Improved plunger for plunger valve

Abstract

The invention relates to a slidable plunger (1) for a plunger valve (21). The plunger (1) comprises at least one annular land (3, 4, 5, 6, 7, 8) surrounding the plunger core (9), wherein the at least one annular land (4, 5, 6, 7) comprises at least one notch (11) on at least one side surface (12) of the at least one annular land (4, 5, 6, 7). The at least one recess (11) is substantially triangular. The triangular shape of the at least one notch (11) may have an opening angle (alpha, beta) of at least 90 DEG near the plunger core (9). In addition or alternatively, a plurality of recesses (11) can be arranged along the circumference of at least one side surface (12) of the at least one annular land (4, 5, 6, 7), with recesses (11) being provided along a majority of the circumferential extent of the at least one side surface (12) of the at least one annular land (4, 5, 6, 7).

Description

Technical Field

[0001] The present invention relates to a slidable plunger for a plunger valve, the plunger comprising at least one annular land surrounding a plunger core, wherein the at least one annular land comprises at least one recess on at least one side surface of the at least one annular land. The present invention also relates to a plunger valve comprising such a slidable plunger. Background Art

[0002] For various reasons, fluidic devices must establish and block fluid connections in a controlled manner. Specifically, fluidic connections must be established and blocked based on input control signals. Furthermore, fluids must be directed to different fluid ports in a controlled manner.

[0003] In order to achieve this controlled fluid distribution, there are various valve designs. One special design is the so-called plunger valve. The plunger valve includes a housing with a hole. In the hole, a plunger is slidably arranged so that it can slide in the hole of the housing. The movement of the plunger can be achieved by various actuators, such as using fluid pressure, electromagnetic force, mechanical springs, etc. In addition, the slidable plunger also has one or more annular lands around the central part of the plunger, the so-called plunger core. In addition, the housing also has some grooves around the hole for connecting to the fluid input and output ports of the plunger valve. Usually, the groove is designed as an annular groove, similar to a collar-like design. With the appropriate design of the plunger valve and the housing, different fluid input ports and output ports can be connected or separated by appropriately moving and positioning the plunger in the hole of the housing.

[0004] Such plunger valves are well known in the prior art and are frequently used in a variety of applications. Furthermore, various improvements have been proposed depending on the specific application. While such plunger valves certainly function satisfactorily, they can sometimes have drawbacks, depending on the specific application.

[0005] For example, one such drawback is that a certain amount of force is required to move the plunger within the housing, particularly in the presence of relatively high fluid pressure, and particularly when such relatively high fluid pressure is present only at certain fluid ports while other fluid ports have significantly lower pressures.

[0006] Another possible issue is operating performance, especially the fluid flow rate related to the position of the plunger valve. Sometimes, a certain opening and closing performance is required, especially a relatively "smooth" and gradual switching performance.

[0007] Given the widespread use of plunger valves, it is not surprising that a wide variety of plunger valve designs have been proposed to address the aforementioned problems (and others).

[0008] For example, U.S. Patent No. 4,862,920 proposes a plunger for a plunger valve. The plunger includes multiple annular lands with multiple partially tapered recesses. These recesses are arc-shaped (circular arc segments). This allows the flow rate through the plunger valve to gradually increase with plunger displacement.

[0009] European Patent EP0581156B proposes another solution, which proposes a hydraulic directional control valve with a piston plunger valve structure. The plunger is provided with an annular land surrounding the plunger. Depending on the design, two or four small control recesses are provided in the side surface of the annular land. The circumferential length of the recess opening is relatively small compared to the total circumference of the corresponding side surface of the annular land. As a result, a large portion of the side surface of the corresponding annular land is free of control recesses. By adopting this design, improved characteristics of fluid flow rate change with plunger displacement can be achieved.

[0010] Although the plunger valves known from the prior art do function in a satisfactory manner, such plunger valves still have drawbacks, at least with regard to certain areas of application and / or certain operating characteristics. Summary of the Invention

[0011] It is therefore an object of the present invention to propose a slidable plunger for a plunger valve which is improved with respect to the slidable plungers for plunger valves known in the prior art.

[0012] Another object of the present invention is to provide a plunger valve with a slidable plunger and a housing with a hole for the plunger, which is improved compared to the plunger valves with a slidable plunger and a housing with a hole for the plunger known in the prior art.

[0013] The presently proposed slidable plunger for a plunger valve and the plunger valve do achieve these objectives.

