Patent Publication Number: US-2018038362-A1

Title: Valve plate with modified suction holes to increase refrigerant flow for compressor

Description:
BACKGROUND 
     In reference to Patent #15933, we have described a suction valve for closed-loop compressor which contains a number of suction holes. The suction and discharge processes of refrigerant are cycling in the refrigeration system. The refrigerant will be processed through suction and discharge holes of a valve plate connected to the top of cylinder. The suction holes are machined to make the rectangle valve plate having chambers, and the rim of chambers are perpendicular to the valve surfaces to which the surfaces are parallel. The surfaces of the valve plate are perpendicular with the outer rim of the plate. The valve plate contains two suction holes which their upper surfaces are designed to have smaller areas than the lower surface of the suction chambers with the partition of suction holes located in the middle of the two holes. 
     In reference to Patent#15933, the enlargement of the suction hole to improve the refrigerant flow rate would create a difficult machinery installation in a limited space, and to increase the stress at the suction valve during the valve opening and closing may lead to suction valve malfunction. In addition, minimizing the partition thickness between two suction holes in a limited space may harm the partition during the opening and closing of the suction valve. Therefore, the improvement of refrigerant flow rate is critically dependent to the size of the suction hole. 
     Thus, Patent#15933 has a weakness. The suction holes in the valve plate are machined to have chambers which are likely formed by tapering slope on the top of holes. The suction holes are machined through the rectangle valve plate, and their centerlines are perpendicular to the valve surfaces to which the surfaces are parallel. The surfaces of the vale plate are perpendicular with the outer rim of the plate. The chambers create connection between the suction holes. The surface area of the suction hole which is smaller than the lower surface of the chamber would create turbulent flow. The flow is impeded by the smaller surface area of the lower part of the chamber resulting in the deviation of flow pathway. This would result in suboptimal velocity, mass flow rate, and coefficient of discharge, which is an interesting area of improvement. 
     This new invention has two suction holes which have larger diameter at the top and smaller diameter at the bottom, in the incremental slope that has the beginning of the top edge angulate less than 90 degree with the center line of the hole. This slope will eliminate the friction loss of the refrigerant in the cylinder, which will result in an improvement of the refrigerant flow rate and the coefficient discharge. 
     The refrigerant will flows through the connection between the suction pipe and the first and the second holes. The height of partition between the holes is equal to the valve plate height (see detail in the full claim). 
     OBJECTS OF THE INVENTION 
     This valve plate modified to improve the refrigerant flow rate for a compressor has two suction holes and it is situated at the end of the cylinder and the suction valve. The two holes have larger diameter at the top and smaller at the bottom of the suction plate. The incremental slope of the holes from the top of the plate angulate with that of the bottom of the plate in less than 90 degree. The two holes have a standard shape with one semi-circular side and a linear shape on the other side. 
     The refrigerant flows through the connection between the suction pipe and the first and the second holes. The partition between the holes remains the same height as the valve plate height. 
     On the valve plate, there is also a discharge hole which is in line with the center of the partition between the first and the second holes. 
     This invention aims to improve the coefficient of discharge of the refrigerant at the suction holes, reduce the turbulent flow causing by from the smaller surface of the lower part of the chamber than that of the hole, and increase the flow velocity and mass flow rate. This would make a compressor working more efficiently. 
     FIELD OF INVENTION 
     An engineering related to the modified valve plate to improve the refrigerant flow rate for a compressor. 
     Complete Invention Description 
       FIG. 1  and  FIG. 2  show schematic view of the valve plate after the modification of the suction holes to increase the refrigerant flow rate in the compressor having a cylinder connected to the electric motor driven piston. The piston draws the refrigerant from the inlet, which has lower pressure, and compress the refrigerant out to the exit hole in order to increase the pressure and liquefy the refrigerant. The refrigerant is flowed through the suction and discharge holes on the valve plate ( 10 ) attached to the end of the cylinder. Any reduction of the suction friction would increase the refrigerant flow efficiency. 
     The valve plate ( 10 ) is composed of two suction holes ( 11 ,  12 ), both of which are placed at the tip of cylinder. The first and the second suction holes are machined to be a semi-circular shape chamber ( 20 ), which have larger diameter at the top ( 13 ) and smaller at the bottom ( 21 ), in the incremental slope that angulate less than 90 degree ( 23 ) with the center line of the hole ( FIG. 4 ). The first and second suction holes are characterized by standard semi-circular shape, which is composed of an arc ( 14 ) on one side and a linear plane ( 15 ) on the other side. The linear planes of both holes are positioned in parallel to each other. This tapering slope reduces the friction loss and improves the efficiency of refrigerant flow into the suction hole. This will result in improved compression efficiency through better coefficient of discharge. The partition ( 16 ) has the same height as the valve plate ( 10 ), which indicates excellent strength. At the valve plate ( 10 ), there is a discharge hole ( 19 ), positioned in the same alignment as the partition ( 16 ) between the first ( 11 ) and second ( 12 ) suction holes. 
       FIG. 3  and  FIG. 4  show the cross section view of the valve plate ( 10 ) that is machined to have semi-circular chambers ( 20 ) with tapering slope, as previously mentioned (See above). 
       FIG. 5  shows the assembly of the valve plate ( 10 ) with the suction pipe ( 18 ), where the center of the suction pipe ( 18 ) is aligned to the suction partition ( 16 ) between the first ( 11 ) and the second ( 12 ) holes. The opening of the suction pipe ( 18 ) is positioned oppositely to the valve plate ( 10 ). On that opposite side, the suction holes are machined as sloped semi-circular chambers ( 20 ) to reduce the suction friction and make refrigerant flow through the cylinder effectively. 
       FIG. 6  illustrates the simulation of refrigerant flowing through the first ( 11 ) and second ( 12 ) holes. The outer radius of the refrigerant flow is magnified by the tapering slope ( 20 ) following the surface area of the valve plate ( 10 ). This indicates that it is designed to efficiently utilize the valve ( 10 ) surface area. This figure demonstrates the greater coefficient of discharge and flow velocity due to the reduced turbulence from the effect of tapering slope. The reduction of the turbulence will lead to better compression efficiency. 
       FIG. 7  demonstrates a result comparison between the valve plate ( 10 ) of this invention and the original valve plate, conducted by Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Thailand. The graph shows the lower turbulent energy of this model compared to the original model showing that the chance to have turbulent of the modified valve plate is lower than the original model. 
       FIG. 8  shows a table of the same study conducted by Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Thailand. The results showed that the modified valve plate had a better performance, particularly in the increased coefficient of discharge by 4.37%, resulting in a greater refrigerant flow. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  and  FIG. 2  show the schematic view of the valve plate after modified to increase refrigerant flow rate of the compressor. 
         FIG. 3  and  FIG. 4  show the cross-section view of the modified valve plate ( 10 ) 
         FIG. 5  shows the assembly of the valve plate ( 10 ) with the suction pipe ( 18 ) of the closed loop compressor. 
         FIG. 6  shows the simulation of the refrigerant flow 
         FIG. 7  shows a graph result of a study by the Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Thailand. This comparison demonstrates the lower turbulent energy of the improved model compared to the original model. 
         FIG. 8  shows a table result of a study by the Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Thailand. This comparison demonstrates that the improved model has more efficient to the original model. 
     
    
    
     BEST INVENTION METHODOLOGY 
     See narrative details in Complete Invention Description section.