EP0969208B1 - Diaphragm pump - Google Patents

Description

Technical area

The present invention relates to a pump for membrane.

State of the art

A document of the prior art, the US-A-4 patent 862,192, describes a jet dot printer of ink, with an ink circuit that includes a transfer device for transferring ink thick of a first feed tank and, independently of it, the additive of a second supply tank, in an ink chamber. Of ink from this ink chamber is supplied under pressure to a writing head. Ink is returned to the ink chamber through a channel of recovery, crossing the writing head and recovering ink droplets that have not been deviated for writing purposes. The device transfer uses pressurized air to transport the ink between an ink tank, connected to the head of writing, a mixing tank, connected to supply tanks, and a reservoir of recovery, connected to the recovery channel. The mixing tank can be alternately connected to a suction line or a discharge line.

In this known art printer, the ink transfer is therefore ensured by a tank intermediate which is either in depression for recover ink from the tank of recovery, either in pressure during the phase tank supply (accumulator) connected to the printhead.

• une consommation d'air importante due aux gonflages et dégonflages successifs de ce volume intermédiaire ;
• une dissolution de l'air dans l'encre car le volume de mélange n'est pas équipé d'un séparateur air/encre ;
• un surdimensionnement et une multiplication des composants pneumatiques (trois régulateurs de pression, des vannes deux et trois voies...).

Figure 1 shows the block diagram of such a printer. In this one, the presence of an intermediate volume is a source of problems. Indeed the dimensions of this volume are not negligible. The volume and the air / ink exchange surface result in:

• a significant air consumption due to successive inflation and deflation of this intermediate volume;
• a dissolution of the air in the ink because the mixing volume is not equipped with an air / ink separator;
• over-sizing and multiplication of pneumatic components (three pressure regulators, two and three-way valves ...).

• le transfert d'encre se fait avec une pompe à membrane située entre le réservoir de mélange et l'accumulateur ;
• le réservoir de mélange est en permanence en dépression et devient en fait le réservoir de récupération, qui d'ailleurs disparaít du circuit primaire.

These various problems result in the implementation on these machines of a different system from that presented above. Indeed on the commercialized machines one can observe that:

• the ink transfer is done with a diaphragm pump located between the mixing tank and the accumulator;
• the mixing tank is permanently depressed and becomes in fact the recovery tank, which also disappears from the primary circuit.

Figure 2 shows a schematic diagram of the system equipping the machines. This system, simpler and better suited to an inkjet printer, uses a diaphragm pump. For this new circuit, the admission of liquid is ensured by a spring built into a pump, which plunges directly into ink. The spring requires guidance and centering which significantly increase the size of this one. The displacement of such a pump is important and obliges the presence of a mechanical regulator of accuracy of air pressure on the accumulator. The internal volume of the pump being important, such a system has many disadvantages in a rapid color change of the ink (surface to cleaning is important). This art printer known does not use the pump so bidirectional, so that we find valves the aspiration and sometimes the repression of pumps. The principle of this known art printer is simple but limited for future applications (control of volumes transferred, ease of rinsing machine, color change, ink addition and additive by the pump). It should be noted that on this machine the pump has only a very limited number of features.

The subject of the invention is a diaphragm pump to overcome these disadvantages.

A first known art document, the request EP-A-0 758 053 discloses a dosing pump of capsule type that includes a diaphragm shape characteristic, which can move between two positions: a forward position and a rear position.

A second known art document, the patent US-A-3,387,566, discloses a motor adapted for operate as a pump capable of providing controllable pressure fluids. This engine includes a carter, a set of two diaphragms attached to this carter and to a moving central body, spaced one from the other and able to flex at the same time.

Presentation of the invention

The present invention describes a pump for membrane comprising a body in which are dug communication channels, and two cavities in which move the two parts of a piston, in which a deformable element is integral with the first of these two parts, in which two joints are arranged between the body and the piston, one being integral with the body (stem seal), the other being attached to the second part of the piston (seal piston), in which the positioning of the piston, provided of the deformable element, within these two cavities makes it possible to make a large room in two connected isobaric parts, a small room as well as an access room to which allow access to different orifices, and in particular two suction / discharge ports, characterized in that what the deformable element is a membrane, and in that that the stroke of the piston, which is delimited by the distance between at least one face of the piston and at least one face of the body, is of the order of 1mm, so that the deformation of the membrane as well as the deformation energy remain weak.

