Automatic delivery and suction valve assembly and pump provided with said valve assembly

Abstract

The invention describes an automatic suction and delivery valve assembly (200, 200 ', 200' ') that can be removably inserted into a high pressure pump (1, 1'), the valve assembly comprising: a valve body (205) provided with a first end (210) and an opposite second end (215); a first conduit (245) extending from a first opening (250) formed in the first end of the valve body to a second opening (255) formed in the valve body; a second conduit (270) formed in the valve body and not intersecting the first conduit, the second conduit being provided with a first opening (275) formed in the valve body and a second opening (280) formed in the second end of the valve body; a first shutter (300) movable at least between a closed position, in which it tightly blocks the first opening (250) of the first conduit, and an open position, in which it is spaced from the first opening (250) of the first conduit and allows flow through the first opening itself; a second shutter (320) movable at least between a closed position, in which it tightly blocks the second opening (280) of the second conduit, and an open position, in which it is spaced from the second opening (280) of the second conduit and allows flow through the second opening. Wherein the valve body (205) provides an annular sealing seat (260) of the first opening and closing piece and an annular sealing seat (285) of the second opening and closing piece at the first opening of the first pipeline and the second opening of the second pipeline respectively. Further, the first and second shutters each comprise a corresponding contact surface (305, 325) that, when the shutters are in the closed position, at least partially contacts the corresponding annular seat along the at least one closed annular path, the contact surfaces (305, 325) each comprising a corresponding convex annular surface or frustoconical surface.

Description

Field of the Invention

[0001] The present invention relates to a valve, in particular to a valve assembly for automatic delivery and suction, which is used for a pump, such as a high-pressure pump, and relates to a pump provided with such a valve assembly, preferably an axial piston pump. Background Art

[0002] Known valve assemblies for automatic delivery and suction, when connected to the pumping chamber, delivery pipe and suction pipe of a pump, will automatically allow the liquid to be pumped to be sucked through the suction pipe towards the pumping chamber based on the pressure difference, and send the pumped fluid from the pumping chamber to the delivery pipe.

[0003] Known embodiments of the automatic valve assembly include a single valve body in which a central pipe is formed, which passes through the valve body from one side to the other, defining a first opening at a first axial end of the valve body and a second opening at a second axial end. Such a central pipe is configured to fluidly communicate the pumping chamber with the delivery pipe.

[0004] The valve assembly further includes a plurality of peripheral pipes eccentric to the central pipe, each peripheral pipe being provided with a first opening formed in a side surface of the valve body between the first end and the second end, and a second opening formed in the second end of the valve body. Each peripheral pipe is configured to fluidly communicate the suction pipe with the pumping chamber.

[0005] The valve assembly further includes a first opening and closing member that tightly closes the first opening of the central pipe under the thrust of a first elastic element, and a second opening and closing member that tightly closes the second openings of all the peripheral pipes under the thrust of a second elastic element.

[0006] In particular, the shape of the valve assembly is such that when the volume of the pumping chamber increases, a low pressure is generated in the pumping chamber that overcomes the force of the second elastic element, thereby releasing the second openings of the peripheral pipes from the second opening and closing member. When the volume of the pumping chamber decreases, an overpressure is generated in the pumping chamber itself that overcomes the force of the first elastic element, thereby releasing the first opening of the central pipe from the first opening and closing member.

[0007] The disadvantage of the prior art is that in order to close the second openings of the peripheral pipes provided eccentrically around the central pipe, an opening and closing member with a flat circular crown contact surface is required, which is perfectly located in the flat circular crown surface formed in the valve body and formed with the second openings of the peripheral pipes when in the closed position. This solution is costly because in order to form the flat surface of the circular crown of the contact surface and the flat circular crown surface in the valve body, precise and expensive machining is required to make the two surfaces completely flat and parallel so that they are in complete contact with each other when the opening and closing member is in the closed position. If this parallelism is not achieved, complete valve sealing cannot be ensured, thus there is a risk of fluid pressure entering the suction pipeline during the pumping process.

[0008] The object of the present invention is to overcome the limitations of the prior art in the context of a reasonable and cost-effective solution. The dependent claims outline the preferred and / or particularly advantageous aspects of the present invention. Summary of the Invention

[0009] In particular, the present invention provides an automatic suction and delivery valve assembly that can be removably inserted into a high-pressure pump, the valve assembly comprising:

[0010] - a valve body provided with a first end and an opposite second end,

[0011] - a first conduit extending from a first opening formed in the first end of the valve body to a second opening formed in the valve body,

[0012] - a second conduit formed in the valve body and not intersecting the first conduit, the second conduit being provided with a first opening formed in the valve body and a second opening formed in the second end of the valve body,

[0013] - a first opening and closing member movable at least between a closed position and an open position, in the closed position, it tightly blocks the first opening of the central conduit, in the open position, it is spaced apart from the first opening of the central conduit and allows flow through the first opening,

[0014] - a second opening and closing member movable at least between a closed position and an open position, in the closed position, it tightly blocks the second opening of the peripheral conduit, in the open position, it is spaced apart from the second opening of the peripheral conduit and allows flow through the second opening, and

[0015] wherein the valve body provides an annular sealing seat for the first opening and closing member and an annular seal for the second opening and closing member at the first opening of the first conduit and the second opening of the second conduit, respectively,

[0016] wherein the first opening and closing member and the second opening and closing member each include corresponding contact surfaces that, when the opening and closing member is in the closed position, contact the corresponding annular seat at least partially along at least one closed annular path, and the contact surfaces each include a corresponding convex annular surface or a frustoconical surface.

[0017] Thanks to this valve assembly architecture that does not use a planar opening / closing member (i.e., its contact surface is not the planar circular crown of the prior art), the valve has a stronger resistance to dirt and stains. This is because any accumulated dirt does not obstruct the seal as it does in a flat opening / closing member, and it is also cheaper to manufacture because the machining precision and cost required for the opening / closing member and the associated sealing seat of the present invention are lower than those required for manufacturing a flat opening / closing member and its perfectly parallel flat seat. The opening / closing member according to the present invention has a stronger resistance to dirt than a flat opening / closing member because any dirt or grime that may deposit between the abutment surface of the opening / closing member and the opening / closing member itself tends to lift a part of the opening / closing member (causing the opening / closing member to tilt), so that fluid can pass uncontrolled between the opening / closing member and its abutment surface.

[0018] According to one aspect of the present invention, the convex annular surface can be a rotational surface obtained by rotating a curved section around a rotation axis.

[0019] According to another aspect of the present invention, the contact surface can be a spherical sector.

[0020] According to yet another aspect of the present invention, the first opening of the first pipe can be formed in the central part of the first end, and the second opening of the second pipe can be formed in the central part of the second end.

[0021] According to another aspect of the present invention, the first opening of the first pipe and the second opening of the second pipe can be coaxial.

[0022] The present invention can also be configured such that the second pipe can include a first section extending from the first opening of the second pipe towards the central region of the valve body and a second section originating from the second opening of the second pipe and formed as a blind hole transverse to and intersecting the first section.

[0023] In the illustrated embodiment, the valve assembly includes a plurality of first pipes that all extend from a first opening formed in the first end of the valve body to a plurality of corresponding second openings formed in the second end of the valve body, and wherein the second opening of the second pipe is formed in the second end of the valve body at a central position relative to the plurality of second openings of the plurality of first pipes.

[0024] According to one aspect of the present invention, the first pipe can include a common first section extending from the first opening as a blind hole and a plurality of second sections extending from the first section, each second section being independent of the other second sections, and the second sections being blind holes that form corresponding second openings among the plurality of second openings in the second end of the valve body.

[0025] According to another aspect of the present invention, the second sections of the first pipe can be eccentric to the second sections of the second pipe and each is provided with at least one part parallel to the second sections of the second pipe.

[0026] According to another aspect of the present invention, the valve assembly may include a tubular (cylindrical) sheath that extends (without interruption) in a direction away from the first end around the second opening of the first first pipe and also around the second opening of the second pipe, for example (wherein the tubular sheath includes an inner tubular surface that is radially more external than the second opening of the first pipe).

[0027] According to another aspect of the present invention, in a portion of the tubular sheath that is remote from the second end of the valve body, a sealing gasket may be inserted (inserted into the seat by interference or elastic deformation), and the sealing gasket is adapted to surround a piston that is slidably received therein.

[0028] The present invention also provides a pump provided with the valve assembly of claim 1, which is in direct fluid communication with the pumping chamber of the pump itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further features and advantages of the present invention will become more apparent after reading the following description, provided by way of non-limiting example, with the aid of the accompanying drawings.

[0030] Figure 1 are isometric views of the first and second embodiments of the pump according to the present invention.

[0031] Figure 2 is Figure 1 the top view of the pump in.

[0032] Figure 3 is according to Figure 2 the sectional view of the first embodiment of the pump in plane III-III in.

[0033] Figure 4 is Figure 3 the enlarged view of detail IV in.

[0034] Figure 5 is a side view of the valve assembly according to the present invention, and the first embodiment of the pump is provided with this valve assembly.

[0035] Figure 6 is Figure 5 the bottom view of the valve assembly in.

[0036] Figure 7 is according to the sectional plane VII-VII of Figure 5 and Figure 6 the sectional view of the valve assembly in.

[0037] Figure 8 is according to the sectional plane VIII-VIII of Figure 5 and Figure 6 the sectional view of the valve assembly in.

[0038] Figure 9 Is a sectional view of a first embodiment of the pump according to the sectional plane IX-IX, but is valid for both embodiments of the pump.

[0039] Figure 10 Is a sectional view of a first embodiment of the pump according to the sectional plane X-X, but is valid for both embodiments of the pump.