[0014] A slidable plunger for a plunger valve is proposed, wherein the plunger comprises at least one annular land surrounding the plunger, and the at least one annular land comprises at least one recess on at least one side surface of the at least one annular land, the at least one recess being substantially triangular in shape, such that the triangular shape of the at least one recess has an opening angle of at least 90° close to the plunger core. Typically, the slidable plunger is of slightly elongated design, and / or its axis is typically much longer than in other directions. This "main" direction can be referred to as the axial direction of the slidable plunger. The cross-sectional shape (i.e., a cross-section along a plane substantially perpendicular to the axial direction of the slidable plunger) can have a variety of shapes, in particular polygonal (n=3, 4, 5, 6, 7, 8, 9 or 10, where n is the number of sides; possibly including sharp and / or rounded corners), circular or elliptical. It should be noted that the cross-sectional shape can vary along the length of the slidable plunger, in particular along the axial direction of the slidable plunger. More specifically, variations may occur between different parts of the slidable plunger, in particular between different parts of the annular land and / or the plunger core of the slidable plunger. The cross-sectional dimensions of the plunger core along the axial direction of the slidable plunger may be somewhat similar or even (substantially) identical. However, the dimensions of the plunger core may also vary to a certain extent, in particular between different parts of the plunger core. For example, such differences may be due to pressure compensation considerations, which are known in the prior art. What has been said about the different parts of the plunger core and / or the plunger also applies to at least one annular land of the slidable plunger, at least in a similar manner. When speaking of different "parts" (in particular parts of the plunger core and / or parts of the annular land), it is to be understood that different parts are separated from each other by at least one intermediate device (in particular in the axial direction). For example: two different parts of the plunger core can be defined by an intermediate annular land (or vice versa). Typically, the cross-sectional dimension of at least one annular land (in particular, the diameter if the cross-section is circular) is greater than the cross-sectional dimension of at least one portion of the plunger core, preferably greater than the cross-sectional dimension of at least one adjacent portion of the plunger core, and more preferably greater than the cross-sectional dimension of (substantially) all portions of the plunger core. According to a typical design of the slidable plunger, the cross-sectional dimension of (substantially) all annular lands is greater than the cross-sectional dimension of (substantially) all portions of the plunger core. The side surface of at least one annular land can be defined as a portion of the slidable plunger that connects the at least one annular land to (at least one) portion of the plunger core adjacent thereto. Additionally or alternatively, the side surface can be defined as any portion of the slidable plunger whose surface is not (substantially) parallel to the axial direction of the slidable plunger. However, typically, there is a large angle between the corresponding surface and the axial direction of the slidable plunger, for example an angle greater than (and possibly including) 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70° or 80°.More preferably, the corresponding surface is arranged substantially perpendicular (substantially at 90°) to the axial direction of the slidable plunger. The definition of the angle is based on the appropriate tangential direction of the corresponding surface portion and the axial direction of the slidable plunger. When considering the normal to the corresponding surface portion, the corresponding relationship is γ = 90° - α or δ = 90° - β. Thus, a perpendicular surface portion refers to a surface portion whose normal is parallel to the axial direction of the slidable plunger. It should be noted that the angle between the corresponding surface portion and the axial direction can vary across the corresponding side surface of the at least one annular land, in particular depending on the radial distance from the center (centerline) of the slidable plunger. Thus, tapered external angles, as well as so-called rounded external angles, can be provided. For the sake of completeness, it should be noted, in addition or alternatively, that the angle can also vary along the circumference of at least one side surface of the at least one annular land. Thus, at least one side surface can be provided with a kind of inverted taper, the taper angle of which varies around the circumference of the at least one annular land. It should be noted that typically an annular land has two side surfaces.

