Electric drive units have to fit more torque into the same space. Analysis shows Convoloid can deliver about 20% less volume and weight at equal power and stresses, or a higher single-stage ratio that replaces a two-stage reduction.
Motor torque keeps climbing while drive units have to fit the same space under the vehicle. The gears are the limiting part.
Every kilogram in the drive unit is carried for the life of the vehicle. Smaller, lighter gears help packaging and handling.
A second reduction stage adds gears, bearings, shafts and housing. A higher single-stage ratio removes them.
Analysis shows about 20% volume and weight reduction at equal power and stresses. The dashed rings show the involute envelope it replaces.
| Involute | Convoloid® | |
|---|---|---|
| Volume, single-stage EV design study | Baseline | −20.3% (analysis) |
| Weight, same study | Baseline | −22.3% (analysis) |
| Single-stage ratio, same envelope | 9.43 : 1 | 13.5 : 1 (analysis) |
| Stage count, 9.72 : 1 example | Two stages | One Convoloid pair (analysis) |
| Powder-metal gears | Yes | Convoloid first gear in a PM 6-speed program (Höganäs/Vicura) |
With no base circle there is no undercut limit, so a Convoloid pinion can run with fewer teeth than an involute (about 13 vs. 25 at equal constraints). That opens higher single-stage ratios.
EV reductions are helical. The Convoloid transverse profile sweeps along the helix like any other.
Automotive programs live on validation. Here is the record behind the analysis.
Under a U.S. DOE/NREL wind-energy research contract (2005–2008), a Convoloid retrofit of a 108 kW two-stage gearbox ran back-to-back against an optimized involute at up to 240% of rated load. Convoloid surfaces stayed stable; the involute’s micro-pitting progressed.
See the source →Published: 20–35% higher torque capability than equivalent involute designs, rated per AGMA/ISO with the same derating factors applied to both (Berlinger & Colbourne, 2011).
See the source →US 10,527,149 in force to ~2036. European patent EP 3 387 294 granted, with Unitary Patent and UK validation, to 2036.
See the source →EV figures are design-study analysis results, not vehicle test results. Gear Innovations makes no noise or efficiency-advantage claims for EV duty. Light-load noise behavior is still being characterized. Powder-metal program: Gear Solutions (2016).
Barney Berlinger, Convoloid's inventor, explains what makes the tooth form different and why it matters for ev & automotive.
A short briefing for engineering and leadership: the problem, the technology, the comparison and the test record, in nine slides.