[0040] Figure 11 Is according to Figure 2 The sectional view of the first embodiment of the pump of the plane XI-XI in.

[0041] Figure 12 Is Figure 11 The enlarged view of detail XII in.

[0042] Figure 13 Is a side view of another embodiment of the valve assembly according to the present invention, and the second embodiment of the pump is equipped with this valve assembly.

[0043] Figure 14 Is Figure 13 The bottom view of the valve assembly in.

[0044] Figure 15 Is according to the sectional plane XV-XV of Figure 13 And Figure 14 The sectional view of the valve assembly in.

[0045] Figure 16 Is according to the sectional plane XVI-XVI of Figure 13 And Figure 14 The sectional view of the valve assembly in.

[0046] Figure 17 Is a sectional view of a third embodiment of the valve assembly according to the present invention. Detailed description

[0047] Particularly referring to these figures, a pump for high pressure (i.e., a pressure of at least 50 bar), particularly a piston pump, preferably a pump suitable for pumping low-viscosity liquids such as water or aqueous solutions, is generally denoted by 1, 1'. In addition, particularly referring to Figure 4 And Figure 12 The enlarged views in, the pump is preferably of such a type that it is provided with a plurality of pumping chambers 20 (parallel to each other, i.e., pumping liquid parallel to each other), particularly at least three pumping chambers 20, for example five pumping chambers 20, and is provided with an automatic valve for regulating the pumping flow rate.

[0048] The pump shown is an inclined plate type multi-cylinder axial piston pump. However, the concept of the present invention can be applied to different types of pumps, such as single-cylinder pumps and / or alternative pumps.

[0049] In particular, the pumps 1, 1' shown are of such a type that they are provided with a rotating plate with a fixed inclination (as further disclosed later) and are provided with an automatic valve for regulating the pumping flow rate.

[0050] The pumps 1, 1' include a head 10 in which at least one (straight) hole 15 is formed, for example a cylindrical or circular hole (formed by one or more cylindrical or circular sections coaxial with each other), and at least partially contained within the hole 15 is a pumping chamber 20. That is, at least a part of the total volume of the pumping chamber 20 is contained within the volume defined by the corresponding hole 15.

[0051] It is not excluded that in alternative embodiments, the hole may have a cross-section other than circular, for example, the hole may have a polygonal cross-section, such as a square or octagon.

[0052] In the illustrated embodiment, the head 10 includes a plurality of holes 15, for example the number of holes is equal to the number of pumping chambers, and at least partially contained within each hole is the volume of the corresponding liquid pumping chamber 20. The pumping chambers 20 are independent of each other and are each defined by corresponding automatic delivery and suction valves, as will become clear hereinafter.

[0053] For example, at least the head portion in which the holes are formed (i.e., a plurality of holes are formed) may be formed as a single-piece body, that is, it can be obtained by machining a single body obtained by curing a single melt or injection of material in a mold.

[0054] In a preferred embodiment, such a single-piece portion is made of a polymer material, for example such that the pump is light, inexpensive and quickly manufactured. More preferably, the entire head is made of a polymer material (and made as a single piece).

[0055] However, it is not excluded that in an embodiment not shown, the head portion in which the holes 15 (i.e., a plurality of holes 15) are formed consists of several components made of polymer material, each component being a single piece and fixed to each other (removably or non-removably, such as by welding).

[0056] The hole 15 (i.e., each hole 15) extends substantially coaxially about its own central axis (the hole is symmetric with respect to the central axis), and, for example, a plurality of holes 15 are arranged in the head in such a way that their respective central axes are parallel to each other.

[0057] For example, in the case of a vane pump having a fixed inclination in the figure, these holes are arranged radially around a common axis, and the central axis of each hole is parallel to the common axis. In addition, these holes are arranged at equal distances from each other and at equal distances from the common axis. In other words, these holes (i.e., the central axes of these holes) are equally angularly spaced from each other along an imaginary circumference centered on the common axis and are located in a plane perpendicular to the common axis.

[0058] Still in the illustrated embodiment, in which there are five holes, the central axes of these holes pass through the vertices of an imaginary regular pentagon, which is located in a plane perpendicular to the central axis of the cylinder block.

[0059] However, in the case of an alternative pump, these holes 15 will be aligned with each other in a direction perpendicular to the central axis.

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

[0061] The holes 15 (i.e., each hole 15) are, for example, formed as holes provided with an opening 35 formed in the first face 25 during a polymer material molding step.

[0062] With particular reference to the enlarged views of Figure 4 and Figure 12 of the illustrated embodiment, the holes (i.e., each hole) are, for example, made as through-holes extending from the first face 25 to the second face 30 during a polymer material molding step, so as to obtain a first opening 35 (circular) in the first face 25 and a second opening 40 (circular) in the second face 30.

[0063] From the second opening 40 towards the opening 35, the hole 15 (i.e., each hole 15) has a narrow portion (relative to at least the second opening 40) that provides a shoulder surface 18. The shoulder surface 18 is transverse to the central axis of the hole, particularly perpendicular to the central axis of the hole, and faces the second opening 40.

[0064] For example, also from the first opening 35 to the second opening 40, the hole 15 (i.e., each hole 15) has a narrow portion (relative to at least the first opening 35) that provides another shoulder opening. The other shoulder opening is transverse to the central axis of the hole and faces the first opening 35 in a direction opposite to the shoulder surface 18.

[0065] Describe in further detail the shape of the holes 15 (i.e., each hole 15). The hole 15 includes at least one internal (cylindrical) tubular surface 16 (coaxial with the central axis of the hole itself), and the internal tubular surface 16 extends directly from the first opening 35 towards the second face 30 of the head 10.

[0066] The hole 15 (i.e., each hole 15) further includes an additional internal (cylindrical) tubular surface 17. The additional internal tubular surface 17 is coaxial with the internal tubular surface 16 and extends from the second opening 40 towards the first face of the head itself. An internal tubular (cylindrical) surface 19 is interposed between the surface 16 and the surface 17, and the cross-sectional area of the internal tubular surface 19 (relative to the central axis) is smaller than the cross-sectional areas of the surface 16 and the surface 17.

[0067] The surface 19 (directly) abuts the surface 17 and is (directly) connected to the surface 17 through the abutting surface 18.

[0068] Similarly, the surface 19 (directly) abuts the surface 16 and is (directly) connected to the surface 16 through an additional abutting surface.

[0069] In the shown case where the surface 19 and the surface 17 are circular (i.e., cylindrical), the surface 18 is circular coronal or annular, particularly located on a surface perpendicular to the central axis of the hole 15.

[0070] In Figure 12 the embodiment of the pump shown, the surface 16 does not exist because the surface 19 extends to the first opening 35.

[0071] The number of the tubular surfaces and the shoulder surfaces will obviously vary depending on the type of the check valve inserted into the hole and the method of centering them and the gasket in the head, as will be made clearer later.

[0072] Therefore, it should not be excluded that there may be a third tubular surface, even a third tubular surface with a diameter larger than the tubular surface 16, which allows the crankcase to be centered relative to the head. Or even the case where the surface 18 faces the first face is not excluded.

[0073] The pumps 1, 1' include pistons 45. The pistons 45 slide into the holes 15 along the sliding axis and are partially contained in the holes 15. That is, the pump includes a plurality of pistons 45, and each piston 45 slides into the corresponding hole 15 in the plurality of holes along the corresponding sliding axis and is partially inserted therein. Preferably, the sliding axis coincides with the central axis of the hole.

[0074] In the shown 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. The second axial end 55 projects from the cylinder 15 through the opening 35 to the outside of the head.

[0075] The pumps 1, 1' include a plurality of annular gaskets adapted to circumferentially and sealingly surround the pistons 45 (i.e., each piston 45) to prevent leakage of the pumped liquid from the pumping chamber towards the opening 35 in the first face 25.

[0076] In particular, the pumps 1, 1' include a first annular sealing gasket 60, commonly referred to as a high-pressure seal, which circumferentially and sealingly contacts a portion of the piston 45, i.e., it circumferentially and sealingly contacts a portion of the piston skirt 45, where the skirt refers to the side surface of the piston that extends coaxially with the sliding axis from one axial end of the piston to the other axial end. It can also be said that the gasket circumferentially surrounds the contacting piston, i.e., it is coaxial with the sliding axis of the piston.

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

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

[0079] In particular, referring to Figure 5 , the first annular sealing gasket includes an inner annular lip 65 and, for example, an outer annular lip 70. The inner annular lip 65 circumferentially and sealingly contacts the said portion of the piston 45, and the outer annular lip 70 preferably forms a V-shaped cross-section with the inner annular lip generally.

[0080] The inner annular lip 65 and the outer annular lip 70 originate from the same side of the ring 75 and have, for example, a generally rectangular cross-section.

[0081] The pump 1 further includes a second annular sealing gasket 80, commonly referred to as a low-pressure gasket, which circumferentially and sealingly contacts a portion of the piston 45 (and thus surrounds the piston and is coaxial with the piston), i.e., it circumferentially and sealingly contacts a portion of the piston skirt 45 of the piston 45 (this portion partially overlaps, almost completely overlaps, with the portion on which the first gasket acts).

[0082] For example, the two gaskets are aligned with each other in a direction parallel to the direction of the cylinder axis, and the first annular sealing gasket 60 is closer to the first axial end 50 of the piston, i.e., closer to the pumping chamber 20, than the second annular sealing gasket.

[0083] The second annular sealing gasket is also elastic, i.e., resilient, and is made of, for example, a polymeric material.

[0084] In addition, the second annular sealing gasket 80 is also preferably of the lip type.

