Fluid metering device

Abstract

A fluid metering device mixes a predetermined quantity of a first fluid with a larger quantity of second fluid supplied to the device at a higher pressure on each cycle. The pressure of the second fluid provides the force necessary to motivate a first pumping means which on movement to an `outlet` position within a housing displaces the mixed fluids on an outlet side of the first pumping means to their destination. Movement of the first pumping means actuates a second pumping means which pumps a predetermined quantity of the first fluid into the housing on each cycle. On the maximum pumping stroke of the first pumping means being reached at the `outlet` position, a passage is opened in the first pumping means which is then restored to an `inlet` position, the second fluid in the housing passing through the passage during such restoration and thus being available for dispatch on the next pumping stroke. When the first pumping means reaches the `inlet` position the passage closes and a further pumping cycle commences.

What I claim is: 
     
       1. A fluid metering device comprising; a. a housing with a hollow interior   b. first and second fluid inlets into said hollow interior for first and second fluids respectively   c. a fluid outlet from said hollow interior   d. first pumping means within said hollow interior and displaceable under fluid pressure between said second fluid inlet and said fluid outlet from an `inlet` position to an `outlet` position to pump mixed first and second fluids through said fluid outlet   e. biasing means tending to retain or restore said first pumping means at or to said `inlet` position in use   f. a passage communicating between said second fluid inlet and said fluid outlet   g. closure means adapted to close said passage at said `inlet` position and also during displacement of said first pumping means, under fluid pressure, from said `inlet` position to said `outlet` position and to open said passage at said `outlet` position and also during movement of said first pumping means from said `outlet` position to said `inlet` position and   h. second pumping means actuated on movement of said first pumping means to cause a predetermined quantity of said first fluid to enter said hollow interior through said first fluid inlet on each cycle of said first pumping means.   
     
     
       2. A fluid metering device as claimed in claim 1 wherein said closure means comprises a closure member within said hollow interior and said closure member moves with but is displaceable relative to said first pumping means; and stop means coacting between said closure member and said first pumping means and adapted to limit such relative displacement so that said passage is closed on maximum relative displacement in one direction and opened on displacement in the reverse direction. 
     
     
       3. A fluid metering device as claimed in claim 2 wherein engagement means are provided to alter the relative speed of said closure member and said first pumping means at said `outlet` position. 
     
     
       4. A fluid metering device as claimed in claim 3 wherein said closure member has a ratio of thrust surface presented to said second fluid inlet at said `inlet` position to biasing force tending in use to retain or restore said closure member at or to said `inlet` position which exceeds that of said first pumping means. 
     
     
       5. A fluid metering device as claimed in claim 4 wherein said engagement means is elastic so that on the point of opening of said passage and equalisation of the fluid pressure on said closure member and said first pumping means, the recoil causes a sudden speed difference to be imparted between said closure member and said first pumping means. 
     
     
       6. A fluid metering device as claimed in claim 5 wherein said second pumping means includes a chamber interposed in said first fluid inlet and first and second one way valve means, said chamber communicating in use with a supply of first fluid via said first one way valve means and with said hollow interior via said second one way valve means, the volume of said chamber being adapted to fluctuate by a predetermined amount on cycling of said first pumping means so that said predetermined quantity of said first fluid is pumped into said hollow interior. 
     
     
       7. A fluid metering device as claimed in claim 5 wherein said second pumping means includes regulator means adapted to regulate or adjust the volume fluctuation of said chamber so that the volume ratio of first to second fluids to be mixed can be altered. 
     
     
       8. A fluid metering device as claimed in claim 7 wherein said chamber is defined by a barrel and a plunger movable within said barrel in the line of movement of said first pumping means. 
     
     
       9. A fluid metering device as claimed in claim 8 wherein said biasing means comprise resilient spring means. 
     
     
       10. A fluid metering device as claimed in claim 9 wherein said first pumping means includes a resilient diaphragm, the perimeter of which is sealingly engaged with said housing. 
     
     
       11. A fluid metering device as claimed in claim 8 wherein said first pumping means comprises a piston, the perimeter of which is in sealing engagement with said housing. 
     
     
       12. A fluid metering device comprising; a. a housing with a hollow interior   b. first and second fluid inlets into said hollow interior for first and second fluids respectively   c. a fluid outlet from said hollow interior   d. first pumping means within said hollow interior comprising a piston in continuous sealing engagement with said housing and displaceable under fluid pressure between said second fluid inlet and said fluid outlet from an `inlet` position to an `outlet` position to cause mixed first and second fluids to be expelled through said fluid outlet   e. biasing means tending to retain or restore said first pumping means at or to said `inlet` position in use   f. a passage through said piston communicating between said second fluid inlet and said fluid outlet   g. closure means adapted to close said passage at said `inlet` position and also during displacement of said first pumping means under fluid pressure from said `inlet` position to said `outlet` position and to open said passage at said `outlet` position and also during movement of said first pumping means from said `outlet` position to said `inlet` position comprising a closure member within said hollow interior adapted to open and close said passage, said closure member moving with, but being displaceable relative to, said piston, stop means coacting between said closure member and said piston and adapted to limit such relative displacement so that said passage is closed on maximum relative displacement in one direction and opened on displacement in the reverse direction, engagement means adapted to alter the relative speed of said closure member and said piston at said `outlet` position, said closure member having a ratio of thrust surface presented to said second fluid inlet at said `inlet` position to biasing force tending in use to retain or restore said closure member at or to said `inlet` position which exceeds that of said first pumping means and   h. second pumping means actuated on movement of said first pumping means to cause a predetermined quantity of said first fluid to enter said hollow interior through said first fluid inlet on each cycle of said first pumping means, said second pumping means including a chamber interposed in said first fluid inlet and first and second one way valve means, said chamber communicating in use with a supply of first fluid via said first one way valve means and with said hollow interior via said second one way valve means, the volume of said chamber being adapted to fluctuate by a predetermined amount on cycling of said piston so that said predetermined quantity of said first fluid is pumped into said hollow interior.   
     
