EP2617997B1 - Diaphragm failure detection device for a hydraulically driven pump. - Google Patents

Description

The invention relates to a device for detecting the rupture of a diaphragm of a hydraulically actuated pump. The invention also relates to a method of mounting such a device on a pump and a pump equipped with such a device.

BACKGROUND OF THE INVENTION

Hydraulically actuated pumps preferably comprise at least two membranes. See FR 2533636 which describes a device for detecting the rupture of such membranes. It is possible to detect in a simple way the rupture of one of the two membranes, by monitoring the pressure prevailing in the space existing between the two membranes.

Hydraulically actuated diaphragm pumps are thus known comprising a composite membrane which comprises between two thin membranes, a thick intermediate membrane in the form of an elastically deformable arch. The pump comprises a duct formed in the thickness of the intermediate membrane which has an end which opens out of the pump and an end connected to at least one drainage channel. The drainage channel is also formed in the thickness of the intermediate membrane to connect to the conduit the spaces extending between each of the faces of the intermediate membrane and the thin membrane opposite. Usually, a device for detecting a rupture of the membrane is implanted at the outlet of the conduit of the intermediate membrane.

However, it turns out that the thin membranes are not always perfectly adjusted on the intermediate membrane. Or the presence of air filling the space between each thin membrane and the intermediate membrane greatly degrades the performance of the pump. This disadvantage is further increased for a small flow pump.

It is therefore necessary to evacuate the air thus trapped between the thin membranes and the intermediate membrane. It is known various so-called degassing processes for purging this air during a start-up phase of the pump.

An example of such a degassing process consists in a first step of injecting, for example by means of a syringe, oil at the level of the conduit of the intermediate membrane. The oil then fills the drainage channel and the gap between the thin membranes and the intermediate membrane.

In a second step, this oil is sucked by means of the syringe, thereby partially entraining air which was trapped between the thin membranes and the intermediate membrane.

In a third step, the detection device is mounted on the pump and the pump is started with a progressive loading which has the effect of expelling the air still present between the thin membranes and the intermediate membrane under the effect of pressure prevailing on both sides of the composite membrane.

However, such a degassing process proves long and delicate.

To overcome this drawback, it is known to implant at the outlet of the conduit of the intermediate membrane an automatic degassing system before implanting the device for detecting rupture of a membrane.

However, such a system is extremely expensive and complex to use.

OBJECT OF THE INVENTION

An object of the invention is to provide a means for improving the degassing process of a hydraulically actuated pump.

BRIEF DESCRIPTION OF THE INVENTION

• un corps creux dans lequel une première chambre est ménagée à une première extrémité du corps, un conduit reliant la première chambre à une deuxième extrémité du corps ;
• un clapet anti-retour disposé dans le conduit pour être passant dans le sens de la deuxième extrémité du corps vers la première chambre.

For this purpose, there is provided a device for detecting the rupture of a membrane of a hydraulically actuated pump, comprising:

• a hollow body in which a first chamber is provided at a first end of the body, a duct connecting the first chamber to a second end of the body;
• a non-return valve disposed in the conduit to be passed in the direction of the second end of the body to the first chamber.

According to the invention, the device comprises a piston mounted to move in translation in the hollow body, the piston comprising a first portion which cooperates sealingly with the first chamber and which is traversed by a bore of diameter greater than the diameter of a ball free of the non-return valve and a second portion which is adapted to cooperate sealingly with the first portion to form a closed end of the piston opposite to the second end of the body.

It is thus possible to arrange from the beginning the rupture detection device on a hydraulically actuated pump and to degas the pump directly from said device. This greatly simplifies the degassing process of the pump.

Indeed, in a first step, the device according to the invention is arranged on the pump without the free ball of the non-return valve and the second portion of the piston. Then, the oil necessary for the degassing of the pump is poured directly through the first portion of the piston. The oil then escapes to the pump through the hollow body duct.

In a second step, the first portion of the piston is closed for example by the second portion of the piston. The piston is then raised and lowered in successive phases in the first chamber which allows to drive a portion of the air that was trapped in the pump at the membrane.

In a third step, the second portion of the piston is removed. The free ball of the non-return valve is inserted into the bore of the first portion so as to naturally be placed on a seat of the non-return valve. The second portion of the piston is then arranged on the first portion to close the end of the piston. The pump is then started with a progressive loading which has the effect of expelling the air still present in the pump at the level of the membrane.

The device according to the invention thus makes it possible to ensure a phase of filling the pump with the oil necessary for degassing and to ensure a degassing phase in addition to ensuring a rupture detection of a membrane.