Advantageously, the control of this pump membrane is achieved by means of a single 2-way / 2-way solenoid valve completed by the presence of a calibrated orifice allowing the depressurization of the rooms.

In addition this pump of the invention no longer requires the use of a spring for the return of the pump, as in US-A-4862192. This spring is, indeed, a mechanical component to be calibrated, subject to dispersions of characteristics: the spring must not be too strong to allow in all cases the discharge control and strong enough to also allow in all cases the control suction. Such difficulty in adapting this component to the operating conditions does not exist with the pump of the invention. Indeed the pump of the invention adapts to any change in operating pressure. Thus this type of pump has a high vacuum capacity independent of its performance in pressure. Indeed the effort involved to create the vacuum is directly associated with the product of the pressure in the small cylinder chamber multiplied by the surface of this small chamber. The maximum possible depression is obtained by dividing the force by the surface of the membrane. The pressure in the small chamber is always the source pressure, so we have: Maximum depression = Source pressure * (small section chamber / membrane section)

The effort put into play to create the pressure is directly associated with the product of the prevailing pressure in the big cylinder chamber multiplied by the surface of the membrane. Discharge pressure maximum possible with this type of pump is therefore the source pressure.

If we note S the surface of the large chamber, s the surface of the small chamber, S membrane the surface of the membrane. The assembly can be schematized as illustrated in Figure 3. During the discharge the driving pressure is applied on (S membrane - s rod + S) and practically the same pressure applies s. We can notice that: s stem = S - s, and therefore: Discharge force = Pressure * ((S membrane - (S - s) + S) - s) is : Discharge force = Pressure * S diaphragm

The driving force of repression is good independent of the section of the small chamber of cylinder.

Advantageously the membrane pump of the invention is equipped with a pressure sensor and temperature, the latter being directly in contact with the fluid inside the pump.

The invention also relates to a circuit hydraulic equipped with this pump.

• des moyens de surveillance de la pression source située en sortie du régulateur ;
• des moyens de détermination du colmatage d'un filtre situé à son refoulement ;
• des moyens de vérification de l'étanchéité des composants du circuit d'encre ;
• des moyens de réalisation de la fonctionnalité débitmètre des différentes quantités de fluides consommés.

Advantageously, it comprises:

• means for monitoring the source pressure at the output of the regulator;
• means for determining the clogging of a filter located at its discharge;
• means for checking the tightness of the components of the ink circuit;
• means for producing the flowmeter functionality of the different quantities of fluids consumed.

The invention also relates to a jet printer of ink equipped with this ink circuit.

• simplicité ;
• faible nombre de pièces ;
• volumes morts très faibles ;
• fiabilité de fonctionnement.

The pump of the invention has many advantages:

• simplicity ;
• low number of pieces;
• very low dead volumes;
• reliability of operation.

Brief description of the drawings

• Figures 1 and 2 show two examples embodiment of devices of the prior art;
• Figure 3 shows the areas concerned for the calculation of the forces involved during a cycle delivery of the pump of the invention;
• Figure 4 illustrates the membrane pump of the invention;
• Figure 5 illustrates the diagram hydropneumatic of an ink circuit implementing the pump of the invention;
• Figures 6 and 7 correspond to the signal pump pressure in a typical cycle suction / discharge.

Detailed presentation of embodiments

The membrane pump of the invention, as shown in Figures 4 and 5, is formed of a body 2 in which are dug channels of communication, and two cavities 3, 4 in which move the two parts 5, 6 of a piston 18, a membrane 19 being integral with the first 5 of these two parts. Two joints 7, 8 are arranged between the body 2 and the piston 18, one 7 being integral with the body 2, the other 8 being attached to the second part 6 of the piston. The positioning of the piston 18, equipped with membrane 19 inside these two cavities 3 and 4 makes it possible to make a large chamber two isobaric parts 16 and 17 connected together, one small room 15, as well as an access room 9 access to, respectively, ports 26, 27, and two suction ports / repression 28 and 29.

