Standard Ejectors

Sonijector offers a wide range of standard ejector designs, available with short lead times.

  • 15kW Class

    For small fuel cell systems such as forklifts, utility vehicles, light transit vehicles in city service, and residential backup power.

    The first ejector we built has been in service in the University of Delaware's Phase 1 fuel cell bus since 2010. It replaced a stainless steel and graphite vane pump that experienced frequent seizing and corrosion of the bearings. With all its wetted parts made of anodized aluminum, it has effectively resisted the corrosive effects of wet hydrogen.

  • 30kW Class

    For systems with higher demand—load-following cars and vans in city service, light transit vehicles in suburban service, and small/medium business backup power.

    This class was introduced for the University of Delaware's Phase 2 fuel cell bus, building on the success of the 15kW model. It introduced an improved coupling between the stepper motor and the needle, and a simplified control algorithm that reduced startup time.

  • 45kW Class

    For load-following powersports vehicles, full-sized transit buses, and more.

    This design was simply a scale-up of the 30kW class. It was introduced along with our latest electronic control module, which brought reduced cost and weight and the capability for underhood installation. It was first installed in the University of Delaware's Phase 3 fuel cell bus.

  • 100kW Class

    Our highest-capacity standard design. For load-following passenger cars operated on the highway, heavy duty over-the-road vehicles, and multifamily/data center backup power.

    The larger channels in this model allow it to develop increased pressure rise compared to the smaller models, or operate despite high inert gas loadings.

Custom Ejector Designs

If you have special requirements, our engineers will work with you to custom-tailor an ejector solution for your system. Different ports and mounting arrangements can easily be accommodated. For customers with system power ratings not covered by our standard designs, special flow conditions, or working fluids other than hydrogen, our computational fluid dynamics capabilities allow us to quickly determine suitable ejector geometry.

Electronic Controls

Ejector ECU rev 3

The latest version of the ejector ECU.

The Sonijector's electronic control unit was designed from the ground up to tolerate the EMI generated by inverter motor drives. The basic design has been in trouble-free service since the first ejector was installed in 2010.

The ejector ECU connects to the ejector's outlet pressure sensor, and receives a pressure command as a differential analog signal from the fuel cell system's ECU. It drives the ejector's stepper motor and provides two open-drain outputs that switch depending on output pressure error. They can be used to control the hydrogen inlet valve, providing a safety measure against overpressure in the event of mechanical failure, and ensuring bubble-tight hydrogen shutoff when stack current is near zero.

The present version of the ECU is packaged in a Deutsch IPD EEC-325X4B enclosure for IP67 environmental resistance, and can be installed underhood. The standard firmware flashed to the MCU allows for field reprogramming of control constants, so the dynamic response of the ejector can be optimized for each application's system volume and supply pressure. Firmware with fixed coefficients for production use can be supplied on request.


Customers with large volume requirements may be interested in licensing the ejector's mechanical design for manufacture, or the ejector control algorithm for incorporation into their own electronic control unit. Please contact us for details.