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System and method for controlling compressor flowSystem and method for controlling compressor flow description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080019842, System and method for controlling compressor flow. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001]The present invention relates to heating and cooling systems. More particularly, the present invention relates to controlling flow through a compressor. [0002]In typical aircraft cabin heating and air conditioning systems, the air used to heat or cool the cabin originates from the compressor stages in the engines of the aircraft. In particular, two streams of air are usually diverted away from the engine and into the temperature control system. In one common system, a modulation valve is used to pull a low stage stream of air and a high stage stream of air into the system. Because the temperature control system is at a different pressure than the low stage and high stage streams of air, the two streams flow into the temperature control system without the use of a fan or similar air device capable of inducing flow. The first, low stage stream of air is pulled off of the engine at a location where the air is at a low pressure and low temperature. The second, high stage stream of air is pulled off of the engine at a second location where the air is at a high pressure and high temperature. The low and high stage streams of air are then mixed together in varying proportions to obtain a desired air mixture, which is then distributed through the temperature control system and into the cabin of the aircraft. [0003]Many newer aircraft cabin heating and air conditioning systems include air cycle machines. In these types of systems, outside air is pulled into the aircraft and provided to the air cycle machines where it is used as a refrigerant. In order to provide proper temperature control within the aircraft, the flow rate of air provided to the air cycle machines must be monitored and controlled. Thus, there exists a need for a system that is capable of determining and controlling flow through a compressor. BRIEF SUMMARY [0004]The present invention is a system for controlling air flow comprising an inlet, a first compressor, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a first controller. The inlet is configured to direct a first stream of air into the system. The first compressor is configured to pull in the first stream of air through the inlet and compress the first stream of air. The first pressure sensor senses a first pressure of the first stream of air prior to compression in the first compressor, the second pressure sensor senses a second pressure of the first stream of air after compression in the first compressor, and the first temperature sensor senses a temperature of the first stream of air after compression in the first compressor. The controller adjusts speed of the first compressor based upon a comparison between a desired flow rate and a calculated flow rate. BRIEF DESCRIPTION OF THE DRAWINGS [0005]FIG. 1 is a schematic cross-sectional view of a commercial aircraft. [0006]FIG. 2 is a schematic diagram of one embodiment of a temperature control system. [0007]FIG. 3 is a schematic diagram of a flow control system according to the present invention having one air supply circuit. [0008]FIG. 4 is a schematic diagram of a flow control system according to the present invention having a pair of air supply circuits. [0009]FIG. 5 is a process flow diagram of a method for calculating compressor flow. [0010]FIG. 6 is a bi-variant graph depicting a corrected flow characteristic. [0011]FIG. 7 is a process flow diagram of a method for adjusting compressor flow rate as a function of a compressor speed reference. DETAILED DESCRIPTION [0012]A high level schematic cross-sectional view of commercial aircraft 10 is shown in FIG. 1. Aircraft 10 includes cargo area 12, electronics power bay 14, temperature control system 16, cabin area 18, flow control system 20, and outflow valve 22. Cargo area 12 is located within the lower portion of aircraft 10. Cargo area 12 typically serves as storage for passenger luggage, but it may also include one or more power electronics power bays 14 housing various electronic components used in the control and operation of aircraft 10. As shown in FIG. 1, temperature control system 16 is also located within the lower portion of aircraft 10, and is configured to provide temperature conditioned air to cabin area 18 for passenger comfort and safety. Temperature control system 16 typically includes one or more air conditioning packs ("packs"), which are typically air cycle machines that use air as a refrigerant. [0013]Temperature control system 16 is supplied with pressurized outside (fresh) air from flow control system 20 to allow temperature control system 16 to condition fresh air for cabin heating and cooling. Thus, flow control system 20 controls the amount of outside air pulled into aircraft 10 for use in temperature control system 16. Supplying the proper amount of outside air to temperature control system 16 is critical to the comfort and safety of passengers within cabin 18. If too much outside air is pulled into temperature control system 16, there is a risk that very hot, high pressure air will be distributed into cabin 18. On the other hand, if too little outside air is pulled into temperature control system 16, there is a risk that very cold, low pressure air will be distributed into cabin 18. Moreover, the Federal Aviation Administration (FAA) has strict guidelines pertaining to the amount of air that must be circulated through a cabin during a flight. For example, in one common model of passenger aircraft, the FAA has dictated that 0.55 pounds per minute per occupant must be circulated through the cabin. As a result, it is important that flow control system 20 accurately control the flow of outside air it supplies to temperature control system 16. [0014]After leaving temperature control system 16, the conditioned air is circulated through cabin 18 and redirected back to the lower portion of aircraft 10 where a portion of the air is exhausted through outflow valve 22 to the outside environment. The remaining portion of the air is recirculated back to temperature control system 16, where it mixes with a new batch of outside air pulled in through flow control system 20 and delivered to temperature control system 16. In typical aircraft temperature control systems, the ratio of recirculated air to new, outside air is approximately one-to-one. [0015]FIG. 2 is a schematic diagram of one embodiment of temperature control system 16. In FIG. 2, flow control system 20 pulls in and controls the flow of air into temperature control system 16. Temperature control system 16 includes primary heat exchanger 30, dual turbine air cycle machine (ACM) 32, secondary heat exchanger 34, condenser 36, and water collector 38. Dual turbine ACM 32 includes compressor 40, first stage turbine 42, and second stage turbine 44. [0016]The stream of compressed air enters temperature control system 16 and is cooled in primary heat exchanger 30 using ram air as a heat sink. The stream of compressed air is then further compressed by compressor 40 of dual turbine ACM 32 and subsequently ported to secondary heat exchanger 34. In secondary heat exchanger 34, the heat of compression resulting from compression within compressor 40 is removed, again using a source of ram air as the heat sink. The compressed air from secondary heat exchanger 34 is then routed to condenser 36 where it is subcooled using cold exhaust air from first stage turbine 42 as the heat sink. This cooling process condenses water from the air to permit it to be collected by water collector 38. The collected water in water collector 38 may subsequently be directed to secondary heat exchanger 34 to enhance heat exchanger performance through evaporative cooling. [0017]After exiting water collector 38, the air flows to first stage turbine 42. After expansion within first stage turbine 42, the air passes through a cold side portion of condenser 36 where it serves as the heat sink for condensation as described above. After regaining the heat of condensation and exiting the cold side of condenser 36, the air enters second stage turbine 44 of dual turbine ACM 32 where it is further expanded and routed to air distribution system 46 to provide a cold air source for cabin cooling. [0018]FIG. 3 is a schematic diagram of flow control system 20A having first air supply circuit 48A. As shown in FIG. 3, first air supply circuit 48A includes inlet 50, first motor controller 51, first pressure sensor 52, first compressor 54, second pressure sensor 56, and first temperature sensor 58. [0019]In a preferred embodiment, first compressor 54 is an electric compressor that includes a plurality of rotating compressor blades, and first motor controller 51 is configured to control the speed of the rotating compressor blades. Since the speed of rotating compressor blades is directly related to the flow initiated by an electric compressor, first motor controller 51 may control the flow through first compressor 54 by controlling the speed of the rotating compressor blades. This relationship between compressor speed and flow is commonly referred to as a "speed reference." [0020]The compressor blade speed directed by first motor controller 51 at any moment in time is determined based upon a "required flow rate" communicated to flow control system 20A by temperature control system 16. The required flow rate may vary with time and is a function of, among other things, the altitude of aircraft 10. Continue reading about System and method for controlling compressor flow... Full patent description for System and method for controlling compressor flow Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this System and method for controlling compressor flow patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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