High pressure nozzle

Abstract

The invention relates to a high-pressure nozzle (1) comprising a longitudinal housing (11, 12) having an internal passage (15) therein, a nozzle head support shaft (20) being partially rotatably arranged in the internal passage (15), a rotating nozzle head (30) being attached to the nozzle head support shaft (20) and arranged outside the housing (11, 12), and an axial bearing seat (40) being located within the housing (11, 12) and comprising an axial bearing surface (41) facing an end surface (22) of the nozzle head support shaft (20). The axial bearing surface (41) and the support shaft end surface (22) cooperate to form an axial bearing for the nozzle head support shaft (20) during use, and the axial bearing seat (40) comprises an axial bore (42) in the axial bearing surface that is concentrically aligned with the rotational axis of the nozzle.

Description

TECHNICAL FIELD

[0001] The present invention relates to a high-pressure nozzle for cleaning a surface, for example a high-pressure nozzle for cleaning the inner surface of a pipe or tube, such as a pipe or tube of a heat exchanger. The present invention further relates to an axial pressure compensator for such a high-pressure nozzle. BACKGROUND

[0002] WO 2019 / 098831 A1 discloses a high-pressure nozzle comprising a longitudinal housing, a nozzle head support shaft arranged partly rotatable within the housing, and a rotating nozzle head attached to the nozzle head support shaft and arranged outside the housing. The nozzle further comprises an axial pressure compensator with an axial bearing surface facing an end surface of the nozzle head support shaft.

[0003] The axial bearing surface is to form a stop surface for the nozzle head support shaft and is configured to form an axial bearing for the nozzle head support shaft when in mechanical contact between the two. During use, the axial bearing surface and the support shaft end surface can be in direct contact with each other, for example in mechanical contact with each other. Alternatively or additionally, a liquid can be provided between them to provide a fluid bearing film, so that the axial bearing surface and the nozzle head support shaft are in indirect contact with each other.

[0004] Hence, such known nozzle can provide a theoretical point contact between the axial bearing surface and the support shaft end surface. However, in practice, this contact will become planar, with a surface area larger than just one point. This planar contact will affect the relative velocity between the axial bearing surface and the nozzle head support shaft when rotating between them, which does not equal zero.

[0005] This provides the disadvantage that a relatively large amount of friction is generated between the stationary part of the nozzle, for example the axial bearing surface, and the rotating part of the nozzle, for example the nozzle head support shaft. This friction will slow down the rotation, which is disadvantageous. The friction will further cause wear, which shortens the life of the nozzle. SUMMARY

[0006] The present invention provides a high-pressure nozzle. The present invention further provides an axial pressure compensator for a high-pressure nozzle.

[0007] The high-pressure nozzle according to the present invention comprises a longitudinal housing comprising a liquid inlet end and a liquid outlet end opposite the liquid inlet end and comprising an internal passage extending from the liquid inlet end to the liquid outlet end. During use of the nozzle, the liquid inlet end can be connected to a pressure source, from which pressurized liquid, for example water with a pressure level of up to 3000 bar, can be supplied to the nozzle. Hence, liquid enters the nozzle at the liquid inlet end and flows through the internal passage towards the liquid outlet end of the housing.

[0008] The nozzle further comprises a nozzle head support shaft which is partially rotatably arranged in the internal channel and which comprises a liquid channel in fluid communication with the internal channel, and a rotating nozzle head which is attached to the nozzle head support shaft and which is arranged outside the housing. The fluid connection between the liquid channel in the nozzle head support shaft and the internal channel of the housing can provide that the pressurized liquid in the nozzle will flow through the liquid channel in the nozzle head support shaft during use.

[0009] The rotating nozzle head and the nozzle head support shaft are configured to rotate relative to the longitudinal housing around a longitudinal rotation axis to provide a rotational spray of liquid ejected from the rotating nozzle head. Thus, liquid can be ejected from one or more ejection channels in the rotating nozzle head which are aligned in a direction which is offset relative to the longitudinal rotation axis. This offset can provide a rotational moment which can influence the rotation of the nozzle head and the nozzle head support shaft relative to the housing.

