Proportioning pump

Abstract

The invention relates to a proportioning pump for introducing a liquid additive into a main liquid flow flowing in a pipe, of the reciprocating differential piston type for extracting and metering the additive from a container, comprising a first inlet (E) for receiving the main liquid flow driving the pump, a second inlet for extracting 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) and at the end of the step (E30) of manufacturing the casing, and means sensitive to the pressure loss in the pump are installed in a second casing (C32), the first casing (C30) and the second casing (C32) and the body containing the reciprocating movement (C1) being assembled together.

Description

Technical Field

[0001] The present invention relates to a method and a proportional metering pump for introducing a liquid additive into a main liquid flow flowing in a pipeline. The pump is a reciprocating differential piston type for extracting and metering the additive from a container. The pump includes a first inlet for receiving the main liquid flow driving a hydraulic press, a second inlet for extracting the additive, and an outlet for a mixture of the additive and the liquid. Background Technology

[0002] In a metering pump, a differential piston performs a reciprocating motion, drawing the additive to be metered during the upward stroke and injecting it into the main fluid or drive fluid during the downward stroke. The pressure loss between the pump's first inlet and outlet varies depending on the pump's operating phase.

[0003] For good pump efficiency, as proposed in prior art documents EP 1773479 and EP 1151196, it is advantageous to use a venturi tube to generate a pressure loss between its inlet and throat that is substantially equal to the pressure loss in the pump.

[0004] Therefore, document WO2014 / 111770 A1 proposes the introduction of a device sensitive to pressure loss in the pump. This device can control the contraction of the throat of the venturi tube to reduce the flow cross-section when the pressure loss in the pump increases and increase the flow cross-section when the pressure loss in the pump decreases. However, the improved proportional metering pump described in document WO2014 / 111770 A1 is complex to design and manufacture because at least one venturi tube and a device sensitive to pressure loss in the pump must be added to the pump.

[0005] Therefore, the main objective of this invention is to provide a proportional metering pump that does not have the aforementioned disadvantages or has only a minor degree of those disadvantages, and which simplifies the manufacturing and assembly of the pump. Summary of the Invention

[0006] The present invention particularly relates to a proportioning metering pump for adding additives to a main liquid, the pump having an inlet and an outlet, and comprising: - A metering mechanism, equipped with a device for drawing up additives stored in a reservoir. - A hydraulic press, defined by a main body having an inlet and an outlet respectively connected to the inlet and outlet of a pump, and containing a component capable of performing reciprocating motion. Supplying main fluid to the pump at the inlet triggers the reciprocating motion of this component. This motion alternately causes an additive to be drawn into the hydraulic press when the suction device is open, and then discharged at the outlet of the hydraulic press as a mixture of main fluid and additive when the suction device is closed. - A device for controlling the pressure loss of a pump based on the flow rate at the pump inlet. The device is equipped with a first venturi tube, which is connected in parallel with the hydraulic press to the inlet and outlet of the pump. The apparatus further includes means for closing the throat of the first venturi tube, the means being slidably mounted in the throat to control its flow cross-section, and means sensitive to pressure loss in the pump, the means being able to control the sliding of the closing means to reduce the flow cross-section when the pressure loss in the pump increases and / or the flow rate decreases, and to increase the flow cross-section when the pressure loss in the pump decreases and / or the flow rate increases. The first venturi tube is formed inside the first housing at the end of the manufacturing step of the housing, while the device sensitive to pressure loss in the pump is installed in the second housing. The first and second housings, as well as the main body of the hydraulic press, are assembled together in a compact manner.

[0007] The optional, supplementary, or alternative features of the present invention are described below.

[0008] According to one particular embodiment, the device sensitive to pressure loss in the pump includes a second venturi tube installed on a first pipeline connecting the pump inlet to the inlet of the hydraulic press, and a pressure comparison device for comparing the pressure at the throat of the first venturi tube and the pressure at the throat of the second venturi tube.