[0085] Similar to the first washer, the second washer includes an inner annular lip 85 and, for example, an outer annular lip 90. The inner annular lip 85 is in sealing circumferential contact with the said portion of the piston 45, and the outer annular lip 90 preferably forms a V-shaped cross-section with the inner annular lip generally.

[0086] The inner annular lip 85 and the outer annular lip 90 originate from the same side of the ring 95 and, for example, have a cross-section of generally rectangular shape.

[0087] In the illustrated embodiment, the pump includes a first annular sealing washer 60 and a second annular sealing washer 80 for each cylinder 45.

[0088] The pump 1 further includes a crankcase 100. The head 10 is rigidly fixed to the crankcase 100 (i.e., without residual degrees of freedom), preferably in a removable manner (e.g., by a plurality of threaded connectors that clamp the head between the crankcase and a part of the threaded connectors themselves (the head)). The head contacts the crankcase, for example, at its first face 25. In particular, the crankcase 100 includes a plane that is placed in direct contact with the first face 25 of the head 10.

[0089] The crankcase 100 houses a drive mechanism configured to move the piston 45 (i.e., a plurality of pistons 45) to pump liquid into a pumping chamber or a plurality of pumping chambers.

[0090] In the illustrated embodiment, the drive mechanism includes a rotating inclined plate 105 adapted to receive the rotational movement of a drive shaft outside the pump and having a fixed inclination.

[0091] The inclined plate 105 is housed in the crankcase 100 and is rotatably associated with the crankcase 100 relative to the rotational axis A (e.g., coaxial with the common axis of the plurality of cylinders) and, for example, includes a flat annular surface that lies in a plane inclined relative to the rotational axis A (the inclination of which is immutable). Specifically, the inclined plate is rotatably associated with a flange 115 by bearings. The flange 115 is bolted to the crankcase 100, and the crankcase can be fixed to a motor or a frame through the flange 115 (by means of holes drilled in the flange), and the external drive shaft is rotatably associated with the motor or the frame.

[0092] In particular, as the inclined plate 105 rotates, the piston (each piston) slides along the sliding axis between the top dead center position and the bottom dead center position. At the top dead center position, the volume of the pumping chamber is the smallest, and at the bottom dead center position, the volume of the pumping chamber is the largest.

[0093] Specifically, the second axial end of the piston (i.e., each piston) remains in contact with the annular guide 107 located on the annular planar surface of the inclined plate 105 by the force exerted by the respective elastic element 106, for example, by inserting a roller axial bearing.

[0094] Each elastic element, for example in the form of a compression helical spring 106 coaxial with the piston, has a first end connected to the crankcase 100 and a second end connected to the piston 45 (e.g., near the second end 55).

[0095] The shape of the second axial end 55 can be circular and convex, and the annular guide 107 can have a planar annular surface parallel to the planar annular surface of the plate.

[0096] Furthermore, the crankcase can include an annular guide surface (i.e., substantially an internal cylindrical surface) 120, for example, cylindrical, and the annular guide surface 120 is adapted to guide the piston (with a small clearance or no clearance) 45 when the piston slides into the hole. That is, the piston is in sliding association with the annular guide surface, and the annular guide surface defines the sliding axis X of the piston itself. Due to production tolerances (in terms of dimensions and geometry), this sliding axis may not be exactly coaxial with the central axis of the hole 15. In other words, after deducting the tolerances due to production and component assembly, especially the manufacturing tolerances of the head and its holes, the crankcase and the associated annular guide surface, and the assembly of the head and the crankcase, the sliding axis X corresponds to the central axis of the hole 15.

[0097] In the illustrated embodiment, there is an annular guide surface 120 for each piston in the crankcase.

[0098] The annular guide surface 120 can be provided, for example, by a (cylindrical) guide bushing 125, and the guide bushing 125 is made of, for example, metal (preferably, steel) and is inserted into the receiving hole formed in the crankcase.

[0099] In the illustrated embodiment, the crankcase includes a plurality of guide bushings 125, each adapted to guide the respective piston 45 along the corresponding cylinder.

[0100] The guide surface 120 is disposed between the volume of the crankcase that houses the piston drive mechanism and the corresponding hole 15.

[0101] In particular, the elastic element 106 that pushes the piston towards the inclined plate is interposed between the part of the crankcase that provides the guide surface (in particular, the part that supports the guide bushing) and the part of the piston near the second end 55.

[0102] This guide bushing 125 (i.e., each guide bushing 125) communicates with the opening 35 formed in the first face of the first head 10, that is, with the corresponding opening formed in the first face.

[0103] In particular, the crankcase includes through holes 130 at the openings 35 (i.e., at each opening 35), the diameter of the through holes 130 being greater than the annular guiding surface, and corresponding openings are formed at the (flat) surface of the crankcase that contacts the first surface 25. The piston passes through the through holes 130, which connect the guiding bushings to the head.

[0104] An annular sealing gasket 135 is received in the through holes 130, surrounds a part of the piston 45, and is configured to prevent the oil contained in the crankcase for lubricating the cylinder drive mechanism and the guiding surface from entering the corresponding holes 15.

[0105] Ignoring the gasket 135, the through holes 130 have a varying cross-section and provide an annular shoulder surface 140 facing the first surface of the head.

[0106] For example, the annular shoulder surface 140 is closer to the head than the guiding surface 120.

[0107] Similar to the head, the crankcase can be made of a polymer material (with a metal guiding bushing inserted during or after the molding of the polymer material).

[0108] In this case, inserts 150 with internal threads are provided in the crankcase, allowing the tightening of threaded connectors, such as screws 145, which are mounted through the through holes 151 formed in the head.

[0109] Preferably, the pump includes a plurality of threaded connectors 145, for example, the number being the same as the number of cylinders, and the plurality of threaded connectors 145 are configured to fix the head 20 to the crankcase 5 and are inserted into the same number of through holes 151 formed in the head 20.

[0110] For example, the pump may include a (rigid) cover 155, which is made of, for example, metal, such as stainless steel or aluminum, and the threaded connectors (i.e., screws) allow the head to be clamped between the crankcase and the cover. In particular, the cover and the head are clamped between the heads of the threaded connectors (i.e., screws) and the crankcase. The through holes 151 also extend through the cover.

[0111] In the illustrated embodiment, the cover includes a first surface 160 that (directly) contacts the second surface 30 of the head 10, an opposite second surface 165 (substantially parallel to the first surface 160), and a blind cavity 175, which is in the form of, for example, a blind (cylindrical) hole, and the blind cavity 175 has an opening 176 (circular) formed in the first surface 160 and aligned with the second opening 40.

[0112] Thus, the hole 15 and the blind cavity 175 together substantially form a blind hole, wherein the blind cavity 175 includes a bottom surface 180 which defines the blind cavity itself (in the direction away from the first face of the lid, further, the bottom surface 180 makes the cavity a blind cavity).

[0113] The bottom surface 180 is spaced from the second face of the head by a non-zero amount and faces the second face and the piston 45 that slides in the hole 15.

[0114] The cross-sectional area (i.e., diameter) of the opening 176 of the passage is smaller than the cross-sectional area (i.e., diameter) of the second opening 40 with which it communicates. Thus, the first face 160 of the lid provides an abutment surface 177 which extends substantially from the periphery of the opening 176 to the periphery of the second opening 40 and is, for example, (flat and) perpendicular to the central axis of the corresponding hole 15.

[0115] The blind cavity 175 includes a tubular side surface 178 extending from the bottom surface 180 to the opening 176 (and thus extending up to the abutment surface 177), which is, for example, a cylindrical surface (coaxial with the central axis of the hole 15).

[0116] The present invention provides a blind cavity as described above for each hole 15.

[0117] The lid 155 further includes a delivery channel, for example, the delivery channel is entirely obtained in the lid (downstream of the pumping chamber with respect to the direction of pumping fluid through the pump).

[0118] With particular reference to Figure 1 and Figure 10 , the delivery channel includes the blind cavity 175 (i.e., a plurality of blind cavities 175) and at least one connecting channel or delivery channel 185 that connects the blind cavity 175 (i.e., a plurality of blind cavities 175) to an outlet 190 (formed in the lid), at which an arrangement adapted to connect a pipe fitting to the outlet itself is provided, for example, an arrangement in the form of a threaded element coaxial with the outlet.

[0119] However, it is not excluded that in an embodiment not shown, the lid does not include a cavity, for example, it is only used to close the hole 15, in which case the bottom surface will be formed by the part of the first face of the lid that closes the second opening of the hole 15.

[0120] Furthermore, it is not excluded that in an alternative embodiment, the hole 15 is a blind hole, and each hole 15 provides a bottom surface (in this case, there is even no lid, or if a lid exists, the lid does not have the function of closing the hole 15).

[0121] In the case where there is no cavity in the cover for the pump or the cover does not exist at all, the abutment surface 177 is provided by a part of the head (and the side surface 178). Additionally, in such a case, the shoulder surface 18 does not exist, or its function would have to be performed by a spacer.

[0122] Thus, regardless of the exact shape, the head alone or the head with the cover fixed thereto provides a plurality of blind holes 15, 175 (straight and generally also cylindrical), the blind holes 15, 175 being provided with a bottom wall 180 that faces the crankcase of the pump and defines the hole itself. In the case where the cover does not have a blind cavity, the delivery channel is formed in the head.

[0123] The pump further includes a suction channel that is provided with an inlet 195, also formed in the cover or the head, and at least one suction duct 196 that is in fluid communication with the hole 15 or the blind cavity 175 originates from the inlet, that is, a plurality of suction ducts 196 that are in fluid communication with the corresponding hole or blind hole originate from the inlet.