In the membrane pump of the invention the embedment diameter on the piston 18 is defined from to minimize the total deformation energy elastic (Von Mises criterion). In addition the piston 18 has a support zone of the membrane 19 used during the repression sequence. This area of support allows to minimize the deformation of the membrane. The thickness of the membrane 19 may be important because the motive power needed for movement is weak (actually the deformation energy of the membrane being minimized, the energy needed to move it is low). It can also be noted that energy pneumatic does not present the problems of torque motor and rotational speed stability (vibrations) that can be met with an engine electric (step by step in particular). The order in air is so much softer.

The increase in membrane thickness 19 allows to obtain an excellent life of the pump (more than three years of operation in 2x8, 300 days per year based on test results).

The internal forms of the pump of the invention remain simple so as not to create zones of retention difficult to clean.

An original feature of the pump the invention lies in its control mechanism fully pneumatic. The repression is obtained by the pressurization of the membrane. aspiration (admission) is also obtained by pressurizing a surface connected to the membrane.

In fact the membrane is connected to a cylinder of control (piston 18). This cylinder is a double cylinder effect for which pressure is always present in the small room 15. When other surfaces (diaphragm and large cylinder chamber) are left to the atmospheric pressure, we can ensure the suction of liquid. Pressurizing the membrane and the big room of the cylinder, one can repress.

The small chamber 15 of the jack is connected in permanence with source pressure and only one two-way / two-position solenoid valve is sufficient to be able to pressurize the other surfaces, in order to create the displacement of the jack and thus by therefore the pumping.

The stroke of this type of pump is associated with the difference of two geometric dimensions. The first one dimension separates the faces B3 and B4 of the piece 6 and the second dimension separates the B1 and B2 faces from the Exhibit 2 (see Figure 4). The reproducibility of this dimension is very good and only really depends on the quality of realization of the room 2 and the piece 6 (in molding or machining). This reproducibility of the race makes it possible to obtain pumps with displacement (volume displaced at each pump stroke) identical. For a jet printer of ink then we can use the pump as flowmeter and measure, for example, the consumptions ink and solvent as well as the jet flow.

• la déformation de la membrane ainsi que l'énergie de déformation restent faibles. Cette caractéristique est très importante et permet d'obtenir une durée de vie de la membrane compatible avec plusieurs années d'utilisation d'une imprimante à jet d'encre ;
• les étanchéités associées au vérin de commande sont ainsi très faciles à réaliser. Deux joints toriques standard (les joints 7 et 8 sur la figure 4) permettent d'assurer la fonctionnalité étanchéité avec en plus deux avantages primordiaux :
• a)Dans le déplacement relatif du piston par rapport à la pièce 2 (voir la figure 4) le mouvement se fait pratiquement sans frottement. Le déplacement étant faible, le joint se déforme et roule dans son logement sans frotter. On observe que l'usure des joints est pratiquement inexistante et que l'effort nécessaire au déplacement du vérin est négligeable devant les pressions mises en jeu. La durée de vie de l'étanchéité est supérieure à 50 millions de manoeuvres d'après les résultats de test.
• b)Le coût de la fonctionnalité étanchéité est faible grâce à l'utilisation d'éléments standards utilisés en masse dans une majorité de composants pneumatiques.

For this type of pump the choice of a low stroke (of the order of 1 mm) brings several interests:

• the deformation of the membrane and the deformation energy remain low. This characteristic is very important and allows to obtain a lifetime of the membrane compatible with several years of use of an inkjet printer;
• the seals associated with the control cylinder are thus very easy to achieve. Two standard O-rings (seals 7 and 8 in Figure 4) provide the sealing functionality with two additional advantages:
• a) In the relative displacement of the piston with respect to the part 2 (see figure 4) the movement is practically without friction. The displacement being small, the seal deforms and rolls in its housing without rubbing. It is observed that the wear of the joints is practically non-existent and that the effort required to move the cylinder is negligible in view of the pressures involved. The service life of the seal is greater than 50 million maneuvers according to the results. test.
• b) The cost of the sealing functionality is low thanks to the use of standard elements used in bulk in a majority of pneumatic components.