[0009] According to the first variant, the second venturi tube and the first pipeline are formed at the end of the step of manufacturing the second housing.

[0010] According to the second variant, a second venturi tube is formed inside the cylinder at the end of the manufacturing step, the cylinder being designed to be inserted into the second housing through an opening.

[0011] More advantageously, the opening is closed by a device forming a cover, which includes an annular member threaded to the second housing and a screw passing through the annular member to the stop face and threaded to the cylinder, thereby unscrewing the annular member to remove the screw and the cylinder assembled with the screw.

[0012] According to a specific configuration, the pressure comparison device includes a first chamber formed inside a first housing at the end of the step of manufacturing the housing, and a second chamber formed inside a second housing at the end of the step of manufacturing the housing. The first chamber is in fluid communication with the throat of a first venturi tube and is sealed to the second chamber by a movable separation device, which itself is in fluid communication with the throat of the second venturi tube. A closing device is fixed to the movable separation device such that deformation of the closing device causes it to slide along its stroke, thereby increasing or decreasing the flow cross-section of the throat of the first venturi tube.

[0013] Preferably, the movable separation device includes a membrane.

[0014] Preferably, in the steps of manufacturing the main body, the first shell, the second shell, and the cylindrical component, at least one step is an injection molding step.

[0015] According to the first embodiment, the first housing and the main body of the hydraulic press are produced from the same injection molding step to form the same component.

[0016] According to the second embodiment, the second housing and the main body of the hydraulic press are produced from the same injection molding step to form the same component.

[0017] Preferably, the injection molding step uses a material selected from polypropylene, polyamide, and polyvinylidene fluoride.

[0018] Even more preferably, the material selected from polypropylene, polyamide, and polyvinylidene fluoride is filled with reinforcing fibers, and preferably polypropylene filled with 30% glass fiber.

[0019] Based on one characteristic, the closing device is a blade.

[0020] According to another feature, the first and second venturi tubes extend substantially parallel to each other, preferably in a direction substantially perpendicular to the longitudinal axis of the hydraulic press. Attached Figure Description

[0021] Other advantages and features of the invention will become apparent from reading the detailed description of the non-limiting embodiments and examples (in no way limiting) and the following drawings: [ Figure 1 This figure depicts a schematic diagram of a proportional metering pump according to an embodiment of the present invention.

[0022] [ Figure 2 This figure depicts a longitudinal perspective section of a hydraulic press used in one embodiment of the present invention.

[0023] [ Figure 3 The figure depicts a cross-section of a proportional metering pump according to another embodiment of the present invention.

[0024] [ Figure 4 The figure depicts a cross-section of a proportional metering pump according to yet another embodiment of the present invention.

[0025] [ Figure 5 The figure depicts a cross-section of a proportional metering pump according to yet another embodiment of the present invention.

[0026] [ Figure 6 This figure depicts schematic details of a pump according to one embodiment of the present invention.

[0027] [ Figure 7 This figure depicts another schematic detail of a pump according to another embodiment of the present invention. Detailed Implementation

[0028] Reference Figure 1 Then refer to Figure 2 An example can be seen of a hydraulic press 1 of the proportional metering pump type according to the present invention.

[0029] This example is by no means limiting, as other machines operating on the same principle apply: supplying the main fluid to the pump at the inlet triggers the reciprocating motion of components, which alternately causes the suction of additives.

