Proportional metering pump

Abstract

The present invention relates to a proportional metering pump for introducing a liquid additive into a main liquid stream circulating in a pipe, the pump being of the reciprocating differential piston type in order to collect the additive from a container and meter it, this pump comprising a first inlet (E) for receiving a main liquid flow which drives the pump, a second inlet for collecting the additive, and an outlet (S) for the mixture of additive and liquid, characterized in that a first venturi (30) is formed inside a first casing (C30) at the end of the step of manufacturing (E30) said casing, while means sensitive to the pressure loss in the pump are mounted in a second casing (C32), the first and second casings (30, 32), and also a body (Cl) enclosing the reciprocating movement, being assembled to one another.

Description

[0001] DESCRIPTION

[0002] TITLE: PROPORTIONAL DOSING PUMP

[0003] The present invention relates to a method and a proportional metering pump for introducing a liquid additive into a main liquid stream, circulating in a pipe, the pump being of the differential piston type with reciprocating movement for taking the additive from a container and metering it, this pump comprising a first inlet for receiving a flow of main liquid which ensures the driving of a hydraulic machine, a second inlet for taking the additive and an outlet for the mixture of additive and liquid.

[0004] In a metering pump, the differential piston reciprocates and drives a plunger to draw up the additive to be metered during an upstroke and to inject this additive into the main liquid or working liquid during a downstroke. The pressure drop between the first inlet of the pump and the outlet varies depending on the operating phases of the pump.

[0005] For good energy efficiency of the pump, it is advantageous, as proposed in the state of the art documents EP 1773479 and EP 1151196, to use a venturi to create a pressure drop between its inlet and the neck, substantially equal to the pressure drop in the pump.

[0006] Thus, document W02014 / 111770 A1 proposes introducing a means sensitive to the pressure drop in the pump, capable of controlling the throttling means of the venturi throat to reduce the passage section when the pressure drop in the pump increases, and to increase the passage section when the pressure drop in the pump decreases.

[0007] However, proportional metering pumps as modified in document W02014 / 111770 A1 have a complex design and manufacturing process, since at least one venturi tube and means sensitive to the pressure loss in the pump must be added to the pump.

[0008] This is why the invention aims, above all, to propose a proportional dosing pump which no longer presents or presents to a lesser degree the disadvantages mentioned above and which makes it possible to simplify the manufacture and assembly of the pump.

[0009] The invention relates in particular to a pump for proportional dosing of an additive in a main liquid, provided with an inlet and an outlet, and comprising

[0010] - a dosing mechanism provided with means for sucking up an additive stored in a tank,

[0011] - a hydraulic machine delimited by a body provided with an inlet and an outlet connected respectively to the inlet and the outlet of the pump, and containing a member capable of carrying out an alternating movement, the supply of the pump with main liquid at the inlet triggering the alternating movement of the member, which movement alternately causes a suction of the additive into the hydraulic machine with opening of the suction means then an expulsion of the mixture consisting of the main liquid and the additive, at the outlet of the hydraulic machine with closing of the suction means,

[0012] - a device for controlling the pump pressure losses, depending on the flow rate at the pump inlet,

[0013] - said device being equipped with a first venturi connected, in parallel with the hydraulic machine, to the inlet and outlet of the pump

[0014] - said device further comprising a means for closing the neck of the first venturi mounted to slide in said neck to control the passage section thereof, as well as means sensitive to the pressure drop in the pump, suitable for controlling the sliding of the closing means to reduce the passage section when the pressure drop in the pump increases and / or the flow rate decreases, and to increase the passage section when the pressure drop in the pump decreases and / or the flow rate increases, the first venturi being formed inside a first housing at the end of the manufacturing step of said housing, while the means sensitive to the pressure drop in the pump are mounted in a second housing, the first and second housings as well as the body of the hydraulic machine being assembled to each other in a compact manner.

[0015] Optional, complementary or substitutive features of the invention are set out below.

