Patent GB-998364-A (GB)
Title: Improvements in or relating to room ventilators
IPC: F24F11/76
Filed: 1962-11-08
Abstract: 998,364. Air conditioning units. AMERICAN AIR FILTER CO. Inc. Nov. 8, 1962 [Nov. 10, 1961], No. 42271/62. Heading F4V. In a unit air conditioner air from damper controlled room air and fresh air inlets 12 and 14 passes through a filter 18 and is apportioned by a set of dampers 20 between a cooling passage 22 containing a cooling coil 28 having a condensate drip pan 32 and a heating passage 24 containing a heating coil 30, the dampers 20 being controlled by a room thermostat. The air inlet dampers comprise two dampers 40 linked to move together and control the fresh air flow and a counterbalanced damper 38 controls the admission of room air to the unit. The air inlet dampers are operated by a rod 48 connected through a bell-crank 50 and links 54, 56 and 58 to the dampers 40 and through further links 62 and 64 having slotted connections to the room air damper 38, the arrangement being such that as the dampers 40 open, the damper 38 closes and vice versa. Dampers 44 control the air flow through the cooling passage 22 and a damper 42 controls the flow through the heating passage 24, these dampers being operated by a rod 66 through a bellcrank 68 and links 70, 72, 74, 76 such that when the heating passage damper 42 is open the cooling passage dampers 44 are closed and vice versa. The above described components, apart from the damper operating mechanism, are housed in a central compartment of the ventilator separated by two walls, Fig. 2 (not shown), in which the various damper shafts 46 are journalled from end compartments housing the damper operating mechanism; the motor for two fans 34, piping connections, and automatic temperature control components. A pneumatic control system for the dampers is shown in Fig. 5. The heating and cooling passage dampers are controlled by a unit 82 supplied with air through a main line 78 including a room thermostat 80 which passes increasing pressure with increasing room temperature and vice versa. The unit 82 and the thermostat 80 are so arranged that a temperature of 2 degrees below the required room temperature corresponds to a supply pressure of 3 p.s.i. and a temperature 2 degrees above the required temperature corresponds to a pressure of 9 p.s.i. and between these two pressures the unit 82 moves the dampers 42 and 44 from fully open to fully closed (Fig. 7) and outside this pressure range the dampers are retained fully open or closed. A valve 84 in the position shown in Fig. 5 connects a unit 86 operating the air inlet dampers with the main air supply line. The unit 86 is arranged to operate the fresh air and room air dampers in accordance with air supply pressure in response to the room thermostat 80 as shown in Fig. 6. Thus, outside the range of required room temperature 2 degrees control of the temperature of air supplied to the room is by means of adjustment of the air inlet dampers while for the greater part of the range between these temperatures the air inlet dampers are at constant settings. In winter the operating arrangement is as above, with a heating medium supplied to the heating coil 30 but no cooling medium supplied to the cooling coil 28 so that any cooling function is carried out solely by the admission of fresh air. During hot weather a cooling medium only is circulated and an outdoor air thermostat responds to temperatures above a given value and actuates a relay 92 which turns the valve 84 90 degrees anticlockwise so that the air inlet damper operating unit 86 communicates with a constant 3 p.s.i. air line 88 so that the air inlet dampers 38 and 40 are at constant settings and temperature is controlled solely by the heating and cooling passage dampers 42 and 40 in response to the room thermostat 80. In modifications, both the heating and cooling coils may be supplied with heat exchange media, the control system may be electric or electronic, the supply of the heating medium may be valve controlled in response to a thermostat, the heating medium temperature may be reset in accordance with outside air temperatures and a cam linkage may be used to operate all the dampers 38, 40, 42 and 44 from a single operating unit. Specification 998,363 is referred to.