[0030] The hydraulic press 1 includes a reciprocating differential hydraulic piston 16 contained within a housing 190. The housing 190 consists of a cylindrical body extending along an axis (Z) and covered by a cover 191 removably assembled to the body, particularly via a threaded connection. The differential piston 16 is arranged within the housing 190 and slides in a reciprocating motion along the axis. The piston 16 includes an upper crown 160 with a large cross-section at its upper part, the periphery of which abuts against the inner wall of the housing in a sealing manner. A piston cylinder, coaxial with the housing and with a diameter smaller than the upper crown 160, is fixed to the crown and extends downward. The lower portion of the piston cylinder slides in a sealing manner within a cylindrical bore 17 coaxial with the housing. The lower portion of the cylinder is closed by a lower base 161. The piston 16 and the cylindrical bore 17 divide the interior of the housing into: a so-called "mixing" chamber 14 defined by the cylindrical bore 17 and the lower base 161 of the piston; a so-called "upper" chamber 13 defined by the upper crown 16 and the cover 191 of the housing; and a so-called "lower" chamber 12, which is substantially annular in shape and defined by the portion below the upper crown 160, the housing, and the cylindrical bore 17.

[0031] The hydraulic press includes 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 housing, extends downward from the mixing chamber to allow connection of the mixing chamber to a suction device 2. This suction device is actuated by the hydraulic press via a piston rod 162 and is itself connected via a nozzle to a device for pumping additives (not shown). Further details about this type of device can be found in documents EP0255791 and EP1151196.

[0032] A hydraulic switching device is provided for supplying and evacuating chambers 12, 13, and 14 separated by pistons. This switching device is operated by the movement of the pistons and includes a linkage 180 acting on a distribution member capable of assuming two stable positions. More specifically, the distribution member includes at least one valve retainer 181 comprising at least one first so-called "upper" valve 182 cooperating with a valve seat 163 formed in the upper crown of the piston, and at least one second so-called "lower" valve 183 cooperating with a valve seat 164 formed in the lower base of the piston.

[0033] The hydraulic press also includes a triggering device comprising a push rod 185. This push rod, at the end of the piston stroke, abruptly changes the position of the switching device under the action of the elastic device 18 by abutting against a stop, thereby reversing the piston stroke. The stop (not shown) is located near the cover 191 to cause the piston to change its upward stroke to a downward stroke. The stop 184 is also located near the lower part of the housing to cause the piston to change its downward stroke to an upward stroke.

[0034] One end of the connecting rod 180 is hinged to a fixed point relative to the piston 16, while the other end of the connecting rod (connecting rod) is movable within the vertical window of the valve retainer 181 and abuts against one end of the window at one of two stable positions of the dispensing member. An elastic device 18 is fixed at both ends to hinge members, which are respectively received in holes provided on the connecting rod and the push rod 185. Each hole opens in a direction substantially opposite to the direction of the force applied to the hole wall by the elastic device 18. The elastic device 18 can advantageously be constructed of a convex spring plate.

[0035] The hydraulic press has an inlet for the main liquid located at the first pipe 10, and an outlet for the mixture located at the second pipe 11.

[0036] According to the circulation associated with this configuration, pressurized main fluid (typically water) enters the lower chamber 12 via pipe 10. The upper valve closes while the lower valve opens, allowing fluid to drain from the upper chamber 13 into the mixing chamber 14, and then the mixture is emptied to the outlet via pipe 11. In practice, the pressure of the main fluid acting on the lower surface of the piston's upper crown causes it to begin its upward stroke, which tends to reduce the volume of the upper chamber, thus driving its contents into the mixing chamber, since the connection is open at this time.

[0037] At the end of the upward stroke, push rod 185 abuts against the stop connected to cap 191, which, under the action of elastic device 18, causes connecting rod 180 to tilt toward another lower stable position, while valve retainer moves toward the base of piston. Lower valve closes, while upper valve opens. Pressurized liquid can flow from lower chamber 12 to upper chamber 13, the communication between upper chamber 13 and mixing chamber 14 is now cut off, and piston movement reverses. This reversal is due to the pressure exerted by the main liquid introduced into upper chamber on the upper surface of upper cap. At the end of the downward stroke, push rod 185 is fixed to stop 184 of housing 190 by its lower end contact, which causes connecting rod to tilt further toward a raised position, and movement of valve retainer 181 causes upper valve to close and lower valve to open. Piston 16 movement reverses again, and piston returns along the upward stroke.

