CN1089853C - Diesel engine - Google Patents

Abstract

A diesel engine comprises a cylinder liner (21) in which the piston (20) moves, and a slide plate (24) adjoining the lower end of the cylinder liner (21) and forming a slide valve together with the cylinder liner (21). The slide plate (24) moves away from the cylinder liner (21) along with the movement of the piston (20) in the bottom dead center area, forming an annular opening between the cylinder liner (21) and the slide plate (24), that is, the scavenging gap (210 ) for supplying scavenging air to the cylinder space (22). When the piston (20) moves upward to the dead center, the scavenging gap (210) is closed again. This novel structure of the diesel engine is especially suitable for low-speed two-stroke diesel engines with long strokes, such as diesel engines used in ships and power generation sites for power generation. In the new structure, the seal (12) of the crankcase space can be omitted, so that the engine can be designed relatively short.

Description

diesel engine

The present invention relates to a diesel engine comprising a cylinder liner in which a piston moves.

Most of the large two-stroke diesel engines with existing structures, such as those used in ships and power plants, have crossheads. The so-called connecting rods that drive the crankshaft are located between the crankshaft and the crosshead. The so-called piston rod, which transmits the linear reciprocating movement of the piston to the crosshead, is located between the crosshead and the piston.

Most modern large-scale two-stroke diesel engines are scavenged (or ventilated) along the longitudinal direction of the working cylinder, that is, once the piston is below the scavenging port, the scavenging air enters the cylinder through the scavenging port on the cylinder liner. . New, unused scavenging air flows through scavenging ports in the cylinder liner, through the combustion chambers, and then pushes exhaust gases through one or more exhaust valves in the cylinder head and into the exhaust system.

When the piston is above the scavenging port, scavenging air can flow unhindered into and out of the crankcase. In order to prevent this phenomenon, the part of the piston located below the piston chamber should be sealed with a seal called a steam seal, or with a sealing box or a stuffing box sealing ring. The piston rod moves in this seal.

In engines with oil-cooled pistons, cooling oil is delivered to the pistons and away from them through oil delivery channels in the piston rods.

The object of the present invention is, inter alia, to provide an engine in which no scavenging air flows into the crankcase even without a seal.

According to the diesel engine of the present invention, it includes a cylinder liner in which the piston moves, and is characterized in that a slide plate adjoins the lower end of the cylinder liner, which forms a slide valve together with the cylinder liner, and the slide plate moves away from the cylinder liner with the movement of the piston. The cylinder liner moves, and in the process an annular opening is formed between the cylinder liner and the sliding plate for feeding the scavenging air into the cylinder space, which opening closes again during the upward dead center movement of the piston.

In the diesel engine of the present invention, the piston drives the sliding plate to perform reciprocating motion.

In the diesel engine of the present invention, there is a first spring and/or damper between the piston and the slide, and additional springs and/or dampers which elastically promote or stop and/or hinder the reciprocating movement of the slide.

In the diesel engine according to the invention, the spring and/or damping device is at least partially pneumatically and/or hydraulically actuated.

In the diesel engine according to the invention, at least one or more spring and/or damping means bear the load of the engine scavenging air.

In the diesel engine of the present invention, the sliding plate is guided by the guide member to move relative to the cylinder liner.

In the diesel engine of the present invention, the partition surface between the slide plate and the cylinder liner is formed in a ring or corrugated shape.

In the diesel engine of the present invention, the sliding plate and the cylinder liner are made of different materials.

In the diesel engine according to the invention, guide vanes are included in the scavenging air delivery duct leading to the cylinder space and the combustion chamber.

In the diesel engine according to the invention, there is also an oil-cooled piston and return channels in the piston, which respectively lead the oil directly into the cylinder space, ie into the crankcase located below the piston.

In the diesel engine of the present invention, a mechanical and/or pneumatic and a hydraulic and/or hydropneumatic driving device for driving the sliding plate to reciprocate are also included.

In the diesel engine of the present invention, it also includes a crosshead and a scavenging device for longitudinally scavenging the cylinder space or combustion space, and has a piston stroke greater than 1 meter, or greater than 3 meters, and the piston rod is located at the crosshead and Multiple parts between the pistons.