[0124] In particular, the suction duct intersects directly with the (corresponding) hole 15 (or, in an embodiment not shown, the blind cavity).

[0125] For example, the suction duct includes a blind hole that passes through the cover (wherein it forms the inlet 196) and the head, and a plurality of suction channels that reach the corresponding hole originate from the blind hole. To prevent liquid leakage at the interface between the cover and the head, an annular sealing gasket that is coaxial with the through-hole of the channel and is located outside the through-hole is provided, and the annular sealing gasket is received in an annular groove formed in the first face of the cover.

[0126] As described above, the pump includes automatic valves for controlling the pumped fluid, including an automatic one-way delivery valve and an automatic one-way suction valve for each pumping chamber.

[0127] The delivery valve and the suction valve (for a single pumping chamber, that is, for each pumping chamber) are intended to be used as means for automatically regulating the input and output of the fluid from the pumping chamber respectively based on the pressure difference between the suction channel and the pumping chamber and the pressure difference between the pumping chamber and the delivery channel.

[0128] The operation based on the pressure difference is basically similar to the operation of a one-way hydraulic valve, wherein the suction valve is configured and oriented to open only when the pressure in the pumping chamber is lower than the pressure in the suction channel, while the discharge valve is configured and oriented to open only when the pressure in the pumping chamber is higher than the pressure in the delivery channel.

[0129] According to the present invention, such a device may be provided by a single delivery and suction valve assembly 200, 200', 200'' (one for each pumping chamber), the delivery and suction valve assembly 200 being removably insertable into the pump, in particular (completely) removably insertable (with a small clearance or by measurement) into the hole 15, and also, for example, removably insertable into the pump blind cavity 175, i.e., (completely) removably insertable into the pump blind hole (15, 175) which contains the volume of the pumping chamber (and in which the piston slides). It is stipulated that "completely" means that the assembly and all its components are removably inserted into the pump as a whole. For example, during maintenance, the entire valve assembly can be removed from the pump as a single body.

[0130] Furthermore, the valve assemblies 200, 200', 200'' are not fixed to the pump by threaded connections or other means (and do not include threaded portions for fixing to the pump), but are held within the pump only by being clamped (in whole or in part) between two abutting or shoulder surfaces provided, for example, by a cover and a head (without excluding that in alternative embodiments, the valve assembly may be clamped only between the head and the crankcase, for example, between the head and a gasket held on a shoulder surface of the crankcase).

[0131] To remove the valve assembly, it is not necessary to unscrew it from the inserted hole, since it is held only by the assembly of the pump, in particular the assembly of the cover and the head (i.e., the crankcase).

[0132] Hereinafter, the delivery and suction valve assemblies 200, 200', 200'' will be abbreviated as valve assemblies 200, 200', 200''.

[0133] Generally speaking, the valve assemblies 200, 200', 200'' are configured to selectively put the suction channel in fluid communication with the pumping chamber and selectively put the pumping chamber in fluid communication with the delivery channel.

[0134] The valve assemblies 200, 200', 200'' include a (rigid) valve body 205, for example, a one-piece body, preferably also made of metal, such as brass or stainless steel.

[0135] In the illustrated embodiment, the valve body 205 can be inserted by measurement (with a small clearance) into the blind hole of the pump containing the pumping volume, which blind hole is provided by the hole 15 in the illustrated embodiment and also, for example, by the blind cavity 175. The valve body 205 then slides by measurement (in contact) along the surfaces 17, 19 of the head side 10 and along the side surface 178 of the blind cavity side 175.

[0136] In addition, the hole 15 and the cover 155 can be shaped such that when the cover is fixed to the head (i.e., fixed to the crankcase), the valve body 205 or a part of the valve body 205 is clamped therebetween. In the illustrated embodiment, this task is performed by the surface 17 and the abutment surface 177, which (directly) contact the valve body 205, i.e., a part of the valve body 205, so as to clamp it, i.e., when the cover is fixed to the head (i.e., fixed to the crankcase), this part is clamped between the two.

[0137] The valve body 205 includes a first (longitudinal) end 210 and an opposite second (longitudinal) end 215, and these longitudinal ends are aligned with each other along the central axis of the valve body itself (these longitudinal ends intersect with the central axis).

[0138] 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., the corresponding hole 15).

[0139] When placed in the pump, the first end 210 is away from the crankcase, i.e., away from the piston 45, and the second end 215 is close to the crankcase, i.e., close to the piston 45. In other words, the first end 210 is close to the bottom surface 180, and the second end 215 is away from the bottom wall 180.

[0140] In addition, when placed in the pump, the first end 210 is located within the blind cavity 175, and the rest of the valve body is located within the hole 15.

[0141] The first end 210 provides a first face, for example, circular, which is transverse (perpendicular) to the central axis of the valve body and faces the opposite direction of the crankcase, i.e., faces (towards) the bottom surface 180.

[0142] Similarly, the second end 215 provides a second face, for example, circular, which is transverse (perpendicular) to the central axis of the valve body and faces the base, i.e., faces the opposite direction of the bottom surface 180.

[0143] The first face and the second face are connected by a tubular (and circular, for example, cylindrical or composed of multiple cylindrical sections) side surface extending from one end of the valve body to the other end.

[0144] The valve body 205 includes a first abutment surface 220, and the first abutment surface 220 (directly) contacts the cover 155, i.e., contacts a part of the first face 160 of the cover, and particularly contacts the (entire) abutment surface 177.

[0145] The first abutment surface 220 is transverse (perpendicular) to the central axis of the valve body. In other words, it is coplanar with the abutment surface 177.

[0146] For example, the shape of the first abutment surface 220 is like a circular crown (so it contacts the cover along the circumference).

[0147] The valve body 205 further includes a second abutment surface 225 that (directly) contacts the head 10, i.e., (directly) contacts the (entire) shoulder surface 18.

[0148] This second abutment surface 225 is transverse (perpendicular) to the central axis of the valve body. In other words, it is coplanar with the shoulder surface 18.

[0149] For example, the second abutment surface 225 is shaped like a circular crown (and thus contacts the head along the circumference).

[0150] When the valve assembly is inserted into the pump and the cover is fixed to the cylinder head (i.e., the crankcase), the valve body is clamped between the abutment surface 117 and the shoulder surface 18 such that the valve body remains in contact with the first abutment surface 220 and the second abutment surface 225 respectively.

[0151] It can also be said that when the valve assembly is inserted into the pump and the cover is fixed to the head (i.e., fixed to the crankcase), the portion of the valve body between the first abutment surface 220 and the second abutment surface 225 is clamped between the cover and the head.

[0152] The valve body 205 can be shaped, for example, like a rotational body formed by rotating about the central axis. For example, the body is composed of a plurality of adjacent cylindrical sections.

[0153] In the illustrated embodiment, the valve body 205 includes a side surface (substantially coaxial with the central axis) extending from a first face of the valve body to a second face.

[0154] The side surface includes a first section 230, e.g., cylindrical (outer cylindrical surface), and the first section 230 extends from the first face of the valve body to the first abutment surface 220.

[0155] The first section 230 is (completely) inserted into the blind cavity 175, particularly inserted into the side surface 178 according to measurement (with a small gap).

[0156] The side surface then includes a second section 235, e.g., cylindrical (cylindrical outer surface), and the second section 235 extends from the periphery of the first abutment surface 220 remote from the first section 230 to the second abutment surface 225.

[0157] The second section 235 is (completely) inserted into the hole 15, particularly inserted into the surface 17 according to measurement (with a small gap).

[0158] The side surface then includes a third section 240, e.g., cylindrical (cylindrical outer surface), and the third section 240 extends from the periphery of the second abutment surface 225 remote from the second section 235 to the second face of the valve body.

[0159] The third section 240 is (fully) inserted into the hole 15, particularly inserted into the surface 19 according to the measurement (with a small gap).

[0160] The valve assembly 205 includes a first conduit 245, which is adapted to selectively connect to the delivery passage (as will become clearer hereinafter). In particular, the first conduit or a plurality of first conduits (as will be described hereinafter) is the only path through which the fluid pumped by the valve assembly (and the entire pump) into the (corresponding) pumping chamber can (selectively) reach the delivery passage.

[0161] The first conduit 245 is (fully) formed in the valve body 205 and extends (only) from a first (single) (circular) opening 250 formed in the first end 210 (particularly, in the first face of the valve body 205) to a second opening 255 formed in the second end 215. In particular, the second opening, i.e., the section of the first conduit close to the first opening, can be selectively connected to the delivery passage, as will become clearer hereinafter.

[0162] For example, the first opening 250 is formed in the central part of the first end 210 of the valve body (i.e., the first face), for example, formed at a central position relative to the side surface of the valve body.

[0163] In addition, the first opening 250 is located in a plane substantially perpendicular to the central axis of the valve body.

[0164] When the valve assembly is inserted into the pump, the second opening 255 is always in direct fluid communication with the pumping chamber. In particular, there is no device in the valve assembly and the pump for regulating the flow rate of the second opening that would prevent the fluid pumped into the first conduit from entering.

[0165] More specifically, there is no closing member that can block (even partially) the second opening 255.

[0166] At the first opening 250, the valve body 205 provides a first annular sealing seat, which includes (i.e., consists of) an annular surface 260 surrounding the opening 250. The annular surface 260 is coaxial with the opening 250 (coaxial with the central symmetry axis of the opening). For example, the annular surface 260 extends from (or consists of) the peripheral (and circular) edge of the first opening 250.

[0167] For example, the annular surface 260 faces the opposite direction of the second end of the valve body.

