Dosage Pump

Abstract

 A dosage pump, of the type comprising a hollow body (11) which is adapted to be interposed between portions of piping of a hydraulic circuit and is provided internally with a vaned rotary element (12), which rotates due to the flowing fluid and is associated with means (13) for speed reduction and transmission and with means (14) for converting rotary motion into reciprocating rectilinear motion, which in turn are connected to means (15) for drawing and pumping the liquid to be dosed; these means for drawing and pumping are provided, inside a container (16) for the liquid, which is fixed to the hollow body (11), by an injection stem (17), which is moved by the motion conversion means (14) so that it enters and exits, with its end (18), a dosage chamber (19) which is closed by a flow control element (20) which is pushed by elastic means (21); the chamber (19) is connected to the inside of the container (16) on the side of the injection stem (17) and to a channel (22) for connection to a pipe (23) for the rise of the dosed liquid toward the hollow body (11) on the side of the flow control element (20). The means (14) for converting rotary motion into reciprocating rectilinear motion are constituted by a cam (28) which is keyed onto a shaft (29) which is turned by the means (13) for mechanical transmission and reduction of rotary motion, the cam (28) being inserted within a slot (30) formed on the head (31) of the injection stem (17), so as to transmit thrust to the stem (17) both downward and upward.

Description

[0001] The present invention relates to a dosage pump.

[0002] The pump is adapted particularly but not exclusively for proportionally dosing small amounts of liquids in order to feed them into a hydraulic circuit or a system for generating hot water.

[0003] It is known that heating systems, particularly for generating sanitary water, are subject to the risk of scale and corrosion due to the presence of calcium and magnesium salts.

[0004] For this reason, it is common to introduce in hydraulic circuits substances which are adapted to achieve suspension of magnesium and calcium salts, preventing them from precipitating upon heating.

[0005] Dosage pumps, such as the one disclosed and claimed in Italian patent No. 1336867 in the name of this same Applicant, are currently known which comprise, within a hollow body to be interposed between portions of piping of a hydraulic circuit, a vaned impeller which rotates by way of the flowing fluid and, by way of means for mechanical reduction and transmission of the rotary motion and means for converting the rotary motion into reciprocating rectilinear motion, moves mechanically associated means for drawing and pumping the liquid to be dosed.

[0006] These means for drawing and pumping the liquid to be dosed are arranged inside a containment vessel for said liquid, which is fixed to the hollow body, and comprise an injection stem which is moved by the motion conversion means so that its lower end enters and exits a dosage chamber.

[0007] The means for converting the rotary motion into a reciprocating rectilinear motion are constituted generally by a cam wheel, whose equidistant and identical protrusions which protrude from its perimeter act on a pusher which is perpendicular to the rotation shaft of the cam wheel and is formed by the upper end of the injection stem.

[0008] The injection stem is adapted to slide within a tubular element arranged within the liquid container, and its upper pusher end is pushed against the cam wheel by a spring arranged between an abutment inside the tubular element and a shoulder into which such pusher widens.

[0009] The injection stem, moved by the motion conversion means, enters and exits with its lower end, which lies opposite the pusher, a dosage chamber, which on the opposite side with respect to the entry side for said injection stem is closed by a flow control element which is pushed closed by elastic means.

[0010] The entry and exit movement of the injection stem with respect to the dosage chamber produces the dosed injection of the liquid into the container toward a channel for connection to a pipe for the rise of the dosed liquid, which is connected to the dosage chamber on the side of the flow control element.

[0011] These known dosage pumps, although being used extensively and highly appreciated commercially, have aspects which can be improved.

[0012] The cam wheel, by acting only by pressing downward on the pusher and on the stem of which the pusher is a part, in fact entails the use of a return spring for the rise of the injection stem.

[0013] However, such spring can break due to wear, or jam, remaining for example in a compressed position, retained by the injection stem if its lower end remains locked in the injection chamber for any reason.

[0014] If one of these malfunctions occurs, the pusher is separated from the cam wheel and the reciprocating motion of the stem ceases, and so does the dosage in the system.

[0015] Further, the continuous thrust applied by the spring to the pusher produces a snap action thereof when it exits a protrusion of the cam wheel, and said snap action, repeated continuously at each passage of the pusher over each protrusion of the cam wheel, in turn generates a ticking sound which can be unpleasant for a user who for any reason is in the vicinity of the pump.

[0016] The aim of the present invention is to provide a dosage pump which is capable of obviating the drawbacks shown by known types of pump.

[0017] Within this aim, an object of the present invention is to provide a dosage pump whose means for converting rotary motion into reciprocating rectilinear motion are more reliable and stronger than in known types of pump.

[0018] Another object of the present invention is to provide a pump which is quiet.

