EP0794333A1 - Pilot by-pass valve for liquid pumps - Google Patents

Abstract

The diverter comprises a body (1) with internal wall (2) delimiting inlet (3) and outlet (4) cavities connected to the discharge (5) and suction (6) sides of the pump. These cavities are separated by a sealing assembly (7) comprising a valve (8), its seat (9) and return spring (10). The valve stem (12) slides in the body and the spring, concentric to the stem, is between the valve head (13) and a stop (14). The valve spring stop is fixed to the rod (16) of the piston (17) of a double acting actuator (18). The actuator inlet (E) and outlet (F) openings are located either side its piston and connected to one or other of two regulating distributors (19,20). The valve (21) of the pressure regulating distributor (19) is sensitive to the pressure difference (Preferably - Pasp) existing between the inlet and outlet cavities. The valve (22) of the vacuum regulating distributor (20) is sensitive to the pressure difference between atmospheric pressure (Patm) and the pressure (Pasp) in the discharge cavity.

Description

The present invention relates to a controlled bypass device for a pump for fluid or viscous liquids, for example a centrifugal or volumetric pump, that is to say an automatic regulation device mounted in bypass or in parallel with respect to the pump and intended protect the latter against overpressure and cavitation.

In the case of a positive displacement pump, it is known that such a pump transfers from the suction to the discharge the same quantity of product for each rotation and that any obstacle appearing in the discharge circuit causes the pump to produce a pressure of higher and higher until the weakest element of the installation breaks.

To protect positive displacement pumps against overpressure, we can limit the available power or cause the pump to stop under the effect of a predetermined overpressure, or even use a calibrated relief valve, but we prefer to use a device bypass which causes recirculation of the discharge to the pump suction in the event of overpressure.

Such a bypass device can be internal or external to the pump and comprises, in the simplest normal case, a movable valve which is applied to a fixed seat under the effect of a calibrated return spring acting against the differential pressure existing between the discharge and the suction of the pump. When the differential hydraulic pressure becomes greater than the mechanical force of the spring, the valve departs from its seat by compressing the spring, which can lead to a further increase in hydraulic force compensation.

In fact, it can be considered that the operation of the bypass device of the normal type is due kind by all or nothing, of which the aforementioned relief valve is only a special case.

There are also known compensated type bypass devices, in which an attempt is made to maintain the hydraulic pressure independent of the flow rate or relatively constant while the valve moves away from its seat, by determining an increase in the application surface as a function of the movement of the valve, that is to say an increase in the useful cross-section of the valve in the same proportions as the increase in the spring force. This can be achieved by adding a straight outer cylindrical wall to the valve and a slightly tapered, flared outer cylindrical wall to the seat, so that the increased valve-seat distance causes a slight radial separation of the two walls, which allows a gradual increase in the flow as the spring is compressed. However, the effectiveness of the compensation depends on the shape of the seat cone, which is particularly difficult to achieve, and also depends on the size of the diameter of the right cylinder of the valve, which imposes a passage diameter and very important piping.

Furthermore, for a pump, for example of the centrifugal or volumetric type, to function correctly, the absolute pressure at its suction port must be sufficient to avoid any cavitation phenomenon, which is manifested by the formation of pockets of gas in the suction area of the pump. These gas pockets pass with the liquid towards the delivery zone where they disappear, generating noise, vibrations, or even relatively rapid destruction of the equipment.

The present invention aims to remedy the aforementioned drawbacks and to provide a solution to the problems mentioned by providing a pilot-operated bypass device constantly and automatically slaving the differential pressure of the pump to a set value, by hydraulic means only, and also allowing purely hydraulic regulation of the relative suction pressure.

In accordance with the invention, the pilot-operated bypass device for a pump for fluid or viscous liquids is of the type comprising a body having an inner wall defining inlet and outlet cavities respectively connected to the discharge and suction sides of the pump and separated l '' from each other by a sealing assembly, which comprises a valve, its seat and its return spring having the same axis of symmetry, the seat being formed in the interior wall of the body, the valve stem being mounted sliding in the body and the return spring being mounted concentric with the valve stem and between the head of said valve and a stop, and which is intended to open to put the cavities in communication when the differential pressure discharge - suction is higher than that of the spring.

According to an essential characteristic of the invention, the stop associated with the return spring of the valve is made integral with the piston rod of a double-acting cylinder, which is housed in the body parallel to the axis of symmetry of the '' sealing assembly and the two orifices forming inlet and outlet and located on either side of the piston are respectively connected to one and / or the other of two regulating distributors, namely a regulating distributor pressure, the drawer of which is sensitive to the difference between the pressures prevailing in the inlet and outlet cavities respectively, and a vacuum regulation distributor, the drawer of which is sensitive to the difference between atmospheric pressure and the pressure prevailing in the outlet cavity.

Preferably, the piston rod of the double-acting cylinder is coaxial with the axis of symmetry of the sealing assembly and the valve is mounted to slide relative to said rod.

