Valve assembly and pump provided with said valve assembly

Abstract

A valve assembly (200,200′) removably insertable in high-pressure pumps is described, said valve assembly comprising: a valve body (205), a duct (245) made in the valve body, and a shutter (300) movable at least between a closed position, in which it obstructs the flow through said duct, and an open position, in which it allows the passage of a flow through the duct. Wherein said valve assembly comprises a tubular sleeve (360,360′) which develops from a portion of the valve body in a direction away therefrom and defines an internal volume in fluid communication with the duct.

Description

TECHNICAL FIELD

[0001] The present invention concerns a valve, in particular an automatic delivery and suction valve assembly for pumps, for example at high pressure, and a pump provided with said valve, preferably an axial piston pump.PRIOR ART

[0002] Automatic delivery and suction valve assemblies are known, which, if connected to the pumping chamber of a pump, to a delivery duct and to a suction duct, make it possible, based on pressure differences, to automatically allow the suction of the liquid to be pumped through the suction duct towards the pumping chamber and the pumped fluid to be sent from the pumping chamber to the delivery duct.

[0003] A known embodiment of said valve assemblies comprises a single valve body in which a central duct is made that crosses it from side to side defining a first opening at a first axial end and a second opening at a second axial end of the valve body. Said central duct is configured to put the pumping chamber in fluid communication with the delivery duct.

[0004] The valve assembly then comprises a plurality of peripheral ducts which is eccentric with respect to the central duct and each provided with a first opening, made in a side surface of the valve body placed between the first end and the second end, and a second opening made in the second end of the valve body. Each peripheral duct is configured to place the suction duct in fluid communication with the pumping chamber.

[0005] The valve assembly also comprises a first shutter, for hermetically sealing the first opening of the central duct under the thrust of a first elastic element, and a second shutter for hermetically sealing all the second openings of the peripheral duct under the thrust of a second elastic element.

[0006] The valve assembly is shaped such that when the volume of the pumping chamber increases, a depression is generated therein which overcomes the force of the second elastic element freeing the second openings of the peripheral ducts from the second shutter. Whereas, when the volume of the pumping chamber decreases, an overpressure is generated in the pumping chamber itself which overcomes the force of the first elastic element freeing the first opening of the central duct from the first shutter.

[0007] A drawback of the prior art is that in order to be able to close the second openings of the peripheral ducts, which are positioned eccentrically around the second opening of the central duct, it is necessary to use a shutter provided with a plane circular crown contact surface which in the closed position perfectly lies on a plane circular crown surface made in the body of the valve assembly and in which the second openings of the peripheral ducts are made. This solution is not very convenient because in order to make the plane surface of the circular crown of the contact surface and the plane surface of the circular crown in the valve body, it is mandatory to employ precise and expensive machining for the two surfaces to be perfectly plane and parallel, so as to be entirely in contact with each other when the shutter is in the closed position. If this parallelism were not respected, it would not be possible to ensure the perfect sealing of the valve, with the con-sequent risk of pressurized fluid passing in the suction ducts during pumping.

[0008] An object of the present invention is to overcome the constraints of the prior art in the context of an efficient, rational and cost-effective solution. The dependent claims outline preferred and / or particularly advantageous aspects of the invention.DISCLOSURE OF THE INVENTION

[0009] In particular, the invention makes available a valve assembly removably insertable into high-pressure pumps, said valve assembly comprising:

[0010] a valve body,

[0011] a duct made in the valve body,

[0012] a shutter movable at least between a closed position, in which it obstructs the flow through said duct, and an open position, in which it allows the passage of a flow through the duct,wherein said valve assembly comprises a tubular sleeve that develops from a portion of the valve body in a direction away therefrom and defines an internal volume in fluid communication with the duct (and adapted to contain at least part of a pumping chamber of a pump).

[0013] Thanks to this solution, the tubular sleeve protects and isolates the pump from the pressure generated in the pumping chamber.

[0014] According to one aspect of the invention, in a portion of the tubular sleeve that is distal from the valve body, an (high pressure) annular sealing gasket can be inserted which is at least partially, preferably entirely, contained in the internal volume and adapted to embrace a piston slidably inserted in the tubular sleeve.

[0015] In this way, when the valve assembly is extracted, the high-pressure gasket is removed, too thus making assembly and maintenance operations faster and easier.

[0016] According to another aspect of the invention, the valve assembly may comprise a tubular spacer contained in the tubular sleeve directly interposed between a surface of the valve body at the portion from which the tubular sleeve develops and the sealing gasket.

[0017] In this way it is avoided that the piston in its movement can bring the sealing gasket out of position.

[0018] According to yet another aspect of the invention, the valve assembly may comprise a further annular sealing gasket, for example a low-pressure one, (also adapted to sealingly embrace the piston slidably insertable in the tubular sleeve), inserted in the tubular sleeve and which is at least partially contained in the internal volume, wherein the further gasket is more distant from the valve body than the gasket.

[0019] In this way, when the valve assembly is extracted, the high-pressure gasket and the low-pressure gasket are also removed, thus making assembly and maintenance operations even faster and easier.

[0020] According to a further aspect of the invention, the tubular sleeve may comprise a portion that is distal from the valve body and through which the gasket can be inserted into the internal volume, and wherein the valve assembly may comprise a retaining body removably fixed to the tubular sleeve and adapted to prevent the gasket and / or the further gasket from exiting from the internal cavity through the opening of the tubular sleeve (the retaining body partially obstructs the portion through which the gasket may be inserted). According to another aspect of the invention, the retaining body may define a rest surface, transverse to the tubular sleeve, for the further gasket.

[0021] The invention may further provide that the tubular sleeve can be made as a single body at least with a portion of the valve body from which it develops.

[0022] According to another aspect of the invention, the duct makes an opening in the valve body and the tubular sleeve develops from a portion of the valve body around said opening.

[0023] According to yet another aspect of the invention, the valve body may comprise a first end and an opposite second end, wherein the opening of the duct is made in the second end, a further opening of the duct is made in the first end, and the tubular sleeve extends from the second end away from the first end.

[0024] The invention further makes available a pump for high pressures comprising:

[0025] a head in which a hole (blind or through hole if closed by a cap) is made to partially define a volume of a pumping chamber,

[0026] a pumping piston slidably inserted in the hole,

[0027] a valve assembly according to claim 1, which is inserted into said hole with the tubular sleeve as a lining for a portion of the hole and wherein the piston is slidably inserted into the tubular sleeve.

[0028] According to another aspect of the invention, the pump may comprise a high-pressure annular gasket which sealingly embraces a portion of the piston, and wherein the tubular sleeve extends from the valve body to at least said high-pressure annular gasket (the high-pressure gasket contacts the tubular sleeve generating in the contact area a hermetic sealing).

[0029] According to yet another aspect of the invention, the high-pressure annular gasket may be sealingly inserted into the tubular sleeve.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the invention will be more apparent after reading the following description provided by way of a non-limiting example, with the aid of the figures illustrated in the accompanying tables.

[0031] FIG. 1 is an axonometric view of a first embodiment and a second embodiment of a pump according to the invention.

[0032] FIG. 2 is a top view of the machine of FIG. 1.

[0033] FIG. 3 is a sectional view of a first embodiment of the pump according to plane III-III of FIG. 2.

[0034] FIG. 4 is an enlargement of a detail IV of FIG. 3.

[0035] FIG. 5 is a side view of a valve assembly according to the invention with which the first embodiment of the pump is equipped.

[0036] FIG. 6 is a bottom view of the valve assembly of FIG. 5.

[0037] FIG. 7 is a sectional view of the valve assembly of FIGS. 5 and 6 according to section plane VII-VII.

[0038] FIG. 8 is a sectional view of the valve assembly of FIGS. 5 and 6 according to section plane VIII-VIII.

[0039] FIG. 9 is a sectional view of the first embodiment of the pump, but valid for both embodiments of the pump, according to the section plan IX-IX.

[0040] FIG. 10 is a sectional view of the first embodiment of the pump, but valid for both embodiments of the pump, according to the section plane X-X.

[0041] FIG. 11 is a sectional view of a first embodiment of the pump according to section plane XI-XI of FIG. 2.

[0042] FIG. 12 is an enlargement of a detail XII of FIG. 11.

[0043] FIG. 13 is a side view of another embodiment of a valve assembly according to the invention, with which the second embodiment of the pump is equipped.

[0044] FIG. 14 is a bottom view of the valve assembly of FIG. 13.

[0045] FIG. 15 is a sectional view of the valve assembly of FIGS. 13 and 14 according to section plane XV-XV.

[0046] FIG. 16 is a sectional view of the valve assembly of FIGS. 13 and 14 according to section plane XVI-XVI.BEST MODE OF THE INVENTION

[0047] With particular reference to such Figures, 1,1′denotes overall a pump, in particular of the type with pistons, for high pressures (i.e. pressures equal to at least 50 bar), preferably suitable for pumping low viscosity liquids, such as for example water or solutions containing water. Furthermore, with particular reference to the enlargements of FIG. 4 and FIG. 12, the pump is preferably of the type provided with a plurality of pumping chambers 20 (parallel to each other, i.e. pumping the liquid in parallel to each other), in particular at least three pumping chambers 20, for example five pumping chambers 20 and for example with automatic valves for regulating the pumping flow.

[0048] The pump illustrated is a multi-cylinder axial piston pump of the inclined plate type, however the concepts of the invention are applicable to different types of pumps, such as for example a single-cylinder pump and / or an alternative pump.

