DC Vacuum pump Simscape model

Hello all, I am trying to model a small DC Vacuum pump(a DC motor with 3 small diaphragms attached on the pump side). Modelling the DC motor part was fairly easy but i am struggling with the pump part. As i am not a mechanical engineer, i do not know how to model the diaphragm action. If anyone of you could guide me in right direction, i'll be grateful.

Thanks in advance.

Parth