[0168] The annular surface 260 of the first annular seal seat can be the annular peripheral edge of the opening 250, preferably chamfered / rounded, or can be a convex annular surface (e.g., spherical sector), or as in the illustrated embodiment, can be flared, i.e., a frustoconical surface, which is arranged such that its cross-sectional area increases from the first opening 250 along the central axis in a direction away from it (i.e., in a direction radially away from the central axis of the hole) and away from the second end of the valve body.

[0169] More specifically, the first opening 250, i.e., the first annular seal seat, is always in fluid communication with the second opening 255. In particular, there is no device in either the valve assembly or the pump for regulating the flow rate of the first conduit between the first opening 250 and the second opening 255 that would prevent the fluid pumped into the first conduit from entering.

[0170] For example, the first opening 250 is coaxial with the central axis of the hole 15 and centered on the central axis of the hole 15.

[0171] The second opening 255 is formed in the second face of the valve body 205 at an eccentric position (and not intersecting) relative to the central axis of the hole, for example, formed as a circular opening.

[0172] More specifically, the first conduit 245 includes a first section 261 that extends from the first opening as a blind hole (coaxial with the central axis of the valve body, i.e., coaxial with the central axis of the hole 15), and a second section that extends from the first section 261 to the second opening 255.

[0173] The second section of the first conduit 245 includes a first part 265 and a second part 266. The first part 265 extends from the second opening 255 as a blind hole parallel to and eccentric to the central axis of the valve body 205, and the second part 266 is formed as a through hole that intersects the first section 261 (i.e., its blind hole). The second part 266 is inclined relative to the central section of the valve body.

[0174] In the illustrated embodiment, there are a plurality (four) of the first conduits 245 that extend from the first opening 250 to a corresponding plurality of second openings 255 formed in the second end (i.e., the second face). The plurality of second openings 255 are independent of each other and are each arranged eccentrically relative to the central axis of the valve body 205. For example, they are also equally angularly spaced apart from the central axis of the valve body (such that the respective centers of the second openings are located on a imaginary circumference whose center is on the central axis and which is in a plane perpendicular to the central axis).

[0175] More specifically, the first conduits each extend from the common section 260 to the second opening 255, and the first part of the second section of each first conduit is eccentrically arranged relative to the central axis of the valve body and is equally angularly spaced from the central axis of the valve body.

[0176] The valve assembly further includes a second conduit 270 which is adapted to be in fluid connection with the suction channel at all times, that is, in fluid connection with the corresponding suction conduit. In addition, the second conduit 270 is adapted to be selectively connected to the pumping chamber, as will become clearer later. In particular, the second conduit, that is, the plurality of second conduits (as will be described below) is the only path through which the fluid pumped in the delivery channel of the valve assembly (and the entire pump) can (selectively) reach the (corresponding) pumping chamber.

[0177] The second conduit 270 is (completely) obtained in the valve body 205 and does not intersect the first conduits 245 (that is, the plurality of first conduits 245) at any point.

[0178] The second conduit is provided with a first opening 275 which is formed in the tubular side surface of the valve body 205 between the first end and the second end; in particular, when the valve assembly is inserted into the pump, the first opening 275 is formed in the section of the side surface close to the intersection area between the hole 15 and the suction conduit so as to be in direct fluid communication with the suction conduit at all times. In particular, the first opening 275 is formed in the second section 235 and is (always) in direct fluid communication with the intersection area between the hole 15 and the suction conduit.

[0179] In addition, there is no device in the valve assembly and the pump for regulating the flow rate of the first opening that would prevent the fluid pumped into the second conduit from entering the second conduit.

[0180] In the illustrated embodiment, the second conduit 270 includes a plurality (four) of first openings 275, all formed in the side surface of the valve body, in particular formed in the second section 235, and are, for example, equally angularly spaced from each other around the central axis (rotation axis) of the valve body (that is, the central axis of the hole 15).

[0181] The second conduit 270 extends from the first opening 275 (or from the plurality of openings 275) to the (only) second opening 280 which is formed in the second end 215 of the valve body 205, in particular formed in the second face of the valve body 205, that is, centered relative to the position of the second opening 255 of the first conduit 245 (and centered relative to the side surface of the valve body). Preferably, the second opening 280 is coaxial with the first opening 250.

[0182] At the second opening 280, the valve body 205 provides a second annular seal seat that includes (or consists of) an annular surface 285 that surrounds the opening 280 and is coaxial with the opening 280 (coaxial with the central symmetry axis of the opening). For example, the annular surface 285 extends (or consists of) from the peripheral (and circular) edge of the second opening 280.

[0183] For example, the annular surface 285 faces in the opposite direction of the first end of the valve body.

[0184] The annular surface 285 of the second annular seal seat can be the annular peripheral edge of the opening 280, preferably chamfered / rounded, or can be a (circular) convex annular surface (e.g., a spherical sector), or as in the illustrated embodiment, can be flared, i.e., a frustoconical surface that is arranged such that its cross-sectional area increases from the second opening 280 along the central axis in a direction away from it (i.e., in a direction radially away from the central axis of the hole) and away from the first end of the valve body.

[0185] More specifically, the second opening 280, i.e., the second annular seal seat, is always in fluid communication with the first opening 255. In particular, there is no means in the valve assembly and the pump for regulating the flow rate of the second pipe between the first opening 275 and the second opening 280 that would prevent the fluid pumped into the first pipe from entering.

[0186] The second pipe is substantially L-shaped and particularly includes a first section 290 and a second section 295. The first section 290 originates from the first opening 275 of the second pipe itself and is formed as a hole (perpendicular to the central axis) towards the central region of the valve body, i.e., towards the central axis of the valve body or towards the central axis of the hole 15. The second section 295 originates from the second opening 280 of the second pipe and is formed as a blind hole that is transverse to the first section 290 and intersects the first section 290.

[0187] In the illustrated embodiment, the second pipe 270 includes a plurality of first openings 275, and a corresponding first section 290 of the second pipe 270 originates from each first opening 275, and these first sections flow into a common second section 295 that originates from the second opening 280 of the second pipe 270. Therefore, it can also be said that the valve body includes a plurality of second pipes.

[0188] The second section of the first pipe 245 passes through the part of the valve body that is located between two adjacent first sections of the second pipe and the tubular side surface of the valve body itself.

[0189] The valve body 205 is a rigid (fully rigid) body, which is also preferably made in one piece, for example, from a metallic material selected from the group consisting of brass and stainless steel. The first conduit (i.e., the plurality of first conduits) and the second conduit are made from the one-piece body by removing material.

[0190] The valve assembly includes a first (rigid) opening and closing member 300 movable between a closed position and an open position. In the closed position, the first opening and closing member 300 tightly blocks the (only) first opening 250 of the first conduit 245. In the open position, the first opening and closing member 300 is spaced apart from the first opening of the first conduit and allows flow through the first opening.

[0191] In particular, when the valve assembly is inserted into a pump, in the closed position, the first conduit is isolated from the delivery passage, i.e., the pumping chamber is isolated from the delivery passage, while in the open position, the pumped fluid can flow from the pumping chamber through the first opening 250 into the delivery conduit.

[0192] Between the open position and the closed position, the opening and closing member moves along a substantially straight sliding axis that is coaxial with the central axis of the first opening 250 (i.e., coaxial with the central axis of the (corresponding) hole 15).

[0193] Furthermore, in the open position, the first opening and closing member is at a greater distance from the second end than in the closed position.

[0194] With particular reference to Figure 7 、 8 、15 to 17, the first opening and closing member 300 includes a contact surface 305 that is adapted to make a (tight) seal (under the action of a force pressing it against the seat) with the first annular sealing seat of the first opening 250 when it is in the closed position. This contact surface is coaxial with the central axis of the first opening 250, i.e., coaxial with the central axis X of the (corresponding) hole 15.

[0195] This contact surface 305 contacts the first annular sealing seat at least partially (directly) along at least one closed annular path (e.g., the path is a circumference) only when in the closed position.

[0196] The contact surface includes (i.e., consists of) an annular surface (which forms a closed annular path and thus forms a complete ring), and this annular surface can be convex or frustoconical.

[0197] The convex surface can also be defined as a circular surface without edges, and in particular, it is obtained by rotating a curved section around a rotation axis. This rotation axis is coaxial with the central axis of the first opening 250, i.e., it is coaxial with the central axis of the (corresponding) hole 15.

[0198] In particular, such a bent section includes a first end that is closer to the second end of the valve body 205 than the second end of the section itself. Additionally, the second end is radially farther from the axis of rotation than the first end. Furthermore, the bent section includes a single concavity, i.e., it is defined by a single radius of curvature, and its concavity faces the axis of rotation.

[0199] In the illustrated embodiment, the convex surface (i.e., the contact surface) consists of a spherical sector.

[0200] Regarding the frustoconical surface, it is defined as the outer lateral surface of a frustum of a cone that lies between the two bases of the frustum of the cone.

[0201] The first opening and closing member includes a first face facing the first opening and the first annular seal seat, which provides the contact surface, and includes an opposite second face on which a receiving seat for the end of the elastic element is formed, preferably an annular recess, as will be described below.

[0202] In the illustrated embodiment, the shape of the opening and closing member is generally a disc-shaped body, formed, for example, by plastic deformation, which provides the first face and the second face, as well as the corresponding contact surface and the receiving seat for the elastic element.

[0203] The valve assembly includes an elastic element, for example in the form of a helical spring 310, which exerts a force on the first opening and closing member in a direction to hold the opening and closing member in the closed position (e.g., by holding one end thereof on the second face of the opening and closing member). When the force exerted by the pressurized fluid in the first pipe on the first opening and closing member (first face) exceeds the sum of the force exerted by the elastic element on the opening and closing member (second face) and the force exerted by the pressurized fluid located downstream (with respect to the flow direction from suction to discharge along the pump) of the first opening on the opening and closing member, the first opening and closing member moves to the open position, and fluid can enter the delivery channel.