To summarize the cylinder sealing functionality for this type of pump is simple, inexpensive and a very interesting life.

For use on jet printer of ink the materials in contact with the ink are chosen according to their chemical compatibility with fluids (ink, solvent). So a 5 axis steel stainless steel and a membrane 19 Teflon (0.5 mm thick, for example) are well adapted to use on an inkjet printer. A overmoulding of the membrane on the axis is incidentally possible and was made for testing.

In an exemplary implementation, the pump of the invention 14 is used in an ink circuit such as as shown in Figure 5. This includes a ink cartridge 10, an additive cartridge 11, a recovery tank 12 and an accumulator 13, each of these different elements being connected to the pump of the invention 14, which allows a transfer of ink, air filters 31 and 44, an ink filter 24, a pressure regulator 30, a condenser 45 and its radiator, connecting channels on which are arranged the solenoid valves 20, 21, 22, 23, 25, 34, 37, 40, 43, and an electronic control board of these different elements.

The lower parts of the ink cartridge 10, of the additive cartridge 11, the upper and lower parts low of the accumulator 13 are connected to the same suction / discharge port of pump 14 to through respectively solenoid valves 20, 21, 22 and 23. A "main" filter 24 is arranged between the bottom of the accumulator 13 and the solenoid valve 23. The bottom of the accumulator 13 is also connected to the head of ink projection. The lower part of the reservoir recovery 12 is connected to a second port of delivery / suction of the pump 14 through a solenoid valve 25.

• à la pressurisation de tête au travers d'une électrovanne 34 et d'un orifice calibré 35 ;
• à l'accumulateur 13 au travers d'une électrovanne 34, d'une électrovanne 43 et d'un orifice calibré 35a ;
• à la grande chambre de la pompe 14 et à un orifice de décompression 38 au travers d'une électrovanne 37 ;
• à la petite chambre 15 de la pompe 14 ;
• à un rejet extérieur au travers d'une électrovanne 40, d'un orifice calibré réglable 41 et d'un venturi 42, le bas du filtre 31 étant également relié à ce rejet extérieur au travers d'un orifice calibré 46.

The ink circuit also comprises a pressure regulator 30 connected at the inlet to the compressed air network (5-10 bar) through an air filter 31 and at the output to electronic scans and ink circuit through two calibrated orifices 32 and 33. The output of the pressure regulator 30 is also connected:

• head pressurization through a solenoid valve 34 and a calibrated orifice 35;
• to the accumulator 13 through a solenoid valve 34, a solenoid valve 43 and a calibrated orifice 35a;
• to the large chamber of the pump 14 and to a decompression orifice 38 through a solenoid valve 37;
• at the small chamber 15 of the pump 14;
• an external discharge through a solenoid valve 40, an adjustable calibrated orifice 41 and a venturi 42, the bottom of the filter 31 being also connected to this external discharge through a calibrated orifice 46.

The upper part of the accumulator 13 is connected at the point common to the solenoid valve 34 and the orifice calibrated by a solenoid valve 43 through the calibrated orifice 35a.

The upper part of the recovery tank 12 is connected to the venturi 42 through a filter 44 and a condenser 45, and its lower part at the suction of the ink gutter located at the base of the head of ink projection. A level sensor, for example a detector 50 without contact, is fixed on the wall of the recovery tank 12. A temperature sensor and pressure 53 is located in the pump 14.

The pressure at the outlet of the pressure regulator 30 is slightly greater than the pressure in the accumulator 13.

The small chamber 15 of the pump is connected to the regulated pressure present at the output of the regulator of pressure 30 and the large chamber at the same pressure at through the solenoid valve 37.

When the solenoid valve 37 is closed, the membrane 19 is "pulled": there is "aspiration" by compared to the liquid located on the other side (volume 9). The piston comes to rear stop B1.

When the solenoid valve 37 is open, the large room 16, 17 is at a slight pressure lower than that of the small chamber 15, because of the existence of the decompression orifice 38. The piston surface 18 on which the pressure of the big room 16, 17 is much more large than the one on which the pressure of the small chamber 15. The piston comes so, as represented in FIG. 1, in front stop B2. There is "Delivery".

