Performance Optimization of Compressor Rotor Clutch Sub-assembly Using Electro- Magnetic Analysis 2018-01-0484

Rotor Clutch sub-assembly is one of the very important sub-assemblies (S/A) of an automotive compressor as it delivers the required torque/power to run the compressor. It mainly consists of rotor and bearing, stator, hub and armature. Rotor is rotated by engine pulley through belt drive system, while stator housing has got number of coils winded around stator slot. The hub sub-assembly is attached to the compressor shaft via spline arrangement and bolted across. When direct current (DC) is supplied to the terminal of the rotor, an electromagnetic field is generated which causes to attract the hub part towards rotor. Once the hub and rotor gets engaged each other, torque is transmitted to the compressor shaft which then helps to complete the suction and compression of refrigerant gas and thus making the vapor cycle run to produce adequate cooling in the air-conditioning (AC) system. Hence it is most important to ensure adequate and even distribution of electromagnetic field which is solely responsible for providing torque to the compressor.

The present paper describes the numerical simulation of electromagnetic field of a clutch sub-assembly of an automotive compressor. ANSYS software was used to simulate the same. 2dimensional geometry of clutch rotor sub-assembly was created from computer aided design (CAD) tool and imported in suitable format. Meshing was performed using shell elements and the necessary material properties like permeability and B-H curve were defined along with the load conditions. The obtained flux density was then optimized by changing the shape and size of clutch sub-assembly. Further to this shaft torque was calculated analytically using the numerically obtained flux density and validated with the required torque for compression/suction process. The validation results exhibit a good trend and correlation, thus helping to develop a procedure to design clutch sub-assembly ‘first time right’ at the design stage. It is also ensured by this to have adequate torque delivered to the compressor.