KR19990072536A - A supercharged internal combustion engine of the diesel type - Google Patents

Abstract

The diesel engine according to the invention has a water mist catcher 7 with a baffle plate 10 which divides the main air flow of the air supply into partial flows. The baffle plate has an inclined baffle surface 14 and also has a first channeled droplet collector 15 with a droplet inlet 16 disposed at the end of the baffle surface. A second channeled droplet collector 17 is disposed in the extension of the first channeled droplet collector and has its droplet inlet 18 on the opposite side of the baffle plate.

Description

Diesel supercharged internal combustion engine {A SUPERCHARGED INTERNAL COMBUSTION ENGINE OF THE DIESEL TYPE}

The present invention provides at least one compressor for supplying air to the air inlet of the cylinder, and at least one air cooler disposed in the flow path of the air supply between the compressor and the air inlet of the cylinder to cool the air supply before being delivered to the cylinder. (air cooler), having at least one water mist catcher having at least one row of baffle plates that divides the main air flow of the air supply into partial flows, each baffle plate having one A diesel type turbocharged internal combustion engine having an active baffle surface extending obliquely with respect to the direction of flow of major airflows on the side and a first channeled droplet collector having a droplet inlet disposed at the end of the active baffle surface.

This type of internal combustion engine is known as a commercial engine structure which has been used for pressurizing air supply by a compressor for many years. In the case of a four-stroke engine, the expression air supply air is appropriate, but in the present invention, the use of the term air supply air should be understood to include both small air and air supply in a two-stroke engine. Compression of the supply air results in an increase in temperature that requires cooling of the air before it is supplied to the cylinder of the engine.

The cooling results in the condensation of water from the air. Upon discharge from the air cooler, the air contains droplets that must be removed before the air is supplied to the cylinder, which is why the droplets are deposited in lubricating oil on the inner surface of the cylinder and between the piston ring and the cylinder. This is because it reduces or destroys lubrication.

In order to prevent such reduction or destruction of lubrication, known water mist catchers are formed with at least two rows of baffle plates, wherein the active baffle surface of the baffle plate changes the direction of flow of air because the air flow is caused by the baffle surface. This is because they collide with the phase and are deflected laterally.

Upon deflection of the air, the droplets in the air tend to continue straight forward, thus destroying the air hold on the droplets and depositing them on the baffle plate. The airflow will then draw water towards the end of the active baffle surface where water collides with the channeled droplet collectors.

Especially in modern engines with high air supply pressures and large amounts of air, known water mist catchers have proven to be inefficient. Attempts have been made to install a larger number of continuous rows of baffle plates, but this results in an inappropriately high pressure drop of air in the passages of the water mist catcher, negatively affecting engine efficiency.

It is an object of the present invention to provide a turbocharged internal combustion engine in which the wear of the cylinder and piston ring due to the deposition of water from the air supply is reduced without excessive pressure drop following the air cooler.

1 shows a general overview of air flow through a turbocharged diesel engine according to the invention, through which air is passed through a water mist catcher.

FIG. 2 is an enlarged horizontal cross-sectional view of three adjacent baffle plates disposed successively in the water mist catcher of FIG. 1.

3 is a cross-sectional view of the outer casing of the air cooler and water mist catcher in another embodiment of the present invention.

FIG. 4 is a cross-sectional view of the outer casing taken along line IV-IV of FIG. 3, but omitting details of the air cooler and water mist catcher.

5 and 6 are enlarged front and side views of the water mist catcher of FIG.

7 is an enlarged horizontal cross-sectional view of the water mist catcher of FIG. 5.

8 is an enlarged cross-sectional view of the passage of the water outlet through the outer casing.

9 is a diagram showing the efficiency of a water mist catcher.

In view of this object, the engine according to the invention has a second channeled droplet collector disposed in a direct extension of the first channeled droplet collector and having its droplet inlet on the other side of the baffle plate. The downstream end of the droplet collector of is characterized by forming an upstream boundary of the droplet inlet of the second droplet collector.

