September 15, 2015
Pierburg
New electric coolant pump for 48-volt systems
For over 40 years now, the power supply on cars has been of the 12-volt variety. However, with more and more auto functions consuming high amounts of electricity, the 12-volt system is being stretched to its limits and so automobile manufacturers are increasingly turning to 48-volt alternatives. For these, Pierburg GmbH has come up with its CWA 950-48V electric coolant pump. It has the same features as the CWA 200 and 400; yet thanks to the higher voltage, it is able to deliver 950 watts. In fact, plans are to raise this to as much as 1,600 watts in future.
Improving fuel efficiency and reducing emissions are currently the driving forces behind developments in automotive engineering. In this context, a key role is played by the electrification of auxiliary components. These can run independently of the IC engine and thus help reduce the latter's power consumption. In the wake of these developments, electrically driven coolant pumps offer certain advantages. They can be used both for cooling the IC engine and for other cooling requirements. It is particularly with regard to engine cooling that 48-volt systems have an important role to play. To address ever rising needs, the output of Pierburg's newest pump has been boosted to 950 watts, and this is only the first step.
A product family for various requirements
With four main models, Pierburg's range of electric coolant pumps covers customer requirements for low, medium and high outputs. The CWA 950-48V rounds off the top end of the portfolio. Another family member at the lower end is the WUP water recirculation pump with an output of between 15 and 20 watts. This pump has a single-phase EC motor fitted with a Hall sensor for commutation.
The CWP 35, CWA 50 and CWA 100 cover outputs ranging from 35 to 100 watts. Fitted with a sensorless 3-phase EC motor they are used for indirectly cooling the charge air on turbo engines. Another function is to cool auxiliary assemblies of the kind found on hybrids and electric vehicles.
The CWA 200 and CWA 400 also feature a sensorless 3-phase EC motor. Outputs range from 200 to 400 watts. Nowadays these pumps are employed on the main cooling circuit of IC engines as well as on the first fuel-cell stacks of fuel-cell vehicles.
Many years of development work
There are three subsystems to an electric water pump: the hydraulics, the motor, and the electronics. Each new development stage takes into account the integration of these three subsystems with a view to further reducing size, weight, and component count. Pierburg can draw on two decades of experience in the development and manufacture of electric coolant pumps. Initial development targets such as the durability of the electronics under extreme ambient temperatures as well as defined vibration profiles have long been achieved. Advanced communication and diagnostic functions have been systematically refined, so customers nowadays benefit from a host of diagnostic information provided by the pump. Another important feature is the low noise emissions on this type of pump achieved through fine-tuning the motor commutation and reducing pressure pulsation through the design of the hydraulics. Even with the engine switched off these electric pumps are barely audible.
Background info: electric coolant pumps
Electric water pumps perform a variety of functions. On an IC engine they ensure optimal thermal management both with the engine running and switched off. When the engine is on, the primary pumps deliver the right amount of coolant required by the drive unit in its respective operating state. The advantage of electric pumps versus the mechanical, belt-driven variety is the ability to supply on-demand cooling in any situation and irrespective of engine speed. The engine's cold-start phase is shortened, and once it arrives at its regular operating temperature, it is cooled. Even when the engine is switched off, as during the new start-stop and ‘sailing’ mode, cooling is still possible. During the latter, electric pumps continue to cool heat-critical components besides maintaining passenger compartment air conditioning for the comfort of the occupants. Even after the engine has been switched off and the car parked, electric pumps are still helping to eliminate any residual hot spots by, for example, lowering the temperature at the turbocharger bearings.