[0038] Meanwhile, during the supply of liquid to the hydraulic press, the reciprocating motion of the piston allows for alternating suction through the sleeve 15 within the mixing chamber 14, or at the outlet 11 of the hydraulic press. The sleeve 15 is connected to the suction device 2, also known as the metering mechanism 2, via a nozzle.

[0039] like Figure 2 As shown, the metering mechanism 2 is equipped with a suction nozzle with a suction valve, so that one end of it is connected to the cavity inside the hydraulic press through a sleeve 15 (also called an access pipe), and the other end of it is connected to the reservoir of the product to be metered.

[0040] During the supply of main fluid to the hydraulic press, the reciprocating motion of piston 16 creates suction for the additive, which is injected into the mixing chamber. Typically, the suction device includes at least one suction valve that opens when the piston moves away from the sleeve (i.e., during the upward stroke) and then closes when the piston moves toward the sleeve (i.e., during the downward stroke), discharging at the outlet via conduit 11.

[0041] like Figures 2 to 5 As shown, the proportional metering pump according to the present invention also includes a device 3 for controlling the pressure loss of the pump, which can be adjusted according to the flow rate at the pump inlet.

[0042] The device 3 is provided with a first venturi tube 30, which is connected in parallel to the hydraulic press to the pump inlet E and outlet S.

[0043] A Venturi tube is a tube comprising a constricting section upstream of the throat and a dilating section downstream of the throat. The constriction or throat is a region of the Venturi tube that can be relatively long axially, with a diameter decreasing relative to the inlet and outlet diameters. It is at the throat that negative pressure is created as the fluid accelerates.

[0044] The device 3 also includes a closing device 32 for closing the throat 301 of the first venturi tube, the closing device 32 being slidably mounted in the throat to control its flow cross-section.

[0045] The device 3 also includes devices 31, 33, 35, and 36 that are sensitive to pressure loss in the pump, which can control the sliding of the shut-off device to reduce the flow cross-section when the pressure loss in the pump increases and / or the flow rate decreases, and to increase the flow cross-section when the pressure loss in the pump decreases and / or the flow rate increases.

[0046] according to Figure 1 , Figures 3 to 5 The specific and advantageous embodiment shown includes a device sensitive to pressure loss in the pump, comprising a second venturi tube 31 installed on a first line 39 connecting the pump inlet E to the inlet of the hydraulic press, and pressure comparison devices 33, 35, 36 for comparing the pressure at the throat 301 of the first venturi tube 30 with the pressure at the throat 311 of the second venturi tube 31.

[0047] In this configuration, a first Venturi tube is provided with a tapering section 300, a throat 301, and a dilating section 302, and is in fluid communication with a second Venturi tube 31 upstream of its throat 301 via a first pipeline 39.

[0048] The second venturi tube 31 is provided with a tapering section 310, a throat 311 and a dilating section 312, and is connected to the inlet 10 of the hydraulic press.

[0049] according to Figure 1 , Figures 3 to 5 In the specific and equally advantageous embodiment shown, the pressure comparison devices 33, 35, 36 include a first chamber 36 and a second chamber 35. The first chamber is in fluid communication with the throat 301 of the first venturi tube and is sealed away from the second chamber 35 by a movable separation device 33. The second chamber 35 is in fluid communication with the throat 311 of the second venturi tube.

[0050] The first chamber 36 is in fluid communication, for example, with the throat 301 of the first venturi tube via a conduit 360.

[0051] The second chamber 35 is in fluid communication, for example, with the throat 311 of the second venturi tube via a conduit 350.

[0052] The closing device 32 is fixed to the movable separation device such that deformation of the device causes the closing device to slide by a stroke, thereby increasing or decreasing the flow cross-section of the throat of the first venturi tube.

[0053] The closing device 32 may take the form of, for example, a thin blade, a cylinder, or a half-tube, wherein the convex surface of the half-tube faces the downstream region of the throat of the first venturi tube.

