KR100291805B1 - An internal combustion engine - Google Patents

Abstract

The present invention relates to a large two-stroke crosshead engine for propulsion of an internal combustion engine, in particular a ship, the engine having a plurality of cylinders (C _n ), each cylinder having a common crankshaft (1). Having a piston connected to a stroke (2,3) associated with respect to the stroke, which is connected via a main bearing journal journaled to the main bearing (MB _n ) such that the stroke has a predetermined relative angle (α). And the relative angles differ for at least some adjacent strokes. The control device is configured to form a larger amount of fuel oil than the amount supplied to the cylinder having a stroke which forms a minimum of the relative angle with respect to the adjacent stroke, and to form the relative angle α which is greater with respect to the adjacent stroke. The cylinder C _{n with} strokes 2 and 3 is supplied. In an eight-cylinder engine, the controller can supply the maximum amount of fuel oil to the first, second, seventh and eighth cylinders. In a twelve-cylinder engine, the controller can supply a minimum amount of fuel oil to the ninth and tenth cylinders.

Description

An internal combustion engine

1 is a perspective view showing the principle of the crankshaft of an eight-cylinder engine.

2 and 3 are diagrams showing the angular difference between the ignition order and the stroke of the 8 cylinder and 12 cylinder engines, respectively.

The invention is particularly useful for large two-stroke crosshead engines used as engines for propulsion of ships or as stationary power generating engines. This is because such engines generate very large power per cylinder at low revolutions, which places a large load on the main bearings. In order to shorten the length of the engine, it is preferable not to make the length of the main bearing too long, but this will limit the area of the main bearing.

The ignition order of the cylinders is determined on the basis of the torsional vibrations that may occur in the engine's mountings or on the ship's hull during operation of the engine, and also in the first and second stages It is determined to limit the free moment of inertia of the car. The relative angle between the strokes for two consecutively ignited cylinders should be 360 ° divided by the number of cylinders of the two-stroke engine, or 720 ° divided by the number of cylinders of the four-stroke engine. For example, in a two-stroke eight-cylinder engine, this relative angle is 45 °, and in a two-stroke 12-cylinder engine, this relative angle is 30 °.

1 shows a crankshaft 1 of an eight-cylinder two-stroke engine. The main bearing journal of the shaft is journaled to the main bearing (MB ₁ -MB ₉ ), bearings MB ₁ and MB ₉ are located at both ends of the shaft, and bearings MB _5a and MB _5b are of two parts It is located in the middle of the shaft on one side of the joint part. When the valves of the fuel pump and the engine are controlled by the camshaft, a chain wheel for driving the camshaft through a chain drive may be mounted to the joint portion of the shaft. For each cylinder C ₁ -C ₈ , the crankshaft _{1 has} a stroke consisting of two crank arms 2 connected to the associated main bearing journal and a connecting rod pin 3 supported on the crank arms. And a connecting rod (not shown) is attached to this pin. The connecting rod is connected to the piston in the associated cylinder via the crosshead and the piston rod.

Typical ignition sequences for an eight-cylinder engine are shown in Table 1 below.

The first column of the table gives the number of the associated cylinder pair and the second column gives the angle α between two adjacent strokes belonging to the cylinder pair shown in the first column. The presented angle α corresponds to the phase difference between the start of the combustion stroke of the associated cylinder pair. Therefore, it is directly understood from the indication of the angle whether the main bearing located between the pair of cylinders can simultaneously receive the compressive force from the cylinders on both sides. The third column of Table 1 gives the ignition order for the first cylinder of the cylinder pairs presented in the first column.

TABLE 1

The content of Table 1 is shown diagrammatically in FIG. 2, where one engine cycle corresponding to 360 ° rotation of the crankshaft is shown by a solid circle. Since the engine is an eight cylinder, in response to the rotation of the shaft between the start of the combustion stroke with respect to two consecutive pistons, the circle is divided into eight at 45 degree angular intervals. Between each rotation interval, n cylinders C _n for executing the combustion stroke are shown. The relative angle between two adjacent strokes can be read directly from the figure as the angle between the radius belonging to the two cylinders. It can be seen that the angle α _1-2 = 225 ° between the cylinder 1 and the cylinder 2. The same applies to other cylinders. For example, it can be seen that the angle α _5-6 = 45 ° between the cylinder 5 and the cylinder 6, and the cylinder 6 is ignited after the cylinder 5. This means that the main bearings between these two cylinders receive a compressive force simultaneously from both connecting rods. This same situation also occurs with respect to the cylinder 3 and the cylinder 4. Thus, the controller supplies the maximum amount of fuel oil to the cylinders 1 and 2, the minimum amount of fuel oil to the cylinders 3-6, and the cylinders 7 and 8 between the maximum and minimum quantities. A quantity of fuel oil is supplied.