The piston 18 has a conventional operation, using the pressure relief port 38. When wants to suck, the system is "deflating" through this orifice 38. The membrane never comes into abutment. The compressibility of the air allows to obtain a movement flexible avoiding in particular the phenomena of shocks and water hammers. The life of the membrane 19 is thus improved compared to the device of the prior art described above.

The accumulator 13 allows a double regulation:

• In normal operation :

• the solenoid valve 43 is closed;
• ink is introduced by blows into the accumulator 13 which, thanks to its air pocket located in the upper part, a hydraulic antipulsatory role to smooth the flow curve. The dimensions of the volumes of the chamber of the pump 14 and of the air bag of the accumulator 13 are such that the instantaneous addition of a pump volume in the accumulator does not significantly modify the pressure of the this accumulator. Typically a ratio of 200 between the volume of the air pocket and the chamber volume of the pump is an acceptable lower limit. Taking into account this ratio 200 and the geometry of the accumulator (at least 80 cm ³ of air at the top) a pump displacement of 0.4 cm ³ is very well suited to use this type of pump for a pump. inkjet printer;
• we measure the pressure permanently using the sensor 53;
• an elementary addition of ink is made to using the pump 14 to replace cyclically the ink consumed by the jet. For use standard (one nozzle diameter 72 microns) the elementary addition of ink takes place about every 6 seconds (10 rounds per minute);

• When the ink cartridge 10 and the recovery tank 12 are empty :

• we no longer go through the pump 14; we check the pressure using the sensor 53;
• since we can not add anymore of ink, because the cartridge 10 and the reservoir of 12 recovery are empty, the accumulator is empty gently and the pressure in it would tend to decrease. Also, the solenoid valve 34 being open, one opens solenoid valve 43 intermittently during very short time, which helps maintain the pressure in the accumulator 13; we add as much of air than loss of volume in liquid.

Fluid transfers between different volumes are made by the pump of the invention 14 located in the center of the circuit. This pump 14 plays the role of "Marshalling yard". It is equipped with a sensor pressure 53. The measure functionality of temperature to the sensor so you can handle more correctly the quality of the ink (measurement of temperature of the ink at the heart of the system). pressure / temperature measurement is done by direct contact fluid located inside the pump with the sensing element of the sensor. The sensor of pressure / temperature is really built into the pump without any pump / sensor separation.

The only condition of operation of the pump 14 is that the pressure prevailing at the output of the regulator 30 is greater than the pressure of operation. So just adjust the pressure in 30 regulator output with a safety margin by compared to the operating pressure (+ 500 mBar per example) to overcome any risk of malfunction of the system. From the standpoint this is a huge advantage because all the machines in a range of printers can be equipped with only one type of pump. The pump 14 Behaves like a self-adapting element to the conditions Operating.

In fact for an ink circuit the only difference for the pump between the different machines of a range is the rate of use of the pump. It can be noted a utilization rate of about three shots per minute for a head of a first type P, about fifty shots per minute for a head having four jets of a second type G or eight jets a third The operating margin of this type of pump remains important because laboratory tests conducted on prototypes have shown that a utilization rate of one hundred and twenty strokes per minute is not difficult. It can also be noted that the operation of the pump does not influence the recovery capabilities of the venturi. Indeed the fact that the volumes 16 and 17 are low and the control solenoid valve 37 is flanged against the pump leads to pressure variations at the output of the regulator 30 which remain low. These variations remain low while the regulator 30 is small. Indeed one chooses a small regulator (for example the smallest of the pneumatic range is about 6 Nm ³ / h) with a very small tank volume and a small passage diameter (about three mm).

• contrôler la pression source ( pression en sortie du régulateur 30) : la pompe étant en butée fin de cycle d'aspiration ( piston sur la face B1 : voir la figure 4), les électrovannes 20, 21, 22, 23, 25 étant fermées, on ouvre alors l'électrovanne 37, la mesure du capteur 53 donne alors la valeur de la pression source ;
• contrôler le niveau de colmatage du filtre 24 : on mesure le travail nécessaire à la pompe 14 pour transférer sa cylindrée à travers le filtre. La mesure de ce travail de transfert est associée au calcul faisant intervenir les pressions dynamiques. En effet ce travail traduisant la difficulté pour la pompe à refouler à travers le filtre est une information que l'on peut trouver dans le diagramme pression en fonction du temps.

