Oil-free air compressor
At present, oil-free air compressors are improved and developed on the basis of oil-air compressors. There are two main ways: the first is water-lubricated; the second is self-lubricating of materials or coatings.
It is more and more widely used in fields with higher requirements for compressed air, such as: gold plating, copper plating, medical, food, laboratory, electronics, chemical, mining and other industries.
In the field of rail transit, the second method is adopted as an oil-free air compressor for locomotive and vehicle braking. Globally, European railways are widely used; domestic applications are in their infancy. In the domestic subway (Qingdao Metro Line 3), KB has been used in batches.
Oil-free scroll air compressor
Oil-free scroll air compressor technology is the best way for small-displacement air compressors. It has the structural characteristics of energy saving, quietness and high reliability. There is no metal contact except the bearing. The oil-free scroll air compressor has few complete components, plus a motor, air filter, and after-cooling to form a complete compression system.
Oil-free scroll air compressors, also known as fourth-generation compressors, have many advantages in the compressor industry:
|Project||Oil-free scroll air compressor|
Two involute dynamic and static scrolls are mutually engaged to complete the working process of suction, compression and exhaust, which can be applied to the working cycle from 0% to 100%.
When working, the moving and static scrolls do not touch, and there are no suction and exhaust valves and complex motion mechanisms, which eliminates the knocking sound of the valve plate and the blasting sound of the airflow, and the suction and supply are stable, with low vibration, noise and vibration.
The main engine has few parts, the dynamic and static scrolls do not contact, the whole machine has no wearing parts, and only the air filter needs to be replaced; in the whole life cycle, it only takes 1.5 hours per year for preventive maintenance, including major repairs; it has a very short life cycle cost characteristics.
Simple structure, less main engine parts, less than 1/6 of the number of screw machines; no lubricating oil, no emulsification risk; no oil/carbon pollution in the air system, long service life.
|Energy saving and environmental protection|
The air compressor with the highest energy efficiency ratio; the compressed air is oil-free, and there is no need to replace the lubricating oil and its oil filter, and there is no problem of waste liquid disposal; at the same time, it avoids the oil leakage of the body and the impact of oil change on the environment.
SFR series oil-free scroll air compressor
|Model||Maximum displacement||Rated displacement||Use|
|SFR-0.3||0.30 m3/min||10bar||Monorail series|
|SFR-0.6||0.60 m3/min||10bar||Light rail, maglev|
Working principle of oil-free scroll air compressor
The movable scroll rotates in the order of Fig. 1→2→3→4→5, the air is sucked into the space between the movable scroll and the fixed scroll, the volume of the crescent-shaped compression chamber gradually decreases, and the air passes through the space. After compression, it is discharged from the exhaust port at the center of the static disc, as shown in the following figure: the dark part is the compressed air.
Bombardier APM300 Brake Air Source
|The main parameters||Unit||Parameter value|
|Air supply unit model||/|
|Nominal volume flow after drying||m3/min||≥0.225|
|Rated exhaust pressure||bar||10|
|Working pressure range||bar||9~10可调|
|Outlet safety valve setting||bar||11|
|Air quality class||级||ISO 8573-1 2|
|Compressed air relative humidity%||≤35（露点降-40℃）|
|Relative humidity of working environment||%||0~100|
|Sound pressure level at 7.5m||db(A)||≤65|
|Cooling method||/||All air cooling|
|Power supply||V/Hz||3AC 240±10% / 60|
|Motor rated power||kW||4|
|Motor rated speed||r/min||2850|
|Degree of protection (electrical)||/||IP65|
|Control power||V||DC 24（-30%～+25%）|
Bombardier APM300 Brake Air Source Third Party Test Report
Oil-free piston air compressor
Reduced scheduled maintenance - no lube checks, no lube refills, no lube and filter changes
Improved air dryer performance - better compressed air quality, fewer pre-filter settings, longer desiccant life
No more dealing with classified and restricted substances - oils, drains, filters
Reduce the impact on the environment---compressed air is oil-free, no need to replace lubricating oil and its filter, no waste liquid disposal problem, and avoid oil leakage from the body
No need to install a drain tank on the locomotive or vehicle
Lower energy consumption---better thermal efficiency, no oil circulation, no viscous friction
Able to adapt to very low temperature conditions - run without oil, no increase in viscosity
No problem with low operating rates --- water does not condense in oil
Higher reliability---reduce 60% failures directly or indirectly caused by lubricating oil
Lower full life cycle (LCC) cost---annual average cost equivalent to 55% of oil-piston air compressors and 65% of oil-injected screw compressors
PFR series oil-free piston air compressor
|0.9~1.0 m3/min||9KW||1.1 ~1.2 m3/min||11KW|
|1.4~1.5 m3/min||14KW||1.7 ~1.8 m3/min||16.5KW|
|Dimensions: (L)1345mmx(b)590mmx(h)460mm||Weight: 260kg|
Brief introduction of structure and principle
|Work cycle allowed|
|Extreme working ambient temperature||-55℃~60℃|
|Maximum allowable ambient humidity||99%|
|Range of rotation||960r/min~1800r/min|
|Outlet compressed air temperature||Ambient temperature+10℃|
laboratory test site
Reliability growth test (ground) over 2000h
still in progress
Main structural properties
Cylinders, pistons and crankcases are cast from aluminium alloys - reduced mass
Special hardening treatment on cylinders - increased thermal efficiency and reduced friction
Patented material sealing ring---wear amount 0.2mm/10000h, to ensure longer service life
Sealed Long Life Roller Bearings - Use Special Lubricants to Ensure Wide Temperature Range
One-piece connecting rod --- reduce the mass of the reciprocating motion
Reed Cylinder Valves - High Dynamic Response Over Wide Operating Speed Range
Combined heat exchanger (intercooler + aftercooler)---high thermodynamic efficiency of air cooling
Axial cooling fan---directly driven by compressor shaft
Elastomeric coupling for motor connection
The high and low pressure cylinders adopt 4-cylinder "V" type opposites---minimize the vibration caused by the unbalance during operation
Low speed motor - lower noise level
The main functions of oil lubricated in oil-filled air compressors are: sealing, lubrication, cooling and noise reduction.
Because of its structure and oil-free characteristics, oil-free piston air compressors have poorer performance in terms of vibration and noise than oil-free air compressors, especially rotary air compressors.
So far, through continuous improvement of structure and materials, the vibration and noise of oil-free piston air compressors have approached or reached the level of oil-based rotary air compressors with the same displacement.
Main components and structural design
Product 3D model display
Oil-free piston air compressor
Standard metro air source device