[0016] According to a particular embodiment, the means sensitive to the pressure loss in the pump comprise a second venturi installed on a first pipe connecting the inlet of the pump to the inlet of the hydraulic machine, and means for comparing the pressure at the neck of the first venturi and the pressure at the neck of the second venturi.

[0017] According to a first variant, the second venturi and the first pipe are formed at the end of the manufacturing step of the second housing.

[0018] According to a second variant, the second venturi is formed inside a cartridge at the end of the manufacturing step of said cartridge, said cartridge being intended to be inserted into the second housing, through an opening.

[0019] Even more advantageously, the opening is closed by means forming a plug comprising a ring cooperating in screwing with the second housing, and a screw passing through said ring up to a stop plane and cooperating in screwing with the cartridge, so that unscrewing the ring causes the removal of the screw and the cartridge assembled to the screw.

[0020] According to a particular configuration, the pressure comparison means comprise a first chamber formed inside the first housing at the end of the manufacturing step of said housing and a second chamber formed inside the second housing at the end of the manufacturing step of said housing, the first chamber being in fluid communication with the neck of the first venturi, and separated in a sealed manner from the second chamber by movable separation means, itself in fluid communication with the neck of the second venturi, the closure means being integral with said movable separation means, so that their deformation causes said closure means to slide along a stroke making it possible to enlarge or reduce the passage section of the neck of the first venturi.

[0021] Preferably, the mobile separation means comprise a membrane.

[0022] Preferably, at least one of the steps of manufacturing the body, respectively the first housing, the second housing, the cartridge is an injection molding step.

[0023] According to a first embodiment, the first housing and the body of the hydraulic machine are produced from a single injection molding step so as to form a single part.

[0024] According to a second embodiment, the second housing and the body of the hydraulic machine are produced from a single injection molding step so as to form a single part.

[0025] Preferably, the injection molding steps use a material chosen from polypropylenes, polyamides, polyvinylidene fluorides.

[0026] Even more preferably, the material chosen from polypropylenes, polyamides, polyvinylidene fluorides, is loaded with reinforcing fibers, and is preferably polypropylene loaded with 30% glass fibers.

[0027] According to a particularity, the means of obturation is a blade.

[0028] According to another feature, the first and second venturi extend substantially parallel to each other, preferably in a direction substantially perpendicular to the longitudinal axis of the hydraulic machine.

[0029] Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments which are in no way limiting, and the following appended drawings:

[0030] [Fig.l] This figure represents a schematic view of a proportional metering pump according to an embodiment of the invention.

[0031] [Fig.2] This figure represents a longitudinal section in perspective of a hydraulic machine used in one embodiment of the invention.

[0032] [Fig.3] This figure represents a cross-section of a proportional metering pump according to another embodiment of the invention.

[0033] [Fig.4] This figure represents a cross-section of a proportional metering pump according to yet another embodiment of the invention.

[0034] [Fig.5] This figure represents a cross-section of a proportional metering pump according to yet another embodiment of the invention.

[0035] [Fig.6] This figure represents a schematic detail of a pump according to a certain embodiment of the invention.

[0036] [Fig.7] This figure represents another schematic detail of a pump according to another embodiment of the invention.

[0037] Referring to Figure 1 and then to Figure 2, we can see an example of a hydraulic machine 1 of the type which can be used in the proportional metering pump according to the invention.

[0038] This example is in no way limiting insofar as other machines operating on the principle of a pump supplying the main liquid at the inlet triggering the alternating movement of a member alternately causing an aspiration of additive, could also be suitable.

