EP1048849B1 - High pressure liquid pump - Google Patents

Description

The present invention relates to a pump capable of pumping and to repress under high pressure practically any liquid such as: water, gasoline, diesel, oils, corrosive chemical liquids and sludge; but more especially for the high pressure supply of fuel injectors for internal combustion engines.

Low pressure pumps for this kind of liquids are known, they are of a generally centrifugal pumps, gear pumps, sometimes piston or others, but with known pumps it's impossible if not very difficult and costly, to obtain a high discharge pressure (greater than 50 bars), because that, when high pressures are encountered, seizures of moving parts and large leaks, because of the often very low viscosity pumped fluids.

To avoid such seizures or leaks, it is known to employ diaphragm pumps, but it is then impossible to obtain a pressure of high backflow. Indeed, the membrane is on one side driven by means (cam, lever or the like) and is on the other subject to the pressure of it results that, as soon as the pressure becomes high, the membrane becomes deteriorates at the points of application of the mechanical forces.

It is also known, for pumping particular liquids such as for example that corrosive liquids, to associate two pumps: a first pump which is a hydraulic pump which represses and reuses hydraulic fluid that drives reciprocating the moving parts of a second pump, this last aspirant and pressurizing the liquid to be pumped. These moving parts which ensure the physical separation between the hydraulic fluid and the liquid to pump, while being reciprocated by the hydraulic fluid, are either deformable membranes or free pistons.

The free pistons have a defect with regard to the sealing, a defect which is essential in the case where one must have an absolute seal. If we put in place a seal between the free piston and the cylinder in which it moves, it is not possible to obtain a perfect seal. If we remove the seal: or there is has a very thin film of oil between the friction surfaces and therefore micro-leaks: or there is no oil film and the friction surfaces will heat up. In the particular case of high-pressure gasoline injection no leak, also little is it, is not admissible and, of course, any warm-up risk of cause an explosion.

Known devices with free pistons, such as, for example, the US patent 4,443,160 are therefore to be proscribed.

The present invention thus relates to a pumping device in which the moving elements, driven by an alternating movement of pumping by the pump hydraulic and ensuring a completely sealed separation between the liquid Hydraulic "motor" and the liquid to be pumped are deformable membranes.

a - si la membrane de séparation et de pompage est mécaniquement liée au piston de la pompe hydraulique, il n'y a pas équipression de chaque côté de la membrane souple et cette dernière ne tient pas dans le temps, elle se détériore ;

b - si la membrane est complètement libre, c'est-à-dire n'est liée à aucun mécanisme d'entraínement et est mue uniquement par le liquide hydraulique refoulé par la pompe, il y a équipression entre les deux côtés de la membrane. Cependant, du fait des inévitables fuites, même très minimes, le volume de liquide hydraulique refoulé augmente à chaque cycle et finit par devenir plus important que celui que peut refouler la membrane : il se produit alors un blocage hydraulique créant une surpression telle que l'une ou l'autre des deux pompes se brise. Dans le cas particulier de l'injection d'essence à haute pression, si c'est l'élément qui refoule l'essence à haute pression qui se brise, l'incendie est inévitable :

c - dans un cas comme dans l'autre, c'est-à-dire que la membrane soit liée au piston ou bien libre, si le volume de liquide hydraulique qui est continuellement refoulé et réaspiré est toujours le même, il va s'échauffer du fait des cycles de compressions indéfiniment répétés, jusqu'à atteindre une température telle que la, ou les, membranes seront détruites.

Generally speaking, pumps of this type with deformable membranes have at least one, if not more than one, of the following disadvantages:

a - if the separation and pumping membrane is mechanically connected to the piston of the hydraulic pump, there is no equipressure on each side of the flexible membrane and the latter does not hold in time, it deteriorates;

b - if the membrane is completely free, that is to say is not linked to any drive mechanism and is moved solely by the hydraulic fluid discharged by the pump, there is equipression between the two sides of the membrane . However, because of the inevitable leaks, even very minimal, the volume of hydraulic fluid discharged increases with each cycle and ends up becoming larger than that which can push back the membrane: there then occurs a hydraulic blockage creating an overpressure such that the either one of the two pumps breaks. In the particular case of the injection of high-pressure gasoline, if it is the element that delivers high-pressure gasoline that breaks, the fire is inevitable:

c - in one case as in the other, that is to say that the membrane is connected to the piston or free, if the volume of hydraulic fluid which is continuously repressed and re-aspirated is still the same, it will s' to heat up because of indefinitely repeated compression cycles, until reaching a temperature such that the, or the membranes will be destroyed.

In US Pat. No. 4,392,787, a set comprising a hydraulic pump with bias plate, each piston of the pump being associated with its end to a flexible membrane that is connected to a sliding rod inside the piston. This device has the defects described above in "a" and "c". Volume of liquid continually put under pressure is always the same and so goes heat. On the other hand the small inevitable leaks are compensated by admission of oil in addition by a check valve, but if accidentally a leak important, the piston comes into mechanical contact with the membrane which will be destroyed.