[0049] In particular, the pump 1,1′illustrated is of the type provided with a rotating plate with fixed inclination, as will be better described below, and with automatic valves for regulating the pumping flow.

[0050] The pump 1,1′comprises a head 10 in which at least one (straight) hole 15 is made, for example a cylindrical or circular hole (formed by one or more cylindrical or circular sections that are coaxial with each other), which contains in its inside at least partially a pumping chamber 20. In other words, at least part of a total volume of a pumping chamber 20 is contained within a volume defined by a respective hole 15.

[0051] It is not excluded that in an alternative embodiment the holes may have a cross-section different from the circular one, for example they may have a polygonal cross-section, such as square or octagonal.

[0052] In the illustrated embodiment, the head 10 comprises a plurality of holes 15, for example in a number equal to the number of pumping chambers, each containing in its inside at least partially a volume of a respective liquid pumping chamber 20. The pumping chambers 20 are independent of each other, each being delimited by respective automatic delivery and suction valves as will become clear hereinafter.

[0053] For example, at least the head portion in which the hole is made, i.e. in which the holes are made, can be made as a monolithic body, i.e. it can be obtained by machining a single body obtained by solidification of a single casting or injection of material into a mould.

[0054] In the preferred embodiment, said monolithic portion is made of a polymeric material, such as to render the pump light, economical and quick to make. Even more preferably the entire head is made of polymeric material (and is monolithic).

[0055] However, it is not excluded that in an embodiment not illustrated, the head portion in which the hole 15 is made, i.e. the holes 15, is formed by several parts made of polymeric material each of them monolithic, which are fixed to each other (removably or also non-removably, for example welded).

[0056] The hole 15, i.e. each hole 15, develops substantially coaxially around its own central axis (with respect to which the hole is symmetrical), and for example the holes 15 are arranged in the head with the respective central axes parallel to each other.

[0057] For example, in the case of the pump with inclined plate with fixed inclination of the figures, the holes are arranged radially around a common axis, with respect to which the central axes of the single holes are parallel. Furthermore, the holes are placed at the same distance from each other and at the same distance with respect to the common axis itself. In other words, the holes, that is the central axes of the holes, are arranged angularly equidistant from each other along an imaginary circumference that is centred on the common axis and lying on a plane perpendicular to the common axis.

[0058] Still in the illustrated embodiment, in which the holes are five in number, the central axes of the holes pass through the vertices of an imaginary regular pentagon lying on a plane perpendicular to the central axes of the holes themselves.

[0059] In the case of an alternative pump the holes 15 would instead be aligned with each other along a direction perpendicular to the central axis.

[0060] The head 10 may comprise a first face 25, which is transverse (perpendicular) to the central axis of the hole, i.e. to the axes of all the holes, and is for example plane, and an opposite second face 30, also transverse (perpendicular) to the central axis of the hole, i.e. to the axes of all the holes.

[0061] The hole 15, Le. each hole 15, is made, for example during the moulding step of the polymeric material, as a hole provided with an opening 35 made in the first face 25.

[0062] With particular reference to the enlargements of FIGS. 4 and 12, in the illustrated embodiment, the hole, i.e. each hole, is made, for example during the moulding of the polymeric material, as a through hole extending from the first face 25 to the second face 30, making a first (circular) opening 35 in the first face 25 and a second (circular) opening 40 in the second face 30.

[0063] Going from the second opening 40 towards the first opening 35, the hole 15, i.e. each hole 15, has a narrow portion (with respect to at least the second opening 40) which makes available a shoulder surface 18, which is transverse to the central axis of the hole, in particular perpendicular thereto, and is turned towards the second opening 40.

[0064] For example, even going from the first opening 35 to the second opening 40 the hole 15, i.e. each hole 15, has a narrow portion (with respect to at least the first opening 35) which makes available a further shoulder surface, which is transverse to the central axis of the hole and is turned in the opposite direction to the shoulder surface 18 and towards the first opening 35.

[0065] Going into more detail of the conformation of the hole 15, i.e. of each hole 15, it comprises at least one internal (cylindrical) tubular surface 16 (coaxial to the central axis of the hole itself) and which develops directly from the first opening 35 towards the second face 30 of the head 10.

[0066] The hole 15, i.e. each hole 15 also comprises a further internal (cylindrical) tubular surface 17 coaxial to the internal tubular surface 16 and which develops from the second opening 40 towards the first face of the head itself. Between the surface 16 and the surface 17 there is interposed an internal (cylindrical) tubular surface 19 having a cross-section (with respect to the central axis) lower than a cross-section of the surface 16 and of the surface 17.

[0067] The surface 19 is (directly) contiguous to the surface 17 and is connected thereto (directly) by the shoulder surface 18.

[0068] Similarly, the surface 19 is (directly) contiguous to the surface 16 and is connected thereto (directly) by the further shoulder surface.

[0069] In the illustrated case where the surfaces 19 and 17 are circular, i.e. cylindrical, the surface 18 is a circular crown, or ring, in particular lying on a surface perpendicular to the central axis of the hole 15.

[0070] In the embodiment of the pump illustrated in FIG. 12, the surface 16 is not present as the surface 19 extends up to the first opening 35.

[0071] The number of tubular and shoulder surfaces obviously varies according to the type of automatic valves inserted in the hole and to the method of centering them and the gaskets in the head, as will also be clearer below.

[0072] Therefore, a possible third tubular surface should not be ruled out, perhaps also with a diameter greater than the tubular surface 16 and which allows the crankcase to be centred with respect to the head. Or a condition in which the surface 18 is turned towards the first face is not ruled out, as well.

[0073] The pump 1,1′ comprises a piston 45 slidably inserted in the hole 15 along a sliding axis and partially contained therein. That is, the pump comprises a plurality of pistons 45, each slidably inserted in a respective hole 15 of the plurality of holes along a respective sliding axis, and partially inserted therein. Preferably, the sliding axis coincides with the central axis of the hole.

[0074] In the illustrated embodiment, the piston 45, i.e. each piston 45, has a first axial end 50 (always) contained in the hole and an opposite second axial end 55 that projects from the cylinder 15 externally to the head through the opening 35.

[0075] The pump 1,1′ comprises a plurality of annular seals adapted to circumferentially sealingly embrace the piston 45, i.e. each piston 45, to prevent leaks of pumping liquid from the pumping chamber towards the opening 35 in the first face 25.

[0076] In particular, the pump 1,1′ comprises a first annular sealing gasket 60, commonly known as a high-pressure gasket, which circumferentially sealingly contacts a portion of the piston 45, i.e. it circumferentially contacts a portion of a shell of the piston 45, where shell means the side surface of the piston extending coaxially to the sliding axis from one axial end to the other of the piston. In addition, said gasket can be said to thus embrace circumferentially with contact the piston and is coaxial with the piston, that is, it is coaxial with the sliding axis of the piston.

[0077] The first annular sealing gasket is elastic, i.e. resilient, for example made of polymeric material.

[0078] The first annular sealing gasket 60 is preferably of the lip type.

[0079] With particular reference to FIG. 5, the first annular sealing gasket comprises an internal annular lip 65, which circumferentially sealingly contacts said portion of the piston 45, and for example an external annular lip 70, preferably substantially forming a V in cross-section with the internal annular lip.

[0080] The internal annular lip 65 and the external annular lip 70 are derived from a same side of a ring 75, for example having a cross-section with a substantially rectangular shape. The pump 1,1′ also comprises a second annular sealing gasket 80, commonly known as a low-pressure gasket, which circumferentially sealingly contacts a portion of the piston 45 (it therefore embraces and is coaxial to the piston), i.e. a portion of the shell of the piston 45 (this portion partially overlaps, almost entirely, the portion on which the first gasket acts).

[0081] For example, the two gaskets are aligned with each other along a direction parallel to the direction of the axis of the cylinder, with the first annular sealing gasket 60 closer to the first axial end 50 of the piston, i.e. to the pumping chamber 20, than to the second annular sealing gasket.

[0082] Also the second annular sealing gasket is elastic, i.e. resilient, for example made of polymeric material.

[0083] Furthermore, the second annular sealing gasket 80 is also preferably of the lip type.

[0084] Like the first gasket, the second one comprises an internal annular lip 85, which circumferentially sealingly contacts said portion of the piston 45, and for example an external annular lip 90, preferably substantially forming a V in cross-section with the internal annular lip.

[0085] The internal annular lip 85 and the external annular lip 90 are derived from a same side of a ring 95, for example having a cross-section with a substantially rectangular shape. In the illustrated embodiment, the pump comprises a first annular sealing gasket 60 and a second annular sealing gasket 80 for each piston 45.

[0086] The pump 1 may comprise a crankcase 100, to which the head 10 is rigidly fixed (i.e. without residual degrees of freedom), preferably removably (for example by means of a plurality of threaded connection members that clamp the head between the crankcase and a portion (head) of the threaded connection member itself. The head, for example, contacts the crankcase at the first face thereof 25. In particular, the crankcase 100 comprises a plane face placed directly in contact with the first face 25 of the head 10.

[0087] The crankcase 100 contains in its inside a driving mechanism configured to set in motion the piston 45, i.e. the pistons 45, in order to pump the liquid into the pumping chamber, i.e. into the pumping chambers.

[0088] In the illustrated embodiment, the driving mechanism comprises a rotating inclined plate 105 adapted to receive a rotary motion from a drive shaft external to the pump and having a fixed inclination.

