What is a direct-connected compressor?

What is a direct-connected compressor?

Direct-connected compressor is a kind of compressor design with special structure. Its core feature is that the output shaft of driving motor (usually motor) is directly connected with the crankshaft or rotor of compressor through rigid coupling (or without intermediate transmission structure), forming a compact and efficient integral power unit.

Compared with the traditional indirect transmission mode, the motor shaft of direct-connected compressor is directly connected with the compressor shaft (usually through high-precision flange and rigid coupling). The rotating power of the motor is directly transmitted to the compressor almost without loss, and the synchronous rotation of 1: 1 is realized.

Core special requirements include:

1. Speed synchronization:

Motor and compressor rotate at the same speed. For piston machines without built-in gearbox, this means that the motor speed directly determines the displacement. In many screw compressors, although they are also directly connected, there will be a speed-increasing gear inside to increase the motor speed to the best working speed required by the screw rotor.

2. High reliability:

Reduced wearing parts (such as belts and tensioning wheels), reduced downtime risk caused by transmission component failure (such as belt breakage and slipping), less maintenance requirements and more stable and reliable operation.

3. High efficiency:

Eliminate the energy loss caused by belt transmission (usually up to 2%-5%), the transmission efficiency is close to 100%, and the long-term operation is more energy-efficient and saves electricity.

4. High requirements for motors:

Due to direct drive, the load of the compressor (such as starting torque and pulsating load) will directly act on the motor, so it is usually necessary to equip the motor with stronger performance and larger starting torque.

The direct-connected compressor is like the "direct drive" system of an automobile, and the power transmission is direct, efficient and reliable; Belt drive, on the other hand, is like transmitting power through a "middleman" (belt). Although it has adjustment flexibility, it has losses and maintenance requirements. In modern industry, especially in the field of screw compressors, direct connection (especially permanent magnet frequency conversion direct connection) has become the mainstream technology and development trend.