Each baffle plate has an active baffle surface and an opposing baffle surface, the active baffle surface extending obliquely with respect to the direction of flow of the main airflow, and on the one side (front) of the baffle plate by the airflow It collides to change the direction of its airflow, the opposite baffle surface delimiting the channel from the adjacent channel in adjacent airflow on the other side (rear) of the baffle plate. Looking at the flow of one of the partial airflows, it flows between two baffle plates extending parallel to each other. When the airflow impinges on the active baffle surface on one baffle plate, it is at the same level as the opposite baffle surface on the second baffle plate. Although airflow does not directly impinge on the opposite baffle surface portion that is shielded from the inlet air, water may deposit on the surface.

By aligning the second droplet collector with an extension of the first droplet collector and having a droplet inlet on the other side of the baffle plate, the water deposited on both sides of the baffle plate is immediately and continuously drained, which is a baffle plate It has been proven to surprisingly significantly improve the efficiency of heat. Here, efficiency means the proportion of water removed, that is, 20 percent efficiency means 20 percent removal and drainage of the amount of water condensed in the inlet air. Since the efficiency decreases at increasing engine loads, the efficiency depends on the flow rate of the air, ie the load on the engine. Under the same operating conditions, baffle plate rows of conventional design have an efficiency of 25 percent or less, while baffle plate rows designed according to the present invention have been demonstrated to have an efficiency of 40-50 percent. This significant improvement is achieved without a marked increase in pressure drop across the water mist catcher.

The reason why the improvement is made cannot be explained precisely, but it is probably because the air does not follow the strict laminar flow, but the droplets pivot to deposit on both sides of the channel. The droplets are also distracted from the baffle plate at the end of the active baffle surface, scattering opposite vessels on the opposite side of the channel to deposit on the surface, where water is captured by other droplet collectors.

Prior to reaching the droplet inlet of the second droplet collector, it is important for the effect achieved that the partial air flow is not exposed to a substantially greater change in direction than when hitting the aggressive baffle surface, the change of direction being: It is presumed to be due to the formation of a vortex that can separate the droplets from the baffle plate such that the droplets are entrained by air.

The first and second droplet collectors are disposed in direct extensions of each other. This fact provides the advantage that the second droplet collector generates a minimum flow resistance because the second droplet collector is completely hidden behind the first droplet collector.

The performance of the second droplet collector for discharging water may be improved by the downstream end of the first droplet collector rounded to allow water on the baffle surface to flow through the droplet inlet before the water leaves its contact with the baffle surface. Can be. A variation of this design is that the downstream boundary of the droplet inlet is projected back into the airflow, so that droplets traveling upstream can impinge on the inner surface of the downstream boundary and flow into the droplet collector.

The second channeled droplet collector and preferably the first droplet collector also have an elongated shape with an inner cavity extending in the flow direction of the air supply from the droplet inlet at least twice the width of the cavity. It is preferable. With regard to the variant design in which the length and width of the cavity are about the same, the elongate shaped droplet collector can better see the water until it is discharged through the outlet at the bottom of the droplet collector. Near the droplet inlet, a vortex of air inside the cavity will often occur. Water in the cavity tends to gather near the lower part of the cavity further away from the inlet, and the thin, elongated shape of the cavity moves the water away from the vortex, making it more difficult for the water to pivot through the droplet inlet. The elongate shape also provides the droplet collector with a moderately large volume, which makes it more difficult for the droplet collector to fill and thus prevents excess flow through the droplet inlet.

In one embodiment, the droplet inlet of the second droplet collector is arranged at least one channel width downstream of the droplet inlet of the first droplet collector of the baffle plates in the same row, preferably with a channel width of 1.5-4. . Firstly, this distance between the two droplet inlets forms a space that provides a moderately large internal volume to the droplet collector without excessively restricting the channel cross section, and then after passing through the droplet inlet of the first droplet collector. In turn, the air will have a certain flow distance that can deposit droplets on opposite sides.

The design of the water mist catcher by the fact that the first and second droplet collectors are arranged in the cross section of the channel extending substantially parallel to the direction of flow of the main airflow and that the bend angle of the baffle plate is the same at both ends of the active baffle plate It is possible to simplify. At the same time, partial airflow achieves an excellent flow path with minimal flow resistance with respect to the droplet removal effect, which means that after passing through the droplet collector downstream of the water mist catcher, the partial airflow is associated with the primary airflow on the inlet side. It will be understood from the fact that with the same flow direction, direction correction is unnecessary. Where other elements are advantageous, such as where the primary airflow has to change direction after the water mist catcher, it may be best to place the droplet collectors in the channel section extending obliquely in the desired direction.