According to another essential characteristic of the invention, the pressure regulating distributor comprises a first end cavity subjected to the discharge pressure, a second end cavity subjected to the suction pressure and containing a pressure spring disposed between the drawer pressure and an adjustable support forming part of a pressure setpoint adjustment device, said drawer comprising first and second annular grooves respectively subjected permanently to the discharge and suction pressures and each capable of being connected to one or the other of two hydraulic circuits depending on one or the other of two opposite extreme positions of the pressure slide.

When the pressure regulator distributor drawer occupies a first extreme position, its two annular grooves are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the valve to close.

When the drawer of the pressure regulation distributor occupies a second extreme position, its two annular grooves are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve.

According to yet another essential characteristic of the invention, the vacuum regulation distributor has a first cavity terminal, containing the pushing member of a piston - membrane subjected on one side to external atmospheric pressure and on the other side to suction pressure, a second terminal cavity subjected to suction pressure and containing a vacuum spring arranged between the vacuum drawer and an adjustable support forming part of a vacuum setpoint adjustment device, the drawer comprising first and second annular grooves respectively subjected permanently to the discharge and suction pressures and capable each to be connected to one or the other of two hydraulic circuits according to one or the other of two opposite extreme positions of the vacuum drawer.

When the drawer of the vacuum regulation distributor occupies a first extreme position, its two annular grooves are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the valve to close.

When the drawer of the vacuum regulation distributor occupies a second extreme position, its two annular grooves are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve.

According to another preferred characteristic of the invention, the pressure and vacuum regulating distributors are hydraulically mounted in cascade.

According to an essential characteristic of the invention, the pressure regulation distributor is disposed at the head of the cascade and when its pressure slide occupies a first extreme position, its two annular grooves, which are respectively permanently subjected to the discharge pressures and are respectively connected to the grooves associated annulars formed in the vacuum drawer of the vacuum control distributor, so that when said vacuum drawer occupies a first extreme position, its two associated grooves are respectively subjected to the discharge and suction pressures and are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the valve to close, while when said vacuum slide occupies a second extreme position, its two associated grooves are directly and respectively subject to discharge and suction pressures and are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve.

In the same way, when the pressure regulation distributor is placed at the head of the cascade and its pressure slide occupies a second extreme position, its two annular grooves, which are respectively permanently subjected to the discharge and suction pressures , are respectively connected directly to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve, regardless of the position of the vacuum slide which, when it occupies a first extreme position has its two annular grooves not receiving any fluid from the associated annular grooves of the pressure slide, and which, when it occupies a second extreme position, has its two annular grooves directly and respectively subjected to the discharge and suction pressures and respectively connected to the orifices of the cylinder to double effect so that its piston also tends to cause the opening of the valve.

According to yet another essential characteristic of the invention, the vacuum regulation distributor is disposed at the head of the cascade and when its vacuum drawer occupies a first extreme position, its two annular grooves, which are respectively subjected permanently to the pressures of discharge and suction, are respectively connected to the associated annular grooves formed in the pressure drawer of the pressure regulation distributor, so that when said pressure drawer occupies a first extreme position, its two associated grooves are respectively subjected to pressures discharge and suction and are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the valve to close, while when said pressure slide occupies a second extreme position, its two associated grooves are directly and respectively subject to discharge pressures and suction and are respectively connected to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve.

In the same way, when the vacuum regulation distributor is placed at the head of the cascade and its vacuum drawer occupies a second extreme position, its two annular grooves, which are respectively permanently subjected to the discharge and suction pressures , are respectively connected directly to the orifices of the double-acting cylinder so that its piston tends to cause the opening of the valve, independently of the position of the pressure slide which, when it occupies a first extreme position has its two annular grooves not receiving any fluid from the associated annular grooves of the vacuum drawer, and which, when it occupies a second extreme position has its two annular grooves directly and respectively subjected to the discharge and suction pressures and respectively connected to the orifices of the double-acting cylinder so that its piston also tends to cause the opening of the valve .

• la figure 1 représente une vue schématique de l'ensemble d'un dispositif de dérivation selon l'invention piloté par un distributeur de régulation de pression ;
• les figures 2 et 3 représentent des vues schématiques du corps à soupape de dérivation et du vérin associé, ce dernier étant respectivement en position de fermeture et d'ouverture de la soupape ;
• les figures 4, 5 et 6 représentent des vues schématiques du distributeur de régulation de pression, dont le tiroir est respectivement en position de fermeture, de régulation et d'ouverture de la soupape ;
• la figure 7 représente une vue schématique de l'ensemble d'un dispositif de dérivation selon l'invention piloté par un distributeur de régulation de vide ;
• les figures 8, 9 et 10 représentent des vues schématiques du distributeur de régulation de vide, dont le tiroir est respectivement en position de fermeture, de régulation et d'ouverture de la soupape ;
• la figure 11 représente une vue schématique de l'ensemble d'un dispositif de dérivation selon l'invention piloté par des distributeurs de régulation de pression et de vide montés en cascade ;
• les figures 12, 13 et 14 représentent des vues schématiques du distributeur de régulation de vide de la figure 11, dont le tiroir est respectivement en position de fermeture, de régulation et d'ouverture de la soupape ;
• la figure 15 représente une vue schématique de l'ensemble d'un dispositif de dérivation selon l'invention piloté par des distributeurs de régulation de vide et de pression intervertis ou montés en cascade inverse par rapport à la cascade représentée sur la figure 11 ;
• les figures 16, 17 et 18 représentent des vues schématiques du distributeur de régulation de pression de la figure 15, dont le tiroir est respectivement en position de fermeture, de régulation et d'ouverture de la soupape.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows of several possible embodiments, made with reference to the appended drawings in which:

• FIG. 1 represents a schematic view of the assembly of a bypass device according to the invention controlled by a pressure regulation distributor;
• Figures 2 and 3 show schematic views of the bypass valve body and associated cylinder, the latter being respectively in the closed and open position of the valve;
• Figures 4, 5 and 6 show schematic views of the pressure regulating distributor, the slide is respectively in the closed, regulating and opening position of the valve;
• FIG. 7 represents a schematic view of the assembly of a bypass device according to the invention controlled by a vacuum regulation distributor;
• Figures 8, 9 and 10 show schematic views of the vacuum regulating distributor, the slide is respectively in the closed, regulating and opening position of the valve;
• FIG. 11 represents a schematic view of the assembly of a bypass device according to the invention controlled by pressure and vacuum regulating distributors mounted in cascade;
• Figures 12, 13 and 14 show schematic views of the vacuum control valve of Figure 11, the slide is respectively in the closed, regulated and open position of the valve;
• FIG. 15 represents a schematic view of the assembly of a bypass device according to the invention controlled by vacuum and pressure regulation distributors reversed or mounted in reverse cascade with respect to the cascade shown in FIG. 11;
• Figures 16, 17 and 18 show schematic views of the pressure control valve of Figure 15, the slide is respectively in the closed, regulated and open position of the valve.

In these drawings, the same references designate the same elements.

Referring to Figure 1, this schematically illustrates a first possible embodiment of the assembly of a bypass device according to the invention, for centrifugal or volumetric pump for example, controlled by a pressure regulation distributor .

More specifically, with reference to Figures 1 to 3, this device is of the type comprising a body generally designated by 1 and having an inner wall 2 delimiting inlet cavities 3 and outlet 4. The cavity inlet 3 is connected to the downstream or discharge side of the pump, which is represented by a discharge arrow 5, while the outlet cavity 4 is connected to the upstream or suction side of the pump, which is represented by a suction arrow 6, the pump itself not being shown for the sake of simplification. The pressures prevailing in the inlet 3 and outlet 4 cavities therefore correspond respectively to the discharge pressures, P.ref, and suction, P.asp, of the pump.

The inlet 3 and outlet 4 cavities are separated from each other by a sealing assembly, which is generally designated by 7 and which comprises a valve 8, its associated seat 9 and its spring return 10, having the same axis of symmetry 11. The seat 9 is formed in the inner wall 2 of the body 1, while the stem 12 of the valve 8 is slidably mounted in the body 1 and that the return spring 10 is mounted concentric with the stem 12 of the valve 8 and disposed between the head 13 of the latter and a stop 14.

In a manner known per se, the sealing assembly 7 is intended to open to put the two cavities 3 and 4 in communication, according to the arrow 15 shown in FIG. 3, when the differential hydraulic pressure discharge - suction is greater to the mechanical pressure exerted by the spring 10.

According to an essential feature of the invention, the stop 14 associated with the return spring 10 of the valve 8 is made integral with the rod 16 of the piston 17 of a double-acting cylinder 18. This jack 18 is itself associated with the body 1 and is preferably housed in the latter, parallel to the axis of symmetry 11 of the sealing assembly 7.

Under these conditions, any movement of the piston 17 of the jack 18 and of its associated rod 16 results in a corresponding movement of the end stop 14 which directly controls the opening or closing of the valve 8. The connection between the stop 14 and the rod 16 of the piston 17 can be produced by any means as soon as the tail 12 of the valve 8 is parallel to the said rod 16 and that any movement of this rod 16 is fully reflected on the stop 14 and, more precisely, on the valve 8. For this purpose, the return spring 10 is in fact an extremely stiff safety spring which is intended to crash only when a large discharge overpressure suddenly appears in the inlet cavity 3.

As regards the connection between the stop 14 and the rod 16 of the piston 17, it is possible in particular to envisage rigid connection devices of the non-deformable parallelogram type or else articulated connection devices of the rack type or other type of deflection, but all these devices are subject to wear and require precise adjustments which are often difficult to carry out. Consequently, according to a preferred embodiment of the invention, the rod 16 of the piston 17 of the double-acting cylinder 18 is coaxial with the axis of symmetry 11 of the sealing assembly 7 and the valve 8 is mounted at sliding relative to said rod 16.

According to yet another essential feature of the invention and with particular reference to Figure 1, the two orifices E, F forming the inlet and outlet of the double-acting cylinder 18 and located on either side of the piston 17 are respectively connected to a distributor 19 for regulating pressure.

