EP3063406B1 - Membrane pump and valve device for such a pump - Google Patents

Description

• un raccord d'aspiration et un raccord de refoulement du fluide à pomper,
• un clapet d'aspiration et un clapet de refoulement associés respectivement aux raccords d'aspiration et de refoulement,
• une chambre de commande dans laquelle est disposée la membrane, et une chambre de travail située du côté de la membrane opposé à la chambre de commande,
• un conduit de commande propre à relier la chambre de commande à un raccord de commande du corps, ce conduit de commande permettant d'appliquer alternativement une dépression et une pression sur la membrane.

The invention relates to a diaphragm pump of the type comprising a body which comprises:

• a suction connection and a discharge connection for the fluid to be pumped,
• a suction valve and a discharge valve associated respectively with the suction and discharge connections,
• a control chamber in which the membrane is placed, and a working chamber located on the side of the membrane opposite to the control chamber,
• a control duct suitable for connecting the control chamber to a control connection of the body, this control duct making it possible to apply alternately a vacuum and a pressure on the membrane.

A diaphragm pump of this type is known in particular from WO 2012/063184 of the Applicant Company. The diaphragm pump is installed at the lower end of a metering pump having a reciprocating hydraulic motor which operates the diaphragm pump to inject an additive into a main stream of liquid.

In such a pump, the membrane constitutes a relatively fragile component which must be able to be replaced from time to time. It is therefore desirable that the operation of disassembling and replacing the diaphragm be as simple as possible, with a minimum of impact on the other components of the pump.

We also know from FR 2 313 578 a diaphragm pump with valves installed on a plate, the diaphragm being controlled by the core of an electromagnet and not by the alternating application of vacuum and pressure. But, here again, disassembly of the diaphragm requires disassembly of several pump components.

In addition, it is important that the design of the diaphragm pump allows to reduce the dead volume that exists between the diaphragm in the rest position, or start of suction, and the discharge valve, to facilitate self-priming of the pump. the pump.

It is also known from the document US 5803122 A1 , a diaphragm valve for a high speed piston pump comprising a valve seat defining at least one channel for the fluid to be passed through. The channel includes a support disposed therein. A diaphragm extends over the canal and is biased to a closed position by a raised lip on the valve seat. A valve face recessed below the diaphragm is formed such that the fluid exerts a forward force on an area of the diaphragm which is greater than the cross-sectional area of the channel. The holder in the channel supports the diaphragm during the reverse cycle of fluid flow. The valve is therefore durable and consumes a minimum amount of energy.

The object of the invention is above all to provide a diaphragm pump which meets the requirements mentioned above better than hitherto and which is of a simple and reliable construction.

WO 2008/031419 a diaphragm pump of the type in question, in which the body has a housing open towards the outside at one end, and closed at its other end by a bottom comprising a suction port and a discharge port, the diaphragm being located near the bottom, or against the bottom, and being held by a stopper engaged in the housing, this stopper having, at its end facing the membrane, a recess constituting the control chamber.

According to the invention, a diaphragm pump, comprising the elements defined above, is characterized in that the housing is oriented transversely, preferably at right angles, relative to the control duct, the recess constituting the control chamber is connected to a passage which opens onto the lateral surface of the plug to establish communication with the control duct, and the plug is held in place in the housing by a ring linked, in particular by a thread, with the body of the pump and comprising a stopper retaining means.

In such a pump, the cap can be removed by simple translation after removing the ring retaining this cap, which allows access to the membrane and to replace it if necessary without having to intervene on the other elements of the pump. The cap is put in place by a simple translational movement.

Preferably, the pump comprises a valve device which comprises a plate in which the suction valve and the discharge valve are mounted, the plate supporting the membrane and being held against the bottom of the housing by the stopper.

The set of valves installed on the plate, and of the diaphragm, constitutes an interchangeable device which can be removed after removing the cap and replaced by a new set without intervention on the other components of the pump.

