Background tank fill based on refrigerant composition

Abstract

A portable recovery unit for automatically filling a background tank of blended refrigerant includes a main tank for holding recovered refrigerant from a vehicle A/C system which has a first chemical composition, and an auxiliary tank for holding an auxiliary supply of fresh refrigerant which has a second refrigerant composition. The auxiliary tank is arranged in fluid communication with the main tank so that fluid can be transferred from the auxiliary tank to the main tank. An electronic controller controls the flow of fluid from the auxiliary tank to the main tank. A refrigerant identifier is coupled to the main tank to sample and analyze the refrigerant in the main tank in order to determine the chemical composition of the refrigerant in the main tank, so the refrigerant in the main tank can be purified to an acceptable level based on that analysis.

What is claimed is: 
     
         1 . A method for using a refrigerant recovery unit, comprising:
 determining if a predetermined amount of time has passed since a recovery of a first refrigerant from a refrigerant system has occurred;   detecting an amount of a second refrigerant in a first refrigerant tank with a scale of the refrigerant recovery unit;   detecting a chemical composition of the second refrigerant in the first refrigerant tank with a composition analyzing device;   comparing the amount and composition of the second refrigerant to a target amount and composition range with a processor of the refrigerant recovery unit; and   adding a third refrigerant to the first refrigerant tank if the amount or composition of the refrigerant is outside the target amount or composition range.   
     
     
         2 . The method according to  claim 1 , wherein the detecting is done by weighing the second refrigerant. 
     
     
         3 . The method according to  claim 1 , further comprising continuously analyzing the chemical composition of the second refrigerant. 
     
     
         4 . The method according to  claim 2 , wherein the third refrigerant is stored in a second refrigerant tank in the refrigerant recovery unit. 
     
     
         5 . The method according to  claim 1 , further comprising placing the refrigerant recovery unit in a normal unit operation status when the predetermined amount of time has passed since the recovery is less than five minutes. 
     
     
         6 . The method according to  claim 1 , further comprising analyzing the chemical composition of the second refrigerant at discrete time intervals. 
     
     
         7 . The method of  claim 1  further comprising determining, with a sensor, if the second refrigerant tank is in a vacuum state. 
     
     
         8 . The method of  claim 7 , wherein if the second refrigerant tank is in the vacuum state, then a prompt is displayed on a display of the refrigerant recovery unit for a user to replace the second refrigerant tank. 
     
     
         9 . A refrigerant recovery unit, comprising:
 a composition analyzing device that analyzes a chemical composition of a first refrigerant contained in a refrigerant container;   a controller that receives a signal about the chemical composition of the first refrigerant from the composition analyzing device;   a scale that receives the refrigerant container and weighs an amount of the first refrigerant in the refrigerant container;   a display that displays an operational status of the refrigerant recovery unit; and   a valve and conduit system that selectively place the first refrigerant in fluid communication with a second refrigerant contained in an auxiliary tank, wherein the valve and conduit system is operatively connected to the controller that allows a certain amount of the first refrigerant to mix with the second refrigerant in the refrigerant container until a predetermined chemical composition is achieved.   
     
     
         10 . The refrigerant recovery unit of  claim 9 , wherein the composition analyzing device continuously monitors the chemical composition in the refrigerant container. 
     
     
         11 . The refrigerant recovery unit of  claim 9 , wherein the controller adds the second refrigerant when the chemical composition of the first refrigerant is below a predetermined purity level. 
     
     
         12 . The refrigerant recovery unit of  claim 9 , wherein the composition analyzing device monitors the chemical composition in the refrigerant container at discrete time intervals. 
     
     
         13 . The refrigerant recovery unit of  claim 9 , wherein the scale sends the weight of the refrigerant container to the controller. 
     
     
         14 . The refrigerant recovery unit of  claim 13 , wherein the controller further allows certain amount of the first refrigerant to mix with the second refrigerant in the refrigerant container until a predetermined weight is achieved. 
     
     
         15 . The refrigerant recovery unit of  claim 9 , wherein the display displays a prompt to replace the auxiliary tank if a vacuum is detected on auxiliary tank.