Advantageously, the fact of keeping a single device for filling, degassing and detection makes it possible to maintain a slight depression in the first chamber of the hollow body. A small portion of the air trapped in the pump at the membrane is thus discharged continuously which increases the efficiency of the degassing process by the device according to the invention.

According to a preferred embodiment, a second chamber is formed in the hollow body between the first chamber and the conduit, the second chamber having a diameter greater than the diameter of the first portion of the piston.

In this way, once the first step and the second step described above have been performed, the second portion of the piston is removed and the first portion of the piston lowered at the level of the second chamber. The free ball of the non-return valve is then inserted into the bore of the first portion so as to naturally be placed on the seat of the non-return valve. The second portion of the piston is then arranged on the first portion so as to close the end of the piston. The piston is then raised to cooperate sealingly with the first chamber, which has the effect of causing a depression in the first chamber and the second chamber. The air still present in the pump at the level of the membrane is thus expelled into said chambers in a natural manner. It is no longer necessary to interrupt a degassing process by stopping the start of the pump since the air is driven continuously from the membrane to the device according to the invention.

Thus, the degassing of the pump by the device according to the invention is even more effective.

Even more preferably, the piston comprises a stop intended to cooperate with the first chamber to stop a stroke of the piston before the first portion of the piston enters the second chamber.

In this way, when the piston is raised, the first portion of the piston is kept in sealed contact with the first chamber which maintains the depression in the hollow body. The degassing is thus carried out continuously without an operator or additional system maintaining the piston in sealed contact with the first chamber which further improves the degassing process.

Indeed, in the prior art, the degassing process is interrupted when an operator considers that the air trapped between the thin membranes and the intermediate membrane has been completely expelled. The operator uses the flow rate of the pump to make this evaluation and it is common to note that several identical pumps commissioned by different operators offer different flow rates depending on when operators have interrupted the degassing process. Flow differentials of 10% to 15% have thus been observed. This disadvantage is further increased for low flow pumps.

With the device of the invention, identical pumps operated by different operators offer much closer flows, the degassing process being continuous through the maintenance of a vacuum in the hollow body. The flow differences are then less than 5%.

The invention also relates to a method of mounting such a device on a pump and a pump equipped with such a device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood in the light of the following description of a particular non-limiting embodiment of the invention.

• la figure 1 est une vue en coupe partielle schématique d'une pompe à membrane équipée d'un dispositif selon l'invention ;
• les figures 2a, 2b, 2c, 2d, 2e, 2f sont des vues en coupe partielle schématique du dispositif illustré à la figure 1 au cours de ses différentes phases de montage sur la pompe ;
• les figures 3a et 3b sont des vues schématiques en coupe partielle d'un dispositif selon une variante de l'invention dans les phases de montage des figures 2e et 2f.

Reference will be made to the attached figures, among which:

• the figure 1 is a schematic partial sectional view of a diaphragm pump equipped with a device according to the invention;
• the Figures 2a, 2b, 2c, 2d , 2nd, 2f are schematic partial sectional views of the device illustrated in FIG. figure 1 during its different phases of mounting on the pump;
• the Figures 3a and 3b are schematic views in partial section of a device according to a variant of the invention in the phases of mounting of Figures 2e and 2f .

DETAILED DESCRIPTION OF THE INVENTION

With reference to the figure 1 , the hydraulically actuated pump here comprises a composite membrane 1 which comprises an intermediate membrane 2 between a first thin membrane 3 and a second thin membrane 4. The intermediate membrane 2 is thick and in the form of an elastically deformable arch. The pump comprises a duct 5 which is formed in the thickness of the intermediate membrane 2 and has a first end opening out of the pump and a second end connected to at least one drainage channel. Here, the second end is connected to a first drainage channel 6 and a second drainage channel 7. Each drainage channel is also formed in the thickness of the intermediate membrane, here transversely to the conduit 5, to connect to the conduit 5 the spaces extending between each of the faces of the intermediate membrane 2 and the thin membrane opposite.

The pump further comprises a pumping chamber 10 delimited here by both the first thin membrane 3 and by a pumping head 11. The pumping head 11 comprises a suction pipe 12a and a discharge pipe 12b of a The pump also comprises an actuating chamber 13 which is filled with fluid and which is delimited here by the second thin membrane 4, a pump body 14, and a part of the pump. front of a piston 15 movably mounted in said actuating chamber 13 for moving the fluid in said chamber.

In use, the composite membrane 1, subjected to this movement of fluid in the actuating chamber 13, will deform. This results in a volume variation of the actuating chamber 13 which corresponds to the displacement of the piston 15 in said actuating chamber 13 and which is transmitted to the pumping chamber 10 by the composite membrane 1.