[0015] The recess on at least one side surface of at least one annular land can be considered a material depression / void / cutout in the corresponding side surface of the at least one annular land. Its shape (currently essentially triangular) can be considered in cross-section, with the corresponding plane being arranged such that one of its tangential directions is essentially parallel to the axial direction of the slidable plunger, and / or its normal is essentially parallel to the radial direction of the slidable plunger, and / or its normal is essentially perpendicular to the axial direction of the slidable plunger. Additionally or alternatively, the recess can exhibit a cross-sectional shape that is visible to an external observer when viewing the slidable plunger, particularly when viewing the slidable plunger in a direction essentially perpendicular to the axial direction (the observer must rotate the plunger in its axial direction for a suitable viewing position). It is proposed to design and arrange the at least one recess to be essentially triangular. The term "triangular" should particularly take into account "missing material" (material removal) of the at least one annular land. Of course, the "triangular" shape can also have rounded corners. For example, such "rounded corners" may be a result of the relevant production process. For example, if a milling cutter is used to machine the side surface of a plunger valve / at least one annular land / at least one recess, the triangular tip pointing toward the annular land and / or away from its bottom line will necessarily have a certain rounding, the radius of which is generally comparable to the diameter of the milling head. Therefore, a rounding with a radius of less than 5 mm, 4 mm, 3 mm, 2 mm, 1 mm, 0.75 mm, 0.5 mm, or 0.25 mm should be considered a so-called "sharp tip" for the purposes of the present invention. An additional or alternative definition of a triangular shape with rounded corners could be that the length of the straight segment of the triangle (particularly the portion defining the cutout, typically forming two straight lines) is greater than the length of the circular arc segment (the apex of the triangle, "pointing" toward the annular land). "Longer" can mean that the length of the straight segment is at least 1, 1.5, 2, 2.5, 3, 4, 5, 7.5, or 10 times the length of the circular arc segment. Preliminary experiments have indeed surprisingly shown that the straight segments of the recess, in particular the substantially triangular shape, contribute to reducing the fluid forces acting on the slidable plunger. Therefore, such a notch has a surprisingly advantageous effect compared to a notch without straight sections (or only very short straight sections) (e.g. parabolic, circular arc segment shaped, etc.). It should be noted that the more or less rounded corners (even if they can be regarded as "sharp tips" in the context of the present invention) usually appear in the direction pointing to the annular land. In fact, as mentioned above, such more or less rounded corners are basically unavoidable due to processing reasons. However, such more or less rounded corners can also appear in the direction pointing to the core of the plunger, or as an alternative. In addition, it is possible and may even be advantageous to achieve a "really sharp" tip, especially in the direction pointing to the core of the plunger of the slidable plunger. The triangle can be arranged (substantially) symmetrically with respect to the axial direction of the slidable plunger (this is usually the preferred design); however, it is also possible to arrange the triangle in an asymmetrical manner with respect to the axial direction of the slidable plunger.As proposed, the angle of at least one notch is at least 90° near the plunger core. For the sake of completeness, it should be noted that this does not necessarily exclude the possibility that the transition from the notch sidewall to the plunger core may have a rounded shape closest to the plunger core due to manufacturing issues. In this final adjacent section, the notch angle may or may not be greater than the currently proposed 90° (or other angles, as proposed later). Therefore, a flat triangular shape with an obtuse apex is adopted. With the proposed design, when the slidable plunger is used in the target machine, the operating force generated in the axial direction of the slidable plunger due to the (static and / or dynamic) fluid pressure (fluid force) applied to the various input and output ports of the plunger valve can be surprisingly reduced. Consequently, the corresponding actuator can be designed with smaller dimensions and / or lower operating force. This, in turn, can achieve faster operating speeds, energy savings when operating the plunger valve, lower noise levels, and a smaller actuator, all of which are beneficial. Furthermore, the proposed design can even extend the service life of the plunger valve and / or actuator.

[0016] In addition to or in lieu of the aforementioned, the present invention provides a slidable plunger for a plunger valve, the plunger comprising at least one annular land surrounding a plunger core, the at least one annular land including at least one recess in at least one side surface of the at least one annular land, the at least one recess being substantially triangular in shape, such that a plurality of recesses are arranged along the circumference of the at least one side surface of the at least one annular land, wherein the recess is provided along a majority of the circumference of the at least one side surface of the at least one annular land. While in principle only one recess can be provided on the at least one side surface of the at least one annular land (forming a triangle, wherein a single side of the triangular recess extends to approximately half the circumference of the annular land, at least when a substantially equiangular triangle is used as the recess), it is preferred to use a plurality of recesses. In general (this also applies to the entire disclosure), two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, or more recesses can be used on the at least one side surface of the at least one annular land. It should be noted that the number of recesses on a side surface of at least one annular land may vary depending on the side surface and / or side surface orientation and / or control surface formed by the annular land within the housing of the plunger valve, and / or may depend on the annular land in question. In other words, only a relatively small circumferential extent of at least one side surface of at least one annular land is formed by a so-called undisturbed / unmodified / unchanged / ungrooved / unmachined side surface (i.e., a surface portion that is substantially perpendicular to the axial direction of the plunger valve; in this context, an inclination resulting from the tapering / rounding of the corresponding portion of the surface side may or may not be present). When using the present aspect of the present invention (whether or not it is combined with the aforementioned aspects of the present invention, particularly with respect to the angle of the at least one recess), it is also possible to reduce the forces that may be generated in the axial direction of the slidable plunger when different pressure levels are applied to different fluid ports, thereby reducing the actuation force and, therefore, shortening the actuation time.

