Industrial pneumatic pump for a viscous fluid

Abstract

An industrial pneumatic pump for a viscous fluid includes a pump body, a pneumatic cylinder, a piston separating first and second chambers, a pump shaft integral with the piston and sliding in a channel, a pressure chamber with inlet and outlet ports for compressed air, and suction and outlet mouths for the viscous fluid. The pump also includes: a connection chamber connected to the chambers, and to the channel; a distributor including a spool connecting the chambers to an air discharge hole and the air outlet port; opposed first and a second pistons acting on the spool, sliding in a first and a second service chamber connected to the channel by ports, the spool including a thickening cooperating with the outlet port to cause a pressure perturbation in the service chambers causing the immediate displacement of the piston to act on the spool.

Claims

1. An industrial pneumatic pump for a viscous fluid comprising: a pump body; a double-acting pneumatic cylinder comprising an external liner, a piston, a first chamber and a second chamber separated by said piston; a pump shaft integral with said piston and sliding in a channel; a pressure chamber arranged along said channel and provided with an inlet port for compressed air and an outlet port for said air; a suction mouth for said viscous fluid; an outlet mouth for said viscous fluid; a connection chamber connected to said first and second chambers by means of a first and a second duct and corresponding access holes, respectively, and to said channel in which said pump shaft slides by means of said outlet port, and provided with a hole for discharging air into the atmosphere; a distributor comprising a spool adapted to put said first chamber and said second chamber in communication respectively and alternatively with an air discharge hole to the atmosphere and with said an outlet port of said air, implementing a reversal system for said double-acting pneumatic cylinder; a first and a second pneumatic pistons acting opposite each other on said spool to move said spool in said connection chamber, sliding respectively in a first and a second service chamber connected to said channel in which said pump shaft slides by means of ports; a base for fixing said pump body to a dip tube in which said suction mouth is formed, wherein said spool sliding in said connection chamber due to the effect of said pneumatic pistons opens or closes the access holes of said first and second duct alternatively, putting the respective chambers of said pneumatic cylinder under pressure or discharging the respective chambers, wherein said spool comprises a thickening adapted to cooperate with said air outlet port from said pressure chamber to modulate the entry of air into said connection chamber and cause a pressure perturbation in the service chambers of said first and second pneumatic piston, causing the immediate displacement of the piston called to act on the spool.

2. The industrial pneumatic pump according to claim 1, wherein said spool has an elliptical disc shape and comprises a first face facing said air outlet port from said pressure chamber and a second face facing said hole for discharge into the atmosphere.

3. The industrial pneumatic pump according to claim 2, wherein said thickening is obtained in a central portion of said first face of said spool.

4. The industrial pneumatic pump according to claim 2, wherein said second face of said spool comprises a raised edge, where said raised edge cooperates alternatively with access holes to said first and second ducts.

5. The industrial pneumatic pump according to claim 1, wherein said pump shaft comprises a first, a second and a third elongated element, each having a first and a second end, where: the first end of said first elongated element is stably associated with said piston; the second end of said first elongated element is stably associated with the first end of said second elongated element with the interposition of a first ring gasket; the second end of said second elongated element is stably associated with the first end of said third elongated element with the interposition of a second ring gasket; the second end of said third elongated element is associated with said dip tube by means of a non-return valve.

6. The industrial pneumatic pump according to claim 5, wherein said first and said second ring gasket delimit said pressure chamber inside said channel.

7. The industrial pneumatic pump according to claim 5, wherein said first and second ring gaskets are supported along said pump shaft by centring bushings comprising a mixture of acetal resin and glass fibre.

8. The industrial pneumatic pump according to claim 5, wherein said third elongated element of said pump shaft is selected from a plurality of elements with different diameters according to the type and flow rates of the viscous fluid pumped and the type of dip tube.

9. The industrial pneumatic pump according to claim 1, wherein said base comprises a hollow cylindrical body reversibly fixed to said pump body by means of screws.