In US Pat. No. 2,960,936 DEAN, a pump has been described in which a completely free membrane is cyclically crushed and released by a volume hydraulic operated by a piston actuated by a cam .. This device has defects "b" and "c". If it happens, for some reason a stop or even a braking of the power supply, the membrane will not redeploy completely and a corresponding amount of hydraulic fluid is going to be introduced at each cycle and this until rupture (disadvantage "b"). on the other hand, as it is always the same volume of hydraulic fluid that is compressed, warm-up is inevitable (inconvenience "c").

In German Patent 2,447,741 WANNER, a diaphragm pump has been described. which is mechanically linked to a piston which slides inside a piston of hydraulic pump. The disadvantages are the same as for the patent US 4,392,787 cited above.

To eliminate these disadvantages, the present invention proposes a device in which which each membrane is free and in which, at the end of each cycle of a piston, the dead chamber, located downstream of the top dead center of this piston (position maximum compression), in which is the liquid in contact with the membrane is put into communication with the reserve of hydraulic fluid; of so that the liquid which is there is pushed back towards this reserve first by the relaxation of the liquid, then by the effect of repression by the membrane which is contretenue by a spring.

Thus, on the one hand, a heat exchange is continuously repeated between the compressed liquid and that which is not, and on the other hand, initial membrane at each cycle or, in other words, an elimination of any increase in the volume of hydraulic fluid acting on the membrane, increase which is inevitably caused permanently by the leaks; because it is not possible to realize a high pressure hydraulic pump with pistons, which does not heat and which has a good performance, without leaks.

According to a first object, the present invention relates to a pump for pump any kind of liquid while printing a pressure of very high discharge, of the type constituted by the association of two pumps: on the one hand, a hydraulic pump; on the other hand, a second pump whose moving means, carrying out the suction and the delivery of the liquid to be pumped, are flexible membranes animated with a reciprocating motion in a more direction in the other by the displacement of the hydraulic fluid pumped and then sucked by the first pump characterized by the fact that the pistons of the first pump are hollow and traversed by the hydraulic fluid which, during the suction phase crosses a lunula or groove dug in the face of the bias or cam plate; the deformable membranes being each controlled by a spring so that that at the end of the compression stroke of each piston, the communication is between the chamber where the hydraulic fluid is pushed back against the membrane and the suction chamber, this liquid being, on the one hand, sucked by the movement of the piston and pushed back by the membrane under the action of its spring, this which ensures: on the one hand an exchange between the hydraulic fluid heated by the compression and the unheated liquid and, on the other hand, a return to the initial position of the membrane.

a - la deuxième pompe comporte autant de volumes ou alésages que la première pompe comporte d'alésages, chaque alésage de la deuxième pompe communiquant directement avec l'alésage correspondant de la première pompe de sorte que chaque piston de la première pompe refoule et aspire cycliquement le liquide hydraulique dans l'alésage correspondant de la deuxième pompe.

b - chaque alésage de la deuxième pompe est divisé en deux parties par une membrane déformable contretenue par un ressort, la partie communiquant avec l'alésage correspondant de la première pompe et recevant le liquide hydraulique refoulé et réaspiré par celle-ci, l'autre partie, munie de clapets d'aspiration et de refoulement, aspirant et refoulant le produit à pomper.

c - la chambre dans laquelle se débattent les têtes des pistons est reliée à un réservoir de liquide hydraulique.

d - le réservoir de liquide hydraulique est extérieur à la première pompe et communique avec cette dernière par une canalisation débouchant dans la chambre.

e - la pompe selon l'invention est destinée à l'alimentation sous haute pression d'injecteurs de carburant pour moteurs à combustion interne, le liquide hydraulique de la première pompe (I) pouvant être l'huile dudit moteur.

The pump according to the invention may also include one or other of the following provisions:

a - the second pump comprises as many volumes or bores as the first pump comprises bores, each bore of the second pump communicating directly with the corresponding bore of the first pump so that each piston of the first pump discharges and cyclically sucks the hydraulic fluid in the corresponding bore of the second pump.

b - each bore of the second pump is divided into two parts by a deformable diaphragm controlled by a spring, the part communicating with the corresponding bore of the first pump and receiving the hydraulic fluid discharged and sucked by it, the other part, equipped with suction and discharge valves, sucking and driving back the product to be pumped.

c - the chamber in which the heads of the pistons are struggling is connected to a reservoir of hydraulic fluid.

d - the hydraulic fluid reservoir is external to the first pump and communicates with the latter by a pipe opening into the chamber.

e - the pump according to the invention is intended for the high pressure supply of fuel injectors for internal combustion engines, the hydraulic fluid of the first pump (I) being the oil of said engine.

According to a second subject, the present invention relates to means for vary the displacement of the first pump and therefore the flow of gasoline to the injection devices.

These means are: either the provision of a variable inclination bias tray, or the arrangement of means in the pistons of the hydraulic pump, having for function to short-circuit all or part of the volume of hydraulic fluid introduced into the bore during the suction phase.