[0204] The elastic element is held in position by being (e.g., removably) fixed to a (sleeve) cage portion 315 of the valve body 205, such that the elastic element is substantially positioned between a part of the cage portion and the first opening and closing member. The cage portion includes passage holes for the liquid.

[0205] The valve assembly includes a second (rigid) opening and closing member 320 that is movable between a closed position and an open position. In the closed position, the second opening and closing member 320 tightly blocks the (only) second opening 280 of the second pipe 270. In the open position, the second opening and closing member 320 is spaced apart from the second opening of the first pipe and allows flow through the first opening.

[0206] The valve assembly does not include any opening and closing members other than the first opening and closing member and the second opening and closing member.

[0207] In particular, when the valve assembly is inserted into the pump, in the closed position, the second conduit is isolated from the pumping chamber, i.e., the pumping chamber is isolated from the suction passage, and in the open position, the pumped fluid can flow from the suction passage to the pumping chamber through the second opening 280.

[0208] Between the open position and the closed position, the opening and closing member moves along a substantially straight sliding axis that is coaxial with the central axis of the second opening 280 (i.e., coaxial with the central axis of the (corresponding) hole 15).

[0209] Furthermore, in the open position, the second opening and closing member is at a greater distance from the first end than in the closed position.

[0210] Both the first opening and closing member and the second opening and closing member are located outside the valve body.

[0211] The second opening and closing member 320 includes a corresponding contact surface 325 that is adapted to make a (tight) seal with the second annular seal seat of the second opening 280 when it is in the closed position (under the action of a force that presses it against the seat). This contact surface is coaxial with the central axis of the second opening 280, i.e., coaxial with the central axis X of the (corresponding) hole 15.

[0212] This contact surface of the second opening and closing member contacts the first annular seal seat at least partially (directly) along at least one closed annular path (e.g., the path is a circumference) only in the closed position.

[0213] As in the case of the contact surface of the first opening and closing member, the contact surface of the second opening and closing member includes (i.e., consists of) an annular surface (which forms a closed annular path and thus forms a complete ring), and this annular surface can be convex or frustoconical.

[0214] The convex surface can also be defined as a circular surface without edges, and in particular, it is obtained by rotating a curved line segment around a rotation axis. This rotation axis is coaxial with the central axis of the second opening 280, i.e., it is coaxial with the central axis X of the (corresponding) hole 15.

[0215] In particular, this curved line segment includes a first end that is closer to the valve body 205 than the second end of the segment itself. Additionally, the second end is radially farther from the rotation axis than the first end. Furthermore, the curved line segment includes a single concavity, i.e., it is defined by a single radius of curvature, and its concavity faces the rotation axis.

[0216] In the illustrated embodiment, the convex surface (i.e., the contact surface) consists of a spherical sector.

[0217] The second opening and closing member includes a first face facing the first opening and the first annular seal seat, which provides a contact surface, and includes an opposite second face on which a receiving seat for the end of the elastic element is formed, preferably an annular recess, as will be described below.

[0218] In the illustrated embodiment, the opening and closing member is generally in the shape of a disc-shaped body, for example formed by plastic deformation, which provides the first face and the second face, as well as the corresponding contact surface and the receiving seat for the elastic element.

[0219] The valve assembly includes an elastic element, for example in the form of a helical spring 330, which exerts a force on the second opening and closing member 320 in a direction to hold the opening and closing member in the closed position (for example by holding one end thereof on the second face of the opening and closing member). When the force exerted by the pressurized fluid in the second conduit on the second opening and closing member (first face) exceeds the sum of the force exerted by the elastic element on the second opening and closing member (second face) and the force exerted by the pressurized fluid downstream (relative to the flow direction from suction to delivery along the pump) of the second opening in the second conduit on the second opening and closing member, the second opening and closing member moves to the open position, and fluid can flow from the delivery passage to the suction chamber.

[0220] The elastic element is held in position by being (for example removably) fixed to a (sleeve) cage portion 335 of the valve body 205, such that the elastic element is substantially disposed between a part of the cage portion and the second opening and closing member. The cage portion includes holes for the passage of liquid.

[0221] For the two opening and closing members, when the corresponding annular seal seats are frustoconical, the contact surface is preferably convex rather than frustoconical. If the annular seal seats are convex or circular edges, the contact surface can be convex or frustoconical.

[0222] To prevent the fluid to be pumped or the fluid being pumped from entering between the valve body 205 and the hole 15 and / or the blind cavity 175, the valve assembly includes a plurality of annular (static) sealing washers, which are received in corresponding annular grooves in the side surface of the valve body 205 and held on the hole 15 and / or the blind cavity 175.

[0223] In particular, the valve assemblies 200, 200' include a first annular sealing washer 340, which is received in an annular groove and contacts the blind cavity, in particular contacts the side surface 178, to form a tight seal between the first section 230 of the side surface of the valve body and the blind cavity (i.e., the side surface 178).

[0224] The valve assembly further includes a second annular sealing gasket 345, which is received in an annular groove and contacts the corresponding hole 15, particularly the surface 17. More specifically, the annular groove for receiving the second annular sealing gasket 345 is formed in a portion of the side surface of the valve body between the first opening (i.e., a plurality of first openings) of the second pipe and the abutting surface 220. Therefore, the pumped fluid cannot leak into the gap between the valve body and the hole, and thus cannot penetrate between the cover and the surface of the contact cover of the head.

[0225] In addition, in combination with the third annular gasket 350, the second gasket prevents the pressurized fluid from entering the second pipe from the pumping chamber and thus entering the suction passage.

[0226] The third annular gasket 350 contacts the corresponding hole 15, particularly the surface 17. Specifically, the annular groove for receiving the third annular sealing gasket is formed in a portion of the side surface of the valve body between the first opening (i.e., a plurality of first openings) of the second pipe and the abutting surface 225.

[0227] Unlike Figure 17 the embodiment of the valve assembly 200”, in the embodiments of the valve assemblies 200, 200’, the valve assembly may include tubular sheaths 360, 360’ (straight, e.g., cylindrical), and the tubular sheath 360 extends from the second end of the valve body, i.e., from the outer peripheral edge of the second surface of the second end (close to the side surface of the valve body), around the opening of the pipe, i.e., around the second opening 255 of the first pipe 245, in a direction away from the first end, particularly without interruption. The tubular sheath 360 can also be said to extend from the second end, particularly from the second surface, as a continuation of the side surface of the valve body, for example, as a continuation of the third section 240 of the side surface.

[0228] The purpose of the tubular sheath 360 is to protect the head (particularly the head made of polymer material) from the pressure generated in the pumping chamber, so it is made of metal, preferably a metal such as brass or stainless steel. Although the head of the pump in the example is made of polymer material, the same consideration can still be made when the head is made of metal with an elastic modulus and fatigue strength such that the integrity of the pump cannot be guaranteed under the designed operating pressure. In addition, if there is a cover, as shown in the embodiment, and the cover houses a part of the valve assembly and at least a part of the delivery passage, the cover must be made of metal, or the inner side of the delivery passage must be lined with a sheath made of metal.

[0229] In addition to these considerations, it should be noted that it is not strictly required to apply the tubular sheath only in the case of a head made of polymeric material or any other material that is not sufficiently resistant to the pressure involved. The tubular sheath can also be applied to a head made of a material that is not sufficiently resistant to the working pressure to protect the head and extend its service life, taking into account that the cost of replacing the valve assembly is lower compared to the entire head.

[0230] In the illustrated embodiment, the tubular sheaths 360, 360' are made in one piece with the (entire) valve body 205, but it is not excluded that in an alternative embodiment not shown, the tubular sheath can be welded to the valve body, in particular to its second face, or the tubular sheath can be fixed to the valve body (at the second end) in a removable manner, for example by means of a threaded connection. In particular, in the case of a threaded connection, the sheath can include a threaded surface that is adapted to be threadedly connected to a corresponding threaded surface formed at the second opening.

[0231] The tubular sheaths 360, 360' include a (single) first end and an opposite (single) second end, the first end being the end that directly originates from the second end of the valve body 205, where the first end and the second end are spaced apart along the central axis of the valve body, i.e., along the central axis of the second opening 255 (when the valve assembly is inserted into the pump, then it is also the central axis of the hole 15). In addition, the tubular sheath extends around an axis that is coaxial with at least one of the above-mentioned central axes, and the first end and the second end are spaced apart along this axis.

[0232] The tubular sheaths 360, 360' have a constant cross-section (relative to the central axis) from the first end to the second end.

[0233] For example, the tubular sheaths 360, 360' are shaped as straight bodies that have a constant cross-section (relative to the central axis) extending from their first end to their second end.

[0234] When the valve assemblies 200, 200' are inserted into the pump, the tubular sheath is, for example, completely contained within the volume of the hole 15. However, as will be made clearer later, if the high-pressure gasket 60 is located in the crankcase, or the low-pressure gasket is accommodated within the tubular body, the tubular sheath can extend into the crankcase. In principle, the extension of the tubular sheath is such that its second end is close to the high-pressure gasket 60, for example preferably in sealing contact, preventing the liquid in the pumping chamber from contacting the hole 15. In the illustrated embodiment, the tubular sheath extends to the first face of the head (regardless of whether the second end is located within the cylinder head or protrudes into the crankcase).

[0235] The tubular sheaths 360, 360' include an internal tubular surface 365, which is, for example, cylindrical and parallel to the central axis of the valve body, i.e., parallel to the central axis of the second opening 255, i.e., parallel to the central axis of the hole 15. Preferably, when the valve assembly is inserted into the pump, the internal tubular surface is also coaxial with these axes.