10. The industrial pneumatic pump according to claim 1, wherein said base comprises a radial outlet sight hole to convey outwards any oil leaks from said dip tube and thus signal leaks.

11. The industrial pneumatic pump according to claim 1, wherein said first and second connection duct between said connection chamber and said first and second chambers separated by said piston are entirely contained within said pump body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The advantages of the invention shall appear more clearly from the following description of a preferred embodiment, made by way of an indicative and non-limiting example with reference to the figures, in which:

(2) FIG. 1 shows a longitudinal section view along a vertical plane of an industrial pneumatic pump for viscous fluids according to the invention;

(3) FIGS. 2 and 3 show a longitudinal section view along a vertical plane of two details of the pneumatic pump of FIG. 1;

(4) FIGS. 4 and 5 show a front view and a plan view from below, respectively, of the pneumatic pump of FIG. 1;

(5) FIGS. 6 and 7 show a longitudinal section along a vertical plane of the pneumatic pump of FIG. 1 during operation, in two opposite working steps;

(6) FIGS. 8 and 9 show an axonometric view of a component of the industrial pneumatic pump according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

(7) With reference to the Figures, an industrial pneumatic pump 1 for a viscous fluid is shown comprising: a pump body 2; a double-acting pneumatic cylinder 3 comprising a liner 4, a piston 5, a first chamber 6 and a second chamber 7 separated by said piston 5; a pump shaft 8 integral with said piston 5, supported and centred by bearings 45, and sliding in a channel 9 coaxial with said pump body 2; a pressure chamber 10 arranged along said channel 9 and provided with an inlet port 11 for compressed air and an outlet port 12 for said air; a connection chamber 15 connected to said first 6 and second 7 chambers by means of a first 16 and a second 17 duct and corresponding access holes 36, 37, respectively, and to said channel 9 in which said pump shaft 8 slides by means of said outlet port 12, and provided with a hole 19 for discharging air into the atmosphere; means for reversing the motion for said piston 5 of said pneumatic cylinder 3; a base 26 for fixing said pump body 2 to a dip tube 27 in which a suction mouth 13 for said viscous fluid and an outlet mouth 14 for the pumped fluid are formed.

(8) Said pump shaft 8 comprises a first 18, a second 28 and a third elongated element 38, screwed together.

(9) The external surface of said pump shaft 8 is advantageously subjected to a treatment made of hard nickel-chromium and subsequently ground h7, to guarantee the duration of the shaft and the relative functionality.

(10) Said elongated elements 18, 28, 38 each comprise a first and a second ends, where: the first end of said first elongated element 18 is stably associated with said piston 5; the second end of said first elongated element 18 is stably associated with the first end of said second elongated element 28 with the interposition of a first ring gasket 35; the second end of said second elongated element 28 is stably associated with the first end of said third elongated element 38 with the interposition of a second ring gasket 39; the second end of said third elongated element 38 is associated with said dip tube 27 by means of a non-return valve 40.

(11) Said second elongated element 28 comprises at its ends grooves suitable for housing said polyurethane ring gaskets 35, 39.

(12) Said gaskets 35, 39, obtained by turning, by virtue of their particular internal section of convex C-shape and the high smoothness given by the polyurethane compound used, reduce ordinary maintenance to a minimum and increase the life of the pump 1 also increasing the response speed of the means for reversing the motion of the piston 5.

(13) Said first 35 and second 39 ring gaskets are supported along said pump shaft 8 by centring bushings 41 comprising a mixture of acetal resin and glass fibre (bearite). Such mixture ensures superior performance to the common bronze traditionally used for bearings and guides, ensuring less power absorption and less friction to the advantage of power delivered and less wear of the sealing elements.

(14) Said first 35 and said second 39 ring gaskets define said pressure chamber 10 inside said channel 9.

(15) Said pressure chamber 10 is always in communication during the entire stroke of the pump shaft 8 with the pneumatic supply of the external air, through said inlet port 11, and with said connection chamber 15, through said outlet port 12.