This pump 14 allows, thanks to particular cycles, the monitoring of certain elements of the circuit. So we can:

• check the source pressure (outlet pressure of the regulator 30): the pump being at the end of the suction cycle (piston on the face B1: see figure 4), the solenoid valves 20, 21, 22, 23, 25 being closed the solenoid valve 37 is then opened, the measurement of the sensor 53 then gives the value of the source pressure;
• check the clogging level of the filter 24: the work required by the pump 14 is measured to transfer its cubic capacity through the filter. The measurement of this transfer work is associated with the calculation involving the dynamic pressures. Indeed this work translating the difficulty for the pump to push through the filter is information that can be found in the pressure diagram as a function of time.

The pace of the pressure signal during the phase transfer is shown in Figure 7 (the completeness of a suction / discharge cycle given in Figure 6).

The transfer work is given by the surface marked S1 on the pressure / time graph. From the mathematical point of view, the exact calculation of this surface is given by the integral:

• que le temps t₀ (ouverture de l'électrovanne accumulateur) est très proche du temps t₁ (équilibre des pressions pompe et accumulateur)
• que la surface exacte S1 peut être approchée par la surface S2.

In fact we can notice:

• that the time t ₀ (opening of the accumulator solenoid valve) is very close to the time t ₁ (equilibrium of the pump and accumulator pressures)
• that the exact surface S1 can be approximated by the surface S2.

The area of S2 is easily calculated and is worth: (t 2 - t 1 ) * (P max - P accumulator)

By confusing the times t ₁ and t ₀ we note that the clogging of the filter is finally in the term (t ₂ -t ₀ ) * (P max - P accumulator).

The calculation of this term and its comparison to a limit allow to set a degree of clogging acceptable filter before it changes. In addition, alert value helps inform the user about a need for next change of this filter.

• l'étanchéité de l'électrovanne 43 : alors que l'accumulateur est à une pression proche de la pression atmosphérique et que toutes les électrovannes sont fermées, on ouvre les électrovannes 34 et 23. La pression lue par le capteur doit alors rester constante. Si la pression évolue (augmentation) alors l'électrovanne 43 présente un défaut d'étanchéité ;
• l'étanchéité de l'accumulateur : après s'être assuré de l'étanchéité de l'électrovanne 43, on ouvre cette électrovanne pour mettre en pression l'accumulateur. Après une temporisation de gonflage de quelques secondes on ferme l'électrovanne 43. La pression lue par le capteur doit alors rester constante. Si la pression évolue (diminution) alors l'accumulateur 13 présente un défaut d'étanchéité ;
• l'étanchéité des électrovannes 22 et 23 de la pompe : après s'être assuré des étanchéités de l'électrovanne 43 et de l'accumulateur 13 on ferme l'électrovanne 23 et on ouvre l'électrovanne 25. Après une temporisation d'attente (quelques secondes) on ferme l'électrovanne 25 et on ouvre l'électrovanne 23. La pression lue par le capteur doit alors être identique à celle mesurée lors de la phase de contrôle de l'étanchéité accumulateur. Si la pression a évolué (diminution) alors l'électrovanne 23 ou l'électrovanne 22 (ou les deux) présentent un défaut d'étanchéité ;
• l'étanchéité des électrovannes 25,20 et 21 de la pompe : après s'être assuré des étanchéités des électrovannes 43,23 et 24 et de l'accumulateur 13 on ferme l'électrovanne 23. La pression lue par le capteur doit alors rester constante à la valeur de la pression accumulateur. Si la pression évolue (diminution) alors l'électrovanne 25 ou/et l'électrovanne 21 ou/et l'électrovanne 20 présente(nt) un défaut d'étanchéité.
• l'étanchéité de l'électrovanne 40 : alors que l'accumulateur est à une pression proche de la pression atmosphérique et que toutes les électrovannes sont fermées, on ouvre l'électrovanne 25. Le signal de pression doit alors avoir une valeur proche de la pression atmosphérique. Si la valeur lue par le capteur est inférieure à celle de la pression atmosphérique alors l'électrovanne 40 présente un défaut d'étanchéité et vient alimenter le venturi.