[0017] In this context, it should be noted that triangular recesses should be provided along a substantial portion of the circumferential extent of at least one side surface of at least one annular land. However, this does not exclude the possibility that the corresponding at least one side surface may include additional recesses having a shape other than triangular. Nevertheless, it is preferred if (substantially) all recesses are triangular.

[0018] According to a preferred embodiment of the present invention, the slidable plunger is designed such that the triangular shape of the at least one recess exhibits an angle of at least 90° along a majority of the radial extent of the at least one recess—preferably at least along (substantially) the entire radial extent of the at least one recess. As previously described, this may or may not include the final proximity segment, i.e., the transition segment from the recess sidewall to the plunger core at the final proximity of the plunger core. Specifically, if such a final proximity segment is excluded, the angle of at least 90° (or other lower limit angle) along the entire radial extent of the at least one recess may be present. However, a certain degree of constriction may occur at the so-called waistline of the recess. Furthermore, the angle of the at least one recess may gradually increase along the radial direction ("height") of the recess. The angular increments may be between 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, and 45° (lower limit) and 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, and 50° (upper limit). When designing the slidable plunger according to the present invention, a particularly favorable fluid flow pattern around the slidable plunger and, ultimately, the plunger valve can be achieved. This, in turn, can result in particularly low fluid forces in the axial direction of the slidable plunger. When referring to the majority of the radial extent of the at least one recess, in particular, at least 50%, 60%, 70%, 80%, 90%, or 95% of its entire radial extent (the "height" of the recess) can be envisioned. In this context, it should be noted that, regardless of whether the majority of the radial extent of the at least one recess exhibits an angle of at least 90°, the angle may or may not vary along the radial direction of the at least one recess (or, in other words, along the height of the respective recess). However, preferably, the angle of at least slightly increases as it extends radially outward. Specifically, a lower angle α (or radially inner angle α, core-adjacent angle α, etc.) and an upper angle β (or radially outer angle β, outer surface angle β, circumferential angle β, housing-adjacent angle β, etc.) may radially limit at least one of the at least one recess. Preliminary experiments have shown that this design can achieve a favorable fluid flow pattern. Once again, it is important to note that the opening angle (including its radial variation) of two, more, or (substantially) all of the recesses can be the same, or at least some of the recesses can be different. As mentioned above, the angle α can be measured with or without the final adjacent section, that is, the transition section from the recess sidewall to the plunger core in the final adjacent area of the plunger core.

[0019] Specifically, it is proposed that the slidable plunger be designed to have an opening angle of at least 100°, preferably at least 110°, and more preferably at least 120°. It should be noted that different angles may also be employed, such as angles greater than (and possibly including) 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, or 150°. Furthermore, it should be noted that if multiple notches are used (even if the angle values used differ from those described above), the angles of at least two or more of the notches may be the same. This may relate to notches provided on the same side surface of at least one annular land and / or different side surfaces of at least one annular land and / or side surfaces of different annular lands (wherein, viewed in the axial direction of the slidable plunger, the side surfaces with the notches face the same direction and / or different directions; preferably, these side surfaces are at least partially opposite each other), and / or on both side surfaces of at least one annular land. However, it has generally been found to be preferred for the recesses provided on one side surface of the annular land to have substantially the same shape, in particular the same opening angle. Preliminary experiments have shown that these angles are particularly effective in reducing the (fluid-induced) forces that may arise in the axial direction due to different pressure levels at different fluid inlet / outlet ports of the slidable plunger / plunger valve.

[0020] If it is proposed to modify a slidable plunger of a plunger valve in such a way that the recess is provided along at least 60%, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95% of the circumferential extent of at least one side surface of at least one annular land. However, according to the present proposal, when referring to the majority of the circumferential extent of at least one side surface, this may also mean that at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% (lower limit) to 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100% (upper limit) of the corresponding circumferential extent of the respective side surface is occupied by the recess (single or preferably multiple recesses). Preliminary experimental embodiments of such a slidable plunger / plunger valve have demonstrated that it has extremely low fluid-acting axial forces.

