EP0353133B1 - Reciprocating-piston pump, especially a manually actuated one - Google Patents

Description

The present invention relates to a reciprocating piston pump, in particular actuable by hand.

The origin of the invention lies in research for the improvement of manual pumps for portable sprayers used in agriculture and horticulture, but the reader will understand, on reading the following, that the invention can find applications in many other areas.

The manual pumps currently used for sprayers are generally pumps of the type comprising a cylinder with circular section in which moves back and forth a piston, also circular, provided with a seal. An actuating rod, provided with a handle, is connected to the piston, and a guide part is provided on the cylinder to hold the rod coaxial with the cylinder. On the side opposite the rod, intake and exhaust passages open into the piston, they are provided with valves arranged to allow the passage of the fluid only in one direction, namely towards the cylinder for the intake valve. , and towards the outside of the cylinder for the exhaust valve.

Such a device is so simple that it seems difficult to improve. However, it has the defect of forcing the operator to move the handle rectilinearly, and of the hand which actuates it. Such a movement is not natural, the human body being rather shaped to execute movements in a semicircle. This makes the guide part necessary, and causes unnecessary operator fatigue.

On the other hand, the friction which results both from the existence of the seal and from that of the guide piece also causes unnecessary fatigue for the operator.

We have known for a long time, for example from document GB-A-509.916, pumps in which the piston does not move in a rectilinear movement, but describes an arc of a circle, and moves not in a cylinder, but in a toroidal chamber. However, these pumps have the disadvantage of comprising a seal between the piston and the chamber, which is a source of unnecessary energy expenditure, as mentioned above.

The document EP-A-0251948 describes a pump with rectilinear displacement of the piston, of the so-called "rolling membrane" type, that is to say where the seal between piston and cylinder is obtained using a membrane flexible, fixed by its periphery to the wall of the cylinder, and by its central zone to the front part of the piston, this membrane coming to bear, during the entire delivery stroke, on an external surface of the piston and / or on an internal surface of the cylinder while the piston is moving. According to this document, the piston is actuated by a crankshaft by means of a connecting rod articulated on the piston, and the latter has an enlarged part which is used for guidance by contact with an extension of the cylinder and which also carries a seal. sealing, intended to allow the formation of a depression between the piston and the cylinder. The friction due to the guide and the seal consumes energy and constitutes a source of fatigue for the operator. It will be observed that guiding the piston through the cylinder wall is practically a necessity in a system with actuation by crankshaft and connecting rod.

Also known, for example from document GB-A-1,294,676, is a pump comprising a diaphragm the central part of which is clamped between two discs not guided by friction and devoid of seals. Pumps of this type, due to the absence of bearing surfaces for the diaphragm and the large distance between the edges thereof and the edges of the discs, have a considerable dead volume and therefore have poor efficiency . In addition, their stroke is reduced relative to the surface of the diaphragm. So they have a relatively low flow for a given discharge pressure, which is determined by the force of the operator and the resistance of the diaphragm. The above document provides for actuating the pump using a lever system, but this does not change the relationship between pressure and flow.

The object of the present invention is to provide a pump of the type described in document EP-A-0251948 above which can be actuated by hand with very reduced fatigue, while retaining the favorable ratio of the flow rate to the discharge pressure. provided by this type of pump.

• une chambre de pompage comportant des orifices d'admission et d'échappement munis de clapets,
• une membrane déformable fixée par sa périphérie à la paroi de la chambre de pompage pour la fermer de façon étanche,
• un prolongement de chambre, formé d'une enceinte ouverte à une extrémité et séparée à l'autre extrémité de ladite chambre de pompage par ladite membrane déformable, et présentant une surface d'appui sur laquelle ladite membrane peut venir en appui,
• un piston mobile à va-et-vient dans ladite chambre de pompage et ledit prolongement, ce piston ayant une face frontale qui est solidaire d'une région approximativement centrale de ladite membrane, ce piston étant solidaire d'une chemise de même forme générale que ledit prolongement et de section transversale un peu plus petite, qui s'étend à partir de sa face frontale en direction opposée à ladite chambre de pompage et qui présente une surface d'appui pour la membrane, cette surface d'appui ayant une section transversale un peu plus petite que ledit prolongement et étant séparée de la surface d'appui dudit prolongement par un intervalle de largeur à peu près constante et supérieur au double de l'épaisseur de la membrane,
  cette pompe ayant pour particularité que :
• ledit prolongement a la forme d'un segment de tore dont l'axe central ne traverse pas la chambre de pompage, ni son prolongement,
• le piston est porté par un support rigide solidaire d'un levier d'actionnement manuel et capable de pivoter autour de l'axe central du tore correspondant au prolongement, grâce à des moyens de pivotement,
• lesdits moyens de pivotement sont calculés pour permettre de faire tourner le piston autour dudit axe sans autre moyen de guidage, en maintenant à peu près constante la largeur dudit intervalle entre les surfaces d'appui du prolongement de chambre et de la chemise.