[0019] Another object of the present invention is to provide a pump which is constructively simple and can be assembled quickly.

[0020] Another object of the present invention is to provide a dosage pump which can be manufactured cheaply with known systems and technologies.

[0021] This aim and these and other objects, which will become better apparent hereinafter, are achieved by a dosage pump, of the type which comprises a hollow body which is adapted to be interposed between portions of piping of a hydraulic circuit and is provided internally with a vaned rotary element, which rotates due to the flowing fluid and is associated with means for mechanical reduction and transmission of rotary motion and with means for converting rotary motion into reciprocating rectilinear motion, which in turn are connected to means for drawing and pumping the liquid to be dosed, which are provided, inside a container for said liquid, which is fixed to said hollow body, by an injection stem, which is moved by said motion conversion means so that it enters and exits, with its end, a dosage chamber which, on the opposite side with respect to the entry side for said injection stem, is closed by a flow control element which is pushed closed by elastic means, said chamber being connected to the inside of said container on the side of said injection stem and to a channel for connection to a pipe for the rise of the dosed liquid toward said hollow body on the side of said flow control element, said dosage pump being characterized in that said means for converting rotary motion into reciprocating rectilinear motion are constituted by a cam which is keyed onto a shaft which is turned by said means for mechanical transmission and reduction of rotary motion, said cam being arranged so as to turn within a slot formed on the head of the injection stem, so as to transmit thrust to the stem both downward and upward.

[0022] Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a sectional side view of a dosage pump according to the invention;

Figure 2 is a front view of the means for converting rotary motion into reciprocating rectilinear motion of the pump according to the invention;

Figure 3 is a view of a detail of Figure 1;

Figure 4 is a top view of a component of the pump according to the invention;

Figure 5 is a bottom view of another component of the pump according to the invention.

[0023] With reference to the figures, a dosage pump according to the invention is generally designated by the reference numeral 10.

[0024] The pump 10 comprises a hollow body 11, which is adapted to be interposed between portions of piping of a hydraulic circuit.

[0025] The hollow body is provided internally with a vaned rotary element 12, which rotates due to the flowing fluid and is associated with means 13 for mechanical reduction and transmission of rotary motion and with means 14 for converting rotary motion into reciprocating rectilinear motion.

[0026] In turn, these last means are connected to means 15 for drawing and pumping the liquid to be dosed.

[0027] The drawing and pumping means 15 are provided, inside a container 16 for the liquid, by an injection stem 17, which is moved by the motion conversion means 14 so that it enters and exits, with its end 18, a dosage chamber 19.

[0028] The dosage chamber 19 is closed, on the opposite side with respect to the entry side for the injection stem 17, by a flow control element 20, which is pushed closed by elastic means 21.

[0029] The chamber 19 is connected to the inside of the container 16 on the side of the injection stem 17 and to a channel 22 for connection to a pipe 23 for the rise of the dosed liquid toward the hollow body 11 on the side of the flow control element 20.

[0030] The chamber 19 and the connecting channel 22 are formed on a single body 24, inside which the flow control element 20 with its elastic closure means 21 is also fitted.

[0031] The injection stem 17 is adapted to perform a translational motion within a tubular guiding element 25, which is rigidly coupled by a first upper end 26, by way of snap-acting quick-coupling means, to a lid 27 of the container 16; the lid 27 in turn is fixed to the hollow body 11.

[0032] The means 14 for converting rotary motion into reciprocating rectilinear motion are constituted by a cam 28, which is keyed onto a shaft 29 which is turned by the means 13 for transmission and speed reduction.

[0033] The cam 28 is inserted in a slot 30 which is formed on a head 31 of the injection stem 17.

[0034] The slot 30 has such a width as to allow the complete rotation of the cam 28 inside it so that the head 31 of the stem 17 is not pushed and moved transversely to the axis of the stem 17; further, the height of the slot 30 is such that the cam 28 can push the stem 17 both upward and downward.

[0035] In particular, in the embodiment described here by way of non-limiting example of the invention, the cam 28 is constituted by an eccentric disk whose diameter is substantially equal to the height of the slot 43.

[0036] This causes the cam 28 to act continuously in contact with the slot 30 and there are substantially no dead centers in the action of the cam 28 on the injection stem 17.

[0037] The cam 28, like the stem 17 with the head 31 provided with the slot 30, can be obtained cheaply by molding plastic material.

[0038] The shaft 29 on which the cam 28 is keyed also supports a first gear 32, which is coupled to a second gear 33 which is keyed to a second shaft 34, which exits from a gear train 35 which belongs to the speed reduction and transmission means 13.

[0039] The gear train 35, together with the reduction ratio determined by the meshing of the second gear 33 with the first gear 32, sets a timing of the dosage which is proportional to the amount of water that flows through the vaned element 12.

