Pressure balancing accumulator

Abstract

An accumulator and associated method substantially reduces if not eliminates a bump energy event associated with the use of a U-tube. A bypass or pressure equalizing passage is provided between upper portions of a U-shape return tube for reducing the pressure difference on opposite sides of any accumulated liquid refrigerant in the bottom of the U-tube upon compressor start-up. This prevents or substantially prevents the liquid “slug” from entering the suction line leading to the compressor. The diameter of the U-tube in the lower region of the accumulator's canister is reduced relative to the diameter of the upper portions of the return tube, thereby reducing the volume of liquid refrigerant that can accumulate in the return tube. The reduction also increases the flow velocity of the gas phase refrigerant for improving oil recirculation.

1 . An accumulator for a refrigerant that circulates in a closed-loop refrigeration system, comprising 
 a closed container having an inlet for receiving refrigerant in mixed liquid/gas phase from an evaporator such that the gas phase will accumulate in an upper region of the container and refrigerant in the liquid phase will accumulate in a lower region of the container;    a return conduit in said container, said return conduit having an inlet portion, an outlet portion, and a lower U-shape portion connecting the inlet portion to the outlet portion, the inlet portion having an inlet end opening to the upper region of the container for drawing gas phase refrigerant into the return conduit, the outlet portion terminating at an outlet connectable to a suction line leading to a compressor of the closed-loop system, and the U-shape portion having a metering device communicating with the lower region of the container for drawing lubricant bearing liquid refrigerant into the return conduit so as to be entrained in the gas phase refrigerant flowing therethrough for lubrication of the compressor; and    a bypass passage for supplying gas phase refrigerant from the upper region of the container to the outlet portion without passage through the U-shape portion, whereby suction at the outlet of the outlet portion draws gas phase refrigerant through both the U-shape portion and the bypass passage.    
   
   
       2 . An accumulator according to  claim 1 , wherein the U-shape portion has a minimum cross-sectional area less than the minimum cross-sectional area of the outlet portion adjacent but downstream of the bypass passage.  
   
   
       3 . An accumulator according to  claim 2 , wherein the U-shape portion has a minimum cross-sectional area less than the minimum cross-sectional area of the inlet portion.  
   
   
       4 . An accumulator according to  claim 1 , wherein the U-shape portion over the length thereof has a reduced cross-sectional area less than the cross-sectional areas of the outlet and inlet portions, whereby the volume of liquid phase refrigerant that may migrate into the U-shape portion through the metering device and assume the level of liquid phase refrigerant in the container will be less than the volume if the U-shape portion had the same cross-sectional areas as the outlet and inlet portions.  
   
   
       5 . An accumulator according to  claim 1 , wherein the return conduit over the portion thereof located in a lower half of the container has a cross-sectional area less than the cross-sectional area of at least one of the inlet and outlet portions located in an upper half of the container.  
   
   
       6 . An accumulator according to  claim 1 , wherein the bypass passage is formed by a connection tube connected between the outlet portion of the return conduit and the inlet portion of the return conduit at a location above the U-shape portion, whereby the connection tube communicates with the upper region of the container via the inlet portion of the return conduit.  
   
   
       7 . An accumulator according to  claim 6 , wherein the inlet portion has a minimum cross-sectional area at least equal the combined minimum cross- sectional areas of the bypass passage and U-shape portion.  
   
   
       8 . An accumulator according to  claim 6 , wherein the connection tube is substantially perpendicular to one or both of the inlet and outlet portions of the return conduit.  
   
   
       9 . An accumulator according to claims  1 , wherein the bypass passage is formed by a bypass inlet tube connected at a downstream end to the outlet portion of the return conduit and having an upstream end opening to the upper region of the container.  
   
   
       10 . An accumulator according to  claim 1 , wherein return conduit is formed by a tube, and the bypass passage is formed by a hole in a wall of the outlet portion of the tube, which hole is located in the upper region of the container.  
   
   
       11 . An accumulator according to  claim 1 , wherein the container has a top wall, and the outlet portion of the return conduit exits the container through the top wall of the container.  
   
   
       12 . An accumulator according to  claim 1 , wherein the return conduit is formed by a tube.  
   
   
       13 . An accumulator for a refrigerant that circulates in a closed-loop refrigeration system, comprising 
 a closed container having an inlet for receiving refrigerant in mixed liquid/gas phase from an evaporator such that gas phase refrigerant will accumulate in an upper region of the container and liquid phase refrigerant will accumulate in a lower region of the container;    an outlet connectable to a suction line leading to a compressor of the closed- loop system; and    a dual flow conduit assembly connected to the outlet for drawing to the outlet gas phase refrigerant from the upper region of the container along first and second conduits, and the first conduit has a U-shape portion having a metering device communicating with the lower region of the container for drawing lubricant bearing liquid refrigerant into the first conduit so as to be entrained in the gas phase refrigerant passing therethrough for lubrication of the compressor.    
   
   
       14 . An accumulator according to  claim 13 , wherein the U-shape portion has along the length thereof a reduced cross-sectional area less than the cross-sectional area of the outlet to which the first and second flow paths connect.  
   
   
       15 . An accumulator according to  claim 13 , wherein the U-shape portion extends between a vertical inlet portion of the first conduit and a vertical outlet portion of the first conduit.  
   
   
       16 . An accumulator according to  claim 13 , wherein the second conduit has a vertical inlet portion opening to the upper region of the container, a horizontal outlet portion, and a curved portion extending between the vertical inlet and horizontal outlet portions of the second conduit.  
   
   
       17 . An accumulator according to  claim 16 , wherein the U-shape portion extends between a vertical inlet portion of the first conduit and a vertical outlet portion of the first conduit.  
   
   
       18 . An accumulator according to  claim 17 , wherein the vertical outlet portion of the first conduit is connected to the horizontal outlet portion of the second conduit.  
   
   
       19 . An accumulator according to  claim 13 , wherein the horizontal outlet portion is located in the upper region of the container and has at an underside thereof a drain opening for allowing any accumulated liquid phase refrigerant to drain out of the horizontal portion of the second conduit.  
   
   
       20 . An accumulator according to  claim 13 , wherein the second conduit has a U-shape portion with a bottom thereof located at a higher level in the container than a bottom of the U-shape portion of the first conduit, and the U-shape portion has at the bottom thereof a drain opening for allowing any accumulated liquid phase refrigerant to drain out of the horizontal portion of the second conduit.  
   
   
       21 . A method for separating liquid phase refrigerant from a mixed liquid/gas phase refrigerant flowing from an evaporator in a closed-loop refrigeration system, comprising the steps of directing the mixed liquid/gas phase refrigerant into a container that has an outlet connected to a compressor of the refrigeration system, and using a dual flow conduit assembly connected to the outlet for drawing to the outlet gas phase refrigerant from the upper region of the container along first and second conduits, wherein the first conduit has a U-shape portion having a metering device communicating with the lower region of the container for drawing lubricant bearing liquid refrigerant into the first conduit so as to be entrained in the gas phase refrigerant passing therethrough for lubrication of the compressor.