[0021] Furthermore, it is proposed that the slidable plunger for the plunger valve according to the present disclosure be designed such that the plunger includes a plurality of annular banks along the plunger core. In this way, the fluid flow through the final plunger valve can be increased simply and efficiently. Furthermore, it is generally particularly easy to achieve a pressure compensation effect with such a design, i.e. the necessary actuating force becomes relatively independent of the various fluid pressures applied to the various fluid flow ports. Furthermore, by providing a plurality of annular banks along the plunger core, certain control tasks can be achieved. Taking a directional valve as an example, the fluid input port is selectively connected to the first or second fluid output port (wherein an intermediate position where the fluid input port is simultaneously connected to the first and second fluid output ports may or may not exist). As previously mentioned, if a plurality of annular banks are provided along the plunger core (axial extent), the cross-sectional dimensions and / or cross-sectional shapes of the respective annular banks may be (substantially) the same or (substantially) different, at least for some of the annular banks.

[0022] It is further proposed to design the slidable plunger so that at least one annular land is provided with a recess only on one side surface thereof. Preliminary tests have shown that this design is sufficient to significantly reduce the axial forces generated by the different pressure levels at the different fluid input and output ports. At the same time, the machining effort (and thus the costs) can be reduced, since fewer recesses need to be machined. Another advantage is that the slidable plunger (and ultimately the plunger valve) can be made more compact if this design is adopted. For the sake of completeness, it should be pointed out that the side surface with the recess should generally point towards the fluid chamber, which is expected to be subjected to particularly high fluid flow pressures in the assembled state of the plunger valve.

[0023] Furthermore, it is proposed that the recesses of at least two annular lands be arranged in different axial directions. This allows for a versatile and compact slidable plunger / plunger valve. Specifically, by adopting this approach, the recesses of adjacent annular lands can be directed toward each other. Consequently, these recesses can point toward the same fluid chamber (at least in conventional plunger valve designs), thus reducing the axial force exerted by the fluid on the slidable plunger in the corresponding fluid chamber, even under extremely high fluid pressures.

[0024] Furthermore, it is proposed to design the slidable plunger such that at least one annular land substantially does not include any notches, wherein the at least one substantially notched annular land is positioned axially outward of the slidable plunger. Preliminary experiments have shown that such a substantially notched side surface does not significantly adversely affect the axial force exerted on the slidable plunger, at least in certain locations. Even if some force is generated, this trade-off, which is generally negligible, is easily offset by the savings in manufacturing costs and the reduction in size of the slidable plunger, and thus, the size of the resulting plunger valve. While the substantially notched annular land can be positioned anywhere, it is generally advantageous to position it (at least) axially outward of the slidable plunger because, for example, a corresponding flange can serve as an actuating surface for causing the slidable plunger to perform a defined actuating movement in the axial direction. Thus, for a typical fluid dispensing valve design, a high-pressure fluid input can be directed in a controlled manner to one of two low-pressure fluid output ports.

[0025] According to another proposal, at least one of the annular lands is radially chamfered and / or inversely tapered and / or rounded. This allows for a design that provides the fluid control characteristics often required by the market. In particular, a smoother fluid flow transition depending on the axial position / displacement of the slidable plunger can be achieved, which is often a desired characteristic.

[0026] It is further proposed to design a plunger valve having a slidable plunger and a housing having a hole for the slidable plunger, wherein the slidable plunger is a slidable plunger designed according to the present disclosure. In this way, the plunger valve can at least similarly exhibit the same features and characteristics as the currently proposed slidable plunger. In addition, the corresponding plunger valve can also be modified at least similarly as described with respect to the slidable plunger, thereby producing at least similar features and advantages.

[0027] Furthermore, it is proposed to design a plunger valve as a fluid distribution valve. This valve is designed in such a way that, depending on the axial position / displacement of the plunger, a fluid input port is selectively connected to a first or second fluid output port. Intermediate positions, in which the fluid input port is simultaneously fluidically connected to the first and second fluid output ports, may or may not be achieved. Similarly, within a certain range of axial positions of the plunger, no fluid connection may be established between the fluid input port and the fluid output port. The plunger valve can be actively or passively controlled, depending on the specific application.