As will be explained in more detail in the remainder of this description, the pressure regulating distributor 19 comprises a pressure slide 21 which is sensitive to the difference between the discharge, P.ref, and suction pressures, P .asp, respectively prevailing in the inlet 3 and outlet 4 cavities.

Referring to Figures 1 and 4 to 6, the pressure regulating distributor 19 is preferably in the form of a cylinder in the bore of which the pressure slide 21 slides freely between two stops (not shown) delimiting two terminal cavities opposite 23 and 24.

The first terminal cavity 23 has an orifice 25 which is connected by a conduit 26 to an orifice 27 formed in the inlet cavity 3. Thanks to the existence of the first stop not shown at the end of travel of the pressure slide 21, the orifice 25 can never be closed by the latter and the terminal cavity 23 is permanently subjected to the discharge pressure, P. ref.

In the same way, the second terminal cavity 24 has an orifice 28 which is connected by a conduit 29 to an orifice 30 formed in the outlet cavity 4. Thanks to the existence of the second stop not shown at the end of the slide travel pressure 21, the orifice 28 can never be closed by said pressure slide and, therefore, the terminal cavity 24 is permanently subjected to the suction pressure, P.asp.

In addition, the second end cavity 24 includes a pressure spring 31 disposed between the pressure slide 21 and an adjustable support 32 forming part of a device 33 for adjusting the pressure setpoint, for example of the type with tight adjustment screw.

Furthermore, the pressure slide 21 has two annular grooves 34 and 35. An orifice A is formed in the bore of the cylinder opposite the groove 34 and is connected to the conduit 26. The groove 34 and the orifice A are arranged so that, whatever the position of the pressure slide 21, the latter never closes the orifice A. Consequently, the groove 34 is permanently subjected to the pressure of delivery, P.ref, at the same time as the cavity 23. In the same way, an orifice B is formed in the bore of the cylinder opposite the groove 35 and is connected to the conduit 29. The groove 35 and the orifice B are arranged in such a way that the pressure slide 21 never closes the orifice B and that the groove 35 remains permanently subjected to the suction pressure, P.asp, at the same time as the cavity 24.

Two other orifices A1 and A2, formed in the bore of the cylinder, are arranged symmetrically on either side of the radial plane corresponding to the axis of the orifice A and are separated by a distance just equal to the width of the groove 34. Consequently, when the pressure slide 21 occupies the extreme position shown in FIGS. 1 and 4, the groove 34 is in communication with the orifice A1 and a conduit 36 which is connected to it. On the other hand, when the pressure slide 21 occupies the opposite position shown in FIG. 6, the groove 34 is in communication with the orifice A2 and a conduit 37 associated with the latter. Finally, when the pressure slide 21 occupies the intermediate position shown in FIG. 5, the two openings A1 and A2 are closed by the wall of the slide, the groove 34 being located exactly between said openings.

In the same way, two other orifices B1 and B2 are formed in the bore of the cylinder, on either side of the median position of the groove 35, which corresponds to the axis of the orifice B. This results in that when the pressure slide 21 successively occupies the positions shown in FIGS. 4 to 6, the groove 35 is first in communication with the orifice B1 and a conduit 38 which is associated with it, then is insulated with respect to the two orifices B1 and B2 which are both closed, and is finally in communication with the orifice B2 to which a conduit 39 is connected.

Furthermore, the conduits 36 and 39 are both connected to a conduit 53 opening into the actuator 18 at the orifice F, while the conduits 37 and 38 are both connected to a conduit 55 opening into the actuator 18 to the level of port E.

Consequently, when the pressure slide 21 occupies the first extreme position shown in FIGS. 1 and 4, its two annular grooves 34, 35 are respectively connected to the orifices F, E of the double-acting cylinder 18 so that its piston 17 tends to cause valve 8 to close.

Conversely, when the pressure slide 21 occupies the second extreme position shown in FIG. 6, its two annular grooves 34, 35 are respectively connected to the orifices E, F of the double-acting cylinder so that its piston 17 tends to cause the opening of the soup 8.

Furthermore, with reference only to FIGS. 4 to 6, an outlet duct 45 is connected to a second orifice 46 formed in the second terminal cavity 24. In the embodiment shown in FIG. 1 and described so far, this conduit 45 and this second orifice 46 do not exist, but their utility will be explained by describing another embodiment of the invention, which is shown in FIG. 11.

Referring now to Figures 7 to 10, these schematically illustrate a second possible embodiment of the assembly of a bypass device according to the invention controlled by a distributor 20 for vacuum regulation. This vacuum regulation distributor 20 has a vacuum drawer 22 which is sensitive to the difference between the external atmospheric pressure, P.atm, and the suction pressure, P.asp, prevailing in the outlet cavity 4.

The vacuum regulation distributor 20 is preferably, like the pressure regulation distributor 19, in the form of a cylinder in the bore of which the vacuum drawer 22 slides freely between two stops not shown delimiting two opposite end cavities 40 and 41.