The novel engine according to the invention can be made relatively low when the seals are omitted. This is particularly advantageous for marine engines where there is less free space above the engine for repair or maintenance work. If the piston rod is made in several parts, it is possible to remove, install or replace the piston rod even if the height of the free space above the engine is small.

A diesel engine with a cylinder liner in which the piston moves, including a slide plate near the lower end of the liner and which together with the liner form a slide valve. When the piston moves to the bottom dead center, the slide plate moves away from the cylinder liner, forming an annular opening between the cylinder liner and the slide plate, that is, the scavenging air gap, which is used to deliver scavenging air into the cylinder. When the piston moves in the direction of the upward dead center, the scavenging gap is closed again. The novel structure of this diesel engine is particularly suitable for large, low-speed two-stroke diesel engines with long strokes such as ships or power plants. In this new structure, the seal of the engine space can be omitted, so that the height of the engine can be reduced.

The invention will now be described in more detail with reference to the schematic drawings showing a prior design of a diesel engine and a preferred embodiment of the invention. The picture shows:

Figure 1 is a schematic cross-sectional view of an engine of prior design having a scavenging gap in the lower portion of the cylinder liner and having a seal;

Figures 2 to 4 are schematic cross-sectional views of the new engine, the way in which it operates, runs and functions according to the invention is explained by means of the various positions of the pistons and slides in the cylinders.

In a diesel engine with a crosshead (not shown) as shown in FIG. 1 according to existing conventional designs, a piston 10 moves in a cylinder liner 11 . The lowermost portion of the cylinder liner 11 has a scavenging port 110, which is not covered by the piston 10 when the piston is at the bottom dead center. Scavenging air then flows from the annular space 110' into the combustion chamber. A part of the annular space 110 ′ below the piston 10 is sealed off from the crankcase or engine space 110 ″ by a seal 12 . In the seal 12 a piston rod 13 is moved between the piston and a crosshead (not shown).

The diesel engine shown in Figures 2 to 4 with a crosshead (not shown) is designed according to the invention. There are no scavenging ports in the lower region of the cylinder liner 21 . But there is a scavenging slide or sliding element 24 attached to the bottom of the cylinder liner 21 which moves up and down with the movement of the piston 20 . During this process, the scavenging gap 210 between the cylinder liner 21 and the slide plate 24 is opened and closed, and the scavenging air flows through the cylinder liner, the cylinder space 22 and the combustion chamber.

A guide 2124 (only shown in FIG. 4 ) may be located between the cylinder liner 21 and the slide plate 24 and act as a guide and support for the piston ring 205 . Here, the guide 2124 may be firmly installed on the cylinder liner 21 as shown in FIG. 4 ; or the guide 2124 may be installed on the slide plate 24 and participate in its reciprocating motion.

An annular piston skirt 201 is mounted on the piston 20 . A piston 20 with a piston skirt 201 is connected to a piston rod 23 . Cooling oil is pressed into the interior of the piston 20 through the passage 230 . The nozzle 202 sprays oil into the cooling hole 203 at the bottom of the piston 20 . In the new engine according to the invention it is possible to conduct the cooling oil back into the engine space via the oil drain channel 204 instead of, for example, having the second channel of the piston rod as return channel for the engine cooling oil of existing designs. In FIG. 2 on the one hand, and in FIGS. 3 and 4 on the other hand, the design of the drain channel 204 is different.

The movement and mode of action of the slide 24 will be explained with reference to the accompanying drawings 2 to 4, which schematically depict a novel diesel engine according to the invention. Assume that the piston 20 moves downwards from FIGS. 2 to 4 , or conversely, moves upwards from FIGS. 4 to 2 .

The principle described here implements the idea of sealing the scavenging air working chamber from the crankcase space with a movable slide plate 24 instead of a piston rod seal as in a two-stroke crosshead engine. In contrast to the existing design which has a scavenging port 10 (Fig. 1) at the lower end of the cylinder liner 11, the new engine has a scavenging slide 24, the movable lower extension of the cylinder liner 21, which together with the movement of the piston 20 acts as a scavenger. The role of gas port and piston rod seals.