The first row of baffle plates closest to the air cooler upstream of the active baffle surface has an inlet portion that extends the distance between the rows of adjacent baffle plates in a straight line and parallel to each other in a direction of inflow of air at least twice the length. It is preferable. The inlet provides a major split of the flow and, by their length, reliably corrects the partial flow for larger laminar flow paths. This limitation of turbulent flow promotes the separation of suspended droplets from partial airflow when they collide with aggressive baffle surfaces.

The water mist catcher preferably does not generate excessive pressure drop of the supply air. In a suitable embodiment, the pressure drop is minimized and the efficiency of the water mist catcher extends downward to the bottom plate which is not broken in the area between the baffle plates and which is broken by the drainage inside the channeled droplet collectors. And by means of a container with an inner partition disposed below the bottom plate. Since water and air can flow out of the vessel from the inside of the droplet collector, air loss from water upon compression is relatively limited. The air loss is further reduced by the vessel separated by the partition, which reduces the risk of air from the slightly underfilled droplet collector which is discharged into the vessel and impedes the outlet function. The partitions are preferably arranged between the rows of baffle plates, that is to say under the container at the transition between the rows. This reduces the likelihood of flow conditions in one row, affecting the conditions in the other rows.

In a suitable embodiment, the compartments have through holes near the bottom of the vessel, the vessel having at least one outlet below the last row of the baffle plate of the water mist catcher, but having an outlet below the preceding row (s). Do not. By forming an outlet only in the last row of the baffle plate, water from the droplet collectors in the other rows is forced to flow past the partition, which is only possible through the through-hole near the bottom of the water-only container, Air is discharged upward through the vessels in row 1 into the droplet collectors in the last row of baffle plates, which will shorten the water mist catcher and separate the water on the discharge side.

An additional limitation of the pressure loss throughout the water mist catcher can be achieved by the outlet being passed in a pressure-tight manner through the outer casing on which the water mist catcher is mounted. This prevents air from escaping into the engine room through the annular gap around the outlet. Previously such gaps were routinely used to drain the water gathered in the main conduit between the air cooler and the water mist catcher, but this results in excessive pressure drop in the air supply.

The water mist catcher and cooler may be arranged continuously between the scavenging air receiver of the two-stroke crosshead engine and the compressor of the supercharger. In general, two-stroke crosshead engines have very high power and correspondingly high air consumption, so it is particularly advantageous to apply the invention to such engines. The application can be carried out in a conventional manner, such as after the discharge from the cooler, the main air flow flows through the 90 ° channel bend and, consequently, through the water mist. However, such an arrangement requires space and can also inadequately limit the design of the air cooler. Therefore, the water mist catcher is preferably arranged immediately after the air cooler.

In one embodiment, the upstream ends of the baffle plate of the water mist catcher are disposed at a distance of 10 mm to 100 mm from the air cooler. This very close deployment of the water mist catcher's air cooler provides the advantage that there is no time for droplets falling off the air cooler to accelerate to the same flow rate as the air before it is inside the water mist catcher. If the droplets have a high velocity, there is a great risk that the droplets will disperse as they hit the baffle plate and bounce back into the air with fewer droplets that are more difficult to remove. Therefore, the arrangement of the water mist catcher at a distance of 100 mm or less from the air cooler is a significant advantage. In operation, the air cooler and water mist catcher are exposed to vibrations generated by air pulsations and engine vibrations. Since both the cooler and the water mist catcher comprise a relatively thin plate, the distance of 10 mm is the lower limit of the possible access of the two elements, since the distance must provide space for vibration. A minimum distance of 30 mm is often used to provide room for inaccuracies in mounting. The distance between the air cooler and the water mist catcher is preferably between 40 and 60 mm, which is appropriate between avoiding damage to the thin plate during operation on the one hand and expectations of capturing droplets when their speed is low on the other. It is a compromise.

If the downstream boundary of the droplet inlet protrudes too much into the partial air flow between adjacent baffle plates, the through flow air is affected by excessive flow resistance and also inside the second droplet collector because too much air is passed into the droplet collector. Excessive force vortex may occur. Thus, the downstream boundary of the droplet inlet preferably projects inwardly by 1-2 mm past the plane extending from the surface upstream of the channel wall of the droplet inlet. This provides adequately good capture of the droplets, while at the same time providing limitations on the air intake of the droplet collector and the flow resistance of the partial flow.