[0089] The inclined plate 105 is housed in the crankcase 100, is rotatably associated with it with respect to an axis of rotation A (for example coaxial to the common axis of the holes), and for example comprises a plane annular surface lying on an inclined plane with respect to the axis of rotation A (the inclination of which is not variable). In particular, the inclined plate is rotatably associated by means of a bearing to a flange 115, which is bolted to the crankcase 100, and by means of which the crankcase can be fixed to a motor or to a frame (thanks to holes made in the flange) with respect to which the external drive shaft is rotatably associated.

[0090] In particular, following the rotation of the inclined plate 105, the piston, each piston, is made to slide along the sliding axis between a top dead centre position, in which the volume of the pumping chamber is minimum, and a bottom dead centre position, in which the volume of the pumping chamber is maximum.

[0091] In detail, the second axial end of the piston, i.e. of each piston, is kept in contact by the force exerted by a respective elastic element 106, of an annular guide 107 lying on the annular plane surface of the inclined plate 105, for example by interposing a roller axial bearing.

[0092] Each elastic element, which for example is in the form of a helical compression spring 106 coaxial to the piston, has a first end connected to the crankcase 100 and a second end connected to the piston 45, for example in proximity to the second end 55.

[0093] The second axial end 55 may be rounded and convex in shape and the annular guide 107 may have a plane annular surface parallel to the plane annular surface of the plate. Furthermore, the crankcase may comprise an annular guide surface (i.e. substantially an internal cylindrical surface) 120, for example cylindrical, adapted to guide the piston (with very little or no play) 45 sliding in the hole. That is, the piston is slidably associated with said annular guide surface, which defines the sliding axis X of the piston itself. This sliding axis may not be perfectly coaxial with the central axis of the hole 15 due to production (dimensional and geometric) tolerances. In other words, the sliding axis X corresponds to the central axis of the hole 15 net of the tolerances due to the production and assembly of the components, in particular of the production tolerances of the head with the relative holes, of the crankcase with the relative annular guide surfaces, and of the assembly of the head with the crankcase.

[0094] In the illustrated embodiment, in the crankcase there is an annular guide surface 120 for each piston.

[0095] The annular guide surface 120 is made available by a (cylindrical) guide bushing 125, for example made of metallic material, preferably steel, inserted in a housing hole made in the crankcase.

[0096] In the illustrated embodiment, the crankcase comprises a plurality of guide bushings 125 each adapted to guide a respective piston 45 sliding along the corresponding cylinder.

[0097] The guide surface 120 is interposed between a volume of the crankcase in which the piston driving mechanism is housed and a respective hole 15.

[0098] The elastic element 106 that pushes the piston towards the inclined plate is in particular interposed between a portion of the crankcase that makes available said guide surface, in particular a portion that supports the guide bushing, and the portion of the piston in proximity to the second end 55.

[0099] Said guide bushing 125, i.e. each guide bushing 125, is in communication with the opening 35 made in the first face of the first head 10, i.e. with the respective opening made in the first face.

[0100] In particular, the crankcase comprises at the opening 35, i.e. at each opening 35, a through hole 130, having a diameter greater than the annular guide surface and which makes a corresponding opening at a (plane) face of the crankcase in contact with the first face 25. This through hole 130 is crossed by the piston and connects the guide bushing to the head.

[0101] In the through hole 130 there is housed an annular sealing gasket 135 that embraces a portion of the piston 45 and is configured to prevent an oil contained in the crankcase for lubrication of the cylinder driving mechanism and for lubrication of the guide surfaces from entering into the respective hole 15.

[0102] Independently of the gasket 135, the through hole 130 is variable in section and makes available an annular shoulder surface 140 turned towards the first face of the head.

[0103] For example, this annular shoulder surface 140 is closer to the head than the guide surface 120.

[0104] The crankcase, like the head, can be made of polymeric material (with metallic guide bushings inserted during or after moulding the polymeric material).

[0105] In this case, in the crankcase there are metallic inserts 150 provided with a female thread that allows to tighten a threaded connection member, for example a screw 145, which is fitted through the head by a through hole 151 made in the head itself.

[0106] Preferably the pump comprises a plurality of threaded connection members 145, for example in a number that is the same as the number of cylinders, configured to fix the head 20 to the crankcase 5 and that are inserted in an equal amount of through holes 151 obtained in the head 20.

[0107] For example, the pump may comprise a (rigid) cover 155, for example in metallic material such as stainless steel or aluminium, and the threaded connection members, i.e. the screws, allow the head to be clamped between the crankcase and said cover. In particular, the cover and the head are clamped between a head of the threaded connection members, i.e. screws, and the crankcase. The through holes 151 also extend through the cover.

[0108] The cover, in the illustrated embodiment, comprises a first face 160 in (direct) contact with the second face 30 of the head 10, an opposite second face 165 (substantially parallel to the first face 160) and a blind cavity 175, for example in the form of a blind (cylindrical) hole, provided with an (circular) opening 176 made in the first face 160 and which is aligned with the second opening 40.

[0109] So that the hole 15 and the blind cavity 175 forms substantially together a blind hole, of which the blind cavity 175 comprises a bottom surface 180 delimiting the blind cavity itself (in a direction away from the first face of the cover; furthermore it is said bottom surface 180 that makes the cavity blind).

[0110] The bottom surface 180 is spaced apart by a non-zero amount from the second face of the head and is turned towards it and towards the piston 45 sliding in that hole 15.

[0111] The opening 176 has a passage section, i.e. a diameter, smaller than a passage section, i.e. a diameter, of the second opening 40 with which it communicates. In this way the first face 160 of the cover makes available an abutment surface 177 which extends substantially from a perimeter of the opening 176 to a perimeter of the second opening 40 and for example is (plane and) perpendicular to a central axis of a corresponding hole 15.

[0112] The blind cavity 175 comprises a tubular side surface 178 extending from the bottom surface 180 to the opening 176 (thus up to the abutment surface 177) and for example is a cylindrical surface (coaxial to the central axis of the hole 15).

[0113] The invention provides for the presence of a blind cavity as described above for each hole 15.

[0114] The cover 155 also comprises a delivery channelling, for example made entirely in the cover, (placed downstream of the pumping chamber with respect to a direction of a pumping fluid through the pump).

[0115] With particular reference to FIGS. 1 and 10, the delivery channelling comprises the blind cavity 175, i.e. the blind cavities 175, and at least one connection, or delivery, channel 185 that connects the blind cavity 175, i.e. all the blind cavities 175, to an outlet port 190 (made in the cover) at which there are means suitable to allow the connection of a pipe to the outlet port itself, for example in the form of a threaded element coaxial to the outlet port.

[0116] However, it is not excluded that in embodiments not illustrated the cover may not comprise the cavities and that for example it only serves to close the holes 15, in which case the bottom surfaces would consist of portions of the first face of the cover that close the second openings of the holes 15.

[0117] Furthermore, it is not excluded that in an alternative embodiment the same holes 15 are blind holes, each of them making a bottom surface available (in this case the cover is not even present or if present it has not the function of closing the holes 15).

[0118] In cases where the pump does not have any cavities in the cover, or the cover is not at all present, the abutment surface 177 is made available by a portion of the head (as well as the side surface 178). Furthermore, in this case the shoulder surface 18 is not present and its function must be performed by a spacer.

[0119] Therefore, regardless of the exact shape, the head alone or the head with the cover fixed to it make available a plurality of blind holes 15, 175 (straight and for example also altogether cylindrical) provided with a bottom wall 180 turned towards the pump crankcase and delimiting the hole itself. In cases where the cover does not have the blind cavity, the delivery channelling is made in the head.

[0120] The pump also comprises a suction channelling, which is provided with an inlet port 195, also made in the cover or in the head, from which at least one suction duct 196 is derived in fluid communication with a hole 15 or a blind cavity 175, i.e. from which a plurality of suction ducts are derived in fluid communication with a respective hole or a blind cavity. In particular, the suction duct directly intersects the (respective) hole 15 (or the blind cavity in an embodiment not illustrated).

[0121] For example, the suction duct comprises a blind hole that passes through both the cover (in which it makes the inlet port 196) and the head and from which suction channels branch off reaching the respective holes. To prevent the leakage of liquid at the interface between the cover and the head, there is an annular sealing gasket coaxial and external to said through hole of the channelling and which is housed in an annular groove made in the first face of the cover.

[0122] As anticipated, the pump comprises automatic valves for the control of the pumped fluid, including an automatic one-way delivery valve and an automatic one-way suction valve for each pumping chamber.

[0123] Said delivery valve and the suction valve (of a single pumping chamber, i.e. of each pumping chamber), are to be understood as means that automatically regulate the entry and the exit of the fluid from the pumping chamber based respectively on a pressure difference between the suction channelling and the pumping chamber and on a pressure difference between the pumping chamber and the delivery channelling.

[0124] The operation based on the pressure difference is substantially that of the one-way hydraulic valves, of which the suction valve is configured and oriented so as to open only when the pressure in the pumping chamber is lower than that in the suction channelling, while the delivery valve is configured and oriented so as to open only when the pressure in the pumping chamber is higher than the pressure in the delivery channelling.