A scavenging slide 24 movable relative to the longitudinal axis of the cylinder is located at the lower end of the cylinder liner. The slide plate 24 bears the pressure of an air cushion 209 formed as an annular working chamber towards or against the lower end of the cylinder liner 21 .

If the lower control edge 206 of the piston 20 moves towards the opposite edge 241 of the slide, the slide 24 will gradually begin to move with the piston 20 . The slide plate 24 moves downward together with the piston 20 away from the cylinder liner 21 . An annular gap 210 opens between the cylinder liner 21 and the sliding plate 24, through which scavenging air (in the direction of the arrow) flows from the scavenging air working chamber into the cylinder space 22, ie the combustion chamber. The annular gap can be bridged by guide bridges 2124 , which prevent bending of the piston ring 205 in the annular gap 210 . Without the guide bridge 2124, the piston ring 205 could bend into the annular gap only if the air cushion 209 fails.

The sealing of the scavenging air working chamber 211 with scavenging air pressure relative to the crankcase space at atmospheric pressure, ie the nacelle, is achieved during the scavenging process by the piston 20 in the region of the slide plate 24 .

If the piston 20 moves upward to the dead center again, the slide plate 24 driven by the air cushion 206 moves together with the piston 20 and closes the scavenging gap 210 again. When the piston 20 continues to move upward to the dead point in the cylinder liner 21 , the slide plate 24 is decelerated and buffered and leans against the bottom of the cylinder liner 21 . The annular gap 210 for the scavenging air is thus closed again. The scavenging air working chamber 211 is always kept isolated from the crankcase space, ie the engine space.

In the illustrated embodiment, the slide 24 moves with the piston 20 driven by an air cushion 209 . However, the sliding plate 24 could also be driven by a hydraulic drive (not shown).

Hereinafter, the acceleration and deceleration process of the slide plate 24 driven by the piston 20 will be described in detail. When the lubricating oil in the damping chamber 207 and possibly the scavenging air escapes from the annular space 207 through the gap, the slide plate 24 accelerates to the speed of the piston 20 .

During the closing process, the deceleration process of the sliding plate from the speed of the piston to the allowable speed limit of the sliding plate 24 on the cylinder liner 21 is completed with the help of the damping chamber 243 filled with compressed air after the edge 242 closes the annular damping chamber 243 of.

The slide plate 24 is manufactured in such a way that its upper and lower sides are loaded by the scavenging air. If the upper and lower sides have equal areas that protrude toward the direction of movement, then the influence of the scavenging air and in particular the influence of changes in the scavenging air pressure cancel each other out, ie they have no effect on the movement of the slide 24 . The movement of the slide 24 can also be influenced as desired by unequal projection areas which produce a resultant force acting on the slide 24 in one direction or in the opposite direction.

An adjustable annular metal guide plate can be placed upstream of the scavenging gap 210 with a vertical guide net. Thus, the rotation or swirl generated by the corresponding operating state can be transferred to the scavenging air flowing into the cylinder space 22 .

Lubricating oil for cooling is conveyed from the crosshead to the working piston 20 via the piston rod 23 . The cooling oil no longer returns to the piston rod 23 but leaves the piston 20 through the channel 204 .

The running-in surface of the cylinder is thus completely wetted by the lubricating oil, which flows back to the engine crankcase along the inner walls of the cylinder liner 21 and the slide plate 24 . The lubricating oil flows out together with the air in the then closed damping chamber 207 below the piston skirt 201 to form a damping mixture after the control edge 206 of the piston support ring 208 slides over the opposite edge 241 of the slide plate 204 . The piston skirt 201 acts as a centering element between the piston 20 and the piston support ring 208 and has an oil wiper ring thereon.

After removing the piston rod seal 12 (Fig. 1), the structural height of the engine can be reduced by about 30% of the cylinder bore size of the engine, while the stroke-to-bore ratio is 4:1, and other dimensions remain unchanged (relative to the length of the connecting rod). After omitting the scavenging air slot, the length of the cylinder liner 21 can be reduced by about 85% of the cylinder bore.

