Air conditioning systems

• US 3,913,833 A
• Filed: 09/15/1972
• Issued: 10/21/1975
• Est. Priority Date: 09/21/1971
• Status: Expired due to Term

• Current Assignee: Hymatic Engineering Co. Ltd. (Garrett Motion, Inc.)
• Original Assignee: Gordon Horsford Stockwell, Herbert Hargrave Basil Minett
• Inventors: Minett, Herbert Hargrave Basil, Stockwell, Gordon Horsford
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US05/289,338
• Time in Patent Office: 1,131 Days
• Field of Search: 137/805,804,821,826,828 236/13,49,76,78,609,610 91/3 318/601 251/133,138 73/357,339A,362AR 235/151.1,151.12 60/39.28T
• US Class Current: 236/49.3
• CPC Class Codes: B60H 1/00007 Combined heating, ventilating, or cooling devices control systems or mechanisms B60H1/00642
• CPC Class Codes: B64D 13/00 Arrangements or adaptations of air-treatment apparatus for aircraft crew or passengers, or freight space , or structural parts of the aircraft treatment rooms with artificial climate for medical purposes A61G10/02; respiratory apparatus in general A62B; for vehicles in general B60H
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 2110/40 Pressure, e.g. wind pressure
• CPC Class Codes: F24F 2203/023 with turbine used for expansion
• CPC Class Codes: G05D 23/185 with auxiliary non-electric power
• CPC Class Codes: Y10T 137/2071 And causing change or correction of sensed condition

Abstract

An air conditioning system, especially for aircraft cabins, has a temperature control loop incorporating a signal processing control stage, in the form of a pulse logic network, to derive, from the difference or error signal received from a comparator, a control output signal suitable for driving a regulating motor to change the air flow conditions in a fresh air duct supplying the cabin. The cabin temperature is advantageously sensed by a resonant tube acoustic device delivering a pneumatic pressure oscillating output which is compared with a reference pulse frequency in fluidic logic of the comparator to derive a pulse frequency representing the difference or error. The control stage in turn derives from the error pulse frequency the regulator driving output, which is advantageously a polyphase output driving a stepping motor.

Claims

1. An air conditioning system for controlling the air supply to an enclosure comprising:

temperature-responsive means responsive to the air temperature in the enclosure and delivering a first variable pulse train signal wherein the number of pulses occurring in unit time represents the actual temperature in said enclosure;

reference signal-generating means delivering a second pulse train signal wherein the number of pulses occurring in unit time represents a desired temperature for said enclosure;

a digital comparator receiving said first and second pulse train signals and having first and second output channels, the comparator being operative to deliver output pulses the number of which occurring in unit time represents the difference between actual temperature and desired temperature, said output pulses appearing on said first output channel if the frequency of pulses in said actual temperature signal pulse train exceeds the frequency of pulses in said reference signal pulse train, said output pulses appearing on said second signal channel if the frequency of pulses in said reference signal pulse train exceeds the frequency of pulses in said actual temperature signal pulse train;

a digital logic network receiving and processing the output pulses on said first and second output channels from said digital comparator, said logic network having at least three phase channels operative in response to said output pulses to deliver processed pulses sequentially in said channels at a rate proportional to the pulse frequency of said output pulses received from the comparator, said processed pulses being delivered by said phase channels in one sequence if the comparator output pulses appear on its first comparator output channel and in the reverse sequence if the comparator pulses appear on its second output channel;

a fluid flow control valve controlling flow of air in a duct leading to said enclosure;

a digital valve actuator operative to change the position of said valve by moving it through a discrete increment in response to each processed pulse delivered thereto on said at least three phase channels by said digital logic network, said actuator operating at a speed determined by the rate of delivery of said processed pulses on said phase channels and in one direction or the reverse direction according to whether the pulses applied to said phase channels are in said one sequence or said reverse sequence.

2. A system according to claim 1, wherein the digital logic network comprises fluidic logic components.

3. A system according to claim 1, wherein the comparator comprises fluidic logic components.

4. A system according to claim 1, wherein the comparator receives a first pneumatic pulse signal from the temperature responsive means having a pulse frequency representative of the temperature being monitored, and a second pneumatic pulse signal from said reference signal generating means having a pulse frequency representative of said desired temperature, and delivers its output in the form of a pneumatiC pulse train on one of said first and second channels.

5. A systemm according to claim 1, wherein the temperature responsive means is an acoustic device comprising a resonant tube delivering a pneumatic pressure output that oscillates at a frequency representative of the temperature being monitored.

6. A system according to claim 1, wherein the valve actuator is a pneumatically-operated stepping motor.