[0125] According to the invention, said means are made available by a single suction and delivery valve assembly 200,200′,200″ (one for each pumping chamber) removably insertable into the pump, in particular (entirely) removably insertable (and with reduced play or to size) into the hole 15, and for example also into the blind cavity 175, i.e. (entirely) removably insertable into a blind hole of the pump (15,175) containing in its inside a volume of a pumping chamber (and in which a piston slides). It is specified that by entirely it is meant that the assembly with all its components is integrally removably inserted into the pump. For example, in case of maintenance it is possible to extract the entire valve assembly from the pump as a single body.

[0126] Additionally, the valve assembly 200,200′,200″ is not fixed by threaded connection members or other means to the pump (and does not comprise threaded portions for the fixing to the pump), but is retained therein only by clamping it (all or part thereof) between two abutment or shoulder surfaces, which for example are made available by the cover and by the head (it is not excluded that the valve assembly in alternative embodiments can be clamped between the head only and the crankcase, for example between the head and a spacer that lies on a shoulder surface of the crankcase).

[0127] Since it is not retained except by the assembly of the pump, in particular of the cover to the head, i.e. to the crankcase, for the extraction of the valve assembly it is not necessary to unscrew it from the hole in which it is inserted.

[0128] Hereinafter the delivery and suction valve assembly 200,200′,200″ will be abbreviated as valve assembly 200,200′,200″.

[0129] Overall, the valve assembly 200,200′,200″ is configured to selectively place the suction channelling in fluid communication with the pumping chamber and to selectively place the pumping chamber in fluid communication with the delivery channelling.

[0130] The valve assembly 200,200′,200″ comprises a (rigid) valve body 205, for example monolithic, preferably also made of metallic material, such as for example brass or stainless steel.

[0131] In the illustrated embodiment, the valve body 205 is insertable to size (with reduced play) in the blind hole of the pump that contains the volume of the pumping chamber, which in the illustrated embodiment is made available by the hole 15, and for example also by the blind cavity 175. The valve body 205 therefore slides to size (in contact) along the surface 17, the surface 19 from the head side 10 and along the side surface 178 from the side of the blind cavity 175.

[0132] Further, the hole 15 and the cover 155 can be shaped so as to clamp the valve body 205, i.e. a portion of the valve body 205, between them when the cover is fixed to the head (therefore to the crankcase). In the illustrated embodiment, this task is carried out by the surface 17 and by the abutment surface 177 that (directly) contact the valve body 205, i.e. a portion of the valve body 205, clamp it, i.e. clamp said portion, between them when the cover is fixed to the head (therefore to the crankcase).

[0133] The valve body 205 comprises a first (longitudinal) end 210 and an opposite second (longitudinal) end 215, which longitudinal ends are aligned with each other along a central axis of the valve body itself (said longitudinal ends are intersected by said central axis). When the valve assembly 200 is inserted into the pump, the central axis of the valve body 205 is substantially coaxial with the central axis of the hole 15, i.e. of the respective hole 15.

[0134] When positioned in the pump, the first end 210 is distal from the crankcase, i.e., from the piston 45, and the second end 215 is proximal to the crankcase, i.e., to the piston 45. In other words, the first end 210 is proximal to the bottom surface 180 and the second end 215 is distal to the bottom wall 180.

[0135] Additionally, when positioned in the pump, the first end 210 is located within the blind cavity 175 and the remainder of the valve body is located in the hole 15.

[0136] The first end 210 makes available a first face, for example circular, transverse (perpendicular) to the central axis of the valve body and turned (facing) in the opposite direction to the crankcase, i.e. turned (facing) towards the bottom surface 180.

[0137] Similarly, the second end 215 makes available a second face, for example circular, transverse (perpendicular) to the central axis of the valve body and turned (facing) towards the crankcase, i.e. turned (facing) in the opposite direction with respect to the bottom surface 180.

[0138] The first face and the second face are connected by a tubular (and circular, e.g. cylindrical or formed by several cylindrical sections) side surface extending from one end of the valve body to the other.

[0139] The valve body 205 comprises a first abutment surface 220 which (directly) contacts the cover 155, i.e. contacts a portion of the first face 160 of the cover, in particular it contacts the (entire) abutment surface 177.

[0140] Said first abutment surface 220 is transverse (perpendicular) to the central axis of the valve body, in other words it is coplanar to the abutment surface 177.

[0141] For example, the first abutment surface 220 is shaped as a circular crown (consequently it contacts the cover along a circumference).

[0142] The valve body 205 also comprises a second abutment surface 225 which (directly) contacts the head 10, i.e. it (directly) contacts the (entire) shoulder surface 18.

[0143] Said second abutment surface 225 is transverse (perpendicular) to the central axis of the valve body, in other words it is coplanar to the shoulder surface 18.

[0144] For example, the second abutment surface 225 is shaped as a circular crown (consequently it contacts the head along a circumference).

[0145] When the valve assembly is inserted into the pump and the cover is fixed to the head (therefore to the crankcase) the valve body is clamped between the abutment surface 117 and the shoulder surface 18, which retain the valve body by lying in contact respectively of the first abutment surface 220 and of the second abutment surface 225.

[0146] It can also be said that when the valve assembly is inserted into the pump and the cover is fixed to the head (therefore to the crankcase), a valve body portion comprised between the first abutment surface 220 and the second abutment surface 225 is clamped between the cover and the head.

[0147] The valve body 205 may for example be shaped as a revolution body obtained by a revolution around said central axis, for example said body being composed of a plurality of cylindrical sections adjacent to each other.

[0148] In the illustrated embodiment, the valve body 205 comprises a side surface (substantially coaxial to the central axis) extending from the first face to the second face of the valve body itself.

[0149] The side surface comprises a first section 230, for example cylindrical (external cylindrical surface), which develops from the first face of the valve body and reaches the first abutment surface 220.

[0150] The first section 230 is (entirely) inserted in the blind cavity 175, in particular it is inserted to size (with reduced play) in the side surface 178.

[0151] The side surface then comprises a second section 235, for example cylindrical (external cylindrical surface), which develops from a perimeter of the first abutment surface 220 that is distal from the first section 230, up to the second abutment surface 225.

[0152] The second section 235 is (entirely) inserted in the hole 15, in particular it is inserted to size (with reduced play) in the surface 17.

[0153] The side surface then comprises a third section 240, for example cylindrical (external cylindrical surface), which develops from a perimeter of the second abutment surface 225 that is distal from the second section 235, up to the second face of the valve body.

[0154] The third section 240 is (entirely) inserted in the hole 15, in particular it is inserted to size (with reduced play) in the surface 19.

[0155] The valve assembly 205 comprises a first duct 245 adapted to be selectively connected, as will be clearer later, with the delivery channelling. In particular the first duct, i.e. a plurality of first ducts as will be described below, is the only passage of the valve assembly (and of the entire pump) through which the fluid pumped into the (respective) pumping chamber can (selectively) reach the delivery channelling.

[0156] The first duct 245 is made (entirely) in the valve body 205 and develops (solely) from a first (single) (circular) opening 250 made in the first end 210, in particular in the first face of the valve body 205, extending up to a second opening 255 made in the second end 215. It is in particular the second opening, that is a section of the first duct proximal to the first opening adapted to be selectively connected, as will be clearer later, with the delivery channelling.

[0157] For example, the first opening 250 is made in a central portion of the first end 210, i.e. of the first face, of the valve body, for example centrally with respect to the side surface of the valve body.

[0158] Further, the first opening 250 lies on a plane substantially perpendicular to the central axis of the valve body.

[0159] The second opening 255, when the valve assembly is inserted into the pump, is always in direct fluid communication with the pumping chamber. In particular, there is no means for regulating the flow through the second opening, neither in the valve assembly nor in the pump, which can prevent the entry of the pumped fluid into the first duct.

[0160] Even more in detail, there is no shutter capable of occluding, even only partially, the second opening 255.

[0161] At the first opening 250, the valve body 205 makes available a first annular sealing seat, which comprises, or consists of, an annular surface 260 that surrounds the opening 250, which is coaxial to it (coaxial to a central axis of symmetry of the opening), and for example which develops (extends) from a perimeter (and circular) edge of the first opening 250 (or consists of said perimeter edge).

[0162] The annular surface 260 is for example turned in opposite direction with respect to the second end of the valve body.

[0163] The annular surface 260 of the first annular sealing seat may be an annular perimeter edge, preferably bevelled / rounded, of the opening 250 or a doomed annular surface (e.g. a sphere sector) or, like in the illustrated embodiment, a flared, i.e. frusto-conical, surface arranged so that its cross-section increases going from the first opening 250 in a direction away from it (i.e. in a direction of radial distancing from the central axis of the hole) and from the second end of the valve body along the central axis.

[0164] As a further detail, the first opening 250, i.e. the first annular sealing seat, is always in fluid communication with the second opening 255. In particular, there is no means for regulating the flow through the first duct located between the first opening 250 and the second opening 255, neither in the valve assembly nor in the pump, which can prevent the passage of the fluid between the first and the second opening.

[0165] For example, the first opening 250 is coaxial and centred to the central axis of the hole 15.

[0166] The second opening 255 is made in the second face of the valve body 205 in an eccentric position with respect to the central axis of the hole (and which does not intersect it), for example as a circular-shaped opening.

[0167] As a further detail, the first duct 245 comprises a first section 261 which develops from the first opening as a blind hole (coaxial to the central axis of the valve body, i.e. coaxial to the central axis of the hole 15) and from which a second section develops that reaches up to the second opening 255.