[0028] For the sake of completeness, it should be noted that "fluid" in this article can be a gas, a liquid, or a mixture thereof. Furthermore, "fluid" may refer to a supercritical fluid, in which the distinction between gaseous and liquid states may no longer exist. Furthermore, the fluid may also contain a certain degree of solid particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further advantages, features and objects of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1 : A schematic top view of a possible embodiment of a slidable plunger according to the present invention;

[0031] Figure 2 : Schematic top view showing a possible embodiment of a slidable plunger according to the present invention in different rotational positions;

[0032] Figure 3 : A partial cross-sectional view of a possible embodiment of a plunger valve, including Figure 1 Possible embodiments of a slidable plunger;

[0033] Figure 4 : A cross-sectional view of a slidable plunger of a possible embodiment of a slidable plunger on a plane perpendicular to the axial direction. DETAILED DESCRIPTION

[0034] Figure 1 A top view of a slidable plunger 1 is shown which is particularly suitable for use in combination with a suitable housing 20 to form a fluid dispensing valve 21 (see Figure 3 ).

[0035] The embodiment of the slidable plunger 1 shown here is designed to have a substantially circular cross section, wherein the cross section is arranged along a plane perpendicular to a centerline 2 of the slidable plunger 1, wherein the centerline 2 extends along the axial direction of the slidable plunger 1. Figure 1 As shown, in the embodiment of the slidable plunger 1 shown here, there are six annular lands 3, 4, 5, 6, 7, 8, which protrude from the central plunger core 9. Specifically, at the axially outer portion of the slidable plunger 1 (i.e., adjacent to the two axial ends of the slidable plunger 1), there are annular lands 3 and 8 without recesses. They mainly serve to seal against the (axial) exterior. However, this function (and possibly an additional valve-type function) depends on the design and dimensions of the housing 20, which will become clearer later, especially in conjunction with the Figure 3 However, the notched annular lands 4, 5, 6, 7 are provided in the middle or “inside” of the slidable plunger 1 and serve as opening / closing control surfaces for opening or blocking the flow of fluid through the corresponding control opening of the plunger valve 21 depending on the actual position / displacement of the slidable plunger 1 within the housing 20 of the plunger valve 21.

[0036] from Figure 1It can be seen that all of the "inner" notched annular lands 4, 5, 6, 7 exhibit a substantially vertical sidewall 10 on one of their respective sidewalls 10, 12. The vertical sidewall 10 is substantially free of any notches 11 and substantially free of any inverted tapers 16, except for a small rounded transition between the vertical sidewall 10 and the corresponding portion of the plunger core 9, which is primarily due to manufacturing process reasons. However, it should be noted that the inverted taper could also be provided on the radially inner side (transition to the plunger core 9) or on the radially outer side (similar to the rounding 16 of the notch side surface 12 with the notch 11 and the inverted taper / rounding 16; see description below).

[0037] On the respective other side surface 12 opposite the vertical side wall 10, the "inner" recessed annular lands 4, 5, 6, 7 present a series of continuous triangular recesses 11 (see also Figure 2 ), these recesses 11 are arranged in sequence along the circumferential direction of the recessed side walls 12 of the corresponding recessed annular banks 4, 5, 6, 7.

[0038] Each individual recess 11 has a substantially triangular cross-section, which, at an appropriate position therein, includes a tangent extending parallel to the centerline 2 of the slidable plunger 1 (the appropriate arrangement of the cross-section, in particular with respect to its "rotational" position in the circumferential direction, will be apparent to a person skilled in the art). Each individual recess 11 has a peripheral plane 13 that limits the clearance of the recess 11 toward the plunger core 9. In the embodiment currently shown, the respective peripheral plane 13 is actually a plane, so that the plunger core 9 is flat in this area and thus deviates slightly from the circular arc curvature of the basic shape of the slidable plunger 1. However, the plane 13 may also follow the original curvature of the so-called "undisturbed" plunger core 9, thus deviating to a certain extent from the "true planar shape" of the plane 13. The lower opening angle α of the peripheral plane 13 is currently selected to be α=100° (or the radial inner opening angle α, the core axis adjacent opening angle α, etc.).

[0039] In the radial direction 14 away from the centerline 2 and outward, the gap of the recess 11 gradually expands, so that at the outer edge 15 of the corresponding recess 11, the upper opening angle β (or radial outer opening angle β, outer surface opening angle β, circumferential opening angle β, shell adjacent opening angle β, etc.) of β=125° is reached. Therefore, when the recessed side wall 12 of one of the recessed annular lands 4, 5, 6, 7 is observed in the axial direction, each recess 11 has a groove-like appearance (at Figure 4 The transition from the lower opening angle α at the peripheral plane 13 to the upper opening angle β at the outer edge 15 is currently non-linear and in particular exhibits a step 34. However, different types of transitions can also be used.