The situation with a 12-cylinder engine is shown in FIG. 3 and the conditions are shown in Table 2 below.

TABLE 2

The controller supplies the maximum amount of fuel oil to the cylinders 6,7 and 12, slightly less fuel oil to the cylinders 3 and 4, and the intermediate amount of fuel oil to the cylinders 1, 2, 4, 5, 7, 8, and 11, and it can be seen that a minimum amount of fuel oil is supplied to the cylinders 9 and 10.

If the engine is an engine of a conventional design having a fuel pump controlled by a camshaft, the controller can be an index rod that adjusts the index of the pump in accordance with the engine load. The pump can be connected to the control index rod so that it is set permanently to supply different amounts of fuel oil, respectively, for the total engine load.

If the engine is to be of a more modern computer-controlled form, the control device may consist of a computer and a fuel pump operating unit, for example electromechanically controlled and hydraulically actuable. From certain information about the relative ratio between the loads of the bearings, the computer can easily determine the respective oil supply to the cylinder so that the main bearings of the crankshaft are loaded as uniformly as possible.

If a problem occurs in the main bearing (for example, when the bearing temperature rises due to a seizure between the bearing and its associated bearing journal), the computer will use less fuel in the cylinders adjacent to the bearing. It can be programmed to supply oil temporarily. It is thus possible to temporarily reduce the load on the selected bearing, which is particularly advantageous for the engine according to the invention. This is because the entire main bearing of the engine is sufficiently loaded when the characteristics provided according to the present invention are fully utilized to increase the power of the engine. In known engines in which only one or two main bearings are sufficiently loaded, there is less need to temporarily reduce the load on the bearings.

FIELD OF THE INVENTION The present invention relates to an internal combustion engine, and more particularly, to a large two-stroke crosshead engine for propulsion of a ship, the engine having a plurality of cylinders, each cylinder having an associated stroke with respect to a crankshaft common to the cylinders. having a piston connected to a row, the stroke being connected through a main bearing journal journaled to the main bearing such that the stroke has a predetermined relative angularity, the relative angle being at least several The adjoining stroke is different and the amount of fuel oil injected into the cylinder during the engine cycle is controlled by the control device.

Japanese Patent Laid-Open No. 62-113844 discloses a control device for adjusting the amount of fuel supplied by a fuel pump to a combustion chamber of a diesel engine during a cycle of an engine. In the engine according to the invention of the above patent publication, the start timing of fuel injection is controlled by a cam fixed on the cam shaft, and the amount of fuel injected is the opening time of a puncture valve installed on the supply side of the pump. It is controlled by changing according to the load of the engine. The fuel injection initiated by the camshaft is optimal for full load operation of the engine, but the timing in partial load operation tends to be slower with respect to the engine cycle, which only injects a limited amount of fuel. Be sure to Thus, in partial load operation, the engine is unable to generate power to provide full load to the various engine components. Therefore, in the Japanese Patent Publication, a computer is used as a control device for controlling the start time of fuel injection, and during partial load operation, an excessive amount of fuel is injected at an early stage of the engine cycle, and the engine at partial load is used. To increase the power of. The computer receives information about the engine speed and signals from the thermal sensors installed on the main bearings so that the bearings are not overloaded due to the increase in engine power at partial loads.

In general, it is desirable to have all the main bearings for the engine in the same format, so that spare parts of different types of main bearings need not be purchased and stored, and also that an unsuitable type of main bearings are not mounted to the engine.

An object of the present invention is to increase the power of an engine at both full load and partial load without exceeding the maximum allowable load of the main bearing.

To this end, the internal combustion engine according to the present invention is characterized in that the control device is capable of producing a larger amount of fuel oil than the amount supplied to the cylinder having a stroke that forms a minimum angle with respect to the adjacent stroke. It is characterized in that the supply to the cylinder having a stroke forming a large angle.