To obtain this result, the invention provides a pump comprising:

• a pumping chamber comprising intake and exhaust ports provided with valves,
• a deformable membrane fixed by its periphery to the wall of the pumping chamber to seal it,
• a chamber extension, formed by an enclosure open at one end and separated at the other end from said pumping chamber by said deformable membrane, and having a bearing surface on which said membrane can come to bear,
• a piston movable back and forth in said pumping chamber and said extension, this piston having a front face which is integral with an approximately central region of said membrane, this piston being integral with a jacket of the same general shape as said extension and of slightly smaller cross section, which extends from its front face in a direction opposite to said pumping chamber and which has a support surface for the membrane, this support surface having a cross section slightly smaller than said extension and being separated from the support surface of said extension by an approximately constant width interval greater than double the thickness of the membrane,
  this pump having the particularity that:
• said extension has the shape of a torus segment whose central axis does not pass through the pumping chamber, nor its extension,
• the piston is carried by a rigid support integral with a manual actuation lever and capable of pivoting around the central axis of the torus corresponding to the extension, by means of pivoting,
• said pivoting means are calculated to allow the piston to rotate around said axis without any other guiding means, keeping the width of said gap between the bearing surfaces of the chamber extension and of the jacket more or less constant.

Preferably, the piston and its jacket are calculated so as not to come into contact with said extension of the pumping chamber.

According to its general geometric definition, a torus is a surface generated by a closed planar curve rotating around a central axis located in the plane of said curve. The closed planar curve may or may not meet the central axis. By torus segment is meant a part of a torus limited by two planes containing the central axis.

Preferably, the pumping chamber and its extension are dismountably assembled, and the periphery of the membrane is clamped in the joint between the wall of said chamber and the wall of said extension.

Preferably, the pivot axis of the piston is situated substantially in the plane of the joint, and this axis is carried by bearings which are in one piece with an element chosen from the pumping chamber and its extension.

Preferably, said membrane has a thicker part, intended to be fixed to the front face of the piston, this part being offset from the center of the membrane to take into account the curvilinear shape of the trajectory.

Preferably, the angular amplitudes of the displacement of the piston in the pumping chamber and in the extension are each about 10 to 40 °.

Preferably, the stroke of the piston is at least 0.5 times and preferably 1.5 times its largest transverse dimension.

The use of a "rolling membrane" and the elimination of any guiding means other than pivoting means make it possible to minimize energy losses. The operator's fatigue is further reduced by the displacement in an arc of the lever mounted on the same pivoting means. The volume pumped back by each reciprocating movement of the piston can be significant for a moderate effort. The cost price of the pump can be reduced by the fact that the absence of a seal between the piston and the chamber and of guiding means other than the bearings of the axis reduces the machining needs. The relative position of the piston and the extension of the pumping chamber does not need to be fixed with very great precision, it suffices that the interval between the jacket and the extension allows normal movements of the membrane. Consequently, the bearings which carry the axis can be integral as well with the pumping chamber as with the extension, in the case where these two elements are assembled in a removable manner.

The pumping chamber can be of any shape. However, to reduce the dead volume, it is preferable that it as a whole has the shape of a torus segment which roughly continues the shape of the extension.

• Figure 1 est une coupe verticale d'une pompe selon l'invention, et
• Figure 2 est une coupe selon la ligne II-II de la figure 1.

The invention will now be explained in more detail with the aid of a practical example, illustrated with the drawings, among which:

• FIG. 1 is a vertical section of a pump according to the invention, and
• Figure 2 is a section along line II-II of Figure 1.

FIG. 1 shows a pump, intended for a spraying device, and designed to pass a liquid from an inlet duct 1 to a discharge duct 2. The pump body 3, which is a part of complex shape, obtained by molding, comprises a pumping chamber 4, in the shape of a torus sector, open downward and extending over an arc of approximately 30 °. At the upper part of the chamber 4 open the intake duct 1 and the exhaust duct 2. The intake duct 1 is provided with an intake valve 5. The exhaust duct 2 is provided with an exhaust valve 6.

At its lower part, the pump body carries two extensions 7, 8, which carry the bearings 9, 10 of the shaft 11 which carries the piston 12. These parts will be described later.