[0168] The second section of the first duct 245 comprises a first portion 265, which develops from the second opening 255 as a blind hole parallel and eccentric with respect to a central axis of the valve body 205, and a second portion 266 which is made as a through hole intersecting the first section 261, i.e. its blind hole, and the second portion 266. Said second portion 266 is inclined with respect to a central portion of the valve body.

[0169] In the illustrated embodiment there are a plurality (four) of first ducts 245, which from the first opening 250 develop to a corresponding plurality of second openings 255 made in the second end, i.e. in the second face, independent of each other and all arranged eccentric with respect to the central axis of the valve body 205, for example also angularly equidistant with respect to the central axis of the valve body (so that the second openings lie with the respective centre on an imaginary circumference centred on the central axis and lying on a plane perpendicular thereto).

[0170] As a further detail, the first ducts all develop from the common section 260 to the second openings 255, and the first portions of the second sections of each first duct are arranged eccentrically with respect to the central axis of the valve body, angularly equidistant with respect to the central axis of the valve body.

[0171] The valve assembly also comprises a second duct 270 adapted to be always in fluid connection with the suction channelling, i.e. with a respective suction duct. Furthermore, the second duct 270 is adapted to be selectively connected, as will be clearer later, with the pumping chamber. In particular, the second duct, i.e. a plurality of second ducts as will be described below, is the only passage of the valve assembly (and of the entire pump) through which the fluid pumped in the delivery channelling can (selectively) reach the (respective) pumping chamber.

[0172] The second duct 270 is (entirely) made in the valve body 205 and does not intersect (at any point thereof) the first duct 245, i.e. the first ducts 245.

[0173] The second duct is provided with a first opening 275, made in the tubular side surface of the valve body 205 comprised between the first end and the second end, in particular it is made, when the valve assembly is inserted into the pump, at a section of said side surface proximal to an intersection area between the hole 15 and the suction duct, so as to always be in direct fluid communication with the suction duct. In particular, the first opening 275 is made in the second section 235 and is (always) in direct fluid communication with the intersection area between the hole 15 and the suction duct.

[0174] Furthermore, there is no means for regulating the flow through the first opening, neither in the valve assembly nor in the pump, which can prevent the pumped fluid from entering into the second duct starting from the suction duct.

[0175] In the illustrated embodiment, the second duct 270 comprises a plurality (four) of first openings 275 all made in the side surface of the valve body, in particular in the second section 235, and for example angularly equidistant from each other around the central axis of the valve body (axis of revolution), i.e. the central axis of the hole 15.

[0176] The second duct 270 extends from the first opening 275, i.e. from the openings 275 to a (single) second opening 280 made in the second end 215 of the valve body, in particular in the second face of the valve body 205, for example in a central position with respect to the second opening 255 of the first duct 245 (and central with respect to the side surface of the valve body). Preferably the second opening 280 is coaxial with the first opening 250.

[0177] At the second opening 280, the valve body 205 makes available a second annular sealing seat, which comprises, i.e. consists of, an annular surface 285 surrounding the opening 280, which is coaxial to it (coaxial to a central axis of symmetry of the opening), and for example which develops (extends) from a perimeter (and circular) edge of the second opening 280 (or consists of said perimeter edge).

[0178] The annular surface 285 is for example turned in the opposite direction with respect to the first end of the valve body.

[0179] The annular surface 285 of the second annular sealing seat may be an annular, preferably bevelled / rounded, perimeter edge of the opening 280 or a doomed (circular) annular surface (e.g. a sphere sector) or, like in the illustrated embodiment, a flared, i.e. frusto-conical, surface arranged so that its cross-section increases going from the second opening 280 in the direction away therefrom (i.e. in the direction of radial distancing from the central axis of the hole) and from the first end of the valve body along the central axis.

[0180] As a further detail, the second opening 280, i.e. the second annular sealing seat, is always in fluid communication with the first opening 255. In particular, there is no means for regulating the flow through the second duct located between the first opening 275 and the second opening 280, neither in the valve assembly nor in the pump, which can prevent the passage of the fluid between the first and the second opening.

[0181] The second duct is substantially L-shaped, in particular it comprises a first section 290 that derives as a hole from the first opening 275 of the second duct itself towards a central area of the valve body, i.e. towards the central axis of the valve body or towards the central axis of the hole 15, (perpendicularly to the central axis) and a second section 295 that derives from the second opening 280 of the second duct 270 as a blind hole transverse to the first section 290 and intersecting said first section 290.

[0182] In the illustrated embodiment, the second duct 270 comprises a plurality of first openings 275 from each of which a corresponding first section 290 of the second duct 270 is de-rived, the first sections of which converge into a common second section 295 that is de-rived from the second opening 280 of the second duct 270. Thus it can also be said that the valve body comprises a plurality of second ducts.

[0183] The second sections of the first ducts 245 cross portions of the valve body that are placed between two adjacent first sections of the second ducts and the tubular side surface of the valve body itself.

[0184] The valve body 205 is a rigid (entirely rigid) body preferably also monolithic, for example made of a metallic material chosen in the group between brass and stainless steel. The first duct, i.e. the first ducts, and the second duct are made in said monolithic body by removal of material.

[0185] The valve assembly comprises a first (rigid) shutter 300 movable between a closed position, in which it hermetically obstructs the (single) first opening 250 of the first duct 245, and an open position, in which it is spaced from the first opening of the first duct and allows the passage of a flow through the first opening itself.

[0186] In particular, when the valve assembly is inserted into the pump, in the closed position the first duct is isolated from the delivery channelling, i.e. the pumping chamber is isolated from the delivery channelling, while in the open position the pumped fluid can flow from the pumping chamber to the delivery channelling through the first opening 250.

[0187] Between the open position and the closed position the shutter moves along a sliding axis that is substantially straight and coaxial to the central axis of the first opening 250, i.e. coaxial to the central axis of the (respective) hole 15.

[0188] Additionally, in the open position, the first shutter is at a greater distance from the second end than when it is in the closed position.

[0189] With particular reference to FIGS. 7,8, 15-17, the first shutter 300 comprises a contact surface 305 adapted to generate a (hermetic) sealing with the first annular sealing seat of the first opening 250 when it is in the closed position (under the action of a force that keeps it pressed against said seat). The contact surface is coaxial to the central axis of the first opening 250, i.e. coaxial to the central axis X of the (respective) hole 15.

[0190] Said contact surface 305 (directly) contacts, (only) in said closed position, at least partially the first annular sealing seat along at least one closed annular path, for example said path being a circumference.

[0191] The contact surface comprises, i.e. consists of, an annular surface (which makes a closed-ring path, therefore a complete ring) which can be either doomed or frusto-conical. The doomed surface can also be defined as a rounded surface, without edges, which in particular is obtained by the revolution of a curved segment around an axis of revolution. This axis of revolution is coaxial to the central axis of the first opening 250, i.e. it is coaxial to the central axis X of the (respective) hole 15.

[0192] In particular, said curved segment comprises a first end closer to the second end of the valve body 205 than to a second end of the segment itself. In addition, the second end is radially more distant from the axis of revolution than the first end. Additionally, the curved segment comprises a single concavity, i.e. it is defined by a single radius of curvature, which concavity is turned towards the axis of revolution.

[0193] In the illustrated embodiment, the doomed surface, i.e. the contact surface, consists of a spherical sector.

[0194] With regard to the frusto-conical surface, it is specified that it is the external side surface of a truncated cone interposed between the two bases of the truncated cone.

[0195] The first shutter comprises a first face turned towards the first opening and the first annular sealing seat that makes the contact surface available, and an opposite second face, on which for example a housing seat of an end of an elastic element is made, preferably as an annular lowering, as will be described below.

[0196] In the illustrated embodiment the shutter is substantially shaped as a discoid body, for example machined by plastic deformation, which makes the first face and the second face available, with the relative contact surface and housing the elastic element.

[0197] The valve assembly comprises an elastic element, for example in the form of a helical compression spring 310, which generates a force on the first shutter, for example by lying with one end thereof on the second face of the shutter, in the direction of keeping the shutter in the closed position. When the force generated on the first shutter (first face) by the pressurized fluid in the first duct exceeds the sum of the force generated by the elastic element on the shutter (second face) and the force generated on the shutter by the pressurized fluid present downstream (with respect to the direction of the flow along the suction and delivery pump) of the first opening, the first shutter moves into the open position and the fluid can go to the delivery channelling.

[0198] The elastic element is retained in position by means of a (cup-shaped) cage 315 fixed, for example removably, to the valve body 205, so that the elastic element is substantially interposed between a portion of said cage and the first shutter. Said cage comprises passage holes for the liquid.

[0199] The valve assembly comprises a second (rigid) shutter 320 movable between a closed position, in which it hermetically obstructs the (single) second opening 280 of the second duct 270, and an open position, in which it is spaced from the second opening of the second duct and allows the passage of a flow through the second opening itself.

[0200] The valve assembly comprises no other shutters than the first and the second shutter.

[0201] In particular, when the valve assembly is inserted into the pump, in the closed position the second duct is isolated from the pumping chamber, i.e. the pumping chamber is isolated from the suction channelling, while in the open position the pumped fluid can flow from the suction channelling to the pumping chamber through the second opening 280. Between the open position and the closed position the shutter moves along a sliding axis that is substantially straight and coaxial to the central axis of the second opening 280, i.e. coaxial to the central axis of the (respective) hole 15.

[0202] Additionally, in the open position, the second shutter is at a greater distance from the first end than when it is in the closed position.

[0203] The first shutter and the second shutter are external to the valve body.