According to the invention, each hollow piston of the hydraulic pump is provided with openings that can be obscured in whole or in part by a mobile shirt, all the moving jackets being moved together by a control member subject to the operating conditions of the engine.

a - les pistons coulissent dans deux supports percés d'orifices, ces deux supports étant séparés l'un de l'autre par un espace annulaire, constituant une chambre, dans laquelle se déplacent les chemises entre deux positions extrêmes, l'une pour laquelle les orifices n'étant pas masqués par les chemises la totalité du liquide refoulé par chaque piston reflue dans la chambre annulaire par les orifices des pistons le débit de la pompe (I) étant nul : l'autre pour laquelle tous les orifices étant masqués par les chemises chaque piston refoule la totalité du liquide hydraulique aspiré, le débit de la pompe étant alors maximum.

b - les chemises peuvent occuper toutes les positions intermédiaires comprises entre les deux positions extrêmes ; de sorte que le débit de la pompe (I) peut être régulé pour toutes les valeurs comprises entre un débit nul et un débit maximum.

c - les chemises sont attelées à un organe de commande commun lequel est asservi à tout dispositif de commande approprié pour réguler le débit d'essence à haute pression en fonction des besoins en alimentation du moteur sans que de l'essence à haute pression ne soit retournée au réservoir.

d - un dispositif amortisseur peut être disposé en aval de la sortie de la deuxième pompe (II) et en amont des injections pour annuler l'effet de pulsation provoqué par la première pompe (I).

e - le dispositif amortisseur peut être une capacité de volume important par rapport au débit d'essence, maintenu sous la pression d'injection par tout moyen approprié et se comporter sensiblement comme un accumulateur hydromécanique.

This device may, in addition, include one or other of the following provisions:

a - the pistons slide in two brackets drilled with orifices, these two supports being separated from each other by an annular space, constituting a chamber, in which the shirts move between two extreme positions, one for which the orifices not being masked by the jackets all of the liquid discharged by each piston flows back into the annular chamber through the orifices of the pistons the flow rate of the pump (I) being zero: the other for which all the orifices are masked by the jackets each piston represses all the hydraulic fluid sucked up, the flow rate of the pump then being maximum.

b - the shirts can occupy all the intermediate positions between the two extreme positions; so that the flow rate of the pump (I) can be regulated for all values between zero flow and maximum flow.

c - the jackets are coupled to a common control member which is controlled by any appropriate control device to regulate the flow of high pressure gasoline according to the engine power requirements without high pressure gasoline is returned to the tank.

d - a damping device may be disposed downstream of the outlet of the second pump (II) and upstream of the injections to cancel the pulsation effect caused by the first pump (I).

e - the damping device can be a large volume capacity with respect to the gasoline flow, maintained under the injection pressure by any appropriate means and behave substantially as a hydromechanical accumulator.

• Figure 1, une vue en coupe longitudinale d'un premier mode de réalisation de l'invention.
• Figure 2, une vue en coupe transversale selon A-A de la figure 1.
• Figure 3, une vue en coupe longitudinale de la pompe double à débit variable, les pièces étant dans la position pour laquelle le débit est maximum.
• Figure 4, une vue de la pompe double de la figure 3, les pièces étant dans la position pour laquelle le débit est nul.
• Figure 5, une vue selon A-A de la face du plateau biais des figures 3 et 4.
• Figure 6, une vue en coupe longitudinale de la pompe de la figure 1 dans laquelle les membranes individuelles ont été remplacées par une membrane unique.
• Fifure 7, une vue en coupe selon A-A de la figure 6.
• Figure 8, une vue en coupe selon B-B de la figure 6.
• Figure 9, une vue de détail à échelle agrandie en coupe longitudinale, d'une variante de réalisation de la pompe selon l'invention dans laquelle les clapets d'aspiration ont été supprimés.
• Figure 10, une vue en coupe longitudinale de la pompe de la figure 6 munie du système d'aspiration par la membrane de la figure 9.
• Figure 11, une vue d'une variante de réalisation dans laquelle la pompe hydraulique est une pompe radiale.

As non-limiting examples and to facilitate the understanding of the invention, there is shown in the accompanying drawings:

• Figure 1 is a longitudinal sectional view of a first embodiment of the invention.
• Figure 2 is a cross-sectional view along AA of Figure 1.
• Figure 3 is a longitudinal sectional view of the dual pump variable flow, the parts being in the position for which the flow is maximum.
• Figure 4 is a view of the double pump of Figure 3, the parts being in the position for which the flow is zero.
• Figure 5 is a view along AA of the face of the bias plate of Figures 3 and 4.
• Figure 6 is a longitudinal sectional view of the pump of Figure 1 in which the individual membranes have been replaced by a single membrane.
• Fifure 7, a sectional view along AA of FIG.
• Figure 8, a sectional view along BB of Figure 6.
• Figure 9 is an enlarged detail view in longitudinal section, of an alternative embodiment of the pump according to the invention in which the suction valves have been removed.
• 10, a longitudinal sectional view of the pump of FIG. 6 provided with the suction system by the membrane of FIG. 9.
• Figure 11 is a view of an alternative embodiment in which the hydraulic pump is a radial pump.

Referring to FIGS. 1 and 2, it can be seen that the device according to the invention comprises a first pump, designated by the general reference I and a second pump, designated by the general reference II.

The first pump I is an axial piston pump driven by a movement alternate back-and-forth by a bias tray 1.