The first terminal cavity 40 has an orifice 60 which is connected by the conduit 29 to the orifice 30 formed in the outlet cavity 4. Thanks to the existence of the first stop, not shown, of the end of travel of the vacuum drawer 22, the orifice 60 can never be closed by the latter and the terminal cavity 40 is permanently subjected to the suction pressure, P.asp.

In addition, this first end cavity 40 contains the thrust member 42 of a piston-membrane 43 which is subjected on one side to the external atmospheric pressure, P.atm, and on the other side to the pressure of suction, P.asp, prevailing in the outlet cavity 4.

The second terminal cavity 41 has an orifice 44 which is connected by the conduit 29 to the suction pressure, P.asp. Thanks to the existence of the second stop, not shown, of the end of travel of the vacuum drawer 22, the orifice 44 can never be closed by said vacuum drawer and the terminal cavity 41 is permanently subjected to the suction pressure. , P.asp.

In addition, the second end cavity 41 includes a vacuum spring 47 disposed between the vacuum drawer 22 and an adjustable support 48 forming part of a device 49 for adjusting the vacuum setpoint, for example of the type with tight adjustment screw as for the pressure regulation distributor 19.

In this regard, it can be considered that the suction pressure acting on both sides of the vacuum drawer 22 in the opposite end cavities 40 and 41 balances said vacuum drawer. However, it should be noted that the section of the piston-membrane 43 is much larger than the section corresponding to the slide in the opposite terminal cavity 41. Consequently, considering the mechanical and hydraulic forces present, it can be seen that the movement of the slide vacuum 22 is mainly due to the force imbalance between the vacuum spring 47 and the diaphragm piston 43, the latter being subjected to the differential pressure between the external atmospheric pressure and the suction pressure.

Because the pressure regulation 19 and vacuum 20 distributors perform similar control functions with respect to the bypass device, the same alphabetical references have been kept to designate the same inlet and outlet orifices provided in the respective bores of the pressure and vacuum cylinders.

More specifically, the vacuum drawer 22 has two annular grooves 50 and 51, the inlet orifice A being formed opposite the groove 50 and connected to the duct 26, while the inlet orifice B is formed opposite groove 51 and connected to conduit 29. As for the pressure slide 21, the grooves 50, 51 and the orifices A, B are respectively arranged so that, whatever the position of the vacuum slide, there is no never closes the orifices A and B. Consequently the grooves 50 and 51 are respectively permanently subjected to the discharge pressures, P. ref, and of suction, P.asp.

As in the case of the pressure slide 21, two pairs of outlet ports A1, A2 and B1, B2 are formed in the bore of the vacuum cylinder, on either side of the median position of the associated groove 50 or 51, which corresponds to the axis of the orifice A or B. It follows that when the drawer vacuum 22 successively occupies the extreme position shown in Figures 7 and 8, then the intermediate position shown in Figure 9 and finally the opposite extreme position shown in Figure 10, the grooves 50 and 51 are respectively in communication with the orifices A1 and B1 and the conduits 36 and 38 which are associated with them, then the grooves 50 and 51 are both isolated and the outlet orifices A1, A2, B1 and B2 closed by the wall of the vacuum drawer 22, and finally the grooves 50 and 51 are respectively in communication with the openings A2 and B2 and the conduits 37 and 39 which are associated with them.

As in the previous embodiment, the conduits 36 and 39 are both connected to the conduit 53 opening into the jack 18 at the orifice F, while the conduits 37 and 38 are both connected to the conduit 55 opening into the cylinder 18 at orifice E.

Consequently, when the vacuum drawer 22 occupies the first extreme position shown in FIGS. 7 and 8, its two annular grooves 50, 51 are respectively connected to the orifices F, E of the double-acting cylinder 18 so that its piston 17 tends to cause valve 8 to close.

Conversely, when the vacuum slide 22 occupies the second extreme position shown in FIG. 10, its two annular grooves 50, 51 are respectively connected to the orifices E, F of the double-acting cylinder 18 so that its piston 17 tends to cause opening the valve 8.

Furthermore, with reference only to FIGS. 8 to 10, an outlet duct 45 is connected to a second orifice 46 formed in the second terminal cavity 41. These duct 45 and orifice 46 do not exist in the embodiment shown in FIG. 7 and described above, but their utility will be explained by describing other embodiments of the invention, which are shown in FIGS. 11 to 18.

Referring now to Figures 11 to 14, these schematically illustrate a third possible embodiment of the assembly of a bypass device according to the invention controlled by both a pressure regulating distributor 19 and a distributor vacuum regulator 20 hydraulically mounted in cascade.

More precisely, with reference to FIG. 11, the pressure regulating distributor 19, whose pressure slide 21 is sensitive to the difference between the discharge and suction pressures, is placed at the head of the cascade and has already has been described with reference to Figures 1 and 4 to 6. Because the pressure regulating distributors 19 shown in these figures fulfill exactly the same control functions, the same numerical and alphabetical references designate the same constituent elements thereof.