[0040] Along the outer edge 15 of the triangular recess 11, a radius 16 is provided on the recessed sidewall 12 of each recessed annular land 4, 5, 6, 7 (currently at an angle of 50° relative to the axial centerline 2). The radius 16 transitions to a circumferential surface 17 of the recessed annular land 4, 5, 6, 7. These circumferential surfaces 17 generally define the outer diameter of the slidable plunger 1. In the embodiment shown, the outer diameter of the recessed annular lands 4, 5, 6, 7 is the same as the outer diameter of the non-recessed "outer" annular lands 3, 8. For simplicity, the circumferential surfaces 17 are designated by the same reference numeral 17.

[0041] Figure 2 Shown in different top views (i.e. different rotation positions) Figure 1 In other words, with the slidable plunger 1 Figure 1 Compared to the position shown in FIG. 1 , the slidable plunger 1 is rotated about its centerline 2 by a certain angle. Specifically, it can be seen that, in the circumferential direction of all the notched sidewalls 12 of all the notched annular lands 4, 5, 6, 7, one notch 11 immediately follows the next adjacent notch 11. Consequently, the notched sidewalls 12 do not present a vertical surface portion (a surface portion lying in a plane perpendicular to the axial centerline 2), particularly between two adjacent notches 11.

[0042] from Figure 1 、 Figure 2 or Figure 3 It can further be seen that the tip 18 of each triangular recess 11 is not formed as a point, but rather as a rounded shape 32. This is due to the fact that the manufacturing process of the slidable plunger 1 utilizes a rotating milling head. The diameter of the tip 18 is currently the same as the diameter of the milling head. However, it can be clearly seen from the figure that the triangular recess 11 forms a straight leg 19 over a large part of the total length of the corresponding edge. In particular, the length of the straight leg 19 of a single recess 11 is longer than the length of the circular arc section 32 of the tip 18 of the corresponding triangular recess 11. In particular, the length of the straight leg 19 is 2, 3, 4, 5, 7.5 or 10 times longer than the length of the circular arc section 18.

[0043] Furthermore, in the embodiment shown here, the limiting angle of the triangular recess 11 towards the plunger core (away from the annular lands 4, 5, 6, 7) does present a sharp corner 33, at least in some parts of its radial extent 14. Of course, this can also be designed differently.

[0044] Figure 3 It is shown that the slidable plunger 1 is arranged in the hole 27 of the housing 20, thereby forming the plunger valve 21. Currently, the plunger valve 21 is designed as a fluid dispensing valve.

[0045] Generally, a slidable plunger 1 can be axially moved within a bore 27 within the housing 20 of the plunger valve 21. Depending on the axial position (displacement) of the slidable plunger 1 within the housing 20, different fluid connections can be established in a controlled manner while other fluid connections are interrupted. The slidable plunger 1 can be moved using any type of actuator known in the art. For simplicity, the actuator is not shown.

[0046] The housing 20 of the plunger valve 21 has a plurality of annular fluid chambers 22 , 23 , 24 , 25 , 26 surrounding the slidable plunger 1 (or more precisely, surrounding the hole 27 in which the plunger 1 is located).

[0047] Annular fluid chambers 22 and 26 are interconnected via fluid conduit 28, which in turn is fluidly connected to a first fluid output port 29. Annular fluid chambers 23 and 25 are fluidly connected to a fluid input port 30, while annular fluid conduit 24 is fluidly connected to a second fluid output port 31.

[0048] Depending on the axial position of the plunger 1 within the housing 20, the fluid input port 29 can be fluidly connected to the first fluid output port 28 or the second fluid output port 31. Such a fluid dispensing valve 21 is known in the art and will not be described in detail for the sake of brevity.

[0049] In order to demonstrate the advantages of the slidable plunger 1 and the plunger valve 21 according to the present invention, Table 1 shows the axial force of the fluid acting on the slidable plunger 1 at different strokes (expressed as a percentage of the maximum stroke) and different opening angles of the triangular recess 11, wherein appropriate combinations of the lower opening angle α and the upper opening angle β are shown. The applied pressure at the fluid input port 30 is 60 bar, wherein the pressure drop on the corresponding control surface of the plunger valve 21 is 5 bar. Therefore, at Figure 3 In the position shown, i.e., where a fluid connection is established between the fluid input port 30 and the first fluid output port 29, the pressure level at the first fluid output port 29 is 55 bar. As is apparent from Table 1, the slidable plunger 21 according to the present invention generates significantly less force at greater strokes than the plunger of the prior art. At smaller strokes, the forces are at least comparable.