A suction port and a discharge port are provided in the bottom of the housing facing the corresponding valves carried by the plate. A sealing ring, mounted on the plate around each valve, is provided to ensure the seal between the plate and the pump body. The plate is crossed, at the level of the suction and discharge openings, by at least one channel for the flow of the fluid. Preferably, a single channel is provided at the level of the discharge orifice to reduce the dead volume between the diaphragm and the discharge valve.

The plate can be snapped onto the end of the stopper, in particular using elastic tabs provided on the stopper.

The suction and delivery valves are advantageously constituted by umbrella type valves, having a core engaged in an orifice of the plate and a flexible flange, or cap, closing the channel or channels passing through the plate. The valves can be in contact with the diaphragm when the pump is at rest or at the end of delivery, so that the dead volume between diaphragm and delivery valve is minimum. As a variant, the suction and discharge valves could be constituted by valves in the form of a duckbill comprising two flexible lips pressing against each other in a V-shaped configuration, the tip of which is turned in the direction. fluid flow.

Also in a variant, the suction and delivery valves, of the umbrella type or in the shape of a duckbill, can be arranged in housings of the pump body, and the membrane is applied directly against the bottom of the housing, without being placed. on a plate.

The angle formed between the geometric axes of the suction and discharge connections is preferably greater than 90 °, and in particular equal to 135 °. Advantageously, the geometric axis of the suction connection is parallel to the geometric axis of the control duct, while the geometric axis of the delivery connection forms an angle of 45 °, or close to this value, with the axis geometry of the control duct.

The stopper may have a surface comprising a cylindrical part and a frustoconical base suitable for pressing against a conjugated frustoconical surface of the housing, the passage provided in the stopper for connection to the control duct opening in this frustoconical part and coming opposite of the control duct, a keying means being provided on the lateral surface of the plug to cooperate with a conjugate keying means of the housing in order to ensure the proper positioning of the passage relative to the control duct.

The keying means may consist of a rib provided on the lateral surface of the stopper to cooperate with a corresponding groove provided in the housing.

The sealing of the connection between the passage of the plug and the control duct is advantageously ensured by a sealing ring, in particular an O-ring, surrounding the outlet of the passage on the frustoconical oblique surface.

This ring is preferably housed in a circular groove provided on the oblique surface of the stopper. This arrangement with an oblique surface makes it possible to reduce the risk of damage to the sealing ring, in particular by pinching, during assembly, and of the translational engagement of the plug in the housing.

Advantageously, the passage provided in the stopper to connect the control chamber to the control duct extends over a length greater than the radius of the stopper to reduce the risk of interrupting the suction by sticking the membrane against the bottom of the control chamber.

Advantageously, the diaphragm pump as defined above comprises a valve device comprising the plate in which the suction valve and the discharge valve are mounted, in particular valves having a cap in the form of an umbrella and a core housed in an orifice in the plate, said plate supporting the membrane. This valve device constitutes an interchangeable assembly for a diaphragm pump. A diaphragm pump according to the invention is advantageously installed in the lower part of a proportional metering device as described in WO 2012/063184 , comprising a metering body with a main liquid inlet and an outlet, a hydraulic motor housed in the body and actuated by the main liquid, the motor driving a plunger which provides suction during a forward stroke transmitted by the duct to the control chamber of the diaphragm pump, and a discharge, pushing the diaphragm, when the plunger makes a return stroke.

Such a proportional metering device, operating without electricity, allows an injection of auxiliary liquid delivered by the diaphragm pump.

Advantageously, the control connector of the diaphragm pump comprises, for the retention of the pump to the metering device, a clip snapped onto the connector, and a means of connection to the metering device, in particular a nut, retained axially by said clip.

