sectional area of the attached protrusion (22). The number and the cross-sectional area of the connecting pipe (23) are such that the temperature of the cooling water flowing therethrough is clearly below 100 ° C., and the wall surface temperature of the inner surface of the exhaust port (13) is higher than the dew point temperature of the exhaust gas. 7. A reciprocating piston engine according to any one of claims 1 to 6, wherein the reciprocating piston engine is selected to remain clearly above. The reciprocating piston engine according to any one of claims 1 to 7, wherein an axially parallel region of the communication pipe (23) is configured as a hole-shaped passage. The passage parallel to the axis of the connecting pipe (23) is adjacent to the lower side through the radial pipe member (26) in the region of the end portion on the radially inner side of the adjacent cooling passage (17). The communication device according to any one of claims 4 to 8, which communicates with the passage (17) and penetrates a circumferential edge region of a bottom surface of the adjacent cooling passage (21) at the upper end portion. Reciprocating piston engine. At least one coolant supply pipe (24) is attached to only one of the circulating cooling passages (17) or (21), and the other of the circulating cooling passages (17) or (21) is at least one. The reciprocating piston engine according to any one of claims 1 to 9, wherein one coolant processing pipe (25) is attached. Four protrusions (22) are provided, each attached to one through bolt (9), and these protrusions are paired with respect to a plane of symmetry S defined by the valve stem and the center line of the exhaust port (13). 11. The projections (22) adjacent to each other so as to form each other, the mutually adjacent projections (22) having a shorter mutual angular interval than the projections (22) facing each other. The reciprocating piston engine according to the item.

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