(16) Said third elongated element 38 of said pump shaft 8, connected below said suction tube 27 with non-return valve 40, during the upward stroke of the piston 5 has the task of suctioning the fluid to be pumped and during the downward stroke of the piston itself has the task of expelling said fluid through said outlet mouth 14.

(17) Said third elongated element 38 of said pump shaft 8 is interchangeable and is selected from a plurality of elements with different diameters according to the type and flow rates of viscous fluid pumped and the type of dip tube.

(18) Said connection chamber 15 includes: an upper inlet port, i.e. the access hole 36 from which said first duct 16 extends inside the pump body 2 for connection with said first chamber 6 of the pneumatic cylinder 3; a lower inlet port, i.e. the access hole 37 from which said second duct 17 (visible dashed) extends inside the pump body 2 for connection with said second chamber 7 of the pneumatic cylinder 3; an intermediate port 46 connected to said discharge hole 19 into the atmosphere.

(19) Said pneumatic pump 1 then comprises a distributor 20 adapted to act as a means of reversing the motion for said piston 5 of said pneumatic cylinder 3.

(20) Said distributor 20 comprises a spool 31 adapted to put said first chamber 6 and said second chamber 7 in communication respectively and alternatively with said discharge hole 19 into the atmosphere 19 and with said outlet port 12 of said air, thus implementing a motion reversal system for said double-acting pneumatic cylinder 3.

(21) The movement of said distributor 20 is obtained pneumatically in an active way by means of two opposite pneumatic pistons 22, 23 which act alternately on the ends of said spool 21 to move it in said connection chamber 15.

(22) Said pistons 22, 23 slide respectively in a first 24 and a second 25 service chamber connected, by means of inlet ports 32, 33, to said channel 9 in which said pump shaft 8 slides.

(23) Said pneumatic pistons 22, 23 comprise a POM-C type acetal resin other than that commonly used for castings (DELRIN 500); they are obtained from machine tools; they are mounted in the respective service chambers 24, 25 with polyurethane gaskets 47 in order to facilitate smoothness and increase their response speed.

(24) Said spool 21, also made of acetal resin, has an elliptical disc shape and slides vertically in said connection chamber 15.

(25) Said spool 21 comprises a first face 30 facing towards said outlet port 12 for the air from said pressure chamber 10, and therefore towards said pump shaft 8, and a second face 31 facing towards the intermediate opening 46 of said connection chamber 15 which defines said discharge hole 19 into the atmosphere.

(26) Said second face 31 of said spool 21 comprises a raised edge 34 which circumscribes an interconnection cavity 50.

(27) Said raised edge 34 cooperates alternatively with the access holes 36, 37 to said first 16 and second 17 connection duct to the chambers 6, 7, while said interconnection chamber 50 cooperates with said discharge hole 19 into the atmosphere.

(28) Said first face 30 of said spool 21 comprises a thickening 29, formed in its central portion.

(29) Said thickening 29 is adapted to cooperate with said air outlet port 12 of said pressure chamber 10 to modulate the entry of air into said connection chamber 15 and cause a pressure perturbation in the service chambers 24, 25 of said first 22 and second 23 pneumatic piston.

(30) Said spool 21 has been designed with very tight tolerances to allow it to move in the connection chamber 15 and work efficiently, ensuring optimal performance.

(31) Said pump body 2, made of cast aluminium, includes within it machining with reduced tolerances to carry out couplings that guarantee seals in all pump working situations, even the most severe ones. Inside the pump body 2, the ducts 16, 17 and the air passage channels and the service chambers 24, 25 of the pistons 22, 23 are sized to facilitate and ensure the greater efficiency of the spool 21 which acts as a means of reversing the motion of the piston 5 and then the pumping selector. Said pump body 2 is devoid of inlets and housings which traditionally had to house springs and spool locking balls, reducing the number of elements inside the pump and thus obtaining a more linear air passage, without harmful dispersions and recirculation.

(32) Said pump body 2 contains all the components inside it, including the ducts 16, 17 connecting the connection chamber 15 to the chambers 6, 7 of the pneumatic cylinder 3: the pump 1 is therefore protected against impacts and damage in all its parts.