The bias plate 1 is integral with a drive shaft 2 (driven by any means not shown) carried by bearings 3. A plurality of hollow pistons 4 take support against the oblique face of the plate 1 each by means of a sliding block 5, which is pierced at its center with a bore 6. Each piston 4 is held by a spring 7 against his stud. On the front face 1 is engraved a lunula 8. When the shaft 2 is rotated, the bias plate 1, the studs 5 and the heads spherical 4a pistons 4 are struggling in a room 9. This room 9 opens, through a plurality of holes 22, through the body 21 of the pump 1, in a tank 11. This tank 11 is constituted by a cylindrical envelope 23 surrounding the body 21.

When the motor shaft 2 rotates, the side of the bias plate 1 oscillates in the chamber 9 so that the pistons 4 are driven reciprocating back and forth: in the direction corresponding to the suction, the pistons 4 are driven by their spring 7; in the other direction which corresponds to the repression under pressure, they are pushed back to against the spring 7 by the bias plate 1. During the suction phase, the hydraulic fluid that is in the chamber 9 gets inside the pistons 4 passing through the lunula 8 and the bore 6 of the studs 5.

This type of pump is known and described in many prior patents owned by the plaintiff.

When the hydraulic pump I is used in known manner, each bore 12 in which slides a hollow piston 4 has at its end a non-return valve ; so that all of said pistons 4 causes a flow under pressure (and even under high pressure since one can exceed 1000 bars with this type of pump).

However, in the context of the present invention, none of the bores 12 in which slide the pistons 4 has a non-return valve.

A pump 1 is associated with the pump I immediately downstream thereof.

With each bore 2 of the pump I, in which slides a piston 4, corresponds, in the pump II, a chamber or bore 13 divided into two parts 13a and 13b by a flexible membrane 24 biased by a spring 15. The part 13a communicates directly with the end of the bore 12, while the portion 13b is provided with its end opposite the membrane 24 of a suction valve 16 and a valve 17. All valves 17 flow in a common pipe 18.

Preferably, as shown, each spring 15 is supported on the rear face of the membrane 24 via a cup 20. The shape of the cup 20 is determined so that the support of the cup 20 on the face rear of the membrane 24 does not cause any deterioration thereof.

The operation is described below:

When the driving shaft 2 is driven, the pistons 4 repress the hydraulic fluid 13. The hydraulic fluid discharged into part 13a of the chamber 13, bears on the front face of the membrane 24 and causes a move it in the direction of the arrow f1 (fig.1). In moving this membrane 24 delivers the liquid contained in the portion 13b of the chamber 13. This backflow is through the non-return valve 17.

Then, when the bias plate 1 continues to rotate, the stud 5 of each piston 4 passes on the lunula 8 which puts the chamber 13a, the interior of the hollow piston 4 and the suction chamber 9 in communication. At the very beginning of the plot race 5 on the lunula 8 the high pressure liquid that is in the chamber 13a relaxes in direction of the chamber 9; then under the action of the spring 7 of the piston 4 and the spring 15 of the membrane 24 the liquid in the chamber 13a is pushed back into the bore 12 and from there to the chamber 9.

So the hydraulic fluid, which is in the dead chamber at the end of each bore 12 when the piston 4 is at the end of its compression stroke and in the chamber 13a, is renewed at the end of each compression cycle, this which avoids any heating up of this liquid, which would be inevitable otherwise. Of moreover, this handing over of direct communication between the chamber 13a and the chamber 9, and this at each cycle, realizes a reset to the initial position of the moving elements so that the volume of hydraulic fluid discharged into the chamber 13a remains strictly equal to itself, the inevitable leaks from the pump hydraulics being returned to chamber 9. This communication between chambers 9 and 13a thus eliminates the disadvantages described previously in "b" and "c".

The displacement of the membrane 24 in the direction of the arrow f2 has the effect to suck the product to be pumped into the part 13b of the bore 13, through the valve anti-return valve 16 and to discharge the hydraulic fluid in the part 13a.

Thus the product to be pumped is alternately sucked and then pushed back by the movement membrane 24, this movement being caused by the variations of the volume occupied by the hydraulic fluid in the parts 13a of the bores 13, these variations in volume being caused by alternations of suction of the hydraulic fluid by the pistons 4 of the first pump I.

Each membrane 24 is subjected on its two front and rear faces and that of uniformly distributed over the entire surface of the membrane, at the same pressure: on one side the pressure of the engine hydraulic fluid, on the other hand the pressure of the liquid discharged. The membrane therefore undergoes no mechanical effort and therefore can not tear.

The pump according to the present invention is therefore a diaphragm pump in which each membrane is, in the phase of repression, an equipression of each side which allows to have a pressure of discharge equal to the pressure hydraulic that can provide the first pump I.

The pump according to the present invention can be used, inter alia, to in pressure of liquids having no grinding power. In particular she can be used to supply internal combustion engine injectors (motor vehicle engines) powered by super-fuel and / or LPG liquid as a substitute fuel for example. The super-fuel is aspirated by the valves 16, discharged under high pressure (more than 50 bar) by the valves 17 without the fuel ever being in contact with organs metal to slide against each other.

