Challenges of Commercial Vehicle Electrification
In 1933, Kenworth Motor Truck Co. became the first American truck manufacturer to introduce the Cummins 4 cylinder, 100 hp, HA4 model diesel engine as standard equipment. By 1938 the first two-stroke diesel powered bus was introduced. In 1940, Cummins was the first diesel engine manufacturer to offer a 100,000-mile warranty. By the 1950s, diesel engines had virtually replaced gasoline engines in commercial trucks. Since 1997, engineers of diesel engine manufacturers have risen to the challenges of meeting new and more stringent limits for particulate matter (PM) and nitrogen oxides (NOx) and increasing the fuel efficiency of the engine.
As the heavy truck and bus market continues to evolve, engineers need to meet new challenges by identifying and adopting innovative technologies.
Consider the trend of commercial vehicle electrification. Driven largely by concerns over emissions and environmental impact, the vehicle electrification market has grown substantially. And enhanced vehicle battery technologies are the key to driving truck and bus electrification.
Challenges remain, however, before these systems will prove feasible and practical over the long term.
Lithium-ion batteries have been the primary solution for electric vehicle manufacturers because they have higher energy densities than lead-acid or nickel-metal hybrid batteries. Li-ion batteries also offer attractive features such as low self-discharge and considerable energy storage, or battery capacity. Yet, there are still many barriers for the vehicle electrification market to overcome. Among these barriers are cost, weight and range, safe storage and thermal management.
Electric vehicle battery technology
A lot of research is being conducted to identify alternative battery chemistries and reduce the use of cobalt. Although cobalt is ideal for rechargeable batteries because of its thermal stability and high energy density, a problem is that it is almost exclusively mined in the Democratic Republic of Congo, an unstable country that has been charged with numerous human rights violations.
Increased ethics concerns and growing costs have universities, private companies and the U.S. military aggressively researching alternatives to cobalt.
- The U.S. Army is focusing on a new electrolyte design using silicon particle anodes in conjunction with lower cost transitional fluorides. The solid polymer electrolyte provides greater stability, even at higher temperatures, overcoming previous heat concerns.
- IBM is researching a cobalt- and nickel-free cathode material and a safe liquid electrolyte with a high flash point.
- Research at Washington University in St. Louis on potassium-air batteries has shown that the effective selection of the electrolyte in battery chemistries can double their capacity.
- Engineers at the McKelvey School of Engineering also have developed a borohydride fuel cell that operates at double the voltage of conventional hydrogen fuel cells.
Battery safe storage
Since it is critical to protect the integrity of a battery from dirt and water, proper sealing is a key design consideration. Electric vehicle battery covers pose unique sealing challenges due to the significant size of the perimeter of the battery, as well as the aggressive performance requirements. Batteries are assigned Ingress Protection (IP) ratings to specify the degree of environmental protection from solids and water that might otherwise enter the enclosure and cause damage. Sealing products from Parker O-ring and Engineered Seals and electronic materials from Parker Lord prevent ingress between battery covers and housings—for both serviceable and non-serviceable batteries.
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Electromagnetic interference (EMI)
Electromagnetic interference is a concern because electric vehicles have multiple battery cells, converters and powered electronics (ADAS, LiDAR and infotainment screens). The signals from one could interfere with those of another. The good news is that special EMI shields now exist to help contain the magnetic signals within the components.
Among them are seals that are made of electrically conductive elastomers and form-in-place (FIP) conductive gaskets and even plastic pellet materials for housings
Thermal management tops the list of priority concerns. Parker offers several material innovations in this area that can stand up to excessively high temperatures and are flame-retardant to prevent a catastrophic thermal event, including thermally conductive gap filler pads and thermally conductive structural adhesives
In addition, there are air ventilation panels that dissipate heat and provide EMI shielding.
Electric vehicle battery technology is a significant, trending topic in the bus and commercial vehicle market. While lithium-ion is currently the most dominant type of EV battery, engineers are driven by concerns over emissions and environmental impact to find a higher performing alternative. Reduced weight, improved storage, and better thermal management are among the features that engineers are hoping to work into EV batteries.
This article was contributed by Christopher Overmyer, Senior Field Application Engineer, Parker Engineered Materials Group