[0039] The hydraulic machine 1 comprises a differential hydraulic piston 16 with reciprocating movement contained in a casing 190 consisting of a cylindrical body C1 extending along an axis (z) and surmounted by a cover 191 assembled to the body C1 in a removable manner, in particular by screwing. The differential piston 16 is arranged in the casing 190 to slide in reciprocating movement along the axis (z). The piston 16 comprises, in the upper part, an upper crown 160 of large section, the periphery of which bears in a sealed manner against the internal wall of the casing. The barrel of the piston, coaxial with the casing and of smaller diameter than the upper crown 160 is integral with this crown and extends downwards. The lower part of the barrel of the piston slides in a sealed manner in a cylindrical housing 17 coaxial with the casing. The barrel is closed in the lower part by a lower base 161.The piston 16 and the cylindrical housing 17 compartmentalize the interior of the casing according to a so-called “mixing” chamber 14 delimited by the cylindrical housing 17 and the lower base of the piston 161, a so-called “upper” chamber 13 delimited by the upper crown 16 and the cover 191 of the casing, and a so-called “lower” chamber 12, of substantially annular shape, delimited by the part below the upper crown 160, by the casing and by the cylindrical housing 17.

[0040] The hydraulic machine comprises a first inlet pipe 10 connecting the lower chamber 12 to the outside, and a second outlet pipe 11 connecting the mixing chamber 14 to the outside. A cylindrical sleeve 15 coaxial with the casing extends from the mixing chamber downwards to allow the mixing chamber to be connected to a suction device 2. This suction device is actuated by the hydraulic machine by means of a rod 162 of the piston, itself connected by a nozzle to a means for pumping the additive (not shown in the figures). For more details concerning this type of device, reference may be made to documents EP0255791 and EP1151196. Hydraulic switching means are provided for supplying and discharging the chambers 12, 13, 14 separated by the piston.These switching means are controlled by the movements of the piston and comprise a connecting rod 180 acting on a distribution member which can take two stable positions. More precisely, the distribution member comprises at least one valve holder 181 comprising at least one first so-called “upper” valve 182 cooperating with a seat 163 made in the upper crown of the piston, and at least one second so-called “lower” valve 183 cooperating with a seat 164 made in the lower base of the piston.

[0041] The hydraulic machine further comprises triggering means comprising a pusher 185 capable of causing, at the end of the piston stroke, by coming to bear against a stop, a sudden change in the position of the switching means under the action of an elastic means 18, for reversing the stroke of the piston. The coming to bear against a stop (not shown in the figures) takes place in the vicinity of the cover 191 to allow the piston to change its upward stroke to a downward stroke. The coming to bear against a stop 184 also takes place in the vicinity of the lower part of the casing to allow the piston to change its downward stroke to an upward stroke.

[0042] The connecting rod 180 is articulated at one end on a fixed point relative to the piston 16, while the other end of the connecting rod can move in a vertical window of the valve holder 181 and come into abutment against one of the two ends of this window, in one of the two stable positions of the distribution member. The elastic means 18 is integral, at each of its ends, with an articulation member received respectively in a housing provided on the connecting rod and on the pusher 185. Each housing is open in a direction substantially opposite to the direction of the force exerted by the elastic means 18 in the wall of the housing in question. This elastic means 18 can advantageously be constituted by a convex spring blade. The inlet of the hydraulic machine for the main liquid is located at the level of the first pipe 10, and the outlet for the mixture is located at the level of the second pipe 11.

[0043] According to the cycle associated with this configuration, the main liquid under pressure, generally water, enters the lower chamber 12 through the pipe 10. The upper valves are closed while the lower valves are open, allowing the liquid to be discharged from the upper chamber 13 towards the mixing chamber 14 and then the mixture to be evacuated towards the outlet via the pipe 11. Indeed, under the action of the pressure of the main liquid on the lower face of the upper crown of the piston, the latter begins an upward stroke, which tends to reduce the volume of the upper chamber and therefore to expel its contents towards the mixing chamber, since the communication is open.

[0044] At the end of the upward stroke, the pusher 185 comes to bear against a stop connected to the cover 191, which causes, under the effect of the elastic means 18, the tilting of the connecting rod 180 towards the other stable lower position, with movement of the valve holder towards the base of the piston. The lower valves close while the upper valves open. The pressurized liquid can pass from the lower chamber 12 to the upper chamber 13, the communication of which with the mixing chamber 14 is now cut off, and the movement of the piston is reversed. This movement is reversed due to the pressure that the main liquid admitted into the upper chamber exerts on the upper face of the upper crown.At the end of the downward stroke, the pusher 185 by its lower end meets a stop 184 secured to the casing 190, which causes a new tilting of the connecting rod towards the raised position and a movement of the valve holder 181 causing the closing of the upper valves and the opening of the lower valves. The movement of the piston 16 is again reversed and the piston starts again following an upward stroke.

