We were asked to design a compact and extremely quiet motor to equip cars in the luxury segment, such as Mercedes S-Class, Audi A8, Lexus GS, Bentley Continental GT and other prestigious models.

The application areas concerned the electrification of the luggage compartment, rear curtain and side curtains.

Silence was required because the motors were housed under the hat rack, inside the luggage compartment or inside the door in the case of side curtains, therefore audible by passengers.
 
 

The solution and its advantages

The design has focused on many aspects:

• gearbox without output shaft, which makes it possible to use the same unit both on the right and left side of the system adopted by the customer, making its positioning flexible during assembly;
• worm screw profile and surface finish, which guarantees a minimum roughness and a surface free of any defect;
• research on the plastic material of the gearwheel, characterised by constant shrinkage during cooling after moulding, which is not hygroscopic in order to avoid dimensional variations;
• decrease in the number of components of the geargroup, in order to limit friction and the consequent noise;
• study of the geometry of the bearings, rotor and magnets aimed at obtaining torque and speed values suitable for the task that the gearmotor had to perform and particular attention to the containment of electrical and mechanical noise;
• the obtained result was a gearmotor with detected operating noise of < 40 dB(A).