Structure and Types of Diesel Generator Sets

 
Diesel generator sets are a type of internal combustion generator that are primarily used to provide power when the main power supply is insufficient or unavailable. They are widely utilized across industrial, commercial, agricultural, and military fields. The core components of a diesel generator set include a diesel engine, a three-phase AC synchronous generator, and a control panel. These components work together to convert the chemical energy of diesel fuel into electrical energy. In addition, the generator set is typically equipped with auxiliary devices such as a radiator, coupling, fuel tank, muffler, and a common base to ensure normal operation in various environmental conditions. Based on different structural designs, diesel generator sets can be classified into two main types: integral body and sectional body.

Integral Body

 
The integral body design casts the cylinder block and crankcase as a single unit, providing high rigidity and structural strength. This integrated design reduces the number of connecting parts, effectively lowering the risk of leakage and ensuring the stability and reliability of the generator set. However, this type of structure is relatively complex and challenging to cast, requiring meticulous handling during the design and manufacturing stages to ensure precise fitting of each component.

1. Engine Cylinder Configurations: Inline and "V" Types

 
Depending on the cylinder arrangement, the integral body can be divided into single-cylinder and multi-cylinder types. Single-cylinder designs are generally used for low-power small generators, while multi-cylinder designs are suitable for applications requiring higher power. Multi-cylinder diesel engines can further be classified into inline and "V" configurations based on the cylinder arrangement.

Inline Arrangement

 
In an inline diesel engine, the cylinders are arranged in a straight line. This design is simple and compact, making maintenance and repairs easier. Due to its cylinder layout, the inline engine has a longer body length but offers optimized weight distribution and cooling system design, making it suitable for medium and small power diesel generator sets.

"V" Configuration

 
In a "V" configuration engine, the cylinders are symmetrically arranged at a certain angle to form a "V" shape. This design results in a more compact engine with a reduced length, increasing power density. Because the "V" configuration lowers the engine's center of gravity, it provides lower vibration and better stability while maintaining high output power, making it widely used in medium and large diesel generator sets.

2. Types of Engine Structures: Gantry, Bedplate, and Tunnel

 
The integral body can be further divided into three types based on the crankshaft support method and crankcase structure: gantry type, tunnel type, and bedplate type.

Gantry Type

 
The gantry-type structure features main bearings split radially into two parts. The upper part serves as the main bearing housing, fixed on the crankcase, while the lower part is the main bearing cap, secured to the main bearing housing with bolts. The advantage of this structure lies in its compact design and smaller dimensions, making the generator lighter and easier to transport and install. Due to its convenient maintenance and repair, the gantry-type structure is often used in gasoline engines and small to medium-sized diesel generators.

Bedplate Structure

 
In the bedplate structure, the crankshaft is mounted on the lower crankcase, which bears the main forces and torques. This design provides good rigidity and makes it easier to maintain and repair the internal components of the diesel generator. However, the lower crankcase structure is more complex and heavier, so this design is typically used in low-speed marine diesel generators that require high stability and long continuous operation.

Tunnel Type

 
The tunnel-type structure integrates the main bearing housing and the main bearing cap into a single unit, with the crankshaft installed and removed axially from one end through the flywheel housing. This design gives the engine body a tunnel-like appearance when viewed from one end. The tunnel-type structure is characterized by its compact design, good rigidity, small axial dimensions, and simple lower body sealing. However, it is heavier and makes crankshaft maintenance and repair inconvenient, especially during disassembly, which is complex and time-consuming. This type of structure is generally used in small to medium-sized diesel generators.

Sectional Body

 
The sectional body design separates the diesel generator's cylinder block and crankcase during manufacturing. This design approach allows for more flexibility in the manufacturing process, enabling individual production and assembly of each part, reducing the difficulty of overall casting. The modular design of the sectional body not only helps improve production efficiency but also allows for customization according to specific application needs, catering to different types of diesel generator sets.
 
In practical applications, the advantage of the sectional body lies in its excellent maintainability and repairability. Since each part is manufactured and assembled separately, maintenance personnel can more easily inspect, maintain, and replace the components of the diesel generator, reducing downtime and maintenance costs. This structural form is particularly suitable for generator sets that require frequent maintenance or component replacement, such as high-power industrial generators and backup power systems.
 
As a crucial power equipment, diesel generator sets meet various power needs through their diverse structural designs and reliable performance. From integral to sectional body designs and various cylinder arrangements and support methods, diesel generator sets offer significant advantages in adaptability, maintainability, and performance.