Greenhouse Automation - Vent Controller

	Greenhouse manually-operated roof vents

The Vent Controller drive unit (green enclosures mounted at the side of each vent opening in the picture at right) contains a geared motor that rotates an actuator shaft through 25 degrees of arc. The actuator shaft is fitted with two lifting arms, ending in grooved bearings that travel in slotted guides mounted at each side of the vent lid. When the actuator shaft rotates, the arms lift or lower the vent lid, according to the commanded action from the centralized environment management system. The two lifting arm guides at the edge of the vent lid provide the bilateral attachments necessary to dampen wobbling of the lid in strong wind. When closed, the guides and arms provide a firm, even closure to minimize air gaps around the vent frame.

A side view of the drive unit and actuator is shown below on the left and a straight-on view is shown on the right.

Vent Controller drive unit and actuator, side view	Vent Controller drive unit and actuator, straight-on view

As described in the System Architecture section, each controller is provided with 12 V DC power and two communication wires through a connecting cable (in the case of the prototypes, 18 gauge thermostat cable—readily seen in the pictures above).

The device circuit board and geared motor are housed in a custom 3-D printed ABS plastic enclosure (shown in the pictures below). The range of motion of the actuator shaft is determined by a cam and limit switch (see picture below on left). The controller includes current limiting provisions to protect the geared motor and other components in the case of stall situations.

Vent Controller enclosure	Vent Controller enclosure, top removed

Continue to Fan Controller

This page last revised on 05/05/2018