• Fig. 1 est une coupe verticale d'une pompe à membrane selon l'invention, le plan de coupe passant par les axes géométriques des différents raccords et du logement prévu pour la membrane.
• Fig. 2 est une vue en perspective éclatée du bouchon, de la membrane, de la plaque, des clapets-ombrelles et des bagues d'étanchéité.
• Fig. 3 est une vue en perspective de la plaque, du côté tourné vers la membrane.
• Fig. 4 est une vue en perspective extérieure de la pompe.
• Fig. 5 est une vue en coupe partielle, à plus petite échelle, de la pompe selon Fig. 1 installée en partie inférieure d'un doseur proportionnel, en fin de course d'aspiration.
• Fig. 6 montre, semblablement à Fig. 5, la pompe à membrane en fin de course de refoulement.
• Fig. 7 montre, semblablement à Fig. 1, à plus petite échelle, une variante de la pompe à membrane avec clapets d'aspiration et de refoulement en bec de canard.
• Fig. 8 est une perspective en extérieur de la pompe de Fig. 7.
• Fig. 9 est une vue en coupe avec partie en extérieur, à plus petite échelle, de la pompe de Fig. 7 installée en partie inférieure d'un doseur proportionnel, qui se trouve en fin de refoulement.
• Fig. 10 une vue extérieure de la pompe à membrane de Fig.1, avec partie coupée au niveau du raccord de commande selon la ligne X-X de Fig.11.
• Fig.11 est une vue de dessus de la pompe de Fig.10 selon la ligne XI-XI de Fig.10, et
• Fig.12 est une perspective en extérieur de la pompe de Fig.10, l'agrafe étant écartée du raccord.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be dealt with more explicitly below with regard to exemplary embodiments described with reference to the accompanying drawings, but which are not in no way limiting. On these drawings:

• Fig. 1 is a vertical section of a diaphragm pump according to the invention, the section plane passing through the geometric axes of the various fittings and of the housing provided for the membrane.
• Fig. 2 is an exploded perspective view of the plug, diaphragm, plate, umbrella valves and sealing rings.
• Fig. 3 is a perspective view of the plate, from the side facing the membrane.
• Fig. 4 is an exterior perspective view of the pump.
• Fig. 5 is a partial sectional view, on a smaller scale, of the pump according to Fig. 1 installed in the lower part of a proportional metering unit, at the end of the suction stroke.
• Fig. 6 shows, similar to Fig. 5 , the diaphragm pump at the end of the delivery stroke.
• Fig. 7 shows, similar to Fig. 1 , on a smaller scale, a variant of the diaphragm pump with duckbill suction and delivery valves.
• Fig. 8 is an exterior perspective of the Fig. 7 .
• Fig. 9 is a sectional view with part outside, on a smaller scale, of the pump Fig. 7 installed in the lower part of a proportional metering device, which is located at the end of delivery.
• Fig. 10 an exterior view of the diaphragm pump Fig. 1 , with part cut off at the control connection according to line XX of Fig.11 .
• Fig.11 is a top view of the pump Fig. 10 along line XI-XI of Fig. 10 , and
• Fig. 12 is an exterior perspective of the Fig. 10 , the clip being moved away from the fitting.

Referring to Fig. 1 from the drawings, we can see a pump P with a diaphragm M comprising a body 1 provided with a suction connection 2 and a delivery connection 3.

A suction valve 4 and a discharge valve 5 are associated respectively with the suction 2 and discharge 3 connections.

The membrane M is placed in a control chamber 6 connected by a passage 7 to a control duct 8 making it possible to alternately apply a vacuum and a pressure in the chamber 6 and on the membrane M. The duct 8 is provided in a connection order 9.

The geometric axes of the connectors 2, 3 and 9, and of their respective pipes, are located in the same plane. Preferably, the pump P is used in the position shown in Fig. 1 , according to which the connection of control 9 is in the upper vertical part, the suction connection 2 is in the lower vertical part, and the delivery connection 3 is inclined upwards. The angle formed between the geometric axes of the pipes provided in the fittings 2 and 3 is greater than 90 °, preferably equal to 135 °, so that the angle A between the geometric axis of the pipe 8 and that of the fitting 3 is equal to 45 °.