[0045] At the same time, the alternating movement of the piston when supplying the hydraulic machine with liquid makes it possible to alternately generate suction through the sleeve 15 into the mixing chamber 14 or at the outlet 11 of the hydraulic machine. The sleeve 15 is connected to the suction device 2, also called the metering mechanism 2, by means of a nozzle.

[0046] As shown in Figure 2, this dosing mechanism 2, equipped with a suction nozzle fitted with a suction valve, therefore communicates at one of its ends, by means of the sleeve 15, also called access pipe, with a cavity inside the hydraulic machine and at the other of its ends with a reservoir of product to be dosed.

[0047] The alternating movement of the piston 16 when supplying the hydraulic machine with main liquid, generates a suction of the additive which is injected into the mixing chamber. Generally the suction device comprises at least one suction valve which opens when the piston moves away from the sleeve (i.e. in upward stroke) then an expulsion at the outlet via the pipe 11 with closing of the first suction valve when the piston approaches the sleeve (i.e. in downward stroke).

[0048] As shown in Figures 2 to 5, the proportional metering pump according to the invention also comprises a device 3 for controlling the pressure losses of the pump, adjustable according to the flow rate at the pump inlet.

[0049] This device 3 is equipped with a first venturi 30 connected, in parallel with the hydraulic machine, to the inlet E and to the outlet of the pump S.

[0050] A venturi is a tube comprising a convergent portion, located upstream of a narrowing or neck, and a divergent portion downstream of the neck. A narrowing or neck refers to a zone of the venturi, the axial extent of which may be relatively long, which has a reduced diameter relative to the inlet and outlet diameters. It is at the neck that a depression is formed with acceleration of the liquid.

[0051] The device 3 also comprises a means 32 for closing the neck 301 of the first venturi, which is slidably mounted in said neck to control the passage section thereof. The device 3 also comprises means 31, 33, 35, 36 sensitive to the pressure drop in the pump, suitable for controlling the sliding of the closing means to reduce the passage section when the pressure drop in the pump increases and / or the flow rate decreases, and to increase the passage section when the pressure drop in the pump decreases and / or the flow rate increases.

[0052] According to a particular and advantageous embodiment shown in figures 1, 3 to 5, the means sensitive to the pressure loss in the pump comprise a second venturi 31 installed on a first pipe 39 connecting the inlet E of the pump to the inlet of the hydraulic machine, and comparison means 33, 35, 36 between the pressure at the neck 301 of the first venturi 30, and the pressure at the neck 311 of the second venturi 31.

[0053] In this configuration, the first venturi, provided with a convergent 300, a neck 301 and a divergent 302, is in fluid communication upstream of its neck 301 with the second venturi 31, by means of the first pipe 39.

[0054] The second venturi 31 is provided with a convergent 310, a throat 311 and a divergent 312, and is connected to the inlet 10 of the hydraulic machine.

[0055] According to a particular and equally advantageous embodiment shown in figures 1, 3 to 5, the pressure comparison means 33, 35, 36 comprise a first chamber 36 and a second chamber 35, the first chamber being in fluid communication with the neck 301 of the first venturi, and separated in a sealed manner from the second chamber 35 by movable separation means 33, itself in fluid communication with the neck 311 of the second venturi.

[0056] The first chamber 36 is in fluid communication with the neck 301 of the first venturi by means, for example, of a pipe 360.

[0057] The second chamber 35 is in fluid communication with the neck 311 of the second venturi by means, for example, of a pipe 350. The closure means 32 is integral with said movable separation means, so that their deformation causes said closure means to slide along a stroke making it possible to enlarge or reduce the passage section of the neck of the first venturi.

