Cross section of diesel 4H 11/13

Contents

Introduction

1. Engine description

2. Pressurizing diesel engines

3. Calculation of the working cycle

3.1. Source Data

3.2. Calculation of filling process

3.3. Calculation of compression press

3.4. Calculation of combustion press

3.5. Calculation of expansion press

3.6. Centrifugal compressor parameters with single-stage pressurizing circuit

3.7. Gas turbine parameters

3.8. Efficient engine performance

4. Building an Indicator Chart

5. Total forces and moments operating in KSM

6. Strength calculation of main parts of KSM

6.1. Piston

6.2. Piston pin

6.3. Piston ring

6.4. Connecting rod

6.5. Crankshaft

Conclusion

List of sources used

Appendix A Specification for 4H diesel cross section 11/

Appendix B Specification to the general type of turbocharger TKR-5.

Introduction

An internal combustion engine (ICE) is a thermal machine in which heat is supplied to the working fluid due to the combustion of fuel in the combustion chamber, that is, the chemical energy of the fuel is converted into mechanical work directly in the cylinder. The working medium of such an engine is at the first stage (filling and compression processes) air or a mixture of air with sprayed fuel, and at the second (after ignition and combustion of fuel) - fuel combustion products - gases that, expanding, perform work.

Compared to other types of heat engines, ICE has significant advantages: a hot heat source is located as if inside the engine itself, which leads to its compactness - there is no need for large heat exchange surfaces through which heat is supplied from the hot source to the working medium, as is the case in the cycles of steam power plants; in the ICE operating cycle, limit values of continuously changing parameters of the working medium (pressure, temperature), which receives heat due to heat release in the volume of the working medium itself, significantly exceed limit values of parameters of the working medium of heat machines with heat supply from an external hot source (steam boiler in the cycle of the steam power plant).

All modern ship internal combustion engines (VDS) are supercharged, that is, with the forced supply of pressurized air to the cylinders of the engine.

Engine classification. Ship ICE can be classified according to the following main characteristics:

method of operating cycle implementation - four-stroke (H), in which the operating cycle is performed in four piston strokes; two-stroke (E), in which the working cycle occurs in two strokes of the piston;

method of action - a simple action, when the working cycle is carried out in only one cylinder cavity above the piston (have preferential distribution); double action (DD), when the working cycle is carried out in two cylinder cavities; oppositely moving pistons (RDP) in one cylinder, forming a common combustion chamber in the RMT;

the method of filling the cylinder - without pressurization, when air is sucked by a piston (in four-stroke ICE) or due to purge air supplied to the cylinder by a purge pump at a pressure slightly higher than atmospheric; supercharged when the cylinder is filled with pressurized air generated by a supercharging compressor with a mechanical or gas turbine drive;

arrangement of cylinders - single-row with vertical arrangement of cylinders in the same plane; two-row rows with parallel arrangement (double) or with arrangement of cylinder rows at an angle (V-shaped); multi-row with arrangement of cylinders at different angles (X-, W- and -shaped);

design of combustion chambers (combustion chamber) - with undivided single-cavity combustion chambers (mainly diesel engines of medium and higher power); with semi-divided combustion chamber (diesel engines with combustion chamber in piston); with separated combustion chamber with two or more cavities (pre-, vortex and air-chamber);

design (KSM) - tronic, in which the guide is the tronic part of the piston, which transmits its lateral (normal) pressure to the cylinder walls; crosshead (K), in which the piston guide is a crosshead slider moving in parallel and transmitting normal pressure to the cylinder walls;

changing the direction of rotation of the crankshaft - non-reversible, having one constant direction of rotation of the shaft (mainly auxiliary ship diesel engines or main ones operating on an adjustable pitch screw - GRS); reversing (P), in which the direction of rotation is changed by a reversing device that changes the gas distribution phases (main ship diesel engines operating directly on the propeller);

crankshaft speed - low-speed (p = up to 350 rpm); medium-speed (p = 350,750 rpm); high-speed (p = 750500 rpm);

purpose - main reversing with direct power transfer to the propeller; main non-revertive, operating on electric generators, GRS; auxiliary non-reversible, operating on the drive of auxiliary mechanisms (diesel generators, diesel compressors, etc.).

1. Engine description

The 4H 11/13 diesel engine is a four-cylinder, four-stroke, non-reversible, single-row, simple-acting, compression-ignition internal combustion engine.

Diesel engines 4H 11/13 are designed to operate as stationary or auxiliary ship units for driving generators, pumps and compressors. Diesel can also be used to drive other machines.

The diesel engine designed for operation on the propeller has a reversreductor, an additional power take-off clutch from the free end of the crankshaft, and an all-mode regulator. Moreover, the diesel engine and the reverse reduction gear are mounted on a common engine frame.