[0040] Where currently applicable statutory provisions require a maximum of 5 ppm of phosphorus pentoxide (P₂O₅) per liter of water, the pump 10 allows precise and repeatable dosage between 3.2 and 3.7 ppm per liter.

[0041] The rotation of the cam 28 therefore acts by pushing alternately against the upper and lower edges of the slot 30.

[0042] In this manner, the cam 28 pushes downward the injection stem 17 within the dosage chamber 19 during injection, and then, as its rotation continues, pushes it upward to release the chamber 19 and allow the inflow therein of a new dose of liquid.

[0043] The double action on the stem 17 prevents said stem from remaining stuck for any reason within the chamber 19, always ensuring full functionality to the pump 10.

[0044] Further, the absence of the pusher spring of a pusher against the cam wheel of known types of pump also eliminates the drawback of ticking due to the snap actions of the pusher against the wheel when said pusher stops moving over a protrusion of the cam wheel.

[0045] The second lower end 36 of the tubular element 25 is arranged so as to press, within the single body 24, against a first annular sealing gasket 37 at the inlet of the dosage chamber 19.

[0046] The flow control element 20 is constituted by a ball and elastic means 21 that push it are constituted by a helical spring which rests against the bottom of a channel 38 for connection between the dosage chamber 19 and the channel 22 for connection to the riser pipe 23.

[0047] The ball is pushed against a second annular sealing gasket 39 arranged at the outlet of the dosage chamber 19.

[0048] A spacer ring 41 is further provided within the dosage chamber 19 and is interposed between the first annular sealing gasket 37, arranged at the inlet of the chamber 19, and the second annular sealing gasket 39, which is arranged in abutment against an underlying shoulder 40 at the outlet of the chamber 19; the hole of said spacer ring allows the passage without play of the end 18 of the injection stem 17.

[0049] The second lower end 36 of the tubular guiding element 25 is formed by protrusions 42 which act as a guide for the end 18 of the stem 17.

[0050] The protrusions 42 press against the first gasket 37.

[0051] The guiding protrusions 42 are arranged symmetrically so as to form between them slots 43 for the passage of the liquid to be dosed toward the dosage chamber 19.

[0052] The liquid passes within the single body 24 through two openings 44 provided in the single body 24 indeed at the slots 43.

[0053] The means for snap-action quick coupling of the tubular guiding element 25 to the lid 27 of the container 16 are constituted by at least two elastically deformable mutually opposite tabs 57, each of which has at its end a tooth 58 which is adapted to snap into engagement on an abutment edge 59 formed by the passage hole provided in the lid 27, for the first end 26 of the tubular guiding element 25.

[0054] Such quick-coupling means increase considerably the speed with which the pump 10 according to the invention is assembled, since it is sufficient to push the first end 26 of the tubular element 25 into the corresponding hole of the lid 27 to achieve the coupling of the two components.

[0055] The single body 24 is adapted to be assembled to the tubular guiding element 25 with a quick coupling of the bayonet type, which further increases the speed of the operations for assembling the pump 10 according to the invention.

[0056] Said bayonet coupling is constituted by two mutually opposite and symmetrical wings 45, which protrude radially from the second lower end 36 of the tubular element 25.

[0057] The wings 45 enter the single body 24 by means of two complementarily shaped openings 46, which extend in terms of depth along the direction of the axis of the single body 24 until they affect the openings 44 for the inflow of the liquid over a height which is at least equal to the thickness of the wings 45.

[0058] A generic opening 46 is therefore connected to the nearby and underlying opening 44; in this manner, the operator who assembles the two components merely inserts the wings 45 of the tubular element 25 in the corresponding openings 46, pushes them to the bottom of the openings 46 and then turns the single body 24 so that the wings 45 slide at the openings 44 in a configuration which prevents extraction and in which they abut against the upper edge 44a of said openings.

[0059] In practice it has been found that the invention thus described solves the problems noted in known types of dosage pump.

[0060] In particular, the present invention provides a dosage pump whose means for converting rotary motion into reciprocating rectilinear motion are more reliable and stronger than in known types of pump.

[0061] Moreover, the present invention provides a pump which is quiet with respect to known types.

[0062] Further, the present invention provides a pump which is constructively simple and quick to assemble.

[0063] Moreover, the present invention provides a dosage pump which can be manufactured cheaply with known systems and technologies.

[0064] In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

[0065] The disclosures in Italian Utility Model Application No. PD2006U000026 from which this application claims priority are incorporated herein by reference.