It should be noted that at high pressures, liquids can no longer be considered as incompressible. When a piston 4 is at the end of the delivery stroke, the hydraulic fluid pressure is at its maximum. As has been said more high, when the stud 5 is on the beginning of the lunula 8 the liquid, in detent will push through the piston 4, the passage 6 of the stud 5 and the lunula 8 in the chamber 9; then it will be discharged by the action of the spring 15. The compressed liquid is hot while the liquid in the chamber 9 and the tank is not; he will therefore there must be at each cycle a small exchange of liquid heated by the compression and unheated liquid which will allow to ensure a thermal balance of the first pump 1. Preferably, although not shown, the envelope cylindrical 23 of the tank can be provided with cooling fins.

In the case where the double pump according to the invention is used, as indicated above, for the high pressure supply of fuel injectors for engines, the engine oil can advantageously be used as hydraulic fluid itself by directly communicating the chamber 9 with the circuit of motor oil distribution, the temperature of this oil being regulated by the appropriate engine parts.

The pump according to the invention can also be used to circulate under pressures the drilling muds.

It can actually be used to pressurize any liquid, including including corrosive or aggressive liquids.

In the case where the hydraulic stage, pump I, is confronted with a liquid of strong viscosity, as is the case with cold use, for example, it is preferable, as is known, to have mechanical means now heads 4a of pistons 4 on their pads 5 during the suction phase.

As explained above, the suction force of the second pump II, which is linked to the power of the springs 15, allows a return to the initial position of the membranes 24, because of the communication with the chamber 9.

If there was not this reset to the original position, allowed by this communication with the reserve of hydraulic fluid, it might occur a slight drift every turn of the pump.

This drift would quickly cause a volume differential between the bore 12 and the portion 13a of the corresponding bore 13, which in turn would cause quickly an abutment of the membranes 24 and, immediately, a rupture pump (either at pump I or at pump II).

It therefore appears that this reset, or reset to initial position movable elements 24 of the second pump II, via the lunula 8 is capital city.

Figures 3 to 5 relate to an improvement to the device of Figures 1 and 2 to by means of which it will be possible to vary at will the flow of the liquid to pump.

When this liquid is gasoline intended to supply an engine, it can be interesting to vary the volume of gasoline pumped by the pump It for adapt it to the operating conditions of the engine.

It takes a motor to run at full speed, determine the displacement of the pump according to the extreme conditions of use of the engine, namely: operating at maximum speed and full load. This therefore defines a debit maximum of the pump which is permanently supplied; so that, apart these extreme conditions of use, the pump provides excess flow, who returned to the tank.

But the essence thus brought back to the tank is to have been heated by the compression, so that hot gasoline is brought back permanently to tank. As the tank empties, gasoline becomes more and more warmer so it may appear in the vapor tank of undesirable gasoline whose treatment is made difficult by standards of more more severe especially with regard to gasoline injection engines direct.

It is therefore necessary to modulate the flow of the pump according to the engine requirements.

The first solution consists in producing the first pump 1, in the form of a variable flow pump using a variable inclination bias 1 tray as this is achieved in some pumps produced by the plaintiff.

But such a pump may be too expensive for automotive production in large series; so that a second solution is described below.

The device according to this second solution is characterized by the fact that it comprises a double pump such as that described in the patent application 96.07043, but in which each piston of the hydraulic pump is provided with means allowing all or part of the flow pumped by said piston to be canceled.

Figures 3 and 4 describe a double pump similar to that of Figures 1 and 2 in which the same elements bear the same references.

Referring to these figures, it can be seen that each hollow piston 4 is traversed by in part by a pipe 30.

On the other hand, the pistons 4 are carried by two supports 31 and 32 pierced with holes in which said pistons slide. The orifices pierced in the support 31 are designated by the reference 33, while the orifices pierced in the support 32 constitute the cylinders 12 mentioned above. For this purpose, the thickness of support 32 is larger than the maximum stroke of the pistons 4.

The space between the supports 31 and 32 constitutes an annular chamber 35.

In this space 35 each piston 4 is partially covered by a shirt 34. These sliding folders are all connected to a connecting rod of control 38 so as to slide all together between two positions extremes, the first being illustrated in Figure 3, the second being illustrated in figure 4.

In the position shown in FIG. 3, said shirts 34 obscure the holes 36 which communicate the internal pipe 30 of each piston 4 with the annular chamber 35.In the position shown in FIG. shirts 34 discover said holes 36.

The springs 7 of FIGS. 1 and 2, whose function is to maintain the heads of the pistons resting against their sliding block 5 are replaced by a pusher 7b which acts on a collar 6 which bears on the back of each head of piston 4. The pusher 7b is counterfeit by a spring 7a.

The pusher 7b, counteracting the collar 6 of each piston head is traversed by a duct 37 which communicates with each other the two chambers 9 and 35.

Thus when, under the effect of the control rod 38, the shirts 34 are in the position shown in Figure 4, the hydraulic fluid discharged by each piston 4 flows back through the pipes 30 and 36 into the annular chamber 35, and from there, through the bore 37, into the chamber 9. As a result, the flow rate of the hydraulic pump I is zero, so that the membranes 24 are not animated by any movement and do not exert any action of pumping and repression under fuel pressure to the injectors: the fuel flow to the injectors is therefore also zero.

