A recent design by Hansen in 1986 shows an elliptical
rotor with two rotor vanes and two stator vanes; each
vane is connected to a cam assembly as shown in
Figure 3 [13]. Rotor vanes are used to compress the
working fluid and are attached to a pin following in a pin
cam within the stator. Stator vanes are used to separate
the intake from the exhaust and are actuated via a cam
and pushrod arrangement, adding complexity to the
rotary design. Vane tip seals are shown and are similar
to the apex seals of the Wankel engine but with an
undersized pin to limit seal motion (so that the seal does
not fall out when a rotor vane and stator vane passes
each other). Springs are incorporated to push the seal
out during startup and the sealing system relies upon
gas pressure to assist in engaging the seal out during
normal operation.