A working chamber 10, visible on Fig. 5 , is located on the side of the membrane M opposite to the control chamber 6, the valves 4 and 5 making this chamber 10 communicate, either with the suction or with the discharge.

The body 1 comprises a housing 11 oriented transversely and, preferably, at right angles to the control duct 8. This housing 11 is provided in a cylindrical protuberance 12 of the body 1, on the side opposite to the delivery connection 3. The housing 11 is open at one end to the outside, and is closed at its other end by a bottom 13 comprising a suction port 14 connected to the pipe of the suction connector 2, and a discharge port 15 connected to the discharge connection pipe 3.

The membrane M is located near the bottom 13 and is held by a plug 16 engaged, by translation, without rotational movement, in the housing 11.

The control chamber 6 is provided at the inner end of the stopper 16 in the form of a bowl flared towards the membrane M. The passage 7 extends orthogonally to the geometric axis of the stopper 16 over a length greater than the radius of the cap 16, this passage 7 opening onto the lateral surface of the cap in line with the control duct 8.

The stopper 16 is held in position by a ring 17 linked to the protuberance 12 of the pump body, advantageously by a thread, in which case the ring 16 constitutes a nut. Other means for connecting the ring 17 to the protuberance 12 could be provided, for example in the form of ramps inclined in a helix.

The ring 17 comprises, at its end remote from the membrane M, a collar 18 projecting radially inwardly constituting a means for retaining the stopper 16 which comprises a peripheral rib 19 cooperating with the collar 18. The housing 11 comprises a part frustoconical intermediate 20 near the membrane M and whose diameter decreases in the direction of this membrane.

The stopper 16 has a conjugated frustoconical part 21 which is applied against part 20 when tightening cap 16 by ring 17.

To ensure correct positioning of the plug 16 in the housing 11, so that the passage 7 is in alignment with the pipe 8, keying means are provided between the plug 16 and the housing 11 to force the engagement of the plug. in the correct position. These D coding means include, as can be seen on Fig. 2 , a rib 22 forming a flat, projecting on the cylindrical outer surface of the stopper, able to cooperate with a corresponding groove, not visible, provided in the housing 11. Preferably, this rib 22 occupies the same angular position as the outlet of the passage 7.

The seal between the plug 16 and the body 1 at the outlet of the passage 7 is advantageously produced with a sealing ring 23, in particular an O-ring, in particular made of elastomeric material, housed in a groove 24 provided on the surface oblique of the frustoconical part. This arrangement of the seal 23 on an oblique surface makes it possible to reduce, if not eliminate, the risk of the seal pinching when the plug 16 is mounted by translation in the housing 1, at the level of the pipe 8.

According to the realization of Fig. 1 , the pump is equipped with a valve device comprising a plate 25 in which the suction valve 5 and the discharge valve 6 are mounted, advantageously made of elastomeric material. Each valve 5, 6 is of the umbrella valve type having a cap in the form of a flexible umbrella and a core engaged, and preferably retained by snap-fitting, in an orifice of the plate 25. The flexible cap of the suction valve 4 is facing the diaphragm M, while the cover of the discharge valve 5 faces the opposite side.

At least one channel 26, 27 passes through the plate in the area covered by the cap of the valve. As best seen on Fig. 2 , three channels 26 are provided to pass through the plate in the area of the seat of the cover of the suction valve 4, while a single channel 27 is provided in the area of the seat of the discharge valve 5. The presence of a only one channel 27 makes it possible to reduce the dead volume of air to be evacuated when the pump is primed, between the diaphragm M and the discharge valve 5.

The plate 25 supports the membrane M which has, at the periphery, a bead 28 received partly in a peripheral groove of the plate 25 and, for another part, in a peripheral groove at the end of the plug 16, surrounding the control chamber 6 The membrane M comprises a thicker central part 29 connected by an annular web 30 to the bead 28. The veil 30, at rest, at the end of delivery, has a section in the form of an arc of convex curve on the side of the valves. In this rest position of the membrane, the suction valve 4 is in contact, by its umbrella cap, with the membrane M, while the core of the discharge valve 5 is in contact with the web 30 so that the The dead space between diaphragm and valve is reduced to a minimum.