The chamber 4 is extended downwards by means of an extension 13, formed of a segment of O-tube, extending over approximately 30 °, and which carries on one of its ends a flange 14. The lower edge of the chamber carries also a flange 15 provided externally with a thread 16. A clamp 17, internally threaded, clamps the flanges 14 and 15 against each other, by screwing onto the thread 16. A membrane 18, which s extends into the chamber 4, is clamped by its edges between the flanges 14 and 15. This membrane 18 which is an important element of the pump, is present, before assembly, in the form of a plane provided, roughly in its central part, with a thicker part 19. This thicker part carries, on one of its faces, two studs 20 and 21 provided with snap projections 22. The piston 12, in the form of a disc, has two holes intended for receive the pins 20 and 21, and thus fix the membrane on the piston for its entry ment. The piston 12 carries a jacket 23, in the shape of a torus segment, extend over approximately 45 °, and provided with a flat upper part 24 which comes to rest on the piston, and which is also provided with holes for the nipples 20 and 21. This jacket 23, immobilized against the piston 12 by the nipples 20, 21, with their latching projections 22, is prevented by them to rotate relative to the axis of the piston.

The piston 12 is carried by a piston rod 25, with cross section, and in the shape of an arc of a circle. At its end opposite the piston, the rod 25 is secured to an arm 26, which is substantially perpendicular to it. The arm 6 is crossed by a square bore 27, of dimensions adapted to the shaft 11, which is itself of square section.

Bearings 28 and 29 are placed between the shaft 11 and the bearings 9 and 10. These bearings have a cylindrical outer surface of revolution, adapted to that of the bearings and 10, and an internal bore with square section, adapted to that of the tree 11.

The shaft 11 can slide in the bearings 28, 29 and in the bore 27 of the arm 26. It can in particular be disassembled, for transport, pushed in to reduce the size of the assembly, or placed in another position allowing easy activation. To immobilize it, in the working position or in the storage position, the bearings 28, 29 each carry a male conical extension 20, onto which a tubular adjustment rod 31 can be screwed, the end of which is also conical. The screwing of the adjustment rod 31 serves to tighten the extensions 30 against the shaft 11, and to immobilize it in position, the bearings being themselves immobilized in axial position by the bearings 9 and 10 and the arm 26.

There is shown at 32, in Figures 1 and 2, a portion of the rod of the actuating lever which controls the shaft 11. In Figure 1, there is shown, in dashes, the position occupied by the rod of the lever when the piston is in the low position.

Claims (6)

1. Pump comprising:

- a pumping chamber (4) having intake and exhaust ports (1,2) fitted with valves,

- a deformable membrane (18) fixed by its periphery to the wall of the pumping chamber in order to seal it in leak tight manner,

- a chamber extension (13) formed by an enclosure which is open at one end and separated from the pumping chamber at the other end by the deformable membrane, and having an abutment surface on which the membrane can abut,

- a piston (12) which is reciprocally movable within the pumping chamber and extension, the piston having a front face which is integral with a substantially central region of the membrane, the piston being integral with a sleeve (23) of the same general shape as the extension and of slightly smaller cross section, which extends from the front face in the opposite direction to the pumping chamber and has an abutment surface for the membrane, the abutment surface being slightly smaller in cross section than the extension and being separated from the abutment surface of the extension by a spacing of substantially constant width which is greater than twice the thickness of the membrane,
characterised in that:

- the extension (13) is in the form of a toridal segment the central axis of which does not pass through either the pumping chamber or its extension,

- the piston is carried by a rigid support (25,26) which is fixedly connected to a manual operating lever (32) and is capable of pivoting about the central axis of the torus corresponding to the extension, by pivoting means (9,10),

- the pivoting means (9,10) are designed to enable the piston to rotate about the axis without any other guide means, whilst keeping the width of the spacing between the abutment surfaces of the chamber extension and the sleeve substantially constant.

2. Pump according to claim 1, characterised in that the pumping chamber and its extension are assembled so as to be demountable and the periphery of the membrane is clamped in the joint between the wall of the chamber and the wall of the extension.

3. Pump according to claim 2, characterised in that the pivoting spindle of the piston is located substantially in the plane of the joint and this spindle is supported on bearings (9,10) which are in one piece with an element selected from the pumping chamber and the extension thereof.

4. Pump according to one of claims 1 to 3, characterised in that the membrane (18) has a thicker portion (19) adapted to be fixed to the front face of the piston, this part being offset relative to the centre of the membrane in order to take account of the curvilinear shape of the trajectory.

5. Pump according to one of claims 1 to 3, characterised in that the angular degrees of movement of the piston in the pumping chamber and in the extension are each from about 10-40°.

6. Pump according to one of claims 1 to 5, characterised in that the travel of the piston is at least equal to 0.5 times its greatest transverse dimension.

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