Another feature of this type of pump is its ability to control seals. For an inkjet application the pump is the central element of the circuit. This particular position associated with the presence of a pressure sensor makes it possible to monitor all the neighboring components at the pump. So we can control:

• the sealing of the solenoid valve 43: while the accumulator is at a pressure close to atmospheric pressure and all the solenoid valves are closed, the solenoid valves 34 and 23 are opened. The pressure read by the sensor must then remain constant. If the pressure changes (increase) then the solenoid valve 43 has a leakage;
• the sealing of the accumulator: after having made sure of the sealing of the solenoid valve 43, this solenoid valve is opened to pressurize the accumulator. After an inflation time of a few seconds the solenoid valve 43 is closed. The pressure read by the sensor must then remain constant. If the pressure changes (decreases) then the accumulator 13 has a sealing defect;
• the sealing of the solenoid valves 22 and 23 of the pump: after ensuring the sealing of the solenoid valve 43 and the accumulator 13 is closed the solenoid valve 23 and opens the solenoid valve 25. After a waiting time delay (a few seconds) the solenoid valve 25 is closed and the solenoid valve 23 is opened. The pressure read by the sensor must then be identical to that measured during the control phase of the accumulator seal. If the pressure has evolved (decrease) then the solenoid valve 23 or the solenoid valve 22 (or both) have a sealing defect;
• the sealing of the solenoid valves 25, 20 and 21 of the pump: after ensuring the sealing of the solenoid valves 43, 23 and 24 and the accumulator 13, the solenoid valve 23 is closed. The pressure read by the sensor must then remain constant at the value of the accumulator pressure. If the pressure changes (decrease) then the solenoid valve 25 and / or the solenoid valve 21 and / or the solenoid valve 20 has a leak.
• the sealing of the solenoid valve 40: while the accumulator is at a pressure close to atmospheric pressure and all the solenoid valves are closed, the solenoid valve 25 is opened. The pressure signal must then have a value close to the atmospheric pressure. If the value read by the sensor is lower than that of the atmospheric pressure then the solenoid valve 40 has a leak and comes to supply the venturi.

Claims (9)

1. Diaphragm pump comprising a body (2) in which are hollowed out two communication channels, and two cavities (3, 4) in which are displaced the two parts (5, 6) of a piston (18), in which a deformable element (19) is integral with the first (5) of said two parts, in which two seals (7, 8) are placed between the body (2) and the piston (18), one (7) being integral with the body (2) (rod seal), whilst the other (8) is integral with the second part (6) of the piston (18) (piston seal), in which the positioning of the piston, equipped with the deformable element (19), within said two cavities (3, 4) makes it possible to obtain a large chamber in two isobaric parts (16, 17), which are interconnected, a small chamber (15), as well as an access chamber (9) to which access can be given to different orifices (26, 27, 28, 29) and in particular two suction/delivery orifices, characterized in that the deformable element (19) is a diaphragm and in that the travel of the piston (18), which is defined by the distance existing between at least one face (B3, B4) of the piston (18) and at least one face (B1, B2) of the body (2) is approximately 1 mm, so that the deformation of the diaphragm and the deformation energy remain low.
2. Diaphragm pump according to claim 1, whose control takes place by means of a single two-way/two-position solenoid valve completed by the presence of a gauged orifice permitting the depressurization of the chambers (16, 17).
3. Diaphragm pump according to either of the claims 1 and 2, equipped with a pressure and temperature sensor (53), which is in direct contact with the fluid within the pump (14).
4. Hydraulic circuit equipped with the diaphragm pump according to any one of the claims 1 to 3.
5. Hydraulic circuit according to claim 4 having means for monitoring the source pressure located at the outlet of the regulator (30).
6. Hydraulic circuit according to claim 4 having means for determining the clogging of a filter (24) located at its delivery.
7. Hydraulic circuit according to claim 4 having means for checking the seal of components of said circuit.
8. Hydraulic circuit according to claim 4 having means for implementing the flowmeter functionality of different consumed fluid quantities.
9. Ink jet printer equipped with an ink circuit according to claim 4.

Images