[0054] The closing device 32 can be oriented perpendicular to the geometric axis of the first venturi tube or tilted.

[0055] The movable separation device 33 is advantageously a membrane.

[0056] The travel of the closing device 32 into position is defined by the distance between the closed position (when the device is pressed into the throat of the first venturi tube) and the position where the closing device abuts the shoulder 380, which is obtained when the pressure in the chamber 36 pushes the membrane 33 away from the throat of the first venturi tube.

[0057] Advantageously, the first and second Venturi tubes extend substantially parallel to each other, thereby giving the device 3 a good compactness.

[0058] More advantageously, the first and second venturi tubes extend substantially parallel to each other in a direction perpendicular to the longitudinal axis (z) of the hydraulic press.

[0059] Regarding pump operation, when the pump is stationary, i.e., when it is not running, the shut-off device 32 closes the throat 301 of the venturi tube 30, so that the flow cross-section s1 of the throat 301 is less than 5mm. 2 , or even zero.

[0060] When the main fluid is supplied to the hydraulic press, the main fluid flows to the pump inlet E and does not flow through or only slightly flows through the throat 301 of the first venturi tube.

[0061] The main fluid flows primarily through the second venturi tube 31, and the hydraulic press 1 is operated by driving the differential piston 16 by means of almost all the main flow from the second venturi tube 31 and the first pipeline 39.

[0062] The metering mechanism 2, driven by the reciprocating motion of the differential piston 16, takes out a certain dose of additive from the container, and the metered mixture is injected downstream of the throat of the venturi tube 302 through the pipe 11, toward the outlet S of the pump.

[0063] When the flow rate of the main liquid reaching the pump inlet E increases, the pressure in chamber 35 decreases and causes the membrane 33 to deform, rising and reducing the volume of chamber 35.

[0064] This causes the shut-off device 32 to shift. The latter no longer closes the throat 301 of the venturi tube 30, and the main fluid can then flow through the throat 301 of the first venturi tube.

[0065] Then, the main liquid can flow through the pipe 360.

[0066] At the throat 301 of the venturi tube 30, the fluid velocity increases and its static pressure decreases.

[0067] At the throat 311 of the venturi tube 31, the fluid velocity decreases and its static pressure increases.

[0068] When the pump is supplied with a defined flow rate at inlet E, the differential piston 16 operates by means of a portion of the main flow rate drawn from the second venturi tube 31 and the first line 39.

[0069] The metering mechanism 2, driven by the reciprocating motion of the differential piston 16, takes out a certain dose of additive from the container, and the metered mixture is injected downstream of the throat of the venturi tube 302 through the pipe 11, toward the pump outlet S.

[0070] During the rise of the differential piston 16 and the plunger piston of the metering mechanism 2, the pressure loss between the inlet 10 and outlet 11 of the hydraulic press is greater than the pressure loss during the fall.

[0071] The increased pressure loss during the ascent results in a decrease in the flow rate through the hydraulic press and thus into the throat 311 of the venturi tube 31, which in turn leads to an increase in pressure at the throat 311.

[0072] Therefore, the pressure at the throat 311 of the second venturi tube 31 is greater than the dominant pressure at the throat of the first venturi tube 301.

[0073] Under these conditions, the pressure in chamber 35 becomes greater than the dominant pressure in chamber 36, and the membrane 33 deforms to allow the shut-off device 32 to slide further into the throat of the venturi tube 301. This results in an increase in the pressure loss between the inlet (constriction section 300) and outlet (expansion section 302) of the venturi tube 30, thereby making the pressure loss at the throat of the venturi tube 30 equal to, or at least minimizing, the pressure loss between, the inlet 10 and outlet 11 of the hydraulic press 1, which helps to improve metering accuracy.

