Designed To Give Thermal Management Engineering Teams Flexibility & Confidence when Considering Power Requirements of Thermal Management Systems
Dennis Jensen, Chad VanRens, Dominic Petri, Michael Osvatic
As both on- and off-highway vehicles continue to take advantage of new technologies that allow them to become more energy and fuel efficient, thermal management has become a key design consideration. Different vehicle architectures—internal combustion engine (ICE), electric (EV), hybrid electric (HEV), and hydrogen fuel cell (HFCV)—have different cooling needs. This means they could need significantly different thermal management systems and components.
When it comes to electric and fuel cell vehicles, and even some newer ICE vehicles, there has been a migration away from wax motor thermostats to electrically controlled valves. These valves can be highly specialized, and as a result, there is very little standardization for design teams to draw from when it comes time to specify thermal management components.
One of the considerations design teams need to address is how to distribute coolant to the various vehicle systems. They may have to decide whether a centralized manifold or a set of distributive valves would be the best choice for a particular vehicle design. They must also consider the power requirements of the thermal management system in conjunction with the demands of other vehicle systems—will the system need 12 or 24 Vdc? They will also need to decide which control strategy will be the best choice for operating the valve or manifold and whether or not feedback is required.
After all of these design decisions are reached, it is not unheard of for the specifications of various vehicle systems to change as the process of the vehicle’s design and development unfolds. In the case of a thermal management system that uses electrically controlled valves, changes to the vehicle’s electrical system or flow control demands, which might include changes in the flow rate, port sizes, and the number of paths of fluid flow, can be complex and costly, especially if a source for the valve has already been selected. A new source may need to be found, and then validation and testing would likely need to be redone.
TLX Technologies has developed their modular valve product family specifically for mobility applications, supporting EVs, HEVs, and HFCVs. The valves in this product family are designed to give engineering teams the greatest amount of flexibility so that changes to flow rates, port sizes, flow paths, power requirements, or control strategies do not require a complete redesign of the system or sourcing a new valve. The valves in TLX’s modular valve product family can handle all of these changes.
TLX’s family of modular valve products currently includes their 3-Way Switching Valve and 4-Way Switching Valve. These high-flow valves can be specified with SAE port sizes up to 25.4 mm and feature an efficient flow path with low pressure drop and minimal cross-flow leakage.
When developing these valves, TLX’s engineers focused on the industry demand for a solution that could adjust to meet changes in system requirements. They took that theme and worked it through each aspect of this family of valve products.
Designing valves that could support both 12 and 24 Vdc operation was only logical. Circuit board components that can handle this range of voltage are readily available, and so making the valves adaptable to either voltage requirement was one of the first steps to making this product family suitable to as wide a range of requirements as possible.
It was also important to provide flexibility in the choice of control strategies. While some systems may require the simpler pulse width modulation (PWM) strategy, others may need the more complex Local Interconnect Network (LIN) strategy. The latter protocol allows the vehicle’s control module to harvest information that includes the valve’s position, circuit board temperature, and other historical events, such as overcurrent incidents, to confirm system operation parameters and aid in diagnosing potential problems. TLX’s customers can choose the control strategy that best meets their system’s requirements.
The next challenge was to make the valves adaptable to the port size the thermal management system may require without the need to design an entirely different valve. By simply changing the inserts for the ports in the valve body molds during production, the valve body can be molded for a variety of port sizes without any changes to the internal valve components. There are limited cases where a redesign of the valve may be required, such as a need for such a small port size that the valve’s current design would over perform and be too large for the application’s requirements, or if a port size larger than 25.4 mm were required. In such cases, the existing valve technology could readily be leveraged for a new valve design, limiting risk, cost, and time to market.
Flexibility was not the only aspect that TLX’s team focused on. They also wanted the valves in this product family to have the best possible performance characteristics. Part of this meant making the valves energy efficient. These valves do not require constant power to maintain a commanded position. They also feature highly efficient flow paths, allowing them to incur minimal energy loss when redirecting and controlling the fluid flow route. This also means that a coolant pump should be able to support system fluid management requirements with less power. These features combine to reduce the vehicle’s overall energy consumption and improve mileage or range, regardless of the vehicle’s fuel type.
Finally, this family of modular valve products helps OEM design teams design a predictable and controllable thermal management system. Nearly all valves suffer from some internal leakage, and this leakage can make precise flow control challenging. The valves in this product family are able to operate with very low and predictably consistent bypass leakage, reducing the number of challenges design teams face when developing a system with the needed flow control.
Changes to the specifications of a thermal management valve during a vehicle’s development can be costly and time-consuming, especially if the valve has already been sourced, tested, and validated. The flexibility afforded by TLX Technologies’ modular valve product family can give thermal management system design teams confidence that they will be able to source a valve that will be capable of handling many of the potential changes to the valve’s specifications, saving both time and money.
Dennis Jensen Business Development Manager, Advanced Products
Chad VanRens Technical Copywriter
Dominic Petri Design Engineer
Michael Osvatic Engineering Manager