[0058] The sealing means 32 may, for example, take the form of a thin blade, a cylinder, or a half-tube whose convexity is oriented towards the downstream zone of the neck of the first venturi.

[0059] The sealing means 32 can be oriented perpendicular to the geometric axis of the first venturi or inclined.

[0060] The mobile separation means 33 are advantageously a membrane.

[0061] The stop stroke of the closure means 32 is defined by the distance between the closure position (when the means is pushed into the neck of the first venturi) and the stop position of the closure means against a shoulder 380, this stop position being obtained when the pressure in the chamber 36 presses the membrane 33 away from the neck of the first venturi.

[0062] Advantageously, the first and second venturi extend substantially parallel to each other, thus allowing good compactness of the device 3.

[0063] Even more advantageously, the first and second venturi extend substantially parallel to each other in the direction (y) perpendicular to the longitudinal axis (z) of the hydraulic machine.

[0064] Concerning the operation of the pump, when the pump is at rest, that is to say when it is not in operation, the closing means 32 closes the neck 301 of the venturi 30, so that the passage section si of the neck 301 is less than 5 mm2, or even zero.

[0065] When the hydraulic machine begins to be supplied with main liquid, the main liquid stream arrives at the inlet E of the pump and does not flow or flows very little through the neck 301 of the first venturi. The main liquid, which flows mainly through the second venturi 31, operates the hydraulic machine 1 by actuating the differential piston 16 using almost all of the main stream diverted by the second venturi 31 and the first pipe 39.

[0066] The dosing mechanism 2 driven by the alternating movements of the differential piston 16 takes doses of additive from the container and the dosed mixture is injected downstream 302 of the venturi neck via the pipe 11 towards the outlet S of the pump.

[0067] When the flow rate of the main liquid arriving at inlet E of the pump increases, the pressure in the chamber 35 decreases and deforms the membrane 33 which rises and reduces the volume of the chamber 35.

[0068] This causes the translation of the closure means 32. The latter no longer closes the neck 301 of the venturi 30 and the main liquid can then flow through the neck 301 of the first venturi.

[0069] The main liquid can then flow through line 360.

[0070] At neck 301 of venturi 30, the flow velocity of the fluid increases and its static pressure decreases.

[0071] At neck 311 of venturi 31, the flow velocity of the fluid decreases and its static pressure increases.

[0072] When the pump is supplied with a determined inlet flow rate E, the differential piston 16 operates using a fraction of the main flow diverted by the second venturi 31 and the first pipe 39.

[0073] The dosing mechanism 2 driven by the alternating movements of the differential piston 16 takes doses of additive from the container and the dosed mixture is injected downstream 302 of the venturi neck via the pipe 11 towards the outlet S of the pump.

[0074] When the differential piston 16 and the plunger piston of the metering mechanism 2 are moving upwards, the pressure drop between the inlet 10 and the outlet 11 of the hydraulic machine is greater than when moving downwards. The increase in pressure drop when moving upwards causes a drop in the flow rate passing through the hydraulic machine, and therefore through the neck 311 of the venturi 31, which results in an increase in pressure at the neck 311.

[0075] The pressure at the neck 311 of the second venturi 31 therefore increases compared to that prevailing at the neck of the first venturi 301.

[0076] Under these conditions, the pressure in the chamber 35 becomes higher than that prevailing in the chamber 36 and the membrane 33 deforms to allow the closure means 32 to slide and enter further into the neck of the venturi 301. This results in an increase in the pressure drop between the inlet (convergent 300) and the outlet (divergent 302) of the venturi 30, which makes it possible to equalize the pressure drop at the neck of the venturi 30 and the pressure drop between the inlet 10 and the outlet 11 of the hydraulic machine 1, or at least to minimize the difference between these pressure drops, which contributes to improving the metering accuracy.