     
       13. A fluid metering device as claimed in claim 12 wherein said closure member has a ratio of thrust surface presented to said second fluid inlet at said `inlet` position to weight which exceeds that of said piston and said `inlet` position is adapted to be lower than said `outlet` position in use so that said piston travels in a substantially vertical direction and the density of said piston is adapted to exceed that of said second fluid. 
     
     
       14. A fluid metering device as claimed in claim 13 wherein said engagement means are elastic so that at the point of opening of said passage and equalisation of the fluid pressure acting on said closure member, the unbalanced recoil force of said engagement means provides an initial acceleration to said closure member, displacing it relative to said piston to open said passage quickly. 
     
     
       15. A fluid metering device as claimed in claim 14 wherein said chamber is defined by a barrel and a plunger movable within said barrel in the line of movement of said first pumping means. 
     
     
       16. A fluid metering device comprising; a. a housing with a hollow interior   b. first and second fluid inlets into said hollow interior for first and second fluids respectively   c. a fluid outlet from said hollow interior   d. first pumping means within said hollow interior slidable under fluid pressure between said second fluid inlet and said fluid outlet from an `inlet` position to an `outlet` position to cause mixed first and second fluids to be expelled through said fluid outlet   e. biasing means tending to retain or restore said first pumping means at or to said `inlet` position in use   f. a passage between said first pumping means and said housing communicating between said second fluid inlet and said fluid outlet   g. closure means adapted to close said passage at said `inlet` position and also during displacement of said first pumping means under fluid pressure from said `inlet` position to said `outlet` position and to open said passage at said `outlet` position and also during movement of said first pumping means from said `outlet` position to said `inlet` position, said closure means comprising a resilient skirt on the inlet side of said first pumping means adapted to open said passage except when the circumference is forced into contact with said housing and a difference in fluid pressure is applied between its sides with a higher fluid pressure on the second fluid inlet side, said fluid outlet being positioned so that said skirt uncovers said fluid outlet at said `outlet` position, thereby equalising the pressure and opening said passage and   h. second pumping means actuated on movement of said first pumping means to cause a predetermined quantity of said first fluid to enter said hollow interior through said first fluid inlet on each cycle of said first pumping means.   
     
     
       17. A fluid metering device as claimed in claim 16 wherein said biasing means coacts with an inwardly coned or curved portion of said housing to spread the circumference of said skirt into sealing contact with said housing at said `inlet` position. .Iadd. 18. A fluid metering device having a housing with a hollow interior and inlet and outlet openings respectively into and out of said hollow interior, first pumping means within said hollow interior and displaceable under fluid pressure between said inlet and outlet openings from an `inlet` position to an `outlet` position to pump fluid through said fluid outlet opening, biasing means tending to retain or restore said first pumping means to said `inlet` position in use, and said first pumping means defining a passage communicating between said fluid inlet and outlet openings; characterized by: closure means adapted to close said passage at said `inlet` position and also during displacement of said first pumping means, under fluid pressure, from said `inlet` position to said `outlet` position and to open said passage at said `outlet` position and also during movement of said first pumping means from said `outlet` position to said `inlet` position; and second pumping means actuated on movement of said first pumping means to meter a predetermined quantity of other fluid into said first mentioned fluid on each cycle of said first pumping means. .Iaddend..Iadd. 19. A fluid metering device comprising: a. a housing with a hollow interior;   b. said housing having inlet and outlet openings respectively into and out of said hollow interior;   c. first pumping means within said hollow interior and displaceable under fluid pressure between said inlet and outlet openings from an `inlet` position to an `outlet` position to pump fluid through said fluid outlet opening;   d. biasing means tending to retain or restore said first pumping means at or to said `inlet` position in use;   e. said first pumping means defining a passage communicating between said inlet and outlet openings;   f. closure means adapted to close said passage at said `inlet` position and also during displacement of said first pumping means, under fluid pressure, from said `inlet` position to said `outlet` position and to open said passage at said `outlet` position and also during movement of said first pumping means from said `outlet` position to said `inlet` position;   g. and at least one second pumping means actuated on movement of said first pumping means to meter a predetermined quantity of other fluid into said first mentioned fluid on each cycle of said first pumping means.