[0066] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A dosage pump, of the type comprising a hollow body (11) which is adapted to be interposed between portions of piping of a hydraulic circuit and is provided internally with a vaned rotary element (12), which rotates due to the flowing fluid and is associated with means (13) for speed reduction and transmission and with means (14) for converting rotary motion into reciprocating rectilinear motion, which in turn are connected to means (15) for drawing and pumping the liquid to be dosed, which are provided, inside a container (16) for said liquid, which is fixed to said hollow body (11), by an injection stem (17), which is moved by said motion conversion means (14) so that it enters and exits, with its end (18), a dosage chamber (19) which, on the opposite side with respect to the entry side for said injection stem (17), is closed by a flow control element (20) which is pushed closed by elastic means (21), said chamber (19) being connected to the inside of said container (16) on the side of said injection stem (17) and to a channel (22) for connection to a pipe (23) for the rise of the dosed liquid toward said hollow body (11) on the side of said flow control element (20), said dosage pump being characterized in that said means (14) for converting rotary motion into reciprocating rectilinear motion are constituted by a cam (28) which is keyed onto a shaft (29) which is turned by said means (13) for mechanical transmission and reduction of rotary motion, said cam (28) being inserted within a slot (30) formed on the head (31) of the injection stem (17), so as to transmit thrust to the stem (17) both downward and upward.

2. The dosage pump according to claim 1, characterized in that said slot (30) has such a width as to allow the complete rotation of the cam (28) inside it without said head (31) of the stem (17) being subjected to thrusts in a direction which is transverse to the axis of said stem (17).

3. The dosage pump according to claim 2, characterized in that said cam (28) is constituted by an eccentric disk whose diameter is substantially equal to the height of said slot (30).

4. The dosage pump according to one or more of the preceding claims, characterized in that said chamber (19) and said connection channel (22) are formed on a single body (24), inside which the flow control element (20) with its elastic closure means (21) is also fitted.

5. The dosage pump according to one or more of the preceding claims, characterized in that said injection stem (17) is adapted to move within a tubular guiding element (25), which is rigidly coupled by a first upper end (26), by way of snap-acting quick-coupling means, to the lid (27) of the container (16), said lid (27) being in turn fixed to the hollow body (11).

6. The pump according to one or more of the preceding claims, characterized in that the second lower end (36) of the tubular element (25) is arranged so as to press, within the single body (24), against a first annular sealing gasket (37) at the inlet of the dosage chamber (19).

7. The pump according to one or more of the preceding claims, characterized in that said flow control element (20) is constituted by a ball and the elastic means (21) which push it are constituted by a helical spring which rests against the bottom of a channel (38) for connection between the dosage chamber (19) and the channel (22) for connection to the riser pipe (23).

8. The pump according to one or more of the preceding claims, characterized in that said ball is pushed against a second annular sealing gasket (39) which is arranged at the outlet of the dosage chamber (19).

9. The pump according to one or more of the preceding claims, characterized in that a spacer ring (41) is further provided inside the dosage chamber (19) and is interposed between the first annular sealing gasket (37) arranged at the inlet of said chamber (19) and the second annular sealing gasket (39) arranged in abutment against an underlying shoulder (40) at the outlet of the chamber (19), the hole of said spacer ring allowing the passage without play of the end (18) of the injection stem (17).

10. The pump according to one or more of the preceding claims, characterized in that said second lower end (36) of said tubular guiding element (25) is formed by protrusions (42), which guide the end (18) of the stem (17) and are adapted to press against the first gasket (37) and are arranged symmetrically so as to form between them slots (43) for the passage of the liquid to be dosed toward the dosage chamber (19).

11. The pump according to one or more of the preceding claims, characterized in that the liquid to be dosed passes within the single body (24) through two openings (44) provided in said single body (24) at said slots (43).

12. The pump according to one or more of the preceding claims, characterized in that said means for snap-acting quick-coupling of the tubular guiding element (25) to the lid (27) of the container (16) are constituted by at least two mutually opposite elastically deformable tabs (57), each provided at its end with a tooth (58) which is adapted to snap into engagement on an abutment edge (59) formed by the passage hole which is formed in the lid (27) for the first end (26) of the tubular guiding element (25).

13. The pump according to one or more of the preceding claims, characterized in that said single body (24) is adapted to be assembled to the tubular guiding element (25) by means of a quick coupling of the bayonet type.

14. The pump according to one or more of the preceding claims, characterized in that said bayonet coupling is constituted by two mutually opposite and symmetrical wings (45) which protrude radially from the second lower end (36) of the tubular element (25), said wings (45) being adapted to enter the single body (24) by means of two complementarily shaped openings (46), which extend in terms of depth along the direction of the axis of the single body (24) until they affect the openings (44) for the inflow of the liquid to a height which is at least equal to the thickness of said wings (45).

Drawing