The seal between the plate 25 and the bottom of the housing, around the orifices 14 and 15, is ensured by means of sealing rings 31, 32, in particular O-rings of elastomeric material, housed in annular grooves provided in the plate 25, to surround the valves and the orifices 14, 15. The device formed by the plate 25, the valves 4 and 5 and the membrane M constitutes an interchangeable assembly which can be easily dismantled and replaced, after removal of the stopper 16 and extraction in translation to the left according to Fig. 1 , without intervention at the level of the other connections.

The reduction, or even the elimination, of the dead volume between the diaphragm M and the valves, in particular the delivery valve 5, allows self-priming of the diaphragm pump.

This mounting on a plate, with lateral introduction into the housing 11, with mounting and tightening of the membrane using the cap 16 and a ring-nut 17 greatly simplifies the mounting.

Advantageously, as illustrated on Fig. 2 , the stopper 16 comprises elastic tabs 33 forming staples, preferably diametrically opposed, in an angular position offset by a quarter of a turn with respect to the rib 22. The tabs 33 allow the stopper 16 to be hooked to the plate 25, by snap-fastening of spouts provided in internal projection of the clips 33 in corresponding housings 34 provided at the periphery of the plate 25 in the form of a disc. The valve 4 is placed on the plate 25 by introduction from the side of the membrane, while the valve 5 is put in place from the opposite side.

The realization according to Fig. 2 is particularly advantageous because the extraction of the plug 16 after unscrewing the ring 17 makes it possible to remove the whole of the plate 25, the membrane M and the valves. The plate 25, which was used, can be replaced by a new plate equipped with a membrane M and new valves 4, 5.

The plate 25 can be easily declined in different materials, and in particular in fluorinated materials to prevent deposits and improve the chemical resistance. The plate 25 can also be made of ceramic in the case of products to be pumped, which would have an abrasive character.

The elastomeric valves 4, 5 allow design versatility by changing the materials, in particular to resist oxidizing products with a high chlorine content.

Fig. 3 shows, in perspective, the plate 25 seen from the side facing the membrane, which is not shown. The umbrella cap of the suction valve 4, located on the membrane side, is visible on Fig. 3 , while only the core of the discharge valve 5 is visible.

Fig. 4 is an exterior perspective view of the pump Fig. 1 .

Fig. 5 represents, on a smaller scale, in vertical section, with part on the outside, the pump P of Fig. 1 mounted at the lower end of a proportional metering device J of an auxiliary liquid pumped into a tank not shown, by a pipe 35 connected to the suction connection 2 of the pump P. The pumped auxiliary liquid is injected into a main liquid which enters the body 36 of the metering device through an inlet 37 and which is discharged through an outlet 38 on which is mounted a connector 39. A hydraulic motor, not visible, is housed in the body 36, generally arranged vertically. The motor, operated by the main liquid, may be of the type described in the patent. EP 1971774 B1 in the name of the Applicant Company. The hydraulic motor is connected to a plunger 40, vertical according to the arrangement of Fig. 5 , to drive it in a reciprocating rectilinear motion. The plunger 40 moves in a cylindrical chamber 41, the lower end of which is connected to the control connection 9 so that the pressure variations in the chamber 41 are transmitted to the control duct 8.

A suction phase corresponds to the upstroke, according to Fig. 5 , or outward stroke, of the plunger 40 which creates a vacuum in the chamber 41 as well as in the pipe 8 and in the control chamber 6 of the pump P. The suction valve 4 opens so that the auxiliary liquid can be sucked into the working chamber 10, while the discharge valve 5 closes. At the end of the upward stroke of the piston 40, as shown in Fig. 5 , the membrane M is applied against the walls of the control chamber 6 and the working chamber 10 has reached its maximum volume.