[0077] When the differential piston 16 and the plunger piston of the metering mechanism 2 descend, the pressure drop between the inlet 10 and the outlet 11 of the hydraulic machine 1 is lower, so that the closure means 32 rises in the chamber 36 and reduces the constriction of the neck of the venturi 301 and therefore the pressure drop between the inlet (convergent 300) and the outlet (divergent 302) of the venturi 30.

[0078] Thus, for high flow rates, the shut-off means 32 and the membrane 33 will oscillate at the speed of the differential piston 16 to ensure a better match between the pressure drop at the throat of the venturi 30 and the total pressure drop in the hydraulic machine 1.

[0079] For small flow rates, the working range of the device is reliable with precise dosing and good operating efficiency, to the extent that the Venturi effect is controlled at the level of the neck 301 of the first venturi 30.

[0080] In other words, as at low flow rates the pressure losses are not negligible, the final dosage would be much too high if all the engine liquid passed through the dosing unit due to the complete blockage by means 32, which would be due to a very marked Venturi effect.

[0081] In summary, the total pressure loss in the hydraulic machine 1 is compensated by the pressure loss at the throat of the venturi 30 with precision for both high flow rates and low flow rates.

[0082] As shown in Figures 1, 3 to 5 and in accordance with the principle of the invention, the first venturi 30 is formed inside a first housing C30 at the end of the manufacturing step E30 of said housing, while the means 31, 33, 35, 36 sensitive to the pressure drop in the pump are contained in a second housing C32, the first and second housings 30, 32 as well as the body C1 of the hydraulic machine being assembled to each other in a compact manner. By "assembled to each other" is meant the fact that the first and second housings 30, 32 as well as the body C1 of the hydraulic machine are fixed against each other without requiring flexible type connections to allow fluid circulation. The first and second housings 30, 32 as well as the body C1 of the hydraulic machine thus form a compact block in one piece when assembled.

[0083] In other words, the internal volume of the first venturi 30 is defined by a recess provided inside the first housing C30, this recess being obtained directly at the end of the manufacturing step of the housing C30.

[0084] In the example illustrated in the figures, the means sensitive to the pressure loss in the pump comprise a second venturi 31 installed on a first pipe 39 connecting the inlet E of the pump to the inlet of the hydraulic machine, and comparison means 33, 35, 36 between the pressure at the neck 301 of the first venturi 30, and the pressure at the neck 311 of the second venturi 31

[0085] According to the principle of the invention, the chambers 35 and 36 as well as the membrane 33 which separates the chambers, are arranged in a cavity of the second housing C32 which opens out of the second housing C32 into the first housing C30. This cavity is also obtained directly at the end of the step of manufacturing the housing C32. Just like the first venturi 30, the internal volume of the second venturi 31 as well as the pipe 39, can be defined by a recess arranged inside the second housing C32, this recess being obtained directly at the end of the step of manufacturing the housing C32.

[0086] According to an advantageous alternative, the second venturi 31 is formed inside a cartridge C31 at the end of the manufacturing step E31 of said cartridge. In this case, said cartridge C31 is intended to be inserted into the second housing C32, through an opening C320, obtained directly at the end of the manufacturing step of the housing C32.

[0087] This makes it possible to adapt the dimensions of the second venturi to the flow rate and dosage parameters of the pump, simply by changing the cartridge. More particularly, the lower the dosages sought, the more the neck 311 of the second venturi 31 is reduced, so as to increase the division of the second venturi, that is to say the ratio between the neck 311 of the second venturi 31 and the neck 301 of the first venturi 30.

[0088] As shown in Figure 6, the opening C320 is advantageously closed, after insertion of the cartridge with means forming a plug 4 comprising a ring 40 and a screw 41.

[0089] The ring 40 cooperates in screwing (or according to a bayonet assembly) with the second housing C32, while the screw 41 passes through said ring up to a stop plane 42 to cooperate in screwing (or according to a bayonet assembly) with the cartridge C31.

[0090] Thus, to mount the cartridge C31 in the second housing C32, the cartridge is first inserted into the opening C320 of the second housing. Then the ring 40 is screwed onto the second housing C32. Then, the screw 41 is screwed into the cartridge C31 until the screw comes into abutment 42 against the ring.