When, under the effect of the command 38, the shirts 34 are in the position shown in FIG. 1, the holes 36 are obscured by said folders and the Flow rate of hydraulic pump I is maximum. As a result, the flow of gasoline towards the injectors is also maximum.

Between these two extreme positions all intermediate flows can be obtained according to the position of the shirts 34, position determined by the position of the connecting rod 38 which is slaved to the operation of the engine by any appropriate control device.

As a result, the output flow of the pump It is regulated according to the flow rate gasoline that is needed for fuel injection and that excess fuel returns to the tank are minimized to the maximum.

It should be noted, however, that the gas flow thus obtained is a pulsed flow. In effect, if for example, the shirts 34 are in a position such that only 10 % of the maximum flow rate of pump I is delivered in part 13a of volume 13, this means that this pump I provides no flow for 90% of the stroke of each piston or that there is only flow on 10% of the stroke of each piston. This has the effect that the flow is a pulsed flow.

This results in a disadvantage that must be removed.

For this purpose, there is downstream of the outlet 29 and upstream of the injectors a device eliminating these pulsations. This device can advantageously be constituted in a similar manner to a hydraulic accumulator that is to say constituted capacity having a significant volume compared to the flow rate provided to the injectors and kept under constant pressure.

This gives an injection flow exactly corresponding to the needs in engine fuel, without return to the tank, this flow being regular, that is to say without urges.

FIG. 6 represents a pump similar to the pump of FIG. 1, in which the same elements carry the same references.

The tank 11 of FIG. 1 which surrounds the hydraulic pump is replaced by an outer tank 1 1a; for the rest, all the components are identical to the only exception of the pump diaphragm II of Figure 1.

In the pump of FIG. 1, each volume 13 is divided into two parts 13a, 13b by a membrane 24 pushed back by a spring 15 bearing on the membrane 24 by means of a cup 20.

In the pump of FIG. 6, the individual membranes 24 are replaced by a single membrane 44, which at the locations of the chambers 13 will deform to partially penetrate into said volume 13 against the spring 15 corresponding.

More specifically, the pump of FIG. 6, like that of FIG. comprises a one-piece pump casing 40. in two cylindrical parts 40a, and 40b, the portion 40b having an internal diameter greater than that of the portion 40a. In the part 40a are arranged the bearings 3, the motor shaft 2, the bias plate 1, the feeding chamber 9 and the rear portion 4a of a workpiece 41 in which are drilled the bores 12. The front part 41b of this part is in the part 40b of greater diameter of the casing 40; so this part before 41b rests against the shoulder which separates the two parts 40a and 40b of the housing 40. The bores 12 of the pistons 4 open to the front face of this part 41b, a circular plate 42 is disposed against said portion 41b and is immobilized in position relative thereto by a pin 42a. This plate 42 has as many 43 holes there are bores 12 and rooms 13. The chambers 13 are formed in a part 45 which is screwed to the open end of the part 40b of the housing 40. Between the piece 45 and the plate 42 is disposed a membrane 44 which has the form of a disc having the same diameter as the plate 42. The membrane 44 is pinch between the plate 42 of the end of the piece 45. Each piercing 43 communicates with a bore 12 of the pump I and is in front of a volume 13.

When a piston 4 will discharge hydraulic fluid under high pressure, this liquid will be discharged out of the bore 12, in the bore 43 and will deform the part of the membrane 44 which faces the corresponding chamber 13, deformation which is against the spring 15 bearing against the other side of the membrane 44 by the cup 20. The liquid to be pumped lying in the chamber 13 (behind the cup 20) is discharged by the non-return valve 17. When the piston 4 moves back into its bore 12, the part of the membrane 44 which had distorted, had entered, partially, in volume 13, is pushed back by the spring 15 and returns to its original shape by sucking the liquid to be pumped by the valve anti-return 16.

As in the previous cases, there is direct communication between the piercing 43 and the chamber 9 by the lunula 8.

Referring to Figure 9, which is an enlarged view, we see that at each chamber 13 is associated a conduit 50 connected to a chamber 51 where the liquid arrives at pump through a pipe 52. The conduit 50 is pierced through the mass of the workpiece 45 and opens at its end opposite the chamber 51 against the membrane 44. The plate 42 which is interposed between the part 41, in which are formed the bores 12 of the pistons 4 and the piece 45, in which the chambers are arranged 13 comprises two housing 53 and 54 connected by a pipe 55. The housing 53 is dug in the face of the part 42 which is in contact with the membrane 44; while the housing 54 is dug in the face that is in contact with the workpiece 41. The housing 54 has a configuration such that it communicates with the bore 12; and the housing 53 reaches the level of the chamber 13.

Thus, when the pressurized liquid is discharged by a piston 4, the liquid under pressure arrives through the housing 54 and the pipe 55 into the housing 53 and the membrane is applied by the hydraulic pressure against the orifice of the pipe 50 which is thus closed. On the other hand, when the piston 4 is in the suction phase, the movement of the cup 20 which pushes the membrane 44 releases it from the orifice of the pipe 50. The membrane 44 being pressed at the bottom of the housing 53, this releases between the membrane 44 and the wall of the room 45 a space 56 which ensures the communication between the pipe 50 and the chamber 13 and thus allows the admission into this chamber 13 of the liquid to be pumped.

