Housings

How E-Sports Motorcycle Energica Ego Has Gotten Its Motor Housing

| Editor: Alexander Stark

Energica engineers and CRP Group employees worked together to redesign the motor housing for the Energica Ego e-sport motorcycle. In addition to the rotor and stator, the gearbox also had to be integrated.

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The synchronous, oil-cooled motor with permanent magnets, installed in the Energica Ego electric racing motorcycle, has an electrical output of 107 kW (145 hp) at 4,900 to 10,500 rpm.
The synchronous, oil-cooled motor with permanent magnets, installed in the Energica Ego electric racing motorcycle, has an electrical output of 107 kW (145 hp) at 4,900 to 10,500 rpm.
( Source: Scott Jones/Energica )

The motor housing of a powerful electric motorcycle like the Energica Ego is an important component. It protects and supports the drive unit. The gearbox of the e-sports motorcycle is equipped with a cascade of straight-toothed gears which increase the number of revolutions of the pinion to the desired angular velocity. The sprocket meshes with the chain to transmit the movement to the ring connected to the rear wheel. All these components interact to form the drive of the motorcycle.

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When redesigning the engine casing, the Energica and CRP team had to take various requirements into account:

  • Light weight (since the electric motor is heavy, the housing must be light)
  • High resistance (because the motor generates a high torque)
  • Accurate dimension of the gears and adequate materials

The motor housing also needs to support the frame.

First Phase: Production of a Prototype on a 3D Printer

Initially, the CRP team produced a 3D-printed prototype and composite materials from Windfire. The material LX 2.0 is a polyamide-based composite material reinforced with glass fibers These materials have now been replaced by the development of Windform LX 3.0, a non-conductive and temperature-resistant material. The prototype was created using SLS technology. The technicians were able to validate the CAD drawing while Energica's mechanics were working on the development of the model. The prototype could be mounted directly on the motorcycle, allowing a complete check of the main critical points related to the assembly of the individual parts (machining tolerances, frame entry, assembly of the gears and their correct functioning, cable bushings).

"It was extremely important for us to be able to touch the prototype of the motor housing produced with 3D printing and Windform with our hands," explain the Energica Motor Company technicians. “In this way, we were able to analyze whether the part was easy to assemble and dismantle, for example, or if all parts were easily accessible and whether it was possible to use standard keys, etc. Because we have to put ourselves in the position of those who have to use the finished motorcycle - i.e. the customers, but also the dealers and mechanics of the authorized workshops. One of the most common design flaws, for example, is that the access to a screw is concealed by the frame. In the CAD drawing you may recognize the error, but due to the many components and the complex interaction, one might overlook some issues. The possibility of analyzing the part in the form of a functional prototype and assembling it directly on the motorcycle is a great help."

Another example on which the technicians explain the advantage of the prototype is the following: The motor housing, manufactured on a 3D printer, allows the oil channels to be seen and the channels leading from the pump to the motor to be analyzed in the best possible way.

Second Phase: Production of the Aluminum Prototype from One Piece

Once the CAD file had been validated, the materials were selected to produce a prototype made of an aluminum alloy. The requirements were as follows:

  • Resistance
  • Light Weight
  • Temperature Stability

After selecting the two aluminum alloys (6082 and Ergal 7075), CRP manufactured the one-piece motor housing using CRP Meccanica 5-axis production systems.

The central part of the housing, which is also the largest part, was initially equipped with a through window. Therefore it was possible to position the engine inside the housing. A closable cover was applied on each side. The assembly of the gearbox cascade was planned on one of the two sides, on which an additional cover was mounted as well. The shaft for the transmission of the movement to the pinion, as well as the oil sump were located on the lower part. The engineers chose alloy 6082 for most of the housing and Ergal 7075 for the covers.

"This phase was completed in a very short time. CRP supported us a lot and we didn't have any problems with the part, neither during the tests on the test bench nor with the assembly on the motorcycle: The required tolerances were very complicated and strict, since the project envisaged two rows of bearings (those on the motor plus those on the outside of the shaft), which had to guarantee the proper functioning of the gears. Then we were able to validate the project on the road," explain Energica's technicians, "and we were able to finalize the project.”

Third Phase: Rapid Casting and Pre-Production

The next phase was the production of the models for the pilot series. In this case, the CRP team opted for the rapid casting process with aluminum castings and sintered sand because this technology can be carried out very quickly. Besides: "For this prototype, we chose the alloy that had been selected for the next phase - the final production," explains the CRP team. In this way, studies, modifications and machining could be carried out directly on the casting, allowing the final validation of the project.

This article was first published by konstruktionspraxis.

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