The air cooler used can be a pipe fin cooler that can be divided into several zones, but it can also carry out cooling by injecting water directly into the air in several stages, which is the applicant's patent. 701 655 is described in detail. In such a cooler, it is important to efficiently remove water between the respective stages, so that the water mist catcher is preferably included in the water cooler between at least two of its cooling stages. Thus there may be several water mist catchers associated with the air cooler.

Embodiments of the invention are now described in more detail in an embodiment manner with reference to the schematic drawings.

1 is a diesel two-stroke uniflow which may be the main engine of a ship or a stationary power generating engine, having a nominal output of 2,000 kw for a small engine and a nominal output of 80,000 kw or less for a large engine. The uppermost part of the scavenging crosshead engine 1 is shown. The engine can also be a four-stroke engine with a power of less than 500 kW.

The engine 1 is supercharged, which is executed by a compressor which is mechanically or electrically driven. In the design shown, the compressor is part of the supercharger 4, the turbine of which is driven by exhaust gas flowing out of the cylinder 2 and through the exhaust valve into the exhaust receiver 3 as shown by the black arrow. The exhaust gas from the exhaust receiver leaves the engine through the supercharger. The compressor of the supercharger (not shown) sucks the air supply into the engine as indicated by the white arrow. The pressurized hot air supply flows downward and pivots into the air cooler 6 in the horizontal flow direction as shown by arrow 5, where the air is cooled and condensed into water. If the cooler is a pipe fin cooler, most of this water is deposited on the plate fins and flows to the discharge end of the cooler, where the water is dissipated from the fins by air pulsation and vibration as well as by the flowable air supply. Air returns in the form of droplets. The water mist catcher 7 is directly aligned with the subsequent air cooler. The supply air flows through the water mist catcher and continues to flow into the scavenging air receiver 8 connected with the air chambers around the lower end of the cylinder. When the piston is near its bottom dead center, the vents 9 open to allow the air supply to flow from the air chamber into the cylinder. Therefore, in this type of engine, the air inlet of the cylinder is formed by the small mechanisms. Instead, if the engine is a four-stroke engine, the air inlet is formed by an intake valve.

The water mist catcher 7 comprises at least one transverse row of baffle plates 10 extending from the top to the bottom of the water mist catcher, which can be blocked by reinforcing horizontal intermediate bottoms. Figure 2 shows a section with three baffle plates from a water mist catcher with a single row of baffle plates. Arrow A shows the direction of flow of the main air flow. The casing of the water mist catcher has a front edge 11 and each baffle plate 10 has an inlet portion 12 that projects upstream past the front edge. If their contribution to overall efficiency is not needed, of course, water mist catchers can be produced without these inlets.

The partial airflow A 'flowing between two adjacent baffle plates impinges on the aggressive baffle surface 14 which extends obliquely at an angle of about 45 ° with respect to the direction A. At the other end of the baffle plate, the baffle plates are bent backwards at a corresponding angle such that the partial airflow leaves the baffle plate in a flow direction that is generally parallel with the direction A on the feed side. The active baffle surface 14 may extend at an inclined angle unlike 45 °, such as an interval of 30-60 °, but 45 ° because the 45 ° angle provides a moderately large drop removal effect with a moderately low flow resistance. The angle of is appropriate.

The first droplet collector 15 is channel-shaped in the height direction of the water mist catcher and has a droplet inlet 16 at the end of the aggressive baffle surface, in which the baffle plate is rearward in its original path. Is curved. In addition, a second droplet collector 17, which is channel-shaped in the height direction of the water mist catcher, is disposed in the direct extension of the droplet collector and has a droplet inlet 18 that opens to an adjacent channel on the other side of the baffle plate. The other side of the baffle plate may be referred to as the rear, while the opposite side with the active baffle surface 14 may be referred to as the front.

The inner cavity of the first droplet collector becomes thin and long in the A direction and has a length corresponding to approximately four times the width in the illustrated embodiment. The downstream end 19 of the first droplet collector is rounded.

