The SBGM QM2 project was dedicated to the full qualification of the Sealed Brushed Gear Motor (SBGM) in accordance to the ECSS standards. The development was driven by requirements issued by Thales Alenia Space, which target for a solar array deployment actuator which is not affected by US Export Control. Generally, the development of the SBGM was driven by the following key requirements:
・ No components affected by US Export Control,
・ Simple and robust,
・ Cost efficient,
・ No complex electronics required like e.g. for stepper motors,
・ Standardised product to be used for different platforms with minor adaptations only.
As one of the main project challenges, the requested compliance to the ECSS Motorisation Factor (MF) has to be mentioned. The qualification tests have shown successful results. The MF values are always above the required factor of 2 at ambient and hot. In cold the MF values almost reached the factor of 2 without the support from the available thermal heating system.
When operated under vacuum in space, brushed DC motors commonly show problematic behaviour with regard to reliability. The presented actuator solves issues like the generation of debris from the brushes, arcing, and an unstable and high brush friction by the use of a hermetically sealed housing that contains its own atmosphere. Due to the low leak rate, the internal pressure is kept at a sufficient level for more than 50 years in orbit. Torque is transferred from the motor to the gear by means of a magnetic hysteresis coupler. A special characteristic of this coupler is its ability to not only limit the transferred torque but also to maintain the adjusted torque during slippage. Depending on the customers specification, the coupler torque can be adjusted. The high end multi stage gear box provides the requested output torque at the spline shaft junction interface.
See SBGM product Data Sheet.
The SBGM actuator consists of a sealed motor with a planetary gear head attached. The torque is transferred from the motor to the gear by means of a magnetic hysteresis coupler. Optionally the SBGM can be equipped with a thermal heating system consisting of redundant heaters mounted on motor and gear box and a thermistor on the motor.
The development of the SBGM was following the guidelines given in the ECSS specifications, tailored to the particular needs for the development of the SBGM. The driving philosophy for the development was to verify compliance of the design with the specifications, and to achieve the required functions and performances with max. reliability. The overall development program of the SBGM was separated into three phases (SBGM EM, SBGM QM1 and SBGM QM2) with a subsequent phase of the production of recurring flight models.
The SBGM QM2 has been qualified successfully in accordance to the ECSS standards and the final phase three of the SBGM project is about to be closed. The production of first SBGM Fight Model for the launch customer has been initiated and the product is available for the market.