Elements, Engineering, and Expertise:
The 3 E's to Successful Electric Drive Module Venting

The future of the automotive industry is accelerating towards the transition to Electric Vehicles. As adoption rates rise, so do the demands for the crucial components that power Electric Vehicles, making them efficient and accessible for those wanting to make the move towards alternative transportation options.

Electric Drive Modules are one of many components in an Electric Vehicle powertrain. This unique mechanism is central to the vehicle’s operations and requires venting technology to maintain functionality, effectiveness, and performance.

What is an Electric Drive Module (EDM)?

An EDM is a combination of an Electric Vehicle (EV) e-motor, gearbox, and power electronics. This component may also be called an Electric Drive Unit (EDU), 3in1, or E-Axle, and is often considered ‘unique’ to other EV components as it is a sealed enclosure that also holds oil.

Why Venting is Required for Electric Drive Modules

Venting performs two key functions that help ensure an EDM can perform as required:

  1. Pressure equalization: An EDM is subjected to pressure changes due to temperature fluctuations. Pressure equalization is a critical vent function as it allows airflow in and out of the enclosure, protecting necessary seals and gaskets in the process.

  2. Contamination control: A successful EDM vent will provide the enclosure with ingress protection against contaminants such as water, dust, and particulate.

In-tandem operation of these key functions is crucial to the successful performance of a vent. For example, pressure equalization could be achieved by simply creating a

hole in a component, however this would provide no contamination protection. A vent provides the solution by allowing pressure equalization with the required protection.

The Elements and Engineering: Ensuring Venting Materials Are EDM-Compatible

Donaldson has been working with EV manufacturers for many years, over this time we have become experts in the intricacies and evolution of components where venting is applied.

For EDMs, we have witnessed a usage shift from traditional transmission fluids to specialized e-fluids. These fluids are formulated by equipment manufacturers to ensure that the fluids (or oils) used in EDMs meet required oil viscosity levels and are suitable for the component’s operating speeds, thermal temperatures, and longevity.

The changing nature of EDMs and the respective e-fluids present a new challenge for venting technology. With several key factors to consider:

  • Changes in oil aerosols: EDMs utilize low viscosity oil to accommodate efficient heat transfer and when this is combined with high RPMs small oil droplets form and are carried in the airflow to the vent.
  • Changes in oil vapors: The high localized temperatures within the EDM create increased levels of oil vapor. This oil vapor travels to the vent during positive pressure differentials.
  • Longevity expectations: An EDM’s oil level is often ‘filled for life’, making oil changes unnecessary. Users do not want to disrupt the component simply for venting changes, resulting in higher longevity expectations for venting technology.
  • ‘New’ fluid additives: A vent’s performance will vary depending on e-fluid formulation and operating conditions. This is why it is so critical to test a vent to application specifications to ensure it is EDM-compatible.

Standard industry venting approaches, namely Jiggle Caps/Hose Breathers and Membrane-only vents often only address part of the picture as an EDM venting solution.

Table 1: Ingress Protection (IP) Rating Values
  Jiggle Cap / Hose Breather Membrane-Only Vent Donaldson EV Vent
Direct Attachment  
Water & Dust Ingress Protection  
EV Oil Resistance    
Table 1: Other venting strategies such as jiggle cap/hose breather and membrane only vents provide some functionality for EDM while the Donaldson EV vent provides full functionality.

This is where Donaldson’s extensive experience in the venting industry has proven to be beneficial for EDM manufacturers. Our venting solution provides both contamination protection and e-fluid capability while allowing pressure equalization. We implement two, internally developed, core technologies in our EDM vents that make this possible.

1. Tetratex® ePTFE Membrane: Tetratex ePTFE membrane has a unique microporous structure. It is comprised of small randomly connected fibrils that render an effective pore size many times smaller than can be seen by the naked eye. This protects the EDM by preventing ingress of water, dirt, and other contaminants.

2. Synteq™ XP Prefilter: Synteq XP prefilter media protects the Tetratex ePTFE from oil contamination. Media material properties and number of layers are optimized to provide high airflow and oil capture efficiency. The specific media grade used in the Donaldson powertrain vent has been extensively tested to ensure compatibility with a wide range of EV fluids.

The Expertise: Applying In-House Testing Methods

Testing is fundamental in the development and evaluation of vents to ensure functionality is maintained for EDM applications. With over 100 testing laboratories across the globe, we can test our venting technologies across a wide range of oils and conditions to help ensure they work across many different applications.

General testing methods for venting assess factors such as airflow, ingress protection, temperature fluctuation capability and structural integrity. We also run additional oil-specific tests that assess oil aerosol and vapor loading which are both important dynamics when evaluating venting for EDM components.

Oil aerosol testing evaluates the vent's ability to capture small oil droplets with the prefilter media. In this test, the vent is challenged with oil droplets carried by airflow.

Oil vapor testing evaluates the vent’s ability to capture oil vapor. In an EDM, vapor is made through oil contacting hot components. In this test, air is passed through a heated container of oil then to the vent.

In both aerosol and vapor testing, pressure drop across the vent is measured to determine how much oil a vent can hold before reaching the rated seal pressure of the EDM. The ideal result is a minimal increase in pressure drop over time.

Talk to the Experts When Searching for a EDM Venting Solution

The complex nature of EDMs presents unique challenges. Traditional venting approaches may not always be suitable for an EDM application as multiple considerations must be accounted for including oil vapor and aerosol levels produced, longevity expectations and compatibility with EDM-specific fluid.

Through extensive research, testing and feedback loops with our customers, we have created optimal venting solutions for EDMs and many other components within the EV powertrain system. Our testing techniques are designed to replicate the real scenarios EDM components may face in both every day and more challenging environments, giving you peace of mind that our venting solutions are ready to meet the evolving needs of this EV component.

Contact Us today and discover how Donaldson’s venting solutions can help you achieve optimized EDM performance and protection.

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