[0010] The nozzle further comprises an axial bearing seat which is located within the housing and which comprises an axial bearing surface facing an end surface of the nozzle head support shaft. The axial bearing seat is located in the vicinity of the nozzle head support shaft, for example upstream in the direction of liquid flow in the internal channel of the nozzle. Thus, the axial bearing seat faces an upstream end surface of the nozzle head support shaft, for example an end surface which is located in the housing and which is positioned opposite the end where the nozzle head is attached.

[0011] The axial bearing surface and the support shaft end surface cooperate with each other during use, for example are in contact with each other, to form an axial bearing for the nozzle head support shaft. This axial bearing is configured to prevent displacement of the nozzle head support shaft along the longitudinal rotation axis. Otherwise, such displacement can be influenced by reaction forces generated by liquid ejected from the nozzle head. These reaction forces can be aligned in a direction opposite to the direction of liquid flow in the internal channel, for example from the liquid outlet end towards the liquid inlet end. The support shaft end surface is in direct contact with the axial bearing surface, i.e. where the support shaft end surface abuts the axial bearing surface, or indirect contact, i.e. where a thin, for example lubricating, fluid film, for example a water film, can be present between the support shaft end surface and the axial bearing surface. The axial bearing surface forms a stop for the nozzle head support shaft to prevent displacement of the nozzle head support shaft.

[0012] According to the invention, the axial bearing seat comprises an axial bore in the axial bearing surface which is concentrically aligned with the rotation axis. The axial bore is centrally located in the axial bearing surface and provides that the support shaft end surface and the axial bearing seat do not contact at a central portion of the axial bearing surface, for example at or in the vicinity of the rotation axis.

[0013] Since the support shaft end surface and the axial bearing surface cannot contact each other at the rotational axis, it is no longer possible to have a theoretical center point contact or a flat plane contact between them. Instead, the contact between the support shaft end surface and the axial bearing surface is distributed over a larger surface, for example, over the remaining portion of the axial bearing surface surrounding the central bore.

[0014] Due to this larger contact area, the pressure resulting from the contact force by which the nozzle head support shaft is forced against the axial bearing seat is reduced. Thus, the high-pressure nozzle according to the present invention is less prone to wear, which means that the lifetime of the high-pressure nozzle is also increased. Furthermore, the reduced wear can provide a reduction in heat generated by the relative rotation between the nozzle head support shaft and the axial bearing seat, which contributes to the reliability and lifetime of the high-pressure nozzle.

[0015] In embodiments, the axial bearing surface has a shape that matches the shape of the support shaft end surface. This matching shape can provide that the axial bearing surface and the support shaft end surface can be in uniform contact with each other over the entire surface of the axial bearing seat, instead of one or more local contact points.

[0016] This distributed contact can provide a uniform distribution of the contact force between the axial bearing surface and the nozzle head support shaft, which further improves the relative rotation between the housing and the nozzle head support shaft by further reducing wear.

[0017] In further embodiments, the axial bearing surface has a concave shape and the support shaft end surface has a matching convex shape. The radius of curvature of the concave axial bearing surface can be similar or, preferably, identical to the radius of curvature of the convex support shaft end surface. Thus, the axial bearing surface and the support shaft end surface can fit closely to each other to provide a uniformly distributed contact between them.

[0018] In alternative embodiments, the axial bearing surface has a flat shape and the support shaft end surface has a matching flat shape. The flat shape of the axial bearing surface and the support shaft end surface can provide that the axial bearing surface and the support shaft end surface can fit closely to each other to provide a uniformly distributed contact between them.

[0019] In embodiments of the nozzle, the axial bearing seat is fluidically connected to the internal channel. Thus, during use of the nozzle, at least a portion of the liquid in the internal channel of the nozzle can flow to the axial bearing seat, instead of only to the nozzle head.

[0020] According to the embodiment, the nozzle is configured to establish a fluid film between the axial bearing surface and the support shaft end surface to form an axial fluid bearing for the nozzle head support shaft. During use of the nozzle, liquid can flow between the axial bearing surface and the support shaft end surface, for example due to an overpressure at the axial bearing seat. The fluid film is configured such that the axial bearing seat and the nozzle head support shaft are no longer in direct mechanical contact with each other. Instead, the fluid film between them will provide an indirect contact between the axial bearing seat and the nozzle head support shaft, for example via the liquid film between them.

[0021] During use of the nozzle, the fluid film can provide a further reduced amount of friction and wear between the nozzle head support shaft and the axial