[0091] Alternatively, the cartridge C31 can be mounted in the second housing C32 by first assembling the screw 41 onto the cartridge C31 and sandwiching the ring 40. Then the assembly is screwed onto the second housing C32. Thus, the screw provides a grip to correctly orient the cartridge in the second housing C32. To disassemble the cartridge C31, the ring 40 is first unscrewed from the second housing C32. The stop plane 42 then drives the screw 41 and also the cartridge in translation, which can thus be extracted from the second housing C32.

[0092] All that remains is to unscrew screw 41 from cartridge C31.

[0093] Preferably, at least one, and preferably all, of the manufacturing steps E1 of the body C1, E30 of the first housing C30, E32 of the second housing C32, E31 of the cartridge C31 is an injection molding step.

[0094] According to an advantageous embodiment, the first housing C30 and the body Cl of the hydraulic machine come from a single injection molding step E130 so as to form a single part.

[0095] According to an equally advantageous alternative, the second housing C32 and the body C1 of the hydraulic machine are produced from a single injection molding step E132 so as to form a single part. As shown in Figure 7, the first housing C30 then comprises an angled portion C300 which makes it possible to connect the outlet 11 of the hydraulic machine with the downstream portion of the first venturi.

[0096] Preferably, the injection molding steps use a material chosen from polypropylenes, polyamides, polyvinylidene fluorides.

[0097] Even more preferably, the material chosen from polypropylenes, polyamides, polyvinylidene fluorides, is loaded with reinforcing fibers, and is preferably polypropylene loaded with 30% glass fibers.

[0098] Thus, the proportional dosing pump according to the invention has a simplified design and assembly.

[0099] The assembly operations firstly comprise the assembly of all the parts contributing to the alternating movement in the body C1. Then the membrane 33 and the closure means 32 are mounted on the second housing C32. The membrane can advantageously be overmolded onto the closure means 32.

[0100] Then the first C30 and second C32 boxes are assembled two by two, as well as the body Cl of the machine, by screwing or other equivalent operation.

[0101] In the case where the body of the hydraulic machine forms a single piece with the first or second housing, it is simply required to assemble the first housing with the second housing.

[0102] The sealing of the device is ensured by a set of seals 37 which are positioned during the assembly of the various components of the pump.

[0103] Advantageously, the first and second housings extend substantially parallel to each other, and preferably in a direction (y) perpendicular to the longitudinal axis (z) of the hydraulic machine, thus allowing good compactness of the pump.

[0104] It appears that the design of the proportional dosing pump is simplified and more compact than that presented in document W02014 / 111770 A1 which required at least a first fixing support for the first venturi, a second fixing support for the hydraulic machine and two pipes to connect the first venturi to the hydraulic machine.

[0105] The use of injection molding also makes it possible to obtain the housings and the body of the hydraulic machine directly and also minimize the number of parts.

[0106] Note that the various features, forms, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Claims

CLAIMS 1. Pump for proportional dosing of an additive in a main liquid, provided with an inlet (E) and an outlet (S), and comprising - a dosing mechanism (2) provided with means for sucking up an additive stored in a tank, - a hydraulic machine (1) delimited by a body (Cl) provided with an inlet (10) and an outlet (11) connected respectively to the inlet and the outlet of the pump, and containing a member (16) capable of carrying out an alternating movement, the supply of the pump with main liquid at the inlet triggering the alternating movement of the member (16), which movement alternately causes a suction of the additive into the hydraulic machine with opening of the suction means then an expulsion of the mixture constituted by the main liquid and the additive, at the outlet (11) of the hydraulic machine with closing of the suction means, - a device (3) for controlling the pressure losses of the pump, as a function of the flow rate at the pump inlet, - said device (3) being provided with a first venturi (30) connected, in parallel with the hydraulic machine, to the inlet and outlet of the pump - said device (3) further comprising a means (32) for closing the neck (301) of the first venturi mounted to slide in said neck to control the passage section thereof, as well as means (31, 33, 35, 36) sensitive to the pressure drop in the pump, suitable for controlling the sliding of the closing means to reduce the passage section when the pressure drop in the pump increases and / or the flow rate decreases, and to increase the passage section when the pressure drop in the pump decreases and / or the flow rate increases, - characterized in that the first venturi (30) is formed inside a first housing (C30) at the end of the manufacturing step (E30) of said housing, while the means (31, 33, 35, 36) sensitive to the pressure drop in the pump are mounted in a second housing (C32), the first and second housings (C30, C32) as well as the body (Cl) of the hydraulic machine being assembled to each other.