The second droplet collector is of substantially the same design as the first droplet collector except for the droplet inlet. If desired, the free plate edges of the droplet inlets may be curved inwardly into the inner cavity to prevent excess flow, but it is desirable to give the droplet collector an appropriately large internal volume by increasing their length, which means that the air is baffle plate It does not affect the flow resistance to a significant degree when passing through

The baffle plate is generally a thin plate of corrosion-resistant steel that is curved in a desired shape and is joined by welding, such as spot welding, high temperature soldering or a suitable joining method, as necessary. Another possibility is to extrude a baffle plate of the desired shape into an aluminum alloy.

For simplicity, in the following specification, the same reference numerals are used for parts of the same type as described above.

In another embodiment of the engine, shown in Figures 3 and 4, the air cooler 6 and the water mist catcher 7 are aligned at the same height as the scavenging air receiver as shown in Figure 4, and the water mist catcher Has three rows of baffle plates, and only one row differs from that of FIG.

The air supply air from the compressor flows downward into the channel bent portion 20, turns toward the air cooler, flows into the air cooler 6, and immediately after leaving the downstream end 21 of the air cooler, the air supply air mist catcher. Flows between the inlets 12. By means of the flange portion 22, the water mist catcher is bolted to the compartment 23, which compartment carries through-holes 24 of the same size as the flow zone of the water mist catcher. This ensures that the air supply simply passes through the water mist catcher by flowing through the baffle plate 10. After the water mist catcher, the airflow flows towards the scavenging air receiver 8 and passes through a number of openings 25 therein. The scavenging air receiver may also be supplied with air supply from an electrically driven auxiliary blower (not shown in FIGS. 3 and 4) mounted in the opening 26 at the end of the receiver.

The water mist catcher is shown in more detail in Figures 5-9. There are three rows of baffle plates 30, 31 and 32, with the baffle plate rows 31 and 32 starting at the downstream end of the second droplet collector 17 in the preceding row. The baffle plates in the rows are interconnected to achieve optimal efficiency. This connection, via one of the above joining methods, causes the active baffle surface to be inclined alternately on one side and the other, thus minimizing extra space inside the casing of the water mist catcher. The first row of baffle plates may have an efficiency of 40-50 percent at operating conditions at the maximum volume of through flow air, the second row of baffle plates may have an efficiency of 20-30 percent, and the third row of baffle plates May have an efficiency of at least 5-10 percent. By allowing the rows of baffle plates to be interconnected, an improvement in efficiency of at least 10 percent is achieved, because it avoids the occurrence of turbulence in the partial flow caused by the vortex emanating airflow through the free end of one row. .

The droplet collectors are not broken in the area between the baffle plates so that the air supply does not blow downward through the channels, but one or more inside each droplet collector so that water can flow into the vessel 35 below the lower plate. The lower plates are terminated downward by the above-described drainage holes 34. Between each row of baffle plates, more specifically between the last drain hole in one row and the first drain hole 34 in the next row, the container is partitioned 36 with a through hole 37 near the bottom of the container. ) A plurality of outlets 38 are mounted at the bottom of the vessel below the last row of baffle plates. The outlet consists of two flange members 39, 40 with gaskets mutually clamped for pressure-sealing joints around the holes of the bottom plate of the outer casing. A conduit (not shown) is connected to the drain pipe, which connects it to the drain tank. Where there are several outlets, the container 35 can be divided between adjacent outlets by a partition 42, which partition 42 extends generally at right angles to the partition 36.

9 is a diagram showing the efficiency of a water mist catcher of the type described above with three connected baffle plates. There are 48 baffle plates covering the inlet area of 1200mm height and 930mm width. The efficiency is presented as a function of the volume of water removed in liters per hour. The efficiency is about 99 percent at 240 l / h and appears to remain very high over most of the operating period. At 500 l / h, the efficiency is about 94 percent

Various modifications of the above embodiments can be made. In particular, when baffle plates are made by bending thin plates, they may have more edge courses than shown in FIG. 2, in which the first and second droplet collectors are extensions of one another. It does not need to be placed on. In addition, the downstream edge of the droplet inlet 18, in other words, allows the free sidewall end of the second droplet collector to project slightly into the inlet air, thereby removing droplets that have not been introduced into the inlet at the upstream end thereof. It is also possible. The channel cross section in the first and second droplet collectors need not extend parallel to the direction A, but can also be oriented at any angle with respect to it. This is especially important in the last row of baffle plates, when the air must turn right after the water mist catcher. This turning can be started by the proper angular position of the channel cross section.