[0204] The second shutter 320 comprises a respective contact surface 325 adapted to generate a (hermetic) sealing with the second annular sealing seat of the second opening 280 when it is in the closed position (under the action of a force that keeps it pressed against said seat). The contact surface is coaxial to the central axis of the second opening 280, i.e. coaxial to the central axis X of the (respective) hole 15.

[0205] Said contact surface of the second shutter (directly) contacts, (only) in said closed position, at least partially the second annular sealing seat along at least one closed annular path, for example said path being a circumference.

[0206] Like in the case of the contact surface of the first shutter, the contact surface of the second shutter comprises, i.e. consists of, an annular surface (which makes a closed-ring path, therefore a complete ring) which can be either doomed or frusto-conical.

[0207] The doomed surface can also be defined as a rounded surface, without edges, which in particular is obtained by the revolution of a curved segment around an axis of revolution. This axis of revolution is coaxial to the central axis of the second opening 280, i.e. it is coaxial to the central axis X of the (respective) hole 15.

[0208] In particular, said curved segment comprises a first end closer to the first end of the valve body 205 than to a second end of the segment itself. In addition, the second end is radially more distant from the axis of revolution than the first end. Additionally, the curved segment comprises a single concavity, i.e. it is defined by a single radius of curvature, which concavity is turned towards the axis of revolution.

[0209] In the illustrated embodiment, the doomed surface, i.e. the contact surface, consists of a spherical sector.

[0210] The second shutter comprises a first face turned towards the first opening and the first annular sealing seat that makes the contact surface available, and an opposite second face, on which for example a housing seat of an end of an elastic element is made, preferably as an annular lowering, as will be described below.

[0211] In the illustrated embodiment the shutter is substantially shaped as a discoid body, for example machined by plastic deformation, which makes the first face and the second face available, with the relative contact surface and housing the elastic element.

[0212] The valve assembly comprises an elastic element, for example in the form of a helical compression spring 330, which generates a force on the second shutter 320, for example by lying with one end thereof on the second face of the shutter, in the direction of keeping the shutter in the closed position. When the force generated on the second shutter (first face) by the pressurized fluid in the second duct exceeds the sum of the force generated by the elastic element on the second shutter (second face) and the force generated on the second shutter by the pressurized fluid present downstream (with respect to the direction of flow along the suction and delivery pump) of the opening of the second duct, the second shutter moves into the open position and the fluid can go from the delivery channelling to the suction chamber.

[0213] The elastic element is retained in position by means of a (cup-shaped) cage 335 fixed, for example removably, to the valve body 205, so that the elastic element is substantially interposed between a portion of said cage and the second shutter. Said cage comprises passage holes for the liquid.

[0214] For both shutters, in case the respective annular sealing seat is frusto-conical, the contact surface is preferably doomed and not frusto-conical. If the annular sealing seat is doomed or a rounded edge, the contact surface can be either doomed or frusto-conical.

[0215] In order to prevent the fluid to be pumped or pumped from inserting between the valve body 205 and the hole 15 and / or the blind cavity 175, the valve assembly comprises a plurality of annular (static) sealing gaskets housed in respective annular grooves in the side surface of the valve body 205 and lying on the hole 15 and / or on the blind cavity 175. In particular, the valve assembly 200,200′ comprises a first annular sealing gasket 340 housed in an annular groove and which contacts the blind cavity, in particular the side surface 178, achieving a hermetic sealing between the first section 230 of the side surface of the valve body and the blind cavity, i.e. the side surface 178.

[0216] The valve assembly also comprises a second annular sealing gasket 345 housed in an annular groove and which contacts the respective hole 15, in particular the surface 17. As a further detail, the annular groove accommodating the second annular sealing gasket 345 is made in a portion of the side surface of the valve body that lies between the first opening of the second duct, i.e. the first openings of the second duct, and the abutment surface 220. In this way the pumped fluid cannot leak into the gap between the valve body and the hole and therefore cannot infiltrate between the cover and the face of the head in contact with the cover.

[0217] Furthermore, in combination with a third annular gasket 350, the second gasket prevents pressurized fluid from being able to enter from the pumping chamber into the second duct and then into the suction channelling.

[0218] The third annular gasket 350 contacts the respective hole 15, in particular the surface 17. In particular, the annular groove accommodating the third annular sealing gasket is made in a portion of the side surface of the valve body that lies between the first opening of the second duct, i.e. the first openings of the second duct, and the abutment surface 225.

[0219] Regardless of the exact conformation of the first duct, the gaskets, the surfaces and of the presence of the second duct, when the valve assembly comprises at least:

[0220] the valve body 205,

[0221] a duct, corresponding for example to the first duct 245, made in the valve body (for example provided with an opening made at the second end, corresponding to the second opening 255)

[0222] a shutter movable at least between a closed position, in which it obstructs the flow through said duct, and an open position, in which it allows the passage of a flow through the duct (for example said shutter corresponding to the second shutter 320)

[0223] the valve body 205 provided with the first end 210 and the opposite second end 215,

[0224] a duct, corresponding for example to the first duct 245, made in the valve body, andthe valve assembly comprises a tubular sleeve 360,360′ (straight, for example cylindrical) which develops, in particular seamlessly, from a portion of the valve body, for example from the second end of the valve body, i.e. from an external perimeter edge (proximal to the side surface of the valve body) of the second face of the second end, in a direction away from the valve body itself, in particular in a direction away from the first end 210.

[0225] As a further detail, the tubular sleeve develops from a portion of the valve body around the opening of the duct, i.e. around the second opening 255 of the first duct 245.

[0226] The valve assembly comprising the tubular sleeve is therefore not necessarily the automatic delivery and suction valve assembly described above, but could be an automatic delivery-only valve assembly, for example therefore provided with a single shutter, for example the first one, which affects the delivery of the pumping chamber, in particular which allows to selectively obstruct the flow along the duct, i.e. along the first duct.

[0227] For the presence of the tubular sleeve as described in the paragraph above, only the characteristics listed in the previous paragraph of the valve body are necessary. Further characteristics and variants of the tubular sleeve will be described below, which may require the presence of other elements of the pump or of the valve body described above and which will be introduced if necessary. Therefore, if not referred to, other pump elements are not essential to the invention.

[0228] It can also be said that the tubular sleeve 360,360′ develops from the second end, in particular from the second face, as a continuation of the side surface of the valve body, for example as a continuation of the third section 240 of said side surface.

[0229] The tubular sleeve has the aim of protecting the head, in particular the head made of polymeric material, from the pressures that are generated in the pumping chamber, therefore it is made of a metal, preferably a metal such as brass or stainless steel. Although the example has been made with the pump having a head made of polymeric material, the same considerations can be made in the case where the head is made of a metal having an elastic modulus and resistance to fatigue such that the integrity of the pump at the operating pressures for which it is designed cannot be guaranteed. Additionally, if the cover is present, like in the illustrated embodiment, and said cover houses part of the valve assembly and at least part of the delivery channelling, the cover must be made of metal, or the delivery channelling must be lined in its inside with a sleeve made of metallic material.

[0230] In addition to these considerations, it is wished to point out that it is not strictly necessary to apply the tubular sleeve only in the case of a head made of polymeric material or of any other material not sufficiently resistant for the pressures involved, but it can also be applied to heads made of a material that is not sufficiently resistant to working pressures, in order to protect said head and increase its durability over time, also in consideration of the lower cost for replacing the valve assemblies compared to the entire head.

[0231] In the illustrated embodiment, the tubular sleeve 360,360′ is a monolithic body with the (entire) valve body 205, however it is not excluded that in an alternative embodiment not illustrated the tubular sleeve could be welded to the valve body, in particular to the second face thereof, or could be removably fixed to the valve body (to the second end), for example by threaded connection members.

[0232] In particular, in the case of threaded connection members, the sleeve could comprise a threaded surface adapted to be screwed onto a corresponding threaded surface made at the second opening.

[0233] The tubular sleeve 360,360′ comprises a (single) first end, which is the one that is derived directly from the second end of the valve body 205 and an opposite (single) second end, where the first end and the second end are spaced along the central axis of the valve body, i.e. along the central axis of the second opening 255 (which is then the central axis of the hole 15 when the valve assembly is inserted into the pump). In addition, the tubular sleeve develops about an axis that is coaxial to at least one of the central axes listed above and the first end and the second end are spaced apart along that axis.

[0234] The tubular sleeve 360,360′ has a constant cross-section (with respect to the central axis) from the first end to the second end.

[0235] The tubular sleeve 360,360′ is for example shaped as a straight body having constant cross-section (with respect to the central axis) along its extension from the first end thereof to the second end.

[0236] When the valve assembly 200,200′ is inserted into the pump, the tubular sleeve is for example entirely contained in the volume of the hole 15. However, if, as will be clearer hereinafter, the high-pressure gasket 60 were located in the crankcase or even the low-pressure gasket were housed in the tubular body, the tubular sleeve could extend as far as the crankcase. In principle, the tubular sleeve has an extension such that the second end thereof is in proximity to, for example at, preferably in sealing contact with the high-pressure gasket 60 preventing the liquid in the pumping chamber from coming into contact with the hole 15. In the illustrated embodiment, the tubular sleeve extends up to in proximity to the first face of the head (regardless of whether the second end is in the head or protrudes into the crankcase).