With further reference to FIG. 11, the vacuum regulation distributor 20, whose vacuum drawer 22 is sensitive to the difference between the external atmospheric pressure and the suction pressure, is arranged at the end of the cascade, has already been mainly described with reference to Figures 7 to 10 and will be described in more detail below as a second element of the cascade with reference to Figures 12 to 14. The vacuum regulating distributors 20 represented in these figures are constituted by the same functional elements which are designated by the same reference numerals. However, since the vacuum regulation distributor shown in FIG. 11 is dependent on a pressure regulation distributor, it is not hydraulically connected in the same way as that represented in FIGS. 7 to 10 and the alphabetical references already used for the pressure regulating distributor 19 have been modified for the sake of clarity.

Referring again to FIGS. 11 to 14, the orifice 44 of the second terminal cavity is connected by a conduit 45 to the suction pressure, P.asp, said conduit preferably being connected to an orifice 46 formed in the second cavity 24 of the distributor 19 for regulating pressure. Preferably, the orifice 60 of the first terminal cavity 40 is itself connected to the conduit 45 via a conduit 61 so that the first and second terminal cavities 40 and 41 are both permanently subjected to the suction pressure, P.asp.

Furthermore, the two annular grooves 50 and 51 are respectively associated with two series of four inlet and outlet orifices respectively arranged two by two on either side of the median position of the groove in question. More specifically, by considering the slide 22 from the first terminal cavity 40 to the second terminal cavity 41 and by first referring to the extreme position shown in FIGS. 11 and 12, the groove 50 is in communication with a inlet orifice A3 connected to the conduit 36, while the groove 51 is in communication with an inlet orifice B3 connected to the conduit 38. In this same position of the drawer 22, the groove 50 is also in communication with an outlet port A4 connected to the conduit 52, itself connected to the conduit 39 and to the conduit 53 opening into the jack 18 at the level of the orifice F, while the groove 51 is also in communication with an outlet orifice B4 connected to the conduit 54, itself connected to the conduit 37 and to the conduit 55 opening into the jack 18 at the level of the orifice E.

Referring next to the extreme opposite position of the slide 22, which is shown in FIG. 14, the groove 50 is in communication with an inlet orifice C connected by a conduit 56 to the conduit 26, while the groove 51 is in communication with an inlet orifice D connected by a conduit 57 to the conduit 45. In this same position of the drawer 22, the groove 50 is also in communication with an outlet orifice C1 connected by a conduit 58 to the conduits 37, 54 and 55, the latter opening into the orifice E of the jack, while the groove 51 is also in communication with an outlet orifice D1 connected by a conduit 59 to the conduits 39, 52 and 53, the latter opening into the orifice F of the cylinder.

Referring finally to the intermediate position of the slide 22, as shown in FIG. 13, all the successive inlet orifices A3, C, B3 and D are closed, and all the successive outlet orifices A4, C1 , B4 and D1 are also closed.

During operation, the pressure regulation distributor 19 being disposed at the head of the cascade, when its pressure drawer 21 occupies the first extreme position shown in FIGS. 4 and 11 and that the vacuum drawer 22 of the vacuum regulation distributor 20 occupies the first extreme position shown in FIGS. 11 and 12, the discharge pressure passes through the channel A, A1, A3, A4, F, while the suction pressure passes through channel B, B1, B3, B4, E, thus causing the valve 8 to close.

When the pressure slide 21 still occupies the first extreme position shown in FIGS. 4 and 11, but the vacuum slide 22 occupies the second extreme position shown in FIG. 14, the reference pressure passes through the path C, C1, E while the suction pressure passes through the channel D, D1, F to cause the valve 8 to open.

Finally, when the pressure slide 21 occupies the second extreme position shown in FIG. 6, the discharge pressure passes through the direct path A, A2, E, while the suction pressure passes through the direct path B, B2, F, thus causing the opening of the valve 8 regardless of the position of the vacuum slide 22, which no longer receives hydraulic fluid when it occupies the first extreme position and which participates in the opening of the valve 8 when it occupies the second extreme position, the discharge pressure then passing through the channel C, C1, E, while the suction pressure passes through the channel D, D1, F.

Furthermore, it seems difficult to mount the two distributors 19 and 20 in parallel, in particular due to the complexity of the hydraulic circuits and the risk of pressure imbalance. On the other hand, it is entirely conceivable to swap the two distributors in their series or cascade mounting, as shown in FIGS. 8 to 10 and 15 to 18, among which FIGS. 8 to 10 obviously represent the three respective positions of the vacuum regulation distributor 20 mounted at the head of the cascade, while FIGS. 16 to 18 represent the three respective positions of the pressure regulating distributor 19 mounted second in the cascade.

More specifically, with reference to FIGS. 15 to 18, these schematically illustrate a fourth possible embodiment of the assembly of a bypass device according to the invention, in which the vacuum regulation distributor 20 is arranged in head of the cascade, the pressure regulating distributor 19 being mounted under its dependence.

Due to the fact that these vacuum and pressure regulating distributor 19 fulfill exactly the same piloting functions as those of the reverse cascade represented in FIGS. 11 to 14, the same numerical and alphabetical references have been kept to designate the same elements and the paths taken by the hydraulic pressures are written identically in both cascades.