The use of the diesel type turbocharged internal combustion engine according to the present invention has the advantage that no excessive pressure drop following the air cooler occurs and wear of the cylinder and piston ring due to the deposition of water from the air supply is reduced.

Claims (14)

At least one compressor for supplying air to the air inlet of the cylinder, and at least one air cooler (6) disposed in the flow path of the air supply between the compressor and the air inlet of the cylinder to cool the air supply before being delivered to the cylinder At least one water mist catcher (7) having at least one row of baffle plates (30, 31, 32) for dividing the main air flow of the supply air into partial flows, each baffle plate having one; First channel-shaped droplet collector 15 having an aggressive baffle surface 14 extending obliquely with respect to the flow direction A of the major airflow on the side and a droplet inlet 16 disposed at the end of the active baffle surface. In the diesel type turbocharged internal combustion engine (1), a second channel type droplet collector (17) is arranged in a direct extension of the first channel type droplet collector (1). It has a droplet inlet 18 on the other side of the plate, with a downstream end 19 of the first droplet collector 15 bounding upstream of the droplet inlet 18 of the second droplet collector 17. Diesel-type supercharged internal combustion engine, characterized in that to form a. 2. The diesel turbocharged internal combustion engine according to claim 1, wherein the downstream end (19) of the first droplet collector (15) is rounded. 2. The inner cavity of claim 1, wherein at least one of the first and second channeled droplet collectors (15, 17) has an inner cavity extending in the flow direction of the air supply air from the droplet inlet with a cavity width of at least twice the length. Diesel type supercharged internal combustion engine characterized in that it has a thin and elongated shape. The droplet inlet 18 of the second droplet collector 17 is preferably at least one channel width downstream of the droplet inlet 16 of the first droplet collector of the baffle plates in the same row. Diesel turbocharged internal combustion engine, characterized in that arranged in the channel width of 1.5-4. 2. The diesel type turbocharger as claimed in claim 1, characterized in that the first and second droplet collectors (15, 17) are arranged in a channel cross section extending substantially parallel to the flow direction (A) of the main air flow. Agency. 2. The baffle plate (10) of the first row (30) closest to the air cooler upstream of the active baffle surface (14) is at least twice as long as the distance between rows of adjacent baffle plates. Diesel turbocharger internal combustion engine, characterized in that it has an inlet portion (12) extending in parallel with each other in a straight line in the direction of inflow of air. The bottom plate (1) according to any one of claims 1 to 6, wherein the baffle plates are not broken in the area between the baffle plates (10) and are broken by a drain hole (34) inside the channeled droplet collectors (7). 33) A diesel type turbocharged internal combustion engine, characterized in that a vessel with an inner partition 36 is disposed below the lower plate, preferably extending between the baffle plate rows. 8. The compartments 36 have through holes 37 near the bottom of the vessel, which vessel has at least one outlet 38 below the last row of the baffle plate of the water mist catcher. , Diesel type turbocharged internal combustion engine, characterized in that it does not have an outlet under the preceding row (s). 9. The diesel turbocharged internal combustion engine according to claim 8, wherein the outlet (38) is passed through the outer casing in which the water mist catcher is mounted in a pressure sealed manner. The diesel turbocharged internal combustion engine according to claim 1, characterized in that the water mist catcher (7) and the cooler (6) are arranged continuously between the scavenging air receiver (8) of the two-stroke crosshead engine and the compressor of the supercharger. . 8. The diesel engine according to claim 7, wherein upstream ends of the baffle plates 10 of the water mist catcher are arranged at a distance of 10 mm to 100 mm, preferably 40 mm to 60 mm from the air cooler 6. Supercharged internal combustion engine. 12. The diesel turbocharged internal combustion engine according to claim 11, wherein the downstream boundary of the droplet inlet (16, 18) projects inwardly by 1-2 mm past a plane extending from the surface upstream of the channel wall of the droplet inlet. 2. The diesel turbocharged internal combustion engine according to claim 1, wherein the water mist catcher is included in the water cooler between at least two cooling stages thereof. 8. The diesel turbocharged internal combustion engine according to claim 7, wherein the water mist catcher is included in the water cooler between at least two cooling stages thereof.