Such a pump being well known from the prior art, it will not be described in more detail here. Such a pump is for example described in the French application FR 2 934 332 or the French application FR 2,670,537 . Such a pump is considered a double diaphragm pump because of its two thin membranes.

The pump here comprises a rupture detection device 20 according to the invention which allows the detection of the rupture of one of the thin membranes of the composite membrane 1. The device 20 is mounted on the pump at the outlet of the conduit 5 of the membrane intermediate 2.

With reference to the figure 2e said device 20 comprises a hollow body 21 in which a first chamber 22 is formed at a first end of the body 21. A conduit 23 connects the first chamber 22 to a second end of the body 21. The device 20 is here arranged on the pump so that the conduit 23 of the body 21 is connected to the conduit 5 of the intermediate membrane 2.

The device 20 further comprises a non-return valve 24 disposed in the conduit 23 to be passed in the direction of the second end of the body towards the first chamber 22. The non-return valve 24 comprises in a manner known per se a free ball 25 resting on a seat formed in the conduit 23.

According to the invention, the device 20 comprises a piston 26 mounted to move in translation in the body 21. The piston 26 comprises a first portion 27 which cooperates sealingly with the first chamber 22 and which is traversed by a bore of diameter greater than diameter of the free ball 25

According to a preferred embodiment, the first portion 27 is shaped into a head 27a and a piston rod 27b, the head 27a being the portion of the first portion 27 adapted to cooperate sealingly with the first chamber 22. For this purpose , the head 27a here comprises a groove in which is disposed a seal 28 which is intended to cooperate with walls of the first chamber 22.

Preferably, the first end of the body 21 has a first stop 29 to stop a stroke of the piston 26 and thus prevent the head 27a of the piston 26 from coming out of the body 21. Here, the first end of the body 21 has a groove in which a resilient ring is arranged to form the first stop 29. The elastic ring cooperates here with the piston head 27a to stop the stroke of the piston.

The piston 26 also comprises a second portion 33 which is adapted to cooperate sealingly with the rod 27b to form a closed end of the piston 26 opposite the second end of the body.

According to a preferred embodiment, a second chamber 30 is formed in the hollow body 21 between the first chamber 22 and the conduit 23 of the body 21, the second chamber 30 having a diameter greater than the diameter of the first portion 27 of the piston.

Preferably, the rod 27b of the piston comprises a second stop 32 to stop a stroke of the piston and prevent the head of the piston 27b from entering the second chamber 30. Here, the rod 27b has a groove in which is arranged an elastic ring to form the second stop 32. The elastic ring forming the second stop 32 cooperating here with the elastic ring forming the first stop 29 to stop the stroke of the piston.

Thus, thanks to the two stops, the piston head 27b is only movable in translation in the first chamber 22.

The device 20 here also comprises means for covering the hollow body 21 which are arranged on the first end of the body 21 to form a closed upper part of the device 20 opposite the part of the device 20 in contact with the pump. According to a particular embodiment, means for covering the hollow body 21 comprise a transparent cover 31 arranged on the first end of the body 21 to form an upper part of the device 20 opposite the part of the device 20 in contact with the pump, the transparent cover 31 being here shaped to allow a stroke of the piston 26 to the first stop 29. Preferably, the second portion 33 of the piston 26 is then colored.

The device 20 is mounted as follows on the pump.

With reference to the figure 2a , the body 21 is mounted on the pump so that the conduit 23 of the body 21 is sealingly connected to the conduit 5 of the intermediate membrane 2. The first portion 27 of the piston is then inserted into the body 21 to be in sealing contact with the first chamber 22.

In this position, a fluid necessary for the degassing of the pump, for example oil, is poured directly through the first portion 27 of the piston. The oil then evacuates towards spaces formed between each thin membrane and the intermediate membrane 2 through the conduit 23 of the body 21, the conduit 5 of the intermediate membrane 2 and the drainage channels 6, 7. Preferably the oil is poured until it fills a portion of the second chamber 30.

Once the oil is poured, the drilling of the first portion 27 of the piston is closed again to form the closed end of the piston 26 opposite the second end of the body 21. Here, a plug 34 is arranged on the first portion 27 of the piston to cooperate sealingly with the drilling of the first portion.

With reference to the figure 2b the piston 26 is then raised and lowered in successive phases in the hollow body 21, the head 27a always remaining in sealed contact with the wall of the first chamber 22. Part of the air present between the thin membranes and the intermediate membrane 2 is then driven to the surface of the volume of oil in the second chamber 30 by the pumping caused by the piston 26.