The discharge connection 3 is connected by a flexible pipe 42 to a transverse extension 43, directed vertically downwards, of the connection 39. The inclination at 45 °, or at an angle close to this value, of the axis geometry of the connector 3 with respect to the geometric axis of the pipe 8 makes it possible to give the pipe 42 a simple shape comprising a rectilinear part followed by a curved arc with a large radius of curvature for the connection to the extension 43.

Fig. 6 represents, similarly to Fig. 5 , the whole of the proportional metering unit J and the pump P at the end of the delivery phase, the plunger 40 being at the end of the downward stroke. The pressure of the liquid in the control duct 8 and in the control chamber 6 having increased, the membrane M was pushed back to the right according to Fig. 6 by causing the exit of the auxiliary liquid (which had been sucked in during the previous phase) through the discharge valve 5. The auxiliary liquid is evacuated towards the pipe 42 and its mixture with the main liquid takes place at the level of the connection 39 The suction valve is closed and prevents a return to the suction line 35. At the end of the discharge, the membrane M is applied against the plate 25, depending on the configuration of the Fig. 6 and 1 .

Fig. 7 is a vertical section, similar to Fig. 1 , of a variant embodiment Pa of the diaphragm pump. The elements of this variant identical, or similar in their functions, to elements already described in connection with Fig. 1 , will be designated by the same references, possibly followed by the letter a, and their description will not be repeated or will only be given briefly.

According to this variant, the suction and discharge valves 4a, 5a are duckbill, that is to say in the shape of an inverted V for the suction valve 4a and inclined for the discharge valve 5a. The tip of the V-shaped valves is oriented in the direction of flow of the liquid. These valves comprise flexible lips which apply against each other to form the inverted or inclined V, and allowing passage of the liquid coming from the concavity of the V, and preventing circulation in the opposite direction.

According to a variant not shown, the duckbill valves 4a, 5a can be mounted on a plate similar to the plate 25 of Fig. 1 .

Depending on the variant of Fig. 7 , the suction valve 4a is installed in a housing 14a of the pump body 1a, communicating with the working chamber 10. The discharge valve 5a is installed at the inlet of the discharge connection 3a, downstream of the pressure chamber. work and at the outlet of an inclined pipe 44 communicating the work chamber with the pipe of the connector 3a.

According to this variant, the diaphragm M at the end of the delivery or in the rest position of the pump is applied directly against the bottom 13a of the housing of the pump body.

The cap 16a similar to the cap 16 of Fig. 1 comprises a central longitudinal well 45 with central partition 46 provided to facilitate the extraction of the plug 16 after removal of the nut 17.

Fig. 8 is a perspective view of the exterior of the Pa pump from Fig. 7 .

The operation of the Pa variant of Fig. 7 is similar to that described in connection with the previous figures.

When a vacuum is created in the control duct 8, the membrane M deforms to the left of Fig. 7 causing an increase in the volume of the working chamber and a suction of an auxiliary liquid through the valve 4a which opens under the effect of the vacuum while the valve 5a remains closed.

When the pressure increases in line 8, the membrane M is pushed to the right according to Fig. 7 and causes the liquid to exit from the working chamber towards the pipe 44, through the discharge valve 5a which opens, while the suction valve 4a remains closed and opposes a return of the liquid in the fitting 2a.

Fig. 9 shows, similar to Fig. 6 , the pump Pa installed in the lower part of a proportional metering device J, while the plunger 40 is at the end of its downstroke and the diaphragm M is at the end of the discharge stroke by being applied against the bottom 13a of the housing.

Fig. 10-12 illustrate an advantageous embodiment of the control connection 9 to ensure the maintenance of the pump P at the lower end of the proportional metering device J, as shown in Fig. 5 and 6 . Elements identical or similar to elements already described are designated by the same references without their description being repeated in detail.

The connector 9 comprises, near its free end on its periphery, a groove 48 in which is mounted a sealing ring 49, in particular an O-ring. The lower end of the proportioner J, as visible on Fig. 6 , has a bore in which the connector 9 with the ring 49 is sealingly engaged.

