General characteristics and parameters of diesel engines type D49
The power range of four-stroke diesel engines of type D49 includes eight-, twelve-, sixteen- and twenty-cylinder modifications of diesel engines with power from 585 to 4410 kW. Diesels of this series are intended for use on mainline and shunting diesel locomotives, mobile power plants, stationary drilling and ship rigs. The power range of diesel engines of the D49 type makes it possible to replace very numerous outdated models with diesel engines of the same type with a high degree of unification and better economic indicators. The requirements for engine life and efficiency determined the choice of a four-stroke diesel engine as the base model. The creation of the power range was based on the principle of providing the entire power range of the row by changing the number of cylinders and the level of boost of Y-shaped diesel engines having the same diameter and piston stroke. All diesel engines of the D49 type have a cylinder diameter and piston stroke of 260 mm, and the camber angle between the cylinders in the Y-shaped model is 42°.
Diesel engines of the D49 type are most widely used in railway transport. The power range provided by eight-, twelve-, sixteen- and twenty-cylinder models of locomotive diesel engines of the D49 type allows the use of these diesel engines for shunting and mainline diesel locomotives. The developed and planned power ranges for each diesel model are determined by the average effective pressure Pe (from 0.743 to 1.922 MPa) and the crankshaft speed (from 750 to 1100 rpm). The degree of unification of parts between the models of the series is 87%. All the main components of diesel engines that determine the service life between repairs (cylinder-piston group, connecting rod and crank mechanism, valve mechanism, fuel equipment, crankshaft bearings, filters, etc.) are the same for all modifications. High unification within the series allowed the use of automatic lines, special modular machines and other equipment. When creating and fine-tuning diesel engines of the D49 type, the best design solutions were used, tested in long-term operation on domestic diesel engines 11D45 and D100, and the experience of the largest foreign companies in the field of diesel engineering was also taken into account.
All main components of a number of diesel engines of the D49 type are manufactured in the form of separate units mounted on the engine cylinder block. This arrangement makes it possible to ensure high quality manufacturing of each component and, if necessary, to test the components on special stands before the start of general engine assembly. This greatly shortens and simplifies the overall assembly. In addition, this solution makes it possible to very widely manufacture some units and components at a number of specialized factories, and to use the aggregate method for repairs in locomotive depots.
The cylinder block is “dry”, welded-cast, the main welds are unloaded from combustion pressure forces. The crankshafts are hardened: the shaft journals are nitrided and the fillets are knurled. Steel shafts for forced modifications have a counterweight on each shaft cheek. The crankshaft bearings are cast in lead bronze and are interchangeable.
Cylinder bushings are of suspended type. The sleeve and cylinder cover form a cylinder set that can be removed from the block along with the connecting rod and piston. The valves rest on “floating” insert seats in the cylinder covers.
The valve mechanism is controlled by a camshaft common to the right and left rows of the diesel engine, and hydraulic pushers are installed in the valve drive to reduce clearances. Composite pistons are oil cooled. The fuel injector is removed from the cavity of the valve mechanism, the entire fuel pipeline is located outside the lubrication system.
All main components and pipelines of the oil system are located on the diesel engine. The exhaust manifolds are water cooled and have a shielded flame tube. The design of diesel components allows the use of high-temperature cooling. On most modifications of diesel engines, the speed and power regulators have devices that correct the flow.
To ensure a high service life of the main parts of diesel engines, modern methods of chemical-thermal treatment and galvanic coatings (cementation, nitriding, chrome plating and other methods) are widely used. In the production of diesel engines, progressive technological processes and high-performance equipment are used: electric butt welding of the crankcase, electrophysical and electrochemical methods for processing parts of fuel equipment and turbochargers, superfinishing of bearing surfaces of shafts with diamond tape, diamond boring, pair grinding, etc.
When creating the power range of diesel engines of the D49 type, a complex of development and research work, full-scale testing of components and the diesel engine as a whole was carried out. Much attention is paid to the issues of mechanical and thermal strength of new engines. The durability of the most critical engine components was assessed using special installations for conducting fatigue tests of full-scale samples of the cylinder block, crankshafts, connecting rods and other components. Fatigue tests under loading with forces significantly exceeding operating forces, in compliance with actual loading patterns, were an effective means of assessing the safety margins of the main components.
All diesel engines of the D49 type have gas turbine supercharging. On diesel engines of type D49 with average boost (Pe = 1.2 MPa), a single-stage pressurization system is used; on diesel engines with increased boost (Pe > 1.6 MPa) at average effective pressure, a two-stage pressurization system is used with double intermediate cooling of the air after each boost stage. On eight-, sixteen- and twenty-cylinder modifications of diesel engines, an isobaric supercharging system is used; on twelve-cylinder modifications, a supercharging system with converters is used.
Indicators for average effective pressure, piston speed, air supply and pressurization system, rationally selected for each modification of the D49 diesel engine, ensure high-quality work process and the necessary parameters for efficiency and resource. As a result of the experimental work carried out, for each modification of the diesel engine, its own gas distribution and fuel supply phases were selected depending on the degree of diesel boost and the adopted supercharging system. For most modifications of D49 type diesel engines, fuel consumption at full power is 204-212 g/(kW*h).