2. Proportional metering pump according to the preceding claim, characterized in that the means sensitive to the pressure loss in the pump comprise a second venturi (31) installed on a first pipe (39) connecting the inlet (E) of the pump to the inlet of the hydraulic machine, and comparison means (33, 35, 36) between the pressure at the neck (301) of the first venturi (30), and the pressure at the neck (311) of the second venturi (31).

3. Proportional metering pump according to the preceding claim, characterized in that the second venturi (31) and the first pipe (39) are formed at the end of the manufacturing step (E32) of the second housing (C32).

4. Proportional dosing pump according to claim 2, characterized in that the second venturi (31) is formed inside a cartridge (C31) at the end of the manufacturing step (E31) of said cartridge, said cartridge (C31) being intended to be inserted into the second housing (C32), through an opening (C320).

5. Proportional metering pump according to the preceding claim, characterized in that the opening (C320) is closed by means forming a plug (4) comprising a ring (40) cooperating in screwing with the second housing (C32), and a screw (41) passing through said ring up to a stop plane (42) and cooperating in screwing with the cartridge (C31), so that unscrewing the ring causes the removal of the screw and the cartridge assembled to the screw.

6. Proportional metering pump according to one of claims 2 to 5, characterized in that the pressure comparison means (33, 35, 36) comprise a first chamber (36) formed inside the first housing (C30) at the end of the manufacturing step (E30) of said housing and a second chamber (35) formed inside the second housing (C32) at the end of the manufacturing step (E32) of said housing, the first chamber being in fluid communication with the neck (301) of the first venturi, and separated in a sealed manner from the second chamber (35) by movable separation means (33), itself in fluid communication with the neck (311) of the second venturi, the closure means (32) being integral with said movable separation means, so that their deformation causes the sliding of said sealing means along a stroke making it possible to enlarge or reduce the passage section of the neck of the first venturi.

7. Proportional dosing pump according to the preceding claim, characterized in that the movable separation means (33) comprise a membrane.

8. Proportional metering pump according to any one of the preceding claims, characterized in that at least one of the manufacturing steps (El) of the body (Cl), respectively (E30) of the first housing (C30), (E32) of the second housing (C32), (E31) of the cartridge is an injection molding step.

9. Proportional metering pump according to claim 8, characterized in that the first housing (C30) and the body (Cl) of the hydraulic machine come from a single injection molding step (E130) so as to form a single part.

10. Proportional metering pump according to claim 8, characterized in that the second housing (C32) and the body (Cl) of the hydraulic machine come from a single injection molding step (E132) so as to form a single piece.

11. Proportional dosing pump according to any one of claims 8 to 10, characterized in that the injection molding steps use a material chosen from polypropylenes, polyamides, polyvinylidene fluorides.

12. Proportional dosing pump according to the preceding claim, characterized in that the material chosen from polypropylenes, polyamides, polyvinylidene fluorides, is loaded with reinforcing fibers, and is preferably polypropylene loaded with 30% glass fibers.

13. Proportional metering pump according to any one of the preceding claims, characterized in that the closing means (32) is a blade.

14. Proportional metering pump according to any one of the preceding claims, together with claim 2, characterized in that the first and second venturi extend substantially parallel to each other, preferably in a direction substantially perpendicular to the longitudinal axis (z) of the hydraulic machine.

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