[0074] During the descent of the differential piston 16 and the plunger piston of the metering mechanism 2, the pressure loss between the inlet 10 and outlet 11 of the hydraulic press 1 is small, so the shut-off device 32 rises into the chamber 36 and reduces the contraction of the throat of the venturi tube 301, thereby reducing the pressure loss between the inlet (constriction section 300) and outlet (expansion section 302) of the venturi tube 30.

[0075] Therefore, for high flow rates, the shut-off device 32 and the diaphragm 33 will oscillate at the speed of the differential piston 16 to ensure a better match between the pressure loss at the throat of the venturi tube 30 and the total pressure loss in the hydraulic press 1.

[0076] For low flow rates, the device’s operating range becomes reliable through precise metering and good operating efficiency, as the Venturi effect is controlled at the throat 301 of the first Venturi tube 30.

[0077] In other words, since the pressure loss is not negligible at low flow rates, if all the driving fluid enters the metering device due to the complete closure of the shut-off device 32, the final metering will be too high, which will be due to a very significant Venturi effect.

[0078] In summary, the total pressure loss in hydraulic press 1 is precisely compensated by the pressure loss at the throat of venturi tube 30, regardless of whether the flow rate is high or low.

[0079] like Figure 1 , Figures 3 to 5 As shown, and according to the principles of the invention, the first venturi tube 30 is formed inside the first housing C30 at the end of the housing manufacturing step E30, while the devices 31, 33, 35, and 36 sensitive to pressure loss in the pump are contained in the second housing C32. The first housing C30, the second housing C32, and the hydraulic press body C1 are assembled to each other in a compact manner. "Assembled to each other" means that the first housing C30, the second housing C32, and the hydraulic press body C1 are fixed to each other without requiring flexible connectors to allow fluid flow. Therefore, the first housing C30, the second housing C32, and the hydraulic press body C1 form an assembled, integrated, compact block.

[0080] In other words, the internal volume of the first venturi tube 30 is defined by a recess formed inside the first housing C30, which is obtained directly at the end of the step of manufacturing the housing C30.

[0081] In the example shown in the accompanying drawings, the device sensitive to pressure loss in the pump includes a second venturi tube 31 installed on a first line 39 connecting the pump inlet E to the hydraulic press inlet, and pressure comparison devices 33, 35, 36 for comparing the pressure at the throat 301 of the first venturi tube 30 and the pressure at the throat 311 of the second venturi tube 31.

[0082] According to the principles of the invention, chambers 35 and 36, and a membrane 33 separating the chambers, are formed in a cavity of the second housing C32, which communicates with the first housing C30. This cavity is also obtained directly at the end of the manufacturing step of housing C32.

[0083] Like the first venturi tube 30, the internal volume of the second venturi tube 31 and the pipeline 39 can be defined by a recess formed in the second housing C32, which is obtained directly at the end of the manufacturing step of the housing C32.

[0084] According to a favorable alternative, the second venturi tube 31 is formed inside the cylindrical member C31 at the end of step E31 of manufacturing the cylindrical member C31. In this case, the cylindrical member C31 is intended to be inserted into the second housing C32 through an opening C320, which is obtained directly at the end of the step of manufacturing the housing C32.

[0085] This allows the size of the second venturi tube to be adapted to the pump's flow rate and metering parameters by simply changing the sleeve. More specifically, the lower the desired quantity to be metered, the smaller the throat 311 of the second venturi tube 31, in order to increase the graduation of the second venturi tube, i.e., the ratio between the throat 311 of the second venturi tube 31 and the throat 301 of the first venturi tube 30.

[0086] like Figure 6 As shown, after the insert is inserted, the opening C320 is advantageously closed by means of a device comprising a cover 4, which includes an annular element 40 and a screw 41.

[0087] The annular member 40 is threaded to the second housing C32 (or mates with it in a bayonet manner), and the screw 41 passes through the annular member to the stop face 42 to be threaded to the cylindrical member C31 (or mates with it in a bayonet manner).