The design layout of the diesel engine and diesel generator provides free access to all the main units and units installed on them, and the presence of a viewing hatch in the unit makes it possible to inspect and, if necessary, replace the parts of the piston-rod group without removing the diesel engine from the frame. Thanks to this, the diesel engine has high repairability.

The diesel crankcase is cast from cast iron. All mechanisms and units of the diesel engine are located in the block crankcase.

The upper part of the casting forms a cylinder block, and the lower, expanded part forms a crank chamber (crankcase). The continuous side walls of the cylinder block, together with the side lower shelves of the crankcase, give the entire structure significant rigidity.

The core bearings are thin-walled steel, filled with lead bronze.

At the corners of the crankcase, in its lower part, four legs are provided to attach the diesel engine to the foundation frame. Holes in two legs located diagonally are made with increased accuracy and are intended for prism foundation bolts when aggregating a diesel engine on a common frame with a generator or other unit (pump, compressor, etc.).

Sealing between upper plane of block-crankcase and heads is provided by gaskets from asbestos web, in which holes are reinforced with metal foil.

Sealing in the lower part of the cylinder bushing is performed by two rubber rings, and in the upper part - by lapping the bushing collar to the unit.

The cylinder sleeves are fixed in their upper part and can be freely extended downwards when heated.

Cylinder head closes from upper end face of cylinder bushing. Compression chamber is formed between head bottom and piston bottom at its position in TDC. In the cylinder head, which is common to two cylinders, inlet and outlet valves and nozzles are mounted, which are fixed by means of clamps. Rocker brackets are installed on upper plane of cylinder head. Inner side and end walls of cylinder head form water jacket through which cooling water passes.

In the inner cavity of the head there are inlet and outlet channels, the inlet ends of which are located on the side wall and have treated flanges, to which inlet and outlet headers are attached.

To eliminate oil leakage through clearances of mating surfaces in fuel pump drive, fresh and sea water pumps, through crankshaft seals on the side of the flywheel and free end at installation of additional power take-off coupling, due to increased pressure in the crankcase, as well as to exclude cases of saturation of crankcase space and environment of the engine room with these vapors and gases to explosive concentration, suction of fuel, oil and gases vapors is provided.

The attachment cover of the units with oil and water pumps mounted on it closes the end of the diesel crankcase on the side opposite to the flywheel.

The cover is cast from aluminum alloy and has a box-like configuration, which gives it the necessary rigidity. On the outer end surface of the cover there are three flanges, on which an oil pump and fresh and sea water pumps are installed respectively.

The flywheel casing consists of two main parts: the casing and the crankshaft seal cover. The cover is installed so that the non-uniformity of the clearance between the crankshaft flange and the bore in the cover does not exceed 0.10 mm. After installation, the cover is bolted and pinned. Oil discarded by the crankshaft oil deflector flows into the diesel tray along the recess in the cover.

The flywheel casing is made of aluminum alloy or cast iron, has sockets for installing an electric starter and a crankshaft turning mechanism. Control instrument board with actuation box is also fixed on flywheel casing.

Flywheel casing has threaded holes on outer end to secure reverser, generator flange or elastic coupling shield. The flywheel casing is bolted to the unit. Bolts are locked by plate locks.

The tray covering the crank chamber of the blockcarter from below serves to collect oil. It is made of steel, and has oil-resistant partitions.

Oil intake filter with magnets, oil pipeline from oil intake filter to oil pump, drain branch pipe with plug for oil drain and sockets for installation of temperature sensors are located in tray.

Crank mechanism is used to convert reciprocating motion of piston into rotary motion of crankshaft and consists of crankshaft, connecting rods, pistons and piston rings.

Crankshaft - steel, five-support; its main bearings are located on both sides of each connecting rod journal. First and fourth crankpins of shaft are arranged in one plane at 180 ° relative to second and third journals.

Working surfaces of main and connecting rod necks are hardened with high frequency current (HF), carefully ground and polished.

One end of shaft has flange to which flywheel is attached by bolts and pins.

Power extraction is carried out through an elastic clutch. Position of flywheel relative to first crankpin is fixed by pin.

Connecting rod. The rod of the connecting rod has an I-section, which provides the greatest strength at the lowest weight. Bushing made of bronze and serving as bearing of piston pin is pressed into upper head of connecting rod. Circular groove with four through holes is made on outer cylindrical surface of bushing. Oil from spraying is supplied through holes in upper head of connecting rod and along groove with holes for lubrication of piston pin.

Pistons are made of aluminium alloy. In the flat bottom of the piston there is a shaped recess - a combustion chamber, and on the cylindrical surface of the piston head there is a thermal barrier (groove) designed to reduce heating, and, as a result, wear of grooves and compression rings.