A nut 50 is mounted to rotate freely around the connector 9. The nut 50 is retained, in the axial direction, by an open clip 51 comprising a substantially U-shaped housing with tightened ends. The staple 51 which can be made of plastic, has a certain elasticity to snap into a groove 52 of the outer wall of the connector 9. The groove 52 has two diametrically opposed flats 53 against which the branches of the U of the 'clip 51 after installation. The clip 51 has a circular outer edge, and constitutes a means for axially retaining the nut 50. This nut comprises a flange 54 projecting radially inwardly capable of abutting against the clip 51. The nut 50 can be moved in translation behind the clip 51.

The lower end of the metering unit J comprises, on its periphery, a thread onto which the nut 50 is screwed to hold the pump P on the metering unit J. This construction makes it possible to easily produce a rotating connection 9, sealed with a single watertight ring.

Whatever the embodiment adopted, the assembly and disassembly of the diaphragm M are carried out quickly and easily, without having to intervene on the other elements of the pump. The priming of the pump is facilitated by the reduction of the dead volume between the diaphragm and the valves, in particular the discharge valve.

Claims (18)

1. A diaphragm pump (M) of the type comprising a body (1, 1a) which comprises:

   - a suction connection (2) and a connection (3) for discharge of the fluid to be pumped, a suction valve (4) and a discharge valve (5) which are associated respectively with the suction and discharge connections;

   - a control chamber (6) in which the diaphragm (M) is disposed, and a working chamber (10) which is situated on the side of the diaphragm opposite the control chamber;

   - a control pipe (8) which can connect the control chamber (6) to a control connection (9) of the body, this control pipe making it possible to apply alternately partial vacuum and pressure on the diaphragm;

   - the body (1, 1a) comprising a receptacle which is open towards the exterior at one end, and is closed at its other end by a base (13, 13a) comprising a suction orifice (14, 14a) and a discharge orifice (15, 15a), the diaphragm (M) being situated in the vicinity of the base, or against the base, and being retained by a cap (16, 16a) which is engaged in the receptacle, this cap having, at its end which faces towards the diaphragm, a recess which constitutes the control chamber (6),