(33) Since the pneumatic pump 1 of the industrial type may have considerable dimensions, being able to satisfy requests for high flow rates, an eyebolt 48 is placed on the top of the pump body 2 for its movement from above.

(34) Said base 26 is made in machine tool from aluminium bar, extremely resistant to traction, it comprises a hollow cylindrical body 42 reversibly fixed, with the interposition of a flange 49, to said pump body 2 by means of screws 43.

(35) Said base 26 comprises a radial outlet sight hole 44 to convey outwards any oil leaks from said dip tube 27 and signal leaks.

(36) The operation of the industrial pneumatic pump 1 according to the invention is illustrated below with particular reference to the sections of FIGS. 6 and 7 relating to the two extreme working positions.

(37) Starting from the conditions highlighted in FIG. 7, the pneumatic pressure feeds, through the inlet port 11, the pressure chamber 10 and, through the port 32, the service chamber 24 of the first pneumatic piston 22 which is then pushed downwards.

(38) The spool 21 of the distributor 20 is carried by said first piston 22 to its lower end stop, at which the second chamber 7 of the pneumatic cylinder 3 is in communication with the atmosphere through the access hole 37 of the second duct 17, the interconnection cavity 50 of the spool 21 and the hole 19 for discharging into the atmosphere, while the first chamber 6 of the pneumatic cylinder 3 is pressurized through the connection chamber 15 and the access hole 36 to the duct 16.

(39) In this condition, the piston 5 of the pneumatic cylinder 3, and consequently the pump shaft 8, continue to descend favouring the expulsion of viscous fluid from the outlet mouth 14 of the pump 1.

(40) When the pump shaft 8 reaches the lower limit switch, the pressure chamber 10 is in communication with the service chamber 25 of the second pneumatic piston 23 through the port 33, realizing the working condition illustrated in FIG. 6.

(41) At this point the second pneumatic piston 23 pushes the spool 21 of the distributor upwards inside the connection chamber 15, up to its upper end stop, at which the first chamber 6 of the pneumatic cylinder 3 is in communication with the atmosphere through the access hole 36 of the first duct 16, the interconnection cavity 50 of the spool 21 and the discharge hole 19 into the atmosphere, while the second chamber 7 of the pneumatic cylinder 3 is pressurized through the connection chamber 15 and the access hole 37 to the duct 17, causing the piston 5 and the pump shaft 8 to rise and therefore the pumping of viscous fluid from the dip tube 27, until it returns to the initial conditions and resumes the cycle described.

(42) When the exchange is completed, the raised edge 34 of the spool 21 has completely opened the access hole of the duct to the chamber of the pneumatic cylinder which in the previous step was discharged into the atmosphere, allowing it to be filled and pushing the piston to the next end of stroke where the process will reverse again in a cyclical manner.

(43) It should be emphasized that, during the transit of the distributor from one position to another, the thickening 29 of the spool 21 partializes the outlet 12 of the air from the pressure chamber 10 towards the connection chamber 15: it follows the creation of a return pressure wave due to the sudden reduction in supply which propagates along the pressure chamber 10, accelerating the alternating movement (depending on the position of the pump shaft) of the pneumatic pistons 22, 23 on the spool 21.

(44) In this way the reversal of motion of the piston 5 of the pneumatic cylinder 3 becomes instantaneous, avoiding dangerous risks of pneumatic stalling and minimizing the reversal times and considerably increasing the flow rate, minimizing pressure fluctuations in the dip tube 27.

(45) This return pressure wave therefore has two functions: the first is to avoid the fluid-dynamic stall of the pump and the second is to be able to halve the exchange time, allowing the pump to remain powered until the last stages of the piston stroke.

(46) Mechanical locking systems of the spool are not necessary, as its design is designed to ensure perfect adhesion of the same to the distribution block by exploiting only the pressure of the supply air which, by pressing on the rear part of the spool itself, is able to efficiently support the low weight of the part even at the minimum operating pressures.