[0236] The surface 365 is located radially (with respect to the central axis) more externally relative to the second opening 255, i.e., it extends from a portion or an edge of the second face that surrounds and is external to the second opening. In this way, the internal volume of the tubular sheath is in fluid communication with the second opening. In particular, the surface 365 is located radially more externally relative to all the second openings 255, i.e., it extends from a portion or an edge of the second face that surrounds the portion or surface of the second face where all the second openings forming the first conduit are located and is external to that portion or surface. In this way, the internal volume of the tubular sheath itself is in fluid communication with all the second openings.

[0237] The surface 365 is also located more radially externally relative to the second opening of the second conduit. It is also more radially external than the cage portion that holds the second opening and closing member, so that such a cage portion can be inserted into the tubular body and fixed to the valve body during the assembly and maintenance steps.

[0238] The tubular sheath 360 further includes an external tubular surface 370. For example, the external tubular surface 370 has the same shape as the hole 15, in particular the same shape as the surface 19, and is substantially the same size, so that the external tubular surface 370 fits into the hole 15, i.e., into the surface 19, with a measurement or with a small clearance.

[0239] Thus, in the illustrated embodiment, the external tubular surface is cylindrical and coaxial with the internal tubular surface 365.

[0240] The external tubular surface 370 is, in the illustrated embodiment, substantially like a continuation of the side surface of the valve body in the direction away from the first end of the valve body, for example, like a continuation of the third section 240 of the side surface.

[0241] For example, the third section 240 and the external tubular surface 370 have the same diameter.

[0242] The tubular sheaths 360, 360' further include an annular surface 375. The annular surface 375 is, for example, flat and transverse (perpendicular) to the internal tubular surface 365 and the external tubular surface 370. The annular surface 375 connects the tubular surfaces and substantially defines the limit of the tubular sheath extending in the direction away from the first end, and thus substantially defines the second end of the tubular body.

[0243] The tubular sheaths 360, 360', i.e., their internal tubular surfaces 365, define the internal volume of the tubular sheaths, which is in fluid communication (directly, always directly) with the opening, i.e., with the second opening 255 of the first conduit 245. This internal volume at least includes a part of the volume of the pumping chamber.

[0244] The cross-sectional area (i.e., diameter) of the internal tubular surface 365 is greater than the cross-sectional area (i.e., diameter) of the piston 45.

[0245] In use, the piston 45 is at least partially contained within the internal volume of the tubular sheaths 360, 360' with (sufficient) clearance. In fact, there is an annular gap of non-zero thickness and length between the internal tubular surface 365 and the piston 45.

[0246] The distance between the surface 365 and the surface 370 defines the thickness of the tubular sheath.

[0247] The tubular sheaths 360, 360' extend from the second end away from the first end along the axis of the valve body or the axis of the second opening of the first conduit or the axis of the hole 15 to an annular sealing gasket that sealingly surrounds a part of the piston that slides through the seal. In particular, the tubular sheath extends to the first annular sealing gasket 60 (in direct contact therewith) such that the gasket 60 sealingly contacts the tubular sheath, i.e., it sealingly contacts the internal tubular surface 365 (to prevent the fluid in the pumping chamber from contacting the hole 15).

[0248] Specifically, this contact is formed such that the internal volume of the tubular body is closed at one end by a fluid seal formed by the contact between the first annular sealing gasket 60 and the contact between the gasket 60 and the piston 45.

[0249] For example, this is achieved by sealingly inserting (by elastic deformation) the gasket 60 into the inner cavity of the tubular body.

[0250] Preferably, the gasket 60 sealingly contacts the internal tubular surface 365 along a closed annular path transverse to the central axis.

[0251] In particular, the gasket 60 is inserted into the internal volume of the tubular sheath and is sealingly assembled on a part of the internal tubular surface 365. For example, the outer annular lip 70 sealingly contacts the said part of the internal tubular surface. In addition, the annular lip 70 is received in the annular gap formed between the internal tubular surface and the piston in use.

[0252] The resulting construction allows the inner cavity to be isolated from the rest of the volume of the hole 15, for example, it isolates the pumping chamber from the rest of the volume of the hole 15. In other words, the pumping chamber is thus at least partially (or completely) defined by the second end of the valve body, the tubular sheath, the gasket 60, the piston, the first conduit 245, the first opening and closing member, and the second opening and closing member (when the opening and closing member is in the closed position).

[0253] Although not shown, in embodiments not shown, it is not excluded that the tubular body may include an annular groove formed in the inner tubular surface 365 and serving as a seat for partially receiving the gasket 60.

[0254] Between the gasket 60 and the second end (i.e., the second face) of the valve body, a (rigid) tubular spacer 400 is inserted, adapted to prevent the piston 45 from moving the gasket towards the second end of the valve body during its stroke.

[0255] The tubular spacer 400 includes a first longitudinal end that (directly) contacts the second face of the valve body and a relative second longitudinal end that contacts the gasket 60 (e.g., through the insertion of a push ring 405).

[0256] The tubular spacer is completely contained within the inner volume of the tubular sheath and, for example, includes a (cylindrical) inner tubular surface 410 and an opposite (cylindrical) outer tubular surface that contacts the inner tubular surface 365.

[0257] The inner 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, for example, is more external with respect to the second opening 280 of the second conduit and more internal with respect to the second opening 255 of the first conduit, i.e., with respect to the plurality of second openings 255 of the first conduit.

[0258] When the surface 410 is also more internal radially with respect to the second opening 255, at least one groove or notch 415 is formed in the tubular spacer, which extends from the inner tubular surface towards the outer tubular surface, enabling fluid communication between the second opening of the first conduit 255 and the inner volume (i.e., with the pumping chamber). The groove or notch 415 extends at least from the middle part (between the first end and the second end) of the tubular spacer to the first end of the tubular spacer itself, thus forming an opening at this end at the second opening 255.

[0259] In particular, since the first conduit 245 has a plurality of second openings 255, the spacer includes a plurality of grooves or notches 415, each groove or notch 415 being located at a respective second opening 255.

[0260] To align the tubular spacer with the valve body, i.e., to align the groove or notch 415 with the opening 255 (or to align the groove or notch 415 with the corresponding opening), the valve assembly includes 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 includes a pin 500 that can be inserted into a hole formed in the second end of the valve body and that projects from the hole so that it can also be inserted into a hole formed in the first end of the tubular spacer.

[0261] The tubular spacer is shaped such that the piston can pass through. Specifically, the cross-section of the internal tubular surface is such that the piston 45 can slide within the internal volume defined by the internal tubular surface with a clearance. Further, the cross-section is such that the second opening and closing member is obstructed and, for example, is greater than the cage portion of the second elastic element in the radial direction.

[0262] The pump, i.e., the valve assembly, may include an annular body 420, 420' (rigid and made / manufactured as a single-piece body different from the valve body and the tubular sheath), in which a through-hole 421 is formed that is in direct fluid communication with the internal volume of the tubular sheath (i.e., with the pumping chamber). Thus, the through-hole is coaxial with the central axis of the valve body and is adapted to be traversed by the piston 45 (during its movement between top dead center and bottom dead center).

[0263] A seat for receiving a low-pressure gasket 80 (located between a first face and a second face) is formed in the through-hole 421. The shape of the receiving seat is similar to an annular groove into which the low-pressure gasket 80 is inserted and held therein to prevent the gasket 80 from being dragged and moved (along the central axis) by the piston 45.

[0264] The low-pressure gasket is arranged such that an outer annular lip 90 forms a tight seal with one surface of the annular groove.

[0265] The annular body 420, 420' includes a discharge channel 424 that is adapted to put the suction channel in communication with the volume contained between the piston, the high-pressure gasket, and the low-pressure gasket so that any pressurized fluid leaking from the high-pressure gasket can be discharged under suction pressure.

[0266] Further, to prevent leakage, the annular body 420, 420' or the portion of the head located at the annular body includes a groove for receiving a static seal gasket 422.

[0267] The annular body 420, 420' includes a side surface 423 that is fitted (i.e., with a small clearance) into the portion of the through-hole 130 located between the abutment surface 140 and the face of the crankcase in contact with the head.

[0268] In an embodiment of the valve assembly 200, only the high-pressure gasket 60 is part of the valve assembly, i.e., although the high-pressure gasket is not part of the valve assembly, it can be removed from the head together with the rest of the valve assembly.

[0269] In this case, the annular body includes a first face 425 (e.g., annular, planar and transverse (i.e., perpendicular) to the central axis of the valve body), and the second end of the tubular sheath and a gasket 60 (i.e., the ring portion 75 of the gasket 60) rest on the first face 425 (the gasket 60 is thereby held in place between the tubular spacer and the annular body (clamped between the tubular spacer and the annular body)).

[0270] The annular body further includes a second face 430 (e.g., annular, planar and transverse (i.e., perpendicular) to the central axis of the valve body), and the second face 430 rests on the annular shoulder surface 140 such that when the cover is fixed to the crankcase, the valve body, the tubular sheath and the annular body 420 are clamped between the cover and the crankcase, i.e., clamped between the annular shoulder surface 140 and the surface 176.

[0271] In this embodiment 420, a seat for the gasket 422 is formed in the annular body.

[0272] In Figure 11 and Figure 16 In an embodiment of the valve assembly 200', both the high-pressure gasket and the low-pressure gasket are part of the valve assembly and are thus removed from the head together with the rest of the valve assembly.

