Refrigeration Cycle

Abstract

Provided is a refrigeration cycle wherein, when an orifice is disposed within a refrigeration circuit, and a differential pressure between the upstream side and the downstream side of the orifice is detected using two pressure sensors, the difference between the characteristics of the pressure sensors can be adequately and easily absorbed in software, to accurately determine an actual differential pressure, so that the flow rate of refrigerant and the torque of a compressor can be accurately estimated. The refrigeration cycle wherein the orifice is provided within a refrigerant circuit, and the pressure sensors are respectively provided on the upstream side and the downstream side of the orifice, is characterized in that, with regard to output characteristics representing the relationship between the detected pressure and the sensor output of each pressure sensor, the difference between the output characteristics of one pressure sensor and the output characteristics of the other pressure sensor is determined based on the outputs of both pressure sensors at a condition where the flow of refrigerant is stopped.

1 . A refrigeration cycle wherein an orifice is provided within a refrigerant circuit, and pressure sensors are respectively provided on an upstream side and a downstream side of said orifice, characterized in that, with regard to output characteristics representing a relationship between a detected pressure and a sensor output of each of said pressure sensors, a difference in characteristics between output characteristics of one pressure sensor and output characteristics of the other pressure sensor is determined based on outputs of both pressure sensors at a condition where a flow of refrigerant is stopped. 
     
     
         2 . The refrigeration cycle according to  claim 1 , wherein a pressure calculation means, into which outputs of said pressure sensors are inputted, is provided, and in said pressure calculation means, based on said difference in characteristics determined, output characteristics of one pressure sensor is calibrated on the basis of output characteristics of the other pressure sensor. 
     
     
         3 . The refrigeration cycle according to  claim 2 , wherein, in a condition where refrigerant flows, using said output characteristics of said pressure sensor calibrated, a differential pressure between said upstream and downstream sides of said orifice is calculated from outputs of both pressure sensors. 
     
     
         4 . The refrigeration cycle according to  claim 3 , wherein, from said differential pressure calculated, a flow rate of refrigerant at that time is calculated referring to a predetermined relationship between a flow rate of refrigerant and a differential pressure between said upstream and downstream sides of said orifice. 
     
     
         5 . The refrigeration cycle according to  claim 4 , wherein, from said flow rate of refrigerant calculated, a torque of a compressor at that time is calculated referring to a predetermined relationship between a flow rate of refrigerant and a torque of said compressor in said refrigeration cycle. 
     
     
         6 . The refrigeration cycle according to  claim 5 , wherein a signal of said torque of said compressor calculated is sent to a control unit for a drive source of said compressor. 
     
     
         7 . The refrigeration cycle according to  claim 2 , wherein calibration of said output characteristics of said pressure sensor is carried out using a preset calculation equation having a correction term. 
     
     
         8 . The refrigeration cycle according to  claim 2 , wherein calibration of said output characteristics of said pressure sensor is carried out using a map preset with a plurality of output characteristics. 
     
     
         9 . The refrigeration cycle according to  claim 1 , wherein said difference in characteristics between output characteristics of said pressure sensors is determined after a predetermined time passes since said refrigeration cycle is stopped. 
     
     
         10 . The refrigeration cycle according to  claim 1 , wherein said refrigeration cycle is used for an air conditioning system for vehicles.