Viewed from the circumferential direction of the crankshaft, the main bearings between the strokes forming a small relative angle are connected by the inertia forces from two adjacent strokes projecting radially on the same side of the crankshaft and also connecting two adjacent strokes. The compression force from the two connecting rods mounted on the rod pins results in very large loads. The reason is that in an engine with a certain number of cylinders, the combustion process in two related cylinders is only phase shifted by an angle corresponding to the angle between two adjacent strokes. Thus, the main bearing is subjected to a compressive load simultaneously from both cylinders. As mentioned above, it is preferable to have all the main bearings in the same structure, which means setting an upper limit on the average pressure and the power of all the cylinders with respect to the bearing under the greatest load in a known engine. By supplying a larger amount of fuel oil to cylinders having strokes that form a large angle with respect to the adjacent strokes, the excess load capacity of the main bearings between these strokes is used to provide great power to the engine. This excess power is obtained at full engine load. Therefore, in the engine according to the present invention, the main bearing is loaded more uniformly than in a known engine.

In a suitable embodiment in which the engine has eight cylinders, the controller supplies the largest amount of fuel oil to the first, second, seventh and eighth cylinders. In an eight-cylinder engine, the angle between the strokes for the third and fourth cylinders is 45 ° and the angle between the strokes for the fifth and sixth cylinders is the same, but between strokes for the other cylinders. The relative angle is 135 ° or 225 °. The angle mentioned here corresponds to the phase difference between the start of the compression stroke of the corresponding cylinder. Since the difference in the above-mentioned angles is large, the first, second, seventh and eighth cylinders may have a main bearing between the first cylinder and the second cylinder, between the second cylinder and the third cylinder. It is possible to increase the amount of power without overloading the main bearing, the main bearing between the sixth and seventh cylinders and the main bearing between the seventh and eighth cylinders.

In another suitable embodiment where the engine has twelve cylinders, the controller supplies a minimum amount of fuel oil to the ninth and tenth cylinders. In a 12-cylinder engine, the phase difference between the angle between adjacent strokes and the start of the compression stroke of adjacent cylinders is 120 °, 210 ° or 300 °, with only one exception between the ninth and tenth cylinders. Is an angle of 30 °. Since the angle between the ninth cylinder and the tenth cylinder is significantly smaller than the angle between the other engine cylinders, the performance of the engine can be remarkably increased for the twelve-cylinder engine without overloading the bearings.

The control provides the amount of fuel oil so that the main bearings between the strokes are substantially uniformly loaded, providing maximum engine performance with respect to the load capacity of the main bearings when all bearings are of the same construction. It is desirable to. 'Main bearing between strokes' means that it does not include the main bearings at both ends of the crankshaft (the main bearings at these ends are loaded from only one cylinder). If two main bearings are arranged between two strokes because the shaft consists of two separate shaft parts, these two main bearings are considered to be substantially loaded from only one cylinder.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

Claims (5)

A large two-stroke crosshead engine for propulsion of an internal combustion engine, in particular a ship, the engine having a plurality of cylinders C _n , each cylinder having an associated stroke with respect to the crankshaft 1 common to the cylinders. Having a piston connected to (2,3), the stroke is connected through a main bearing journal journaled to the main bearing MB _n such that adjacent strokes have a predetermined relative angularity (α). And wherein the relative angle is different for at least a few adjacent strokes, wherein the amount of fuel oil injected into the cylinder during the cycle of the engine is adjustable by the controller. An adjacent row of fuel oil, in an amount larger than the amount supplied to the cylinder having a stroke that forms a minimum of said relative angle relative to the adjacent stroke, An internal combustion engine characterized by being supplied to said cylinder (C _n ) having strokes (2,3) forming a larger relative angle (α) with respect to the positive. The internal combustion engine according to claim 1, wherein the engine has eight cylinders, and the control device supplies a maximum amount of fuel oil to the first, second, seventh and eighth cylinders. . The internal combustion engine of claim 1, wherein the engine has twelve cylinders, and the controller supplies a minimum amount of fuel oil to the ninth and tenth cylinders. 2. An internal combustion engine according to claim 1, wherein the control device supplies an amount of fuel oil such that the main bearing (MB _n ) between the strokes (2,3) is substantially uniformly loaded. The method according to any one of claims 1 to 4, wherein when a problem occurs in the main bearing (MB _n ), the controller temporarily dispenses a smaller amount of fuel oil into the cylinder (C _n ) adjacent to the main bearing. Internal combustion engine, characterized in that the supply.