[0088] Therefore, in order to install the cylinder C31 into the second housing C32, the cylinder is first inserted into the opening C320 of the second housing. Then, the annular member 40 is threaded onto the second housing C32. Then, the screw 41 is threaded onto the cylinder C31 until the screw abuts against the annular member at 42.

[0089] Alternatively, the cylinder C31 can be installed in the second housing C32 by first assembling the screw 41 onto the cylinder C31 and clamping the annular member 40. The assembly is then threaded together with the second housing C32. Thus, the screw allows for a gripping portion to properly orient the cylinder within the second housing C32.

[0090] To disassemble the cylinder C31, first unscrew the annular member 40 from the second housing C32. Then, the stop surface 42 causes the screw 41 and the cylinder to translate, thereby allowing the cylinder to be removed from the second housing C32.

[0091] Then simply unscrew screw 41 from cylinder C31.

[0092] Preferably, at least one of the steps E1 in manufacturing the main body C1, E30 in manufacturing the first shell C30, E32 in manufacturing the second shell C32, and E31 in manufacturing the cylindrical part C31 is an injection molding step, and preferably all steps are injection molding steps.

[0093] According to an advantageous embodiment, the first housing C30 and the body C1 of the hydraulic press originate from the same injection molding step E130 in order to form the same part.

[0094] According to another advantageous alternative, the second housing C32 and the main body C1 of the hydraulic press originate from the same injection molding step E132, so as to form the same part. For example... Figure 7 As shown, the first housing C30 then includes a bend C300 that allows the outlet 11 of the hydraulic press to be connected to the downstream portion of the first venturi tube.

[0095] Preferably, the injection molding step uses a material selected from polypropylene, polyamide, and polyvinylidene fluoride.

[0096] Even more preferably, the material selected from polypropylene, polyamide, and polyvinylidene fluoride is filled with reinforcing fibers, and preferably polypropylene filled with 30% glass fiber.

[0097] Therefore, the proportional metering pump according to the present invention has a simplified design and assembly.

[0098] The assembly operation first involves assembling all the components that contribute to the reciprocating motion in the main body C1.

[0099] The membrane 33 and the closing device 32 are then mounted on the second housing C32. The membrane can advantageously be molded over the closing device 32.

[0100] Then the first housing C30 and the second housing C32, along with the main body of the machine C1, are assembled in pairs via a threaded connection or another equivalent operation.

[0101] When the main body of the hydraulic press is formed as a single component with the first housing or the second housing, it is only necessary to assemble the first housing and the second housing.

[0102] The device is sealed by a set of seals 37, which are positioned during the assembly of the pump's various components.

[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 press, thereby giving the pump good compactness.

[0104] Clearly, the design of the proportional metering pump is simpler and more compact than that proposed in document WO2014 / 111770 A1, which requires at least one first fixed support for the first venturi tube, one second fixed support for the hydraulic press, and two lines for connecting the first venturi tube to the hydraulic press.

[0105] Injection molding also allows for the direct acquisition of the housing and the main body of the hydraulic press, while minimizing the number of parts.

[0106] It should be noted that various features, shapes, variations and embodiments of the present invention can be associated with each other in various combinations, as long as they are not incompatible or mutually exclusive.