During operation, the vacuum regulation distributor 20 being disposed at the head of the cascade, when its vacuum drawer 22 occupies the first extreme position shown in FIGS. 8 and 14, and that the pressure drawer 21 of the pressure 19 occupies the first extreme position shown in FIGS. 15 and 16, the discharge pressure again passes through channel A, A1, A3, A4, F and the suction pressure passes again through channel B, B1, B3, B4, E to cause the valve 8 to close.

In the same way as previously, when the vacuum drawer 22 still occupies the first extreme position shown in FIGS. 8 and 4, but that the pressure drawer 21 occupies the second extreme position shown in FIG. 18, the pressure of discharge passes through path C, C1, E, while the suction pressure passes through path D, D1, F, to cause the valve 8 to open.

Finally, when the vacuum slide 22 occupies the second extreme position shown in FIG. 10, the discharge pressure passes through the direct path A, A2, E, while the suction pressure passes through the direct path B, B2, F, to cause the opening of the valve 8 independently of the position of the pressure slide, which no longer receives hydraulic fluid when it occupies the first extreme position and which participates in the opening of the valve 8 when it occupies the second extreme position, the discharge pressure then passing through the channel C, C1, E, while the suction pressure passes through the channel D, D1, F.

With regard to the operation of one or the other of the cascades, it is necessary to consider all the possible cases represented by the combination of the various positions of the two pressure drawers 21 and of vacuum 22, as they are determined by the differential pressures and instructions relating to the two respective pairs of pressures:

Repression - Aspiration Atmosphere - Aspiration

These different cases are summarized in the table below, in which the main paths taken by the discharge and suction pressures have been indicated, the figures representing the positions of the drawers, and the final result obtained on valve and regulation.

In general, a bypass device controlled as indicated above can have several uses, in particular the protection of a pump for fluid or viscous liquids and the automatic regulation of its various operating parameters, for example pressure regulation suction, the regulation of a discharge pressure level in the case where the suction pressure is stable, the regulation of both suction and discharge pressures.

It is understood that the present invention has been described and shown for explanatory purposes but in no way limitative and that any useful modification may be made to it, in particular in the field of technical equivalences, without going beyond its ambit.

Claims (13)