[0237] The tubular sleeve 360,360′ comprises an internal tubular surface 365, for example cylindrical, and parallel to the central axis of the valve body, i.e. to the central axis of the second opening 255, i.e. to the central axis of the hole 15. Preferably the tubular internal surface is also coaxial to said axes when the valve assembly is inserted into the pump.

[0238] The surface 365 is radially (with respect to the central axes) more external than the second opening 255, i.e. it develops from a portion or edge of the second face that is around and external to the second opening. In this way the internal volume of the tubular sleeve itself is in fluid communication with said second opening. In particular, the surface 365 is radially more external than all the second openings 255, i.e. it develops from a portion or edge of the second face that is around and external to a portion or surface of the second face in which all the second openings of the first duct are made. In this way the internal volume of the tubular sleeve itself is in fluid communication with all the second openings. The surface 365 is also radially more external than the second opening of the second duct. In addition, it is also radially more external than the cage that retains the second shutter, so that it is possible to insert this cage into the tubular body and fix it to the valve body during the assembly and maintenance phases.

[0239] The tubular sleeve 360 also comprises an external tubular surface 370, for example having the same shape as the hole 15, in particular of the surface 19, and substantially the same size, so that the external tubular surface 370 fits to size or with reduced play in the hole 15, i.e. in the surface 19.

[0240] Thus, in the illustrated embodiment the external tubular surface is cylindrical and coaxial to the internal tubular surface 365.

[0241] The external tubular surface 370 is substantially configured, in the illustrated embodiment, as a continuation of the side surface of the valve body, for example as a continuation of the third section 240 of said side surface, in a direction away from the first end of the valve body.

[0242] For example, the third section 240 and the tubular external surface 370 have the same diameter.

[0243] The tubular sleeve 360,360′ also comprises an annular surface 375, for example plane and transverse (perpendicular) to the internal tubular surface 365 and to the external tubular surface 370, which joins said tubular surfaces and substantially defines the limit of the extension of the tubular sleeve in a direction away from the first end, therefore substantially defines the second end of the tubular body.

[0244] The tubular sleeve 360,360′, i.e. the internal tubular surface 365 thereof, defines an internal volume of the tubular sleeve itself in fluid communication (direct, always direct) with the opening, i.e. with the second opening 255 of the first duct 245. Such internal volume comprises at least a portion of the volume of the pumping chamber.

[0245] The internal tubular surface 365 has a cross-section, i.e. a diameter, larger than a cross-section, i.e. a diameter, of the piston 45.

[0246] In use, the piston 45 is at least partially contained, with (abundant) play, in the internal volume of the tubular sleeve 360,360′. In practice, between the internal tubular surface 365 and the piston 45, there is an annular gap with non-zero thickness and length.

[0247] The distance between the surface 365 and the surface 370 defines the thickness of the tubular sleeve.

[0248] The tubular sleeve 360,360′ extends from the second end away from the first one, along the axis of the valve body or the axis of the second opening of the first duct or the axis of the hole 15, up to an annular sealing gasket that sealingly embraces a portion of the piston, which slides through said sealing. In particular, the tubular sleeve extends up to (in direct contact with) the first annular sealing gasket 60 so that said gasket 60 sealingly contacts the tubular sleeve, i.e. sealingly contacts the internal tubular surface 365, (so as to prevent the fluid present in the pumping chamber from being able to contact the hole 15).

[0249] In detail, such contact takes place in such a way that the internal volume of the tubular body is closed at one end thereof by the fluidic sealing formed by the contact between the first annular sealing gasket 60 and the contact between said gasket 60 and the piston 45

[0250] For example, this is achieved with the gasket 60 sealingly inserted (by elastic deformation) into the internal cavity of the tubular body.

[0251] Preferably, said gasket 60 sealingly contacts the internal tubular surface 365 along a closed annular path transverse to the central axis.

[0252] In particular, the gasket 60 is inserted into the internal volume of the tubular sleeve and is fitted sealingly on a portion of the internal tubular surface 365. For example, the external annular lip 70 sealingly contacts said portion of the internal tubular surface. Additionally, the annular lip 70 is housed in the annular gap that is formed in use between the internal tubular surface and the piston.

[0253] The configuration thus obtained allows to isolate internal cavities from the rest of the volume of the hole 15, for example it allows to isolate the pumping chamber from the rest of the volume of the hole 15. In other words, the pumping chamber is therefore delimited at least partially (or entirely) by the second end of the valve body, by the tubular sleeve, by the gasket 60, by the piston, by the first duct 245, by the first shutter and by the second shutter (when said shutters are in the closed position).

[0254] Although not illustrated, it is not excluded that in an embodiment not illustrated the tubular body may comprise an annular groove made in the internal tubular surface 365 adapted to act as a seat for the partial housing of the gasket 60.

[0255] The internal tubular surface 365 is seamlessly continuous from the valve body at least to the portion of contact with the gasket 60. The entire tubular sleeve is seamlessly continuous from the valve body at least up to the portion of contact with the gasket 60. The tubular sleeve, to be understood as the wall placed between the internal tubular surface and the external tubular surface, is not crossed by the fluid. In other words, from the portion in which it is derived from the valve body up to at least the portion of contact with the gasket 60, the tubular sleeve does not comprise any hole or channel that passes through the tubular sleeve itself, in particular it does not comprise any hole or channel that passes through the internal tubular surface 365 and the external tubular surface 370. Preferably the extension in radial direction to the axis X of the tubular sleeve is defined solely by the surfaces 365 and 370.

[0256] Between the gasket 60 and the second end, i.e. the second face, of the valve body, a tubular (rigid) spacer 400 is interposed so as to prevent the piston 45 in its stroke from being able to move said gasket towards the second end of the valve body.

[0257] The tubular spacer 400 comprises a first longitudinal end in (direct) contact with the second face of the valve body and an opposite second longitudinal end in contact (for example by interposing a pusher ring 405) with the gasket 60.

[0258] The tubular spacer is entirely contained in the internal volume of the tubular sleeve and, for example, it comprises an internal (cylindrical) tubular surface 410, and an opposite external (cylindrical) tubular surface in contact with the internal tubular surface 365.

[0259] The internal tubular surface 410 of the tubular spacer is arranged radially, with respect to the central axis of the second opening, or of the valve body or of the hole and, more external to the second opening 280 of the second duct, and for example more internal than the second opening 255 of the first duct, i.e. than the plurality of second openings 255 of the first duct.

[0260] When the surface 410 is also radially more internal than the second opening 255, at least one groove or cut 415 is made in the tubular spacer and which develops from the internal tubular surface towards the external tubular surface placing in fluid communication the second opening 255 of the first duct with the internal volume defined by the tubular spacer, thus allowing a fluid communication between the second opening 255 and said internal volume, i.e. with the pumping chamber. Said groove or cut 415 extends at least from an intermediate portion (between first and second end) of the tubular spacer, up to the first end of the tubular spacer itself, making at said end an opening at the second opening 255.

[0261] In particular, there being a plurality of second openings 255 of the first duct 245, the spacer comprises a plurality of grooves or cuts 415 each positioned at a respective second opening 255.

[0262] In order to align the tubular spacer to the valve body, i.e. to align the groove or cut 415 to the opening 255 (i.e. to align the grooves or cuts 415 to the respective opening), the valve assembly comprises at least one reference element adapted to allow a single mechanical alignment between the valve body and the tubular spacer. In the illustrated embodiment the reference element comprises a pin 500 insertable in a hole made in the second end of the valve body and from which it protrudes so as to be inserted also in a hole made in the first end of the tubular spacer.

[0263] The tubular spacer is shaped so that it can be crossed by the piston. In detail, the internal tubular surface has a cross-section such that the piston 45 can slide with play within an internal volume defined by said internal tubular surface itself. Furthermore, said cross-section is such that the second shutter is not hindered, and for example is radially larger than the cage of the second elastic element.

[0264] The pump, i.e. the valve assembly, may comprise an annular body 420,420′ (rigid and made / produced as a monolithic body distinct from the valve body and from the tubular sleeve) in which a through hole 421 is made in direct fluid communication with the internal volume of the tubular sleeve, i.e. with the pumping chamber. This through hole is therefore coaxial to the central axis of the valve body and is adapted to be crossed by the piston 45 (during its movement between top dead centre and bottom dead centre)

[0265] A housing seat for the low-pressure gasket 80 (placed between the first face and the second face) is made in the through hole 421. This housing seat is formed as an annular groove in which the low-pressure gasket 80 is inserted and retained so as to prevent the gasket 80 from being able to move (along the central axis) dragged by the piston 45.

[0266] The low-pressure gasket is arranged so that the external annular lip 90 achieves a hermetic sealing with one surface of the annular groove.

[0267] The annular body 420,420′ comprises a drainage channel 424 adapted to place in fluid communication the suction channelling with a volume comprised between the piston, the high-pressure gasket and the low-pressure gasket, so that any leaks of pressurized fluid from the high-pressure gasket can be discharged at the suction pressure.

[0268] Further, in order to prevent leaks, the annular body 420,420′ or a portion of the head at the annular body comprises a groove for housing a static sealing groove 422.

[0269] The annular body 420,420′ comprises a side surface 423 which is fitted to size, i.e. with reduced place, in a portion of the through hole 130 which lies between the shoulder surface 140 and the face of the crankcase in contact with the head.

[0270] In the embodiment of the valve assembly 200, only the high-pressure gasket 60 is part of the valve assembly, i.e. it is extracted from the head with the rest of the valve assembly, while the high-pressure gasket is not part of the valve assembly.