It is preferable that the liquid to be pumped (which is, for example, gasoline) arrives by the pipe 52 at a low pressure, of the order of 1 to 2 bars, given by a electric pump of known type, so that, as soon as the hydraulic pressure disappears in the housing 53, the membrane 44 is pushed back to clear the passage 56.

It is also preferable that at each conduit port 50 the membrane 44 is provided with a reinforcing cup 57, of a diameter greater than that of the orifice, the purpose of which is to prevent the membrane from being pushed by the pressure in the orifice of the pipe 50 and thus deteriorated.

It is also advantageous to mold the membrane in such a way that rest, in the absence of any pressure, it fills the housing 53 and releases the passage 56.

Thus, the membrane 44 is deformed between a position where it is at the bottom of the housing 53 and a position where it closes the suction duct 50 plays the role a suction check valve.

There are, of course, as many conduits 50, housing 53, ducts 55, housing 54 there are bores 12 and rooms 13.

The arrangement thus described in relation with FIG. 9 is independent of the configuration of the hydraulic pump I and can be transposed into the pump of the Figures 6 to 7 as shown in Figure 9.

In all the examples represented in FIGS. 1 to 9, the hydraulic pump I is a swash plate pump or bias plate and the pistons are pistons Axial.

But it should be noted that we can achieve the same result with a pump. radial pistons with the essential condition that the pistons are hollow and that their heads rest on the drive cam (playing the same role as the bias tray 1) by sliding studs overlapping a lunula; so that at the end of each compression cycle the chamber in which the membrane moves put in direct communication with the liquid intake chamber hydraulic.

Such a radial piston pump is shown in FIG.

This pump comprises a cam 101, which is an eccentric carried by a tree motor 102, carried by bearings 103. Each piston is a hollow piston 104 counteracted by a spring 107, so that its head 104a bears against the cam 101 via a sliding stud 105 through which a hole 106. The cam 101 is struggling in a chamber 109 communicating with a reservoir hydraulic fluid (not shown). The communication between the room 109 and the inside of each hollow piston 104 is established when the stud 105 overlaps the groove 108 dug in the cam 101.

The pump It is identical to that of Figure 1, the same elements bearing the same references.

The cam 101 corresponds to the bias plate 1; the pistons 104 to the pistons 4; the pads 105 to the pads 5; the groove 108 to the lunula 8 and the chamber 109 to the chamber 9.

The operation of the double pump (I-II) shown in Figure 10 is identical to that of the pumps previously represented.

Claims (27)

