Pumps and filter assemblies

Abstract

A combined pump and filter assembly having backwashing apparatus for the filter assembly and apparatus for offsetting the tendency for an increase in pump output flow resistance.

1 . A combined pump and filter assembly comprising in flow series: 
 a) an inlet in communication with a source of fluid and arranged in use to admit a flow of fluid from said source,    b) a filter assembly which is adapted in use to filter the flow of fluid admitted through said inlet and to obstruct any debris entrained within the fluid    c) a main pump which is connected to a main pump drive,    d) a main outlet which is connected to the main pump and through which fluid admitted through the inlet and filter assembly is discharged by operation of the main pump as a main output flow,    the assembly also including a backwashing means which is supplied with a flow of backwashing fluid and which is arranged, in use, for backwashing the filter to in use remove any debris from the filter;    characterised in that the pump and filter assemblies are combined into a single unit, and that there is a backwashing pump which is arranged, in use, to supply backwashing fluid to the backwashing means, the backwashing pump and main pump are functionally connected so that in use the tendency for an increase in pump output flow resistance to cause an increase in fluid flow to the backwashing assembly is offset.    
     
     
         2 . A combined pump and filter assembly as claimed in  claim 1  in which the backwashing pump is drivingly connected to the main pump and drive.  
     
     
         3 . A combined pump and filter assembly as claimed in  claim 1  in which backwashing pump is drivingly connected to a backwashing drive which is separate to the main pump drive, the backwashing drive and main pump drive are connected to a control means which maintains a relationship between the outputs of the main pump and the backwashing pump and offsets the tendency for an increase in the main pump output resistance to cause an increase in fluid flow to the backwashing assembly  
     
     
         4 . A combined pump and filter assembly as claimed in any preceding claim in which an inlet to the backwashing pump is disposed on a suction side of the main pump so that in use the backwashing flow is drawn from the suction side of the main pump.  
     
     
         5 . A combined pump and filter assembly comprising backwashing means for the filter assembly and comprising means for offsetting the tendency for an increase in pump output flow resistance to cause an increase in fluid flow to the backwashing assembly.  
     
     
         6 . A combined pump and filter assembly as claimed in  claim 5  in which the means for offsetting the tendency for increased flow to the backwashing assembly to occur is provided by the use of dual pump means for the main pump output and the backwashing function.  
     
     
         7 . A combined pump and filter assembly as claimed in  claim 6  in which the dual pump means are drivingly connected to a common drive.  
     
     
         8 . A combined pump and filter assembly as claimed in  claim 7  in which the dual pump means are coaxially disposed and a shaft drivingly interconnects the dual pump means to a common drive means.  
     
     
         9 . A combined pump and filter assembly as claimed in  claim 6  in which each of the pumps of the dual pump means are drivingly connected to separate independent drive means, the independent drive means being connected to a control means which maintains a relationship between the outputs of the dual pump means and provides the means for offsetting the tendency for an increase in the main pump output resistance to cause an increase in fluid flow to the backwashing assembly.  
     
     
         10 . A combined pump and filter assembly as claimed in any preceding claim in which the pump and filter assembly are combined into a single unit.  
     
     
         11 . A combined pump and filter assembly as claimed in any preceding claim in which the filter assembly, and pump are arranged in flow series, the assembly comprising a main pump to provide a main outlet flow from a pressure side of the main pump, and the backwashing means being arranged so that a supply of fluid for the backwashing means is provided from a suction side of the main pump.  
     
     
         12 . A combined pump and filter assembly as claimed in any preceding claim in which means are provided to increase the backwashing flow in response to an increase in the pump output flow.  
     
     
         13 . A method of operating a pump which is adapted to drive a filter and backwashing assembly wherein dual output facilities are provided by said pump, the method including the step of arranging and operating the pump so that an increase in flow resistance in one output of the pump causes a less than a proportionate increase in fluid flow to the other output of the pump, the latter being the output adapted for the connection to the backwashing assembly.  
     
     
         14 . A method according to  claim 11  wherein said method of operating the pump comprises providing dual pumping means having at least a degree of independence of operation whereby a reduction in flow output from one portion of the pump due to flow resistance is accompanied by less than a proportionate corresponding increase in output of the other pump function.  
     
     
         15 . A method of operating a combined pump and filter assembly comprising a pump and filter assembly arranged in flow series and backwashing means for backwashing the filter assembly, the method including the step of arranging and operating the combined pump and filter assembly so that in response to an increase in output flow from the combined assembly a flow of fluid to the backwashing means is maintained at at least substantially the same level.  
     
     
         16 . A method as claimed in any one of  claims 10  to  12  in which in response to an increase in output flow from the pump a flow of fluid to the backwashing means is increased.