Each piston has five grooves. Compression rings are installed in upper three grooves, and oil-collecting rings are installed in lower two grooves.

Holes for removal of oil removed by rings are drilled in grooves for oil collecting rings. In internal cavity of piston there are two bosses in which holes for piston pin are drilled.

The diameter of the piston head is smaller than the diameter of the skirt, which prevents the piston from jamming when heated .

Piston pin is hollow. The external surface of the pin is cemented and hardened, ground and polished. The piston pin of the floating type, that is, has the ability to rotate in the sleeve of the upper head of the connecting rod and in the bosses of the piston.

Compression rings. Rectangular section with straight lock, made of special cast iron.

The upper compression ring is coated with porous chromium. In order to improve the run-in, the outer cylindrical surface of the remaining compression rings is tapered.

Oil removal rings. Scraper type, two rings are installed in one groove with a groove down, with a scraper up.

Inlet and outlet valves are made of heat-resistant steel and heat-treated. End faces of valves are ground and hardened to increase wear resistance.

Diameter of intake valve trays is larger than that of exhaust valves. Working chamfers of valve plates are made at an angle of 45 °, ground and when valves are installed in the cylinder head they are lapped to their seats .

2. Pressurizing diesel engines

Supercharging is a method of increasing the power of a diesel engine based on supplying air under pressure above atmospheric pressure to the working cylinder and corresponding increase in the cycle portion of fuel.

The average effective pressure varies directly in proportion to the pressure change,. Keeping the excess air ratio constant during pressurization means that as the charge density increases (as a result of increasing the pressurization), the cycle portion of the fuel increases accordingly. The additional fuel supply is a source of additional heat supply to the working medium in the cylinder, which provides increased specific effective cycle operation.

Due to pressurization, the problem of supplying the cylinder with air necessary for fuel combustion is solved. But the pressurization capabilities are limited by the maximum permissible level of thermal and mechanical stress of the diesel engine. The average effective pressure at the nominal operating mode depends on how successfully the heat and mechanical stress reduction issues are solved .

In ship diesel engines, two methods of pressurization are used: gas turbine and combined.

Gas turbine supercharging is used in four-stroke diesel engines and two-stroke diesel engines with a direct-flow valve gas exchange scheme. Compressed air is supplied to the diesel cylinders by a special additional unit - a turbocharger. One to four turbochargers can be installed on one diesel engine.

A turbocompressor is a centrifugal compressor and a single-stage gas turbine connected in one housing. Rotor of turbocompressor has no kinematic connection with crankshaft of diesel engine. The compressor is connected to the diesel engine only by the air supply pipeline to the receiver, and the turbine - by the gas supply pipeline to the nozzle apparatus from the exhaust organs of the diesel engine.

Supercharging air cooling is used to reduce heat stress and further increase diesel power.

In case of gas turbine pressurization, at all steady-state modes of the diesel engine, the equality between the power consumed by the compressor and the power developed by the gas turbine is observed. The pressurization pressure also changes in the application of the diesel operating mode. For example, when the diesel load increases as a result of increasing the cycle portion of fuel, the exhaust gas temperature, the turbine power, the rotation speed of the turbocompressor rotor increase, and as a result, the pressurization pressure increases, providing combustion of the fuel in the cylinder at an almost unchanged excess air coefficient. Thus, with gas turbine pressurization, self-regulation of the joint operation of the diesel engine and the turbocharger is provided. In a gas turbine, a significant part of the energy of the exhaust gases in the cylinders is used, which is carried away from diesel engines without pressurization with gases into the atmosphere.

A four-stroke diesel engine with gas turbine supercharging has features that distinguish it from a diesel engine without supercharging.

The first feature is associated with an increase in the flow rate of air and gases through the inlet and outlet valves during pressurization. To ensure this, during pressurization, the opening and closing advance angles of the valves are increased, four valves (two inlet and two outlet) are installed in the cylinder cover instead of two valves.

The second feature is the difference between the supercharging air pressure and the gas pressure in the exhaust pipeline (upstream of the turbine). Due to pressure drop during valve closing, combustion chamber blowdown is provided, as a result of which residual gas coefficient is reduced to values = 0.01 ± 0.02. This helps to increase the filling ratio and excess air ratio, improve the quality of fuel combustion, reduce the specific fuel consumption and heat stress of the diesel engine.

Third feature consists in necessity of gas supply to turbine through separate outlet pipelines. In case of connection of outlet nozzles of all cylinders to one outlet pipeline (header) at low pressurization pressure (up to 250 kPa), pressure pulses prevent blowing of other cylinders and cause throwing of gases in them. The connection of the outlet branch pipes to the separate pipelines eliminates this phenomenon and provides a sufficient pressure drop for the normal purging of each cylinder.