The coupling thread between the piston rod 23 and the piston support ring 208 is easily accessible from the crankcase side. The coupling can be released for maintenance work, thus avoiding removal of the piston rod. The disassembly height of the piston can thus be reduced by about the length of the piston rod.

The omission of the internal lubricating oil overflow pipe also simplifies the structure of the piston rod 23, which can also be composed of many parts with flanged connections between the parts.

Finally, the cylinder liner 21 and slide plate 24 can be produced directly from different materials. Thus, for example, slide plate 24 may be made of a material that is particularly resistant to chemically aggressive acids, such as sulfuric acid escaping from the cooler lower portion. Although the cylinder liner 21 has been described as a separate component, the cylinder liner could of course also be part of the engine block. When referring to the upper and lower parts connected to the cylinder liner 21 or the piston 20, the top dead center of the piston 20 refers to the stroke dead center located at the upper part, and the bottom dead center of the piston 20 refers to the stroke dead center located at the lower part, which is different from the engine Consistent with the structural conventions of the cylinder, it is independent of the actual orientation of the cylinder. The invention is applicable to the situation that the engine has nothing to do with the number of cylinders.

In the illustrated embodiment, the illustrated annular opening, ie, the annular gap 210 has planar boundary surfaces on the slide plate 24 and the cylinder liner 21 . However, the separating surface between the cylinder liner 21 and the slide plate 24 can also be bordered, for example corrugated or serrated. It is likewise conceivable for the separating surface to be designed, for example, stepped or corrugated in the radial direction.

Claims (12)

1. diesel engine, comprise a cylinder sleeve (21) that piston (20) motion is wherein arranged, it is characterized in that, a slide plate (24) adjoins with the lower end of cylinder sleeve (21), it constitutes a guiding valve with cylinder sleeve (21), slide plate (24) then moves away from cylinder sleeve (21) along with the motion of piston (20), and in this process, between cylinder sleeve (21) and slide plate (24), formed an annular opening (210), be used for scavenging air is transported in the cylinder space (22), this opening is closed in the process of upper dead center motion again at piston (20).

2. diesel engine according to claim 1 is characterized in that, piston (20) drives slide plate (24) and moves back and forth.

3. diesel engine according to claim 1 and 2, it is characterized in that, one first spring and/or damping device (206) are arranged between piston (20) and slide plate (24), but also having other spring and/or damping device (207), they flexibly promote or prevent and/or hinder the to-and-fro motion of slide plate (24).

4. diesel engine according to claim 3 is characterized in that, spring and/or damping device (206) are at least partially with pneumatic and/or hydraulic pressure is operated.

5. diesel engine according to claim 3 is characterized in that, has one at least, or the load that has a plurality of springs and/or damping device (207) to bear the motor scavenging air.

6. diesel engine according to claim 1 and 2 is characterized in that, slide plate (24) is moved with respect to cylinder sleeve (21) by guide elements (2124) guiding.

7. diesel engine according to claim 6 is characterized in that, is positioned at separation surfaces between slide plate (24) and the cylinder sleeve (21) and does and circularize or corrugated.

8. diesel engine according to claim 1 and 2 is characterized in that, slide plate (24) and cylinder sleeve (21) are made by different materials.

9. diesel engine according to claim 1 and 2 is characterized in that, also comprises the guide vane (212) that is arranged in scavenging air conveyance conduit (211), and this pipeline leads to cylinder space and firing chamber (22).

10. diesel engine according to claim 1 and 2, it is characterized in that, also comprise the return flow line (204) in an oil cooled piston (20) and the piston (20), this passage is directly introduced cylinder space with oil respectively, promptly introduces to be arranged in the following crankcase of piston (20).

11. diesel engine according to claim 1 and 2 is characterized in that, also comprises (20) and/or pneumatic (209) that are used to drive the machinery that slide plate (24) moves reciprocatingly, drive unit (209 hydraulic pressure and/or hydropneumatic; 207).

12. diesel engine according to claim 1 and 2, it is characterized in that, comprise that also a crosshead and a countercylinder space (22) or combustion space (22) carry out longitudinally scavenged scavenging arrangement, and have greater than 1 meter, or greater than 3 meters stroke of piston, piston rod (23) is made of a plurality of parts that are positioned between crosshead and the piston (20).

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