[0050]

[0051] Figure 4 Shown according to Figure 1 and Figure 2 The slidable plunger 1 of the embodiment shown is arranged along Figure 1 A cross-sectional view of plane IV is shown. This view is intended to clarify the geometrical design of the slidable plunger 1 to a person skilled in the art.

[0052] In particular, more details of the recess 11 can be seen. Specifically, the rounded tip 32 and the sharp tip 33 of the triangular recess 11 can be seen (only in the radially outermost portion in the presently shown view). Furthermore, the gradually decreasing opening angle from the lower peripheral plane 13 (lower opening angle α) toward the outer edge 15 (upper opening angle β) can be seen, with a distinct step 34 in the change in opening angle being visible. However, even in the presently shown embodiment, the opening angle increases monotonically outward in the radial direction 14.

[0053] It should be noted that one or more features of the presently disclosed detailed embodiments may be used in combination with the general description of the disclosure.

Claims

1. A slidable plunger (1) for a plunger valve (21), the plunger (1) comprising at least one annular land (3, 4, 5, 6, 7, 8) surrounding a plunger core (9), the at least one annular land (4, 5, 6, 7) comprising at least one recess (11) in at least one side surface (12) of the at least one annular land (4, 5, 6, 7), the at least one recess (11) being substantially triangular in shape, It is characterized by: The triangular shape of the at least one recess (11) has an opening angle (α, β) of at least 90° near the plunger core (9).

2. A slidable plunger (1) for a plunger valve (21) according to the preamble of claim 1, in particular according to claim 1, characterized in that A plurality of notches (11) are provided along the circumference of at least one side surface (12) of the at least one annular bank (4, 5, 6, 7), wherein the notches (11) are provided along most of the circumferential extent of the at least one side surface (12) of the at least one annular bank (4, 5, 6, 7).

3. The slidable plunger (1) for a plunger valve (21) according to claim 1 or claim 2, in particular according to claim 1, characterized in that: The triangular shape of the at least one recess (11) has an opening angle (α, β) of at least 90° along most of the radial extent (14) of the at least one recess (11), preferably at least along substantially the entire radial extent (14) of the at least one recess (11).

4. A slidable plunger (1) for a plunger valve (21) according to any one of the preceding claims, characterized in that The opening angle (α, β) is at least 100°, preferably at least 110°, and more preferably at least 120°.

5. The slidable plunger (1) for a plunger valve (21) according to any one of the preceding claims, in particular according to any one of claims 2 to 4, characterized in that At least 60%, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95% of the circumferential extent of at least one side surface (12) of the at least one annular land (4, 5, 6, 7) is provided with a notch.

6. A slidable plunger (1) for a plunger valve (21) according to any one of the preceding claims, characterized in that The slidable plunger (1) comprises a plurality of annular lands (3, 4, 5, 6, 7, 8) along the plunger core (9).

7. A slidable plunger (1) for a plunger valve (21) according to any one of the preceding claims, characterized in that The at least one annular bank (4, 5, 6, 7) is provided with a notch (11) only on one side surface (12) thereof.

8. The slidable plunger (1) for a plunger valve (21) according to claim 6 or 7, characterized in that: The recesses (11) of at least two annular lands (4, 5, 6, 7) are arranged along different axial directions.

9. A slidable plunger (1) for a plunger valve (21), characterized in that At least one annular land (3, 8) is substantially notch-free, wherein the at least one substantially notch-free annular land (3, 8) is arranged axially outside the slidable plunger (9).

10. A slidable plunger (1) for a plunger valve (21), characterized in that At least one annular land (3, 4, 5, 6, 7, 8) is chamfered and / or tapered and / or rounded (16) in a radial direction (14).

11. A plunger valve (21) comprising a slidable plunger (1) and a housing (20) having a hole (27) for the slidable plunger (1), characterized in that: The slidable plunger (1) is a slidable plunger (1) according to any one of the preceding claims.

12. The plunger valve (21) according to claim 11, characterized in that The plunger valve (21) is designed and arranged as a fluid dispensing valve (21).

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