1. Pump allowing any type of liquid to be pumped whilst transmitting to it a very high backflow pressure of the type formed by associating two pumps: a hydraulic pump (I) on one hand comprising a plurality of pistons (4, 104) and a skewed plate (1) or shaft (101): and a second pump (II) on the other hand whose mobile means which carry out the suction and backflow of the liquid to be pumped, are flexible membranes driven by an alternating movement in one direction then in another by moving the hydraulic liquid pumped and sucked by the first pump (I) characterised by the fact that the pistons (4, 104) of the first pump (I) are hollow and crossed by the hydraulic liquid which, during the suction phase, crosses a lunule (8, 108) hollowed into the face of the skewed plate (1) or shaft (101); the membrane which can be distorted (24, 44) being held up by a spring (15) such that at the end of the compression stroke of each piston (4, 104), communication is made between the chamber (12 - 13) where the hydraulic liquid flows back against the membrane (24, 44) and the suction chamber (9, 109), this liquid is then, on one hand, sucked by the movement of the piston (4, 104) and, on the other, flowed back by the membrane (24, 44) under the action of its spring (15) which ensures at the same time: an exchange between the hydraulic liquid heated by the compression and the non-heated liquid; and a return to the initial position of the membrane (24, 44).
2. Pump according to claim 1 in which the first pump (I) or hydraulic pump is a pump with a skewed plate (1) and axial pistons (4) the said axial pistons being hollow and held up by springs (7, 7a) so that the head (4a) of each hollow piston (4) rests against the skewed plate (1) using a sliding stud (5) crossed by a central bore (6), this stud straddling a lunule (8) which is engraved on the face of the skewed plate (1) during the suction phase of the corresponding piston, in order, during this phase, to make direct communication between the chamber (9) with the skewed plate (1) and the chamber (13a) where the hydraulic liquid was back flowed during the compression phase.
3. Pump according to claim 1 in which the first pump (1) or hydraulic pump is a pump with radial pistons (104) driven by a shaft (101); the said radial pistons (104) being hollow and held up by springs (107) so that the head (4a) of each hollow piston (104) rests against the shaft (101) using a sliding stud (105) crossed by a central bore (106), this stud straddling a lunule (108) which is engraved on the face of the shaft (101) during the suction phase of the corresponding piston, in order, during this phase, to make direct communication between the chamber (109) where the shaft (101) works and the chamber (13a) where the hydraulic liquid was back flowed during the compression phase.
4. Pump according to claim 2 in which the second pump (II) comprises as many chambers or bores (13) as the first pump (I) contains bores (12), each chamber (13) of the second pump (II) communicating directly with the corresponding bore (12) of the first pump (I) so that each piston (4, 104) of the first pump (I) cyclically sucks and back flows the hydraulic liquid in the corresponding chamber (13) of the second pump (II).
5. Pump according to claim 4 in which each bore (13) in the second pump (II) is divided into two parts (13a, 13b) by a membrane which can be distorted (24) and held up by a spring (15), the part (13a) which communicates with the corresponding bore (12) of the first pump (I) and taking the hydraulic liquid which has been back flowed and sucked by it; the other part (13b), fitted with suction valves (16) and backflow valves (17) sucking and back flowing the product to be pumped.
6. Pump according to claim 5 in which each spring (15) is supported against the rear face of the corresponding flexible membrane (24) using a cap (20) shaped so as not to cause damage to the said rear face of the membrane (24).
7. Pump according to one of the previous claims in which the chamber (9, 109) in which the heads (4a, 104) of pistons (4, 104) work is connected to a tank of hydraulic liquid.
8. Pump according to claim 7 in which the tank (11) of hydraulic liquid is outside the first pump (I) and communicates with the latter by means of a pipe (10), which opens outs into the chamber (9).
9. Pump according to claim 7 in which the tank (11) is formed from a cylindrical casing (23) surrounding the body (21) of the first pump and communicating with the chamber (9) using a plurality of orifices (22).
10. Pump according to claim 2 in which the individual membranes (24), which can be distorted, are replaced by a single membrane (44) placed between the bores (12) of the pistons (4) and the chambers (13).
11. Pump according to claim 10 in which a circular plate (42) is placed between the part (41) in which the bores (12) are housed and the part (45) in which the chambers (13) are fitted this part making each bore (12) communicate using drillings (43) with the corresponding chamber (13).
12. Pump according to claim 10 in which each chamber (13) has a spring (15), which rests on the membrane (44) by means of a cap.
13. Pump according to claim 12 in which each chamber (13) is linked to a one-way suction valve (16) and a one-way back flow valve (17).
14. Pump according to claim 12 in which each chamber (13) is only linked to a one-way back flow valve (17), the one-way suction valve (16) being removed and its function carried out by the membrane (44) itself.
15. Pump according to claim 14 in which the inlet pipe (5) for the liquid to be pumped opens out against the membrane (44) which is held against the opening of this pipe during the back flow phase and is moved aside during the suction phase.
16. Pump according to claim 15 in which the part of the membrane (44) which rests against the opening (50) of the liquid inlet is fitted with a strengthening cap (57).
17. Pump according to claim 15 in which during the suction phase the membrane (44) goes to the base of the housing (53) to free a communication passage (56) between the liquid inlet pipe (5) and the chamber (13).
18. Pump according to claim 17 in which the membrane (44) is pre-shaped to occupy the base of the housing (53) during suction to free the passage (56).
19. Pump according to any of the previous claims characterised by the fact that it is designed for high pressure supply to fuel injectors for internal combustion engines, the hydraulic liquid from the first pump (I) could be the oil for the said engine.
20. Pump according to claim 19 characterised by the fact that it comprises means to make the flow of the hydraulic pump (I) vary, and, as a consequence, the flow of the pump (II) so as to adapt the flow of petrol which is pumped at a high pressure, towards the injectors when the engine is running.
21. Pump according to claim 20 in which the skewed plate (1) of the hydraulic pump (I) is a plate whose incline can be varied.
22. Pump according to claim 20 characterised by the fact that each piston (4) on the hydraulic pump (I) is fitted with openings (36) which can be hidden, fully or partially, using a mobile lining (34), all the mobile linings (34) being moved together by a command part (38) driven in running conditions of the engine.
23. Device according to claim 22, in which the pistons slide in to supports (31, 32) drilled with orifices (33, 12), these two supports being separated from each other by an annular space making a chamber (35) in which the linings (34) move between two extreme positions: one where, since the orifices (36) are not hidden by the linings (34), all the liquid back flowed by each piston (4) flows into the annular chamber (35) through the piston orifices (36), the flow of pump (I) being nil; the other, where all the orifices (36) are hidden by the linings (34), each piston (4) back flows in volume all the sucked hydraulic liquid, the flow of pump (I) then being maximum.
24. Device according to claim 23 in which the linings (34) can occupy all the intermediary positions between the two extreme positions: so that the flow of pump (I) can be regulated for all values between zero flow and maximum flow.
25. Device according to claim 24 in which all the linings (34) are coupled to a common command part (38) which is driven by any appropriate command device to regulate the high pressure flow of petrol according to the supply requirements of the engine without the high pressure petrol returning to the tank.
26. Device according to claim 25, in which a shock absorber device is placed upstream of the outlet (29) of the second pump (II) and downstream of the injectors to cancel the pulsating effect brought about by the first pump (I).
27. Device according to claim 26, in which the shock absorber device is significant volume capacity in relation to the flow of petrol, kept under injection pressure by any appropriate means in the manner of a hydraulic accumulator.

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