Part of the degassing is thus performed by the device according to the invention.

With reference to the Figure 2c the plug is removed from the first portion 27 of the piston. Preferably, the elastic ring of the second stop 32 is removed from the rod 27b and the first portion 27 of the piston is lowered so that the head 27a of the first portion is at the level of the second chamber 30. The pressure prevailing in the first chamber 22 and in the second chamber 30 is then equal to the atmospheric pressure.

The free ball 25 is inserted into the bore of the first portion 27 so as to naturally be placed on the seat of the non-return valve 24 by gravity. The second portion 33 of the piston is then arranged on the first portion 27 so as to close the end of the piston 26.

With reference to the figure 2d , the piston 26 is then raised until the head 27a cooperates sealingly with the first chamber 22.

The pressure in the first chamber 22 and in the second chamber 30 then becomes less than atmospheric pressure, which creates a vacuum in said chambers. The air still present between thin membranes and the intermediate membrane is then naturally driven to the surface of the volume of oil in the second chamber 30 due to this depression.

Advantageously, the degassing of the pump is done continuously and automatically by the vacuum maintained in the chambers. The degassing can be done during a handling and a transport of the pump to a customer so that at the start of the pump by the customer, there is almost no residual air between the thin membranes and the membrane intermediate. The thin membranes are then very well bonded to the intermediate membrane which ensures a good performance of the pump from its start.

Advantageously, it is very easy for an operator to know if the head 27a is still at the level of the second chamber 22 or if it is at the level of the second chamber 30 even if the operator can not visually see it. Indeed, when the seal 28 is engaged against the walls of the first chamber 22 it generates friction forces and the operator then very clearly feels resistance to the rise of the piston 26.

Preferably, the piston 26 is raised until the elastic ring of the second stop 32 can be replaced on the rod 27b that is to say until the two stops cooperate.

The piston 26 is then held in a raised position where the head 27a cooperates sealingly with the first chamber 22, the cooperation of the two stops preventing the head 27a from descending into the second chamber 30. The depression in the first chamber 22 and in the second chamber 30 is maintained without an operator or additional system is required to maintain the piston in this raised position.

With reference to the figure 2d , the cover 31 is mounted on the device, once the piston 26 raised.

With reference to Figures 2e and 2f when one of the two thin membranes breaks, the oil present between the thin membranes 3, 4 and the intermediate membrane 2 and / or the fluid to be dosed and / or the fluid filling the actuating chamber 13 is forced back into the drainage channels 6, 7 and in the duct 5 of the intermediate membrane 2 up in the conduit 23 of the device 20. Due to a pressure exerted by the oil and / or the fluid to be dosed and / or the filling fluid the actuating chamber, the free ball 25 is raised and the liquid rises in the second chamber 30 and then in the first chamber 22 causing the displacement of the piston of the second stop 32 to the first stop 29.

The operator can easily detect a problem of rupture of the membrane, the second colored portion 33 of the piston 26 then being easily visible through the transparent cover 31.

The device according to the invention makes it possible to perform other functions than the rupture detection of one of the membranes, such as filling the pump with oil necessary for degassing and degassing of the pump. The device is particularly suitable for small flow pumps comprising two membranes for which the trapping of the smallest volume of air between the two thin membranes degrades the performance and accuracy of the pump.

The invention is not limited to what has just been described, but on the contrary encompasses any variant within the scope defined by the claims.

In particular, the device according to the invention may be arranged on other types of pumps than that described. For example, the device can be arranged on a hydraulically actuated pump comprising two membranes tightly sealed at their periphery on a fixed structure comprising an annular piece interposed between the two membranes, an internal space between the two membranes being in communication with at least one duct formed in the thickness of the annular piece, said duct being connected to the conduit of the device according to the invention. Such a pump is for example described by the French application FR 2,624,922 .

The different parts of the piston may be shaped differently from what has been described. For example, the first portion 27 may form a piston head and the second portion 33 a piston rod.

The body of the device may not include a second chamber 30 between the first chamber 22 and the conduit 23 of the device 20. The degassing of a pump on which the device will be mounted will however be less effective with a device without second chamber, no depression can not be created in the hollow body.

The device may not include cover means. For example, if the detection of the rupture of a membrane is done visually, the device may not have a transparent cover 31. Preferably, the second portion 33 of the piston 26 will then be colored.