Pilot-operated bypass device for pump for fluid or viscous liquids, of the type comprising a body (1) having an interior wall (2) delimiting inlet (3) and outlet (4) cavities respectively connected to the discharge sides (5) and suction (6) of the pump and separated from each other by a sealing assembly (7), which comprises a valve (8), its seat (9) and its return spring (10) having the same axis of symmetry (11), the seat (9) being formed in the interior wall (2) of the body (1), the stem (12) of the valve (8) being slidably mounted in the body (1) and the return spring (10) being mounted concentric with the stem (12) of the valve (8) and between the head (13) of said valve (8) and a stop (14), and which is intended to open to put the cavities (3, 4) in communication when the differential pressure discharge - suction is higher than that of the spring (10), characterized in that the stop (14) associated with the spring (10) of the valve (8) is made integral with the rod (16) of the piston (17) of a double-acting cylinder (18), which is housed in the body (1) parallel to the axis of symmetry (11) of the sealing assembly (7) and of which the two orifices (E, F) forming an inlet and an outlet and situated on either side of the piston (17) are respectively connected to one and / or the other of two regulating distributors, namely a pressure regulating distributor (19), the slide valve (21) of which is sensitive to the difference between the pressures (P.ref - P.asp ) prevailing respectively in the inlet (3) and outlet (4) cavities, and a distributor (20) for vacuum regulation, the slide (22) of which is sensitive to the difference between atmospheric pressure (P.atm) and the pressure (P.asp) prevailing in the outlet cavity (4). Device according to claim 1, characterized in that the rod (16) of the piston (17) of the double-acting cylinder (18) is coaxial with the axis of symmetry (11) of the sealing assembly (7) and the valve (8) is slidably mounted relative to said rod (16). Device according to either of Claims 1 and 2, characterized in that the pressure regulating distributor (19) has a first end cavity (23) subjected to the discharge pressure (P.ref), a second end cavity ( 24) subjected to the suction pressure (P.asp) and containing a pressure spring (31) disposed between the pressure slide (21) and an adjustable support (32) forming part of an adjustment device (33) pressure setpoint, said slide (21) comprising first and second annular grooves (34, 35) respectively permanently subjected to the discharge (P.ref) and suction (P.asp) pressures and each capable of being connected to one or the other of two hydraulic circuits according to one or the other of two opposite extreme positions of the pressure slide (21). Device according to claim 3, characterized in that when the pressure slide (21) occupies a first extreme position, its two annular grooves (34, 35) are respectively connected to the orifices (F, E) of the double-acting cylinder of such that its piston (17) tends to cause the valve (8) to close. Device according to claim 3, characterized in that when the pressure slide (21) occupies a second extreme position, its two annular grooves (34, 35) are respectively connected to the orifices (E, F) of the double-acting cylinder of so that its piston (17) tends to cause the opening of the valve (8). Device according to either of Claims 1 and 2, characterized in that the vacuum regulation distributor (20) has a first end cavity (40), containing the thrust member (42) of a piston - membrane ( 43) subjected on one side to the external atmospheric pressure (P.atm) and on the other side to the suction pressure (P.asp), a second terminal cavity (41) subjected to the suction pressure ( P.asp) and containing a vacuum spring (47) disposed between the vacuum drawer (22) and an adjustable support (48) forming part of a device (49) for adjusting the vacuum setpoint, said drawer (22) comprising first and second annular grooves (50, 51) respectively permanently subjected to the discharge (P.ref) and suction (P.asp.) pressures and each capable of being connected to one or the other two hydraulic circuits depending on one or the other of two opposite extreme positions of the vacuum slide (22). Device according to claim 6, characterized in that when the vacuum drawer (22) occupies a first extreme position, its two annular grooves (50, 51) are respectively connected to the orifices (F, E) of the double-acting cylinder of such that its piston (17) tends to cause the valve (8) to close. Device according to Claim 6, characterized in that when the vacuum drawer (22) occupies a second extreme position, its two annular grooves (50, 51) are respectively connected to the orifices (E, F) of the double-acting cylinder of so that its piston (17) tends to cause the opening of the valve (8). Device according to one of claims 1 or 2, characterized in that the distributors pressure control (19) and vacuum (20) are hydraulically mounted in cascade. Device according to claim 9, characterized in that the pressure regulating distributor (19) is disposed at the head of the cascade and when its pressure slide (21) occupies a first extreme position, its two annular grooves (34, 35 ), which are respectively permanently subjected to the discharge (P.ref) and suction (P.asp) pressures, are respectively connected to the associated annular grooves (50, 51) formed in the vacuum drawer (22) of the dispenser (20) for regulating the vacuum, so that when the said vacuum slide (22) occupies a first extreme position, its two associated grooves (50, 51) are respectively subjected to the discharge and suction pressures and are respectively connected to the orifices (F, E) of the double-acting cylinder (18) so that its piston (17) tends to cause the valve (8) to close, while when said vacuum slide (22) occupies a second extreme position , its two gorg he associates (50, 51) are directly and respectively subjected to the discharge and suction pressures and are respectively connected to the orifices (E, F) of the double-acting cylinder (18) so that its piston (17) tends to cause the opening of the valve (8). Device according to Claim 9, characterized in that the pressure regulating distributor (19) is arranged at the head of the cascade and when its pressure slide (21) occupies a second extreme position, its two annular grooves (34, 35 ), which are respectively permanently subjected to the discharge (P.ref) and suction (P.asp) pressures, are respectively connected directly to the orifices (E, F) of the double jack (18) effect so that its piston (17) tends to cause the opening of the valve (8), independently of the position of the vacuum slide (22) which, when it occupies a first extreme position has its two annular grooves (50 , 51) receiving no fluid from the associated annular grooves (34, 35) of the pressure slide (21), and which, when it occupies a second extreme position has its two annular grooves (50, 51) directly and respectively subjected at the discharge and suction pressures and respectively connected to the orifices (E, F) of the double-acting cylinder so that its piston (17) also tends to cause the opening of the valve (8). Device according to claim 9, characterized in that the vacuum regulating distributor (20) is arranged at the head of the cascade and when its vacuum drawer (22) occupies a first extreme position, its two annular grooves (50, 51 ), which are respectively permanently subjected to the discharge (P.ref) and suction (P.asp) pressures, are respectively connected to the associated annular grooves (34, 35) formed in the pressure drawer (21) of the distributor. (19) for regulating pressure, so that when said pressure slide (21) occupies a first extreme position, its two associated grooves (34, 35) are respectively subjected to discharge and suction pressures and are respectively connected to the orifices (F, E) of the double-acting cylinder (18) so that its piston (17) tends to cause the valve (8) to close, while when said pressure slide (21) occupies a second extreme position , his two associated grooves (34, 35) are directly and respectively subjected to the discharge and suction pressures and are respectively connected to the orifices (E, F) of the jack (18) double acting so that its piston (17) tends to cause the opening of the valve (8). Device according to claim 9, characterized in that the vacuum regulating distributor (20) is arranged at the head of the cascade and when its vacuum drawer (22) occupies a second extreme position, its two annular grooves (50, 51 ), which are respectively permanently subjected to the discharge (P.ref) and suction (P.asp) pressures, are respectively connected directly to the orifices (E, F) of the double-acting cylinder (18) so that its piston (17) tends to cause the opening of the valve (8), independently of the position of the pressure slide (21) which, when it occupies a first extreme position has its two annular grooves (34, 35) not receiving no fluid coming from the associated annular grooves (50, 51) of the vacuum slide (22), and which, when it occupies a second extreme position, has its two annular grooves (34, 35) directly and respectively subjected to the discharge pressures and suction and respectively connected s at the orifices (E, F) of the double-acting cylinder so that its piston (17) also tends to cause the opening of the valve (8).

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