   characterized in that the receptacle (11) is oriented transversely, and preferably at right-angles relative to the control pipe (8), the recess which constitutes the control chamber (6) is connected to a passage (7, 7a) which opens onto the lateral surface of the cap, in order to establish communication with the control pipe (8), and the cap (16, 16a) is retained in place in the receptacle by a ring (17), which is connected, in particular by means of a thread, to the body of the pump, and comprising a means (18) for retention of the cap.
2. The pump as claimed in claim 1, characterized in that it comprises a valve device which comprises a plate (25) in which the suction valve (4) and the discharge valve (5) are fitted, with the plate supporting the diaphragm (M), and being retained against the base (13) of the receptacle by the cap (16) .
3. The pump as claimed in claim 2, characterized in that a suction orifice (14) and a discharge orifice (15) are provided in the base of the receptacle (13) opposite the corresponding valves which are supported by the plate, and a sealing ring (31, 32) is fitted on the plate around each valve, in order to ensure the sealing between the plate and the pump body
4. The pump as claimed in claim 2 or 3, characterized in that at least one channel (26, 27) for flow of the fluid passes through the plate (25) at the suction and discharge orifices, and preferably a single channel (27) is provided at the discharge orifice (15), in order to reduce the dead volume between the diaphragm and the discharge valve.
5. The pump as claimed in any one of claims 2 to 4, characterized in that the plate (25) is snapped onto the end of the cap (16), in particular by means of resilient lugs (33) which are provided on the cap.
6. The pump as claimed in any one of claims 2 to 5, characterized in that the suction (4) and discharge (5) valves are constituted by valves of the umbrella type with a core engaged in an orifice in the plate (25), and a flexible flange or cover which closes the channel(s) (26, 27) which pass(es) through the plate.
7. The pump as claimed in claim 6, characterized in that the valves (4, 5) are in contact with the diaphragm (M) when the pump is at rest or at the end of discharge, such that the dead volume between the diaphragm and the discharge valve is minimum.
8. The pump as claimed in any one of claims 2 to 5, characterized in that the suction (4a) and discharge (5a) valves are constituted by valves in the form of a duckbill comprising two flexible lips which are applied against one another according to a configuration in the form of a "V", the tip of which faces in the direction of flow of the fluid.
9. The pump as claimed in any one of claims 1 to 8, characterized in that the suction and discharge valves of the umbrella type or in the form of a duckbill are disposed in receptacles in the pump body, and the diaphragm (M) is applied directly against the base (13a) of the receptacle.
10. The pump as claimed in any one of the preceding claims, characterized in that the geometric axis of the suction connection (2, 2a) is parallel to the geometric axis of the control pipe (8), whereas the geometric axis of the discharge connection (3, 3a) forms an angle (A) of 45°, or close to this value, with the geometric axis of the control pipe (8).
11. The pump as claimed in any one of the preceding claims, characterized in that the cap (16, 16a) has a surface comprising a cylindrical part and a frusto-conical part (21, 21a) which can be applied against a conjugated frusto-conical surface (20) of the receptacle, with the passage (7, 7a) provided in the cap for connection to the control pipe opening in this frusto-conical part, and being opposite the control pipe.
12. The pump as claimed in claim 11, characterized in that a means (D) for polarization is provided on the lateral surface of the cap in order to cooperate with a means for polarization which is conjugated with the receptacle, in order to ensure the appropriate positioning of the passage (7, 7a) relative to the control pipe (8).
13. The pump as claimed in claim 11 or 12, characterized in that the sealing of the connection between the passage (7, 7a) of the cap and the control pipe (8) is ensured by a sealing ring (23), in particular an O-ring seal, which surrounds the output of the passage on the frusto-conical oblique surface.
14. The pump as claimed in claim 13, characterized in that the ring (23) is accommodated in a circular groove provided (24) in the oblique surface of the cap (16).
15. The pump as claimed in any one of the preceding claims, characterized in that the passage (7, 7a) which is provided in the cap (16, 16a) in order to connect the control chamber (6) to the control pipe (8) extends along a length which is longer than the radius of the cap, in order to reduce the risk of interruption of the suction by adhesion of the diaphragm against the base of the control chamber.
16. The diaphragm pump as claimed in any one of claims 1 to 15, characterized in that it is installed in the lower part of a proportional metering device (J), comprising a metering device body (36) with a main liquid input (37) and an output (38), a hydraulic motor which is accommodated in the body and is activated by the main liquid, the motor driving a plunger piston (40) which ensures suction during an outward course which is transmitted by the control pipe (8) to the control chamber (6) of the diaphragm pump, and a discharge, which thrusts the diaphragm when the plunger piston carries out a return course.
17. The pump as claimed in any one of claims 1 to 16, characterized in that, for the retention of the pump on a metering device, the control connection (9) of the pump comprises a clamp (51) snapped onto the connection, and a means for connection to the metering device, in particular a nut (50), which is retained axially by said clamp.
18. A diaphragm pump as claimed in claim 7, characterized in that it comprises a valve device comprising the plate (25) in which the suction valve (4) and the discharge valve (5) are fitted, which have a cover in the form of an umbrella and a core which is accommodated in an orifice in the plate, said plate supporting the diaphragm (M), at least the channel (26, 27) passing through the plate in the area covered by the cover of the valve, the diaphragm M having on its periphery a rim 28 which is received partly in a peripheral throat in the plate 25, and also partly in a peripheral throat at the end of the cap 16, surrounding the control chamber 6 of the pump, the diaphragm (M) comprising a thicker central part 29, which is connected by an annular ring 30 to the rim 28, the ring 30 at rest and at the end of the displacement having a curved-arc-shaped section of a convex curve on the side of the valves.

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