Claims

1. A proportional metering pump for adding an additive to a main liquid, having an inlet (E) and an outlet (S), and comprising: - Measuring mechanism (2), which is equipped with a device for extracting additives stored in the reservoir, - A hydraulic press (1), defined by a body (C1) having an inlet (10) and an outlet (11) respectively connected to the inlet and outlet of the pump, and including a component (16) capable of performing reciprocating motion, wherein supplying main fluid to the pump at the inlet triggers the reciprocating motion of the component (16), such motion alternately causing the additive to be drawn into the hydraulic press when the suction device is open, and then discharged at the outlet (11) of the hydraulic press when the suction device is closed. -A device (3) for controlling the pressure loss of the pump based on the flow rate at the pump inlet. The device (3) is provided with a first venturi tube (30), which is connected in parallel with the hydraulic press to the inlet and outlet of the pump. The device (3) further includes: a closing device (32) for closing the throat (301) of the first venturi tube, the closing device (32) being slidably mounted in the throat to control its flow cross-section; and devices (31, 33, 35, 36) sensitive to pressure loss in the pump, the devices (31, 33, 35, 36) being capable of controlling the sliding of the closing device to reduce the flow cross-section when the pressure loss in the pump increases and / or the flow rate decreases, and to increase the flow cross-section when the pressure loss in the pump decreases and / or the flow rate increases. - Characterized in that, at the end of the step (E30) of manufacturing the first housing, the first venturi tube (30) is formed inside the first housing (C30), while the device (31, 33, 35, 36) sensitive to pressure loss in the pump is installed in the second housing (C32), the first housing (C30) and the second housing (C32) and the body (C1) of the hydraulic press are assembled together with each other.

2. The proportional metering pump according to claim 1, characterized in that, The device sensitive to pressure loss in the pump includes: a second venturi tube (31) installed on a first line (39) connecting the inlet (E) of the pump to the inlet of the hydraulic press; and a pressure comparison device (33, 35, 36) for comparing the pressure at the throat (301) of the first venturi tube (30) with the pressure at the throat (311) of the second venturi tube (31).

3. The proportional metering pump according to claim 2, characterized in that, At the end of step (E32) of manufacturing the second housing (C32), the second venturi tube (31) and the first pipeline (39) are formed.

4. The proportional metering pump according to claim 2, characterized in that, At the end of the manufacturing step (E31), the second Venturi tube (31) is formed inside the cylinder (C31), which is designed to be inserted into the second housing (C32) through an opening (C320).

5. The proportional metering pump according to claim 4, characterized in that, The opening (C320) is closed by a device constituting a cover (4), the cover including an annular member (40) threaded to the second housing (C32), and a screw (41) passing through the annular member to the stop face (42) and threaded to the cylinder (C31), such that unscrewing the annular member removes the screw and the cylinder assembled with the screw.

6. The proportional metering pump according to any one of claims 2 to 5, characterized in that, The pressure comparison device (33, 35, 36) includes a first chamber (36) formed inside the first housing (C30) at the end of the step (E30) of manufacturing the housing, and a second chamber (35) formed inside the second housing (C32) at the end of the step (E32) of manufacturing the housing; the first chamber is in fluid communication with the throat (301) of the first venturi tube and is sealed to the second chamber (35) by a movable separation device (33), the second chamber (35) being in fluid communication with the throat (311) of the second venturi tube, and the closing device (32) being fixed to the movable separation device such that deformation of the closing device causes the closing device to slide by a stroke, which allows the flow cross-section of the throat of the first venturi tube to be increased or decreased.

7. The proportional metering pump according to claim 6, characterized in that, The movable separation device (33) includes a membrane.

8. The proportional metering pump according to any one of the preceding claims, characterized in that, At least one of the steps of manufacturing the main body (C1) (E1), manufacturing the first shell (C30) (E30), manufacturing the second shell (C32) (E32), and manufacturing the cylindrical part (E31) is an injection molding step.

9. The proportional metering pump according to claim 8, characterized in that, The first housing (C30) and the body (C1) of the hydraulic press are produced from the same injection molding step (E130) to form the same part.

10. The proportional metering pump according to claim 8, characterized in that, The second housing (C32) and the body (C1) of the hydraulic press are produced from the same injection molding step (E132) to form the same component.

11. The proportional metering pump according to any one of claims 8 to 10, characterized in that, The injection molding step uses materials selected from polypropylene, polyamide, and polyvinylidene fluoride.

12. The proportional metering pump according to claim 11, characterized in that, The material is selected from polypropylene, polyamide, and polyvinylidene fluoride and filled with reinforcing fibers, and preferably polypropylene filled with 30% glass fiber.

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

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

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