Although here the detection of the rupture of a membrane is done visually, the detection of the rupture can be done electronically. For example, with reference to Figures 3a and 3b , the device comprises means for covering the hollow body 21 which comprise a cover 40 arranged on the first end of the body to form an upper part of the device opposite to the part of the device in contact with the pump, the cover 40 being shaped to allow a stroke of the piston 26 to the first stop 29. An inductive sensor is arranged on said cover 40 so as to generate an electromagnetic field in a closed volume defined by the cover 40, the hollow body 21 and the piston 26. The second portion 33 of the piston 26 is then made of an electrically conductive material, for example a metallic material. In case of rupture of one of the membranes, by the movement of the piston 26, the second portion 33 of the piston will change the electromagnetic field generated by the inductive sensor which will identify said membrane rupture.

Preferably, the cover 40 is transparent. Thus, if the inductive sensor detects a change in the electromagnetic field that it generates, the operator can visually check whether the piston 26 has moved or not and thus ensure whether or not there is a problem of rupture. of membrane.

The different mounting steps of the device 20 on the pump may be different from those described. In particular, although here a plug 34 is arranged on the first portion 27 of the piston to cooperate sealingly with the drilling of the first portion 27 during a first degassing phase, it will be possible to directly arrange the second portion 33 of the piston. piston to cooperate tightly with the drilling of the first portion 27 during said first degassing phase.

Claims (10)

1. A device for detecting a break in a diaphragm of a hydraulically-actuated pump, the device comprising:

   · a hollow body (21) in which a first chamber (22) is formed at a first end of the body, a duct (23) connecting the first chamber to a second end of the body; and

   · a check valve (24) arranged in the duct to pass fluid from the second end of the body towards the first chamber;

   the device being characterized in that it comprises a piston (26) mounted to move in translation in the hollow body, the piston having a first portion (27) that co-operates in sealed manner with the first chamber and that has a hole passing therethrough of diameter greater than the diameter of a free ball (25) of the check valve, and a second portion (33) that is suitable for co-operating in sealed manner with the first portion to form a closed end of the piston remote from the second end of the body.
2. A device according to claim 1, wherein a second chamber (30) is provided in the hollow body (21) between the first chamber (22) and the duct (23), the second chamber having a diameter greater than the diameter of the first portion (27) of the piston.
3. A device according to claim 2, wherein the piston (26) includes an abutment (32) for co-operating with the first chamber (22) to stop a stroke of the piston before the first portion (27) of the piston penetrates into the second chamber (30).
4. A device according to claim 1, including an abutment (29) that is arranged level with the first end of the body (21) and that is designed to co-operate with the piston (26) to stop a stroke of the piston before the first portion (27) of the piston exits completely from the hollow body (21).
5. A device according to claim 1, including cover means (31, 40, 41) for covering the hollow body (21), which means are arranged on the first end of the body (21) to form a closed top portion of the device remote from a bottom portion of the device provided with means for connection to the pump.
6. A device according to claim 5, wherein the cover means of the hollow body (21) comprise a transparent cap (31) arranged on the first end of the body (21), and the second portion (33) of the piston (26) is colored.
7. A device according to claim 1, wherein the first portion (27) is shaped as a piston head (27a) and as a piston rod (27b), the head being that part of the first portion that is suitable for co-operating in sealed manner with the first chamber (22).
8. A mounting method for mounting the device of claim 1 on a pump, the method comprising the steps of:

   · arranging the body (21) on the pump;

   · inserting the first portion (27) of the piston in the body in order to be in sealed contact with the first chamber (22);

   · pouring a fluid needed for degassing the pump directly through the first portion of the piston;

   · inserting the free ball (25) in the hole in the first portion; and

   · arranging the second portion (33) of the piston on the first portion.
9. A mounting method according to claim 8, wherein the device includes a second chamber (30) arranged in the hollow body (21) between the first chamber (22) and the duct (23), the second chamber having a diameter greater than the diameter of the first portion (27) of the piston, the method then including the following steps:

   · lowering the first portion of the piston to the level of the second chamber prior to inserting the free ball (25) of the check valve (24), and arranging the second portion (33) of the piston on the first portion; and

   · raising the piston (26) so that the first portion co-operates in sealed manner with the first chamber.
10. A hydraulically-actuated diaphragm pump including a composite diaphragm (1) having a thick intermediate diaphragm (2) between two thin diaphragms (3, 4), the thick diaphragm forming an elastically deformable dome, the pump including a duct (5) that is arranged in the thickness of the intermediate diaphragm (2) and that has one end opening out to the outside of the pump and one end connected to at least one drain channel (6, 7), the drain channel also being provided in the thickness of the intermediate diaphragm (2) in order to connect the duct (5) of the pump to the spaces that extend between each of the faces of the intermediate diaphragm and the facing thin diaphragm, the end of the duct that opens to the outside of the pump being connected to the duct (23) of a device according to any one of claims 1 to 7.

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