Picture a traditional, rear-wheel drive internal combustion engine (ICE) powered vehicle. Engine power is routed from the engine through a transmission and to the rear differential, which drives the rear wheels and propels the vehicle forward. The linkage that transfers power from the back of the transmission to the rear differential is a big, hefty steel driveshaft.
- BorgWarner is a major parts supplier to the auto industry
- While most Internal combustion engine cars require geared transmissions, EVs and hybrids can use chain drive
- Chains, like BorgWarners HY-VO, are more efficient and quieter
- Right now, the HY-VO system is at use in the Chevrolet Volt
What is BorgWarner’s HY-VO Chain Drive System?
For the last century rear wheel-drive vehicles have utilized drive shafts for power transfer delivery. Now, however, with the rise of complex hybrid electrified powertrains, for which compactness and efficiency are key, a long, bulky, and heavy driveshaft won’t suffice.
Because of this, engineers have essentially looked backwards to chain-drive technology — best recognized as the driveline component of choice for bicycle makers — to achieve the efficiency and durability requirements of today’s hybrid, plug-in hybrid (PHEV), and electric vehicles. While chains might seem oddly outmoded for an era dominated by high-tech electric propulsion systems largely optimized by computers and algorithms, they make a lot of sense.
Keen to underscore this, automotive parts supplier BorgWarner put out a press release this week touting its chain-drive bona fides, specifically, its HY-VO (High Velocity Chain on Involute Profile Sprockets) chain drive systems.
Why Do EVs Use Chain Drives?
BorgWarner explains that its HY-VO chain “delivers improved efficiency, reduces noise, vibration and harshness, generates less heat and … have proven to be more efficient than two-mesh gear systems.” In short: chains are quieter and more efficient than gears.
They’re more efficient not only because they’re lighter than some of the alternatives, they generate less heat. And heat is energy loss, which, in an electrified powertrain, is a big issue. With long recharge times and finite range, drivers want their electrified vehicle to go as far as possible. Limiting parasitic powertrain loss, like with the utilization of BorgWarner’s HY-VO chain tech, is one step toward achieving a quiet and efficient PHEV and EV propulsion system.
Where Is Chain Drive Used
If you look closely, you can see BorgWarner’s HY-VO chain tech in the technical rendering from the propulsion system of the second-generation Chevrolet Volt PHEV. The first-generation Volt had gears that connected the transmission to the electric motor. These were not only heavier and less efficient but also noisier. If you’ve ever driven in a PHEV or EV, you know that one of their distinctive driving characteristics is their relative silent ride. You can partly thank HY-VO chains for that.
Now, why did I decide to spend time on something as innocuous as an electrified powertrain chain — something you’ll never see (or, thankfully, hear)? Because it’s important to highlight the depth of development engineering resourcefulness companies are implementing in order to achieve new levels of drivetrain efficiency and refinement. That, and I am a nerd (sorry not sorry).
There’s more to an EV than a battery pack and an electric motor. We shouldn’t forget that. What’s more, the alternative energy vehicles of the future that are designed to reduce the greenhouse gas emissions from transportation will require ever-increasingly diversified powertrains. That means even more clever engineering solutions like the HY-VO chain from BorgWarner.