[0271] In such a case, the annular body comprises a first face 425 (e.g. annular, planar and transverse, i.e. perpendicular, to the central axis of the valve body) on which the second end of the tubular sleeve rests and for example the gasket 60, i.e. the ring 75 of the gasket 60, (in this way the gasket 60 is retained in position (clamped) between the tubular spacer and the annular body).

[0272] The annular body 420 also comprises a second face 430 (e.g. annular, planar and transverse, i.e. perpendicular, to the central axis of the valve body) resting on the annular shoulder surface 140, for example so that when the cover is fixed to the crankcase, the valve body, the tubular sleeve and the annular body 420 are clamped between the cover and the crankcase, i.e. between the annular shoulder surface 140 and the surface 176. In this embodiment 420, the seat of the gasket 422 is made in the annular body.

[0273] In the embodiment of the valve assembly 200′ of 11 and 16, both the high-pressure gasket and the low-pressure gasket are part of the valve assembly and therefore are extracted from the head with the rest of the valve assembly.

[0274] In this case the annular body 420′ is configured as a retaining body fixed to the second end of the tubular sleeve, for example removably, preferably screwed to the tubular sleeve. In particular, in the illustrated embodiment the tubular sleeve comprises a threaded portion 435 (at the second end) on which a corresponding threaded portion of the annular body 420′is screwed.

[0275] In this embodiment 420′, the seat of the gasket 422 is preferably made in the portion of the head at the annular body 420′, for example in the surface 19.

[0276] The annular body 420′ has a first face 425 (e.g. annular, planar and transverse, i.e. perpendicular, to the central axis of the valve body) on which the gasket 60 rests, i.e. the ring 75 of the gasket 60, (in this way the gasket 60 is retained in position (clamped) between the tubular spacer and the first face of the annular body 420′, i.e. clamped between the tubular spacer and the first face of the annular body 420′).

[0277] The annular body 420′also comprises a second face 430 (e.g. annular, planar and transverse, i.e. perpendicular, to the central axis of the valve body) resting on the annular shoulder surface 140.

[0278] Although illustrated only for the embodiment of the valve assembly 420′, in an embodiment not illustrated in which only the gasket 60 and not the gasket 80 are present within the internal volume of the tubular sleeve, there may still be the retaining body, which in such an embodiment directly contacts the gasket 60 so that it is retained in position (clamped) between the retaining body and the tubular spacer.

[0279] In all the embodiments of the valve assembly illustrated in FIGS. 1-16, the tubular sleeve 360 is preferably a monolithic body, for example monolithic with the valve body 205, however it is not excluded that it can be formed by several sections in series interlocked or screwed to each other, possibly where the sealing between one section and the other is guaranteed by annular sealing gaskets of the static type.

[0280] The first opening 250 (with relative annular sealing seat 260) of the first duct, the first shutter and the first elastic element together substantially make a one-way delivery valve. The second opening 280 (with relative annular sealing seat 285) of the second duct, the second shutter and the second elastic element together substantially make a one-way delivery valve.

[0281] Although only one embodiment of the valve assembly with tubular sleeve and comprising both the first duct and the second duct is illustrated in the figures, it is not excluded that the valve assembly may comprise the tubular sleeve and not the second duct. In this case the valve assembly would be a one-way delivery valve with tubular sleeve.

[0282] The operation of the pump according to the invention is as follows.

[0283] The piston 45, i.e. each piston 45, under the action of the driving mechanism contained in the crankcase moves along the respective sliding axis in the hole 15 between a bottom dead centre position, in which the volume of the pumping chamber is maximum, and a top dead centre position, in which the volume of the pumping chamber is minimum.

[0284] When the piston moves from the top dead centre towards the bottom dead centre, in the pumping chamber there is a pressure lowering that closes the first shutter (delivery shutter) and when the pressure gets lower than that in the suction channelling, it opens the second shutter (suction shutter) thus allowing the suction of fluid from the delivery channelling to the pumping chamber. In particular, the fluid enters from the delivery channelling in the first opening 275, i.e. in the first openings 275, passes through the first duct and exits from it through the second opening 280.

[0285] Once the bottom dead centre is reached, the piston moves towards the top dead centre by compressing the fluid and then increasing the pressure in the pumping chamber. As a result of the increase in pressure, the second shutter moves into the closed position and the first shutter moves into the open position, allowing the pumped fluid to reach the delivery channelling. In particular, under the thrust of the piston the fluid flows in the second opening of the first duct, i.e. the second openings of the first duct, and from there, passing through the first opening 250, arrives in the delivery channelling.

[0286] In the event that the tubular sleeve is present, the fluid under the thrust of the piston, before reaching the second openings of the first duct, crosses the grooves or cuts present in the tubular spacer.

[0287] The tubular sleeve allows to contain and direct the pressurized fluid, preventing it from coming into contact with the internal surfaces of the hole 15.

[0288] When it is necessary to carry out maintenance on the pump or assemble it, the user simply unscrews the screws that fix the cover to the crankcase, removes the cover and, thanks to the shape of the hole and of the side surface of the valve body, it is sufficient to pull the valve assembly to extract it out of the hole, for example in the embodiment of FIGS. 3-10 in doing so the high-pressure gasket is also extracted, and in the embodiment of FIGS. 11-16 the high-pressure gasket and the low-pressure gasket are also extracted.

[0289] It should be noted that in this discussion, rigid is understood as not deformable in a sensitive way under the normal workloads to which it is subjected. In other words, a rigid element does not perform its function for which it was designed also by means of its own deformation.

[0290] Elastic element means a body that instead is shaped so as to deform (only) elastically under the workloads to which it is subjected and therefore performs its function also (or only) by means of its elastic deformation. It should be noted that the definition of elastic deformation is to be understood in contrast to plastic deformation.

[0291] In this case a gasket deforms elastically to adhere to certain surfaces in order to generate a possibly hermetic sealing.

[0292] Furthermore, it should be noted that monolithic body means a body obtained by solidification of a single casting, or injection, of (a single) material into a mould and possibly by a subsequent processing of said solidified body by removal of material.

[0293] When sphere sector is mentioned, it is specified that said geometric element is an annular surface that realizes a closed-and that is defined as a portion of spherical surface directly interposed between two planes parallel to each other and intersecting both the spherical surface.

[0294] By to size and with reduced play it is meant that the elements characterized by such coupling can slide with respect to each other without particular effort and without tilting significantly with respect to the sliding direction. If, on the other hand, there were abundant play, the elements could instead tilt significantly with respect to the direction of advancement.

[0295] The invention thus conceived is susceptible to several modifications and variations, all falling within the scope of the inventive concept.

[0296] Moreover, all details can be replaced by other technically equivalent elements.

[0297] In practice, the materials used, as well as the contingent shapes and sizes, can be what-ever according to the requirements without for this reason departing from the scope of protection of the following claims.

Claims

1. A valve assembly removably insertable into high-pressure pumps, said valve assembly comprising:a valve body,a duct made in the valve body,a shutter movable at least between a closed position, in which it obstructs the flow through said duct, and an open position, in which it allows the passage of a flow through the duct,wherein said valve assembly comprises a tubular sleeve which develops from a portion of the valve body, in a direction away therefrom, and defines an internal volume in fluid communication with the duct.

2. The valve assembly according to claim 1, wherein, in a portion of the tubular sleeve distal from the valve body, an annular sealing gasket is inserted which is at least partially contained in the internal volume of the tubular sleeve and adapted to embrace a piston slidably insertable in the tubular sleeve.

3. The valve assembly according claim 2, comprising a tubular spacer contained in the tubular sleeve (360,360′) and directly interposed between a surface of the valve body at the portion from which the tubular sleeve develops and the sealing gasket4. The valve assembly according to claim 2, comprising a further annular sealing gasket which is at least partially contained in the internal volume, wherein the further gasket is more distant from the valve body than the gasket.

5. The valve assembly according to claim 2, wherein the tubular sleeve comprises a portion that is distal from the valve body and through which the gasket can be inserted into the internal volume, and wherein the valve assembly comprises a retaining body removably fixed to the tubular sleeve and adapted to maintain the gasket and / or the further gasket in position from the internal cavity.

6. The valve assembly according to claim 4, wherein the retaining body defines a housing seat, for the further gasket.

7. The valve assembly according to claim 1, wherein the tubular sleeve is made as a single body at least with a portion of the valve body from which it develops.

8. The valve assembly according to claim 1, wherein the duct makes an opening in the valve body and the tubular sleeve develops from a portion of the valve body around said opening.

9. The valve assembly according to claim 8, wherein the valve body comprises a first end and an opposite second end, wherein the opening of the duct is made in the second end, a further opening of the duct is made in the first end, and the tubular sleeve extends from the second end away from the first end.

10. A pump for high pressures comprising:a head in which a hole adapted to partially define a volume of a pumping chamber is made,a pumping piston slidably inserted in the hole,a valve assembly according to claim 1, which is inserted into said hole with the tubular sleeve as a lining for a portion of the hole and wherein the piston is slidably inserted into the tubular sleeve.

11. The pump according to claim 10, comprising a high-pressure annular gasket which sealingly embraces a portion of the piston, and wherein the tubular sleeve extends from the valve body (205) up to at least said high-pressure annular gasket.

12. The pump according to claim 11, wherein the high-pressure annular gasket is sealingly inserted into the tubular sleeve.

13. The valve assembly according to claim 5, wherein the retaining body defines a housing seat, for the further gasket.

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