[0273] In this case, the annular body 420' is shaped as a retaining body fixed to the second end of the tubular sheath, and the retaining body is fixed, for example, removably, preferably threadedly connected to the tubular sheath. In particular, in the illustrated embodiment, the tubular sheath includes a threaded portion 435 (at the second end), and a corresponding threaded portion of the annular body 420' is threadedly connected to the threaded portion 435.

[0274] In this embodiment 420', the gasket seat 422 is preferably formed in a portion of the head at the annular body 420', e.g., formed in the surface 19.

[0275] The annular body 420' has a first face 425 (e.g., annular, flat and transverse (i.e., perpendicular) to the central axis of the valve body), and the gasket 60 (i.e., the ring portion 75 of the gasket 60) rests on the first face 425 (thereby the gasket 60 is held in place between the tubular spacer and the first face of the annular body 420' (clamped between them), i.e., clamped between the tubular spacer and the first face of the annular body 420').

[0276] The annular body 420’ further includes a second face 430 (e.g., annular, flat and transverse (i.e., perpendicular) to the central axis of the valve body), and the second face 430 rests on the annular shoulder surface 140.

[0277] Although only an embodiment of the valve assembly 420’ is shown, in an unshown embodiment where there is only the gasket 6 and no gasket 80 within the internal volume of the tubular sheath, there can still be a retaining body. In such an embodiment, the retaining body is in direct contact with the gasket 60 such that the gasket 60 is held in place (clamped between them) between the retaining body and the tubular spacer.

[0278] In Figures 1 to 16 In all embodiments of the valve assembly shown, the tubular sheath 360 is preferably a one-piece body, e.g., integral with the valve body 205, but this does not exclude the possibility that it can be formed by several continuously interlocked or threaded-together sections, where the seal between one section and another is ensured by a static annular gasket.

[0279] The first opening 250 of the first pipe (and its annular seal seat 260), the first opening and closing member, and the first elastic element together basically constitute a one-way conveying valve.

[0280] The second opening 280 of the second pipe (and the associated annular seal seat 285), the second opening and closing member, and the second elastic element together basically constitute a one-way conveying valve.

[0281] Although only one embodiment of the valve assembly having a tubular sheath and including both the first pipe and the second pipe is shown in the figure, it does not exclude the valve assembly from including a tubular sheath and not including the second pipe. In this case, the valve assembly will be a one-way conveying valve with a tubular sheath.

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

[0283] The piston 45, i.e., each piston 45, under the action of the drive mechanism contained in the crankcase, moves between the bottom dead center position and the top dead center position along its sliding axis in the hole 15. At the bottom dead center position, the volume of the pumping chamber is the largest, and at the top dead center position, the volume of the pumping chamber is the smallest.

[0284] When the piston moves from the top dead center to the bottom dead center, a pressure drop occurs in the pump chamber, which causes the first opening and closing member (conveying opening and closing member) to close, and when the pressure is lower than the pressure in the suction passage, causes the second opening and closing member (suction opening and closing member) to open, thereby allowing fluid to be sucked from the conveying passage into the pumping chamber. Specifically, the fluid enters the first opening 275, i.e., enters a plurality of first openings 275, passes through the first pipe, and leaves the first pipe through the second opening 280.

[0285] After reaching the lower bottom dead center, the piston moves towards the upper dead center, thereby compressing the fluid and thus increasing the pressure in the pumping chamber. Due to the increase in pressure, the second opening and closing member moves to the closed position, and the first opening and closing member moves to the open position, thereby allowing the pumped fluid to reach the delivery passage. Specifically, under the thrust of the piston, the fluid flows into the second openings of the first pipe, i.e., the plurality of second openings of the first pipe, and from there passes through the first opening 250 to reach the delivery passage.

[0286] In the presence of the tubular sheath, before reaching the plurality of second openings of the first pipe, the fluid will pass through the grooves or cuts in the tubular spacer under the thrust of the piston.

[0287] The tubular sheath allows the pressurized fluid to be accommodated and guided, preventing it from contacting the inner surface of the hole 15.

[0288] When the pump needs maintenance or assembly, the user only needs to unscrew the screw fixing the cover to the crankcase, remove the cover, and due to the shape of the hole and the shape of the side surface of the valve body, the user only needs to pull the valve assembly to remove it from the hole. For example, in Figures 3 to 10 the embodiment, by doing so, the high-pressure gasket is removed, and in Figures 11 to 16 the embodiment, the high-pressure gasket and the low-pressure gasket are also removed.

[0289] It should be noted that in this disclosure, rigidity means not being significantly deformed under the normal working load it bears. In other words, a rigid element does not perform its designed function through its own deformation.

[0290] An elastic element is defined as such a body whose shape causes it to undergo (only) elastic deformation under the working load it bears, and thus also (or only) performs its function through its own elastic deformation. It must be pointed out that elastic deformation should be understood as being opposite to plastic deformation.

[0291] In this example, the gasket elastically deforms to fit a certain surface, thereby creating a possible tight seal.

[0292] Furthermore, it must be pointed out that a one-piece body refers to a body obtained by a single casting or injection curing of (a single) material in a mold, and possibly, subsequent processing of the cured body by removing material.

[0293] When we refer to a spherical sector, it must be pointed out that this geometric element is an annular surface that forms a closed loop and is defined as a part of the spherical surface directly inserted between two mutually parallel planes that both intersect the spherical surface.

[0294] The term "with a small clearance" in the measurement means that the elements characterized by this connection can slide relative to each other without special effort and without significant tilting relative to the sliding direction. On the other hand, if there is a large clearance, the elements may tilt significantly relative to the advancing direction.

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

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

[0297] In practice, the materials used, as well as the accompanying shapes and dimensions, may vary according to requirements, but this does not thereby deviate from the scope of protection of the following claims.

Claims

1. A valve assembly (200, 200’, 200”) for automatic suction and delivery, which can be removably inserted into a high-pressure pump (1, 1’), the valve assembly comprising: - A valve body (205) provided with a first end (210) and an opposite second end (215), - A first pipe (245) extending from a first opening (250) formed in the first end of the valve body to a second opening (255) formed in the valve body, - A second pipe (270) formed in the valve body and not intersecting with the first pipe, the second pipe being provided with a first opening (275) formed in the valve body and a second opening (280) formed in the second end of the valve body, - A first opening and closing member (300) movable at least between a closed position and an open position, in the closed position, the first opening and closing member (300) tightly blocks the first opening (250) of the first pipe, in the open position, the first opening and closing member (300) is spaced apart from the first opening (250) of the first pipe and allows fluid to flow through the first opening, - A second opening and closing member (320) movable at least between a closed position and an open position, in the closed position, the second opening and closing member (320) tightly blocks the second opening (280) of the second pipe, in the open position, the second opening and closing member (320) is spaced apart from the second opening (280) of the second pipe and allows fluid to flow through the second opening, and wherein the valve body (205) provides an annular sealing seat (260) for the first opening and closing member and an annular sealing seat (285) for the second opening and closing member at the first opening of the first pipe and the second opening of the second pipe respectively, wherein the first opening and closing member and the second opening and closing member each include corresponding contact surfaces (305, 325), when the opening and closing member is in the closed position, the contact surfaces contact at least partially with the corresponding annular seats along at least one closed annular path, and the contact surfaces (305, 325) each include a corresponding convex annular surface or a frustum-conical surface.

2. The valve assembly (200, 200’, 200”) according to claim 1, wherein, The convex annular surface is a rotating surface obtained by rotating a curved section around a rotation axis.

3. The valve assembly (200, 200’, 200”) according to claim 1 or 2, wherein, The contact surface is a spherical sector.

4. The valve assembly (200, 200', 200") according to any one of the preceding claims, wherein, The first opening (250) of the first pipe is formed in the central part of the first end (210), and the second opening (280) of the second pipe is formed in the central part of the second end (215).

5. The valve assembly (200, 200’, 200”) according to claim 4, wherein, The first opening (250) of the first pipe and the second opening (280) of the second pipe are coaxial.

6. The valve assembly (200, 200’, 200”) according to any one of the preceding claims, wherein, The second pipe includes a first section (290) extending from the first opening (275) of the second pipe towards the central region of the valve body, and a second section (295) extending from the second opening (280) of the second pipe and formed as a blind hole transverse to and intersecting with the first section.

7. The valve assembly (200, 200’, 200”) according to any one of the preceding claims, comprising a plurality of first conduits (245), the plurality of first conduits (245) each extending from the first opening (250) formed in the first end of the valve body to a respective plurality of second openings (255) formed in the second end of the valve body, and wherein the second opening (280) of the second conduit (270) is formed in the second end of the valve body at a central position relative to the plurality of second openings (255) of the plurality of first conduits.

8. The valve assembly (200, 200’, 200”) according to the preceding claim, wherein, The first conduit (245) comprises a first common section (261) extending from the first opening (250) as a blind hole and a plurality of second sections extending from the first section, each second section being independent of the other second sections (265, 266), and each second section forming a respective second opening (255) of the plurality of second openings in the second end of the valve body.

9. The valve assembly (200, 200', 200") according to the preceding claim, wherein, The second sections (265, 266) of the first conduit are eccentric to the second section (295) of the second conduit and each is provided with at least one portion (265) parallel to the second section of the second conduit.

10. The valve assembly (200, 200’, 200”) according to claim 1, comprising a tubular sheath (360, 360’), the tubular sheath (360, 360’) extending from the second end (215) around the second openings (255) of the first conduits in a direction away from the first end (210).

11. The valve assembly (200, 200’, 200”) according to claim 10, wherein, A sealing washer (60) is inserted in a portion of the tubular sheath (360, 360’) remote from the second end (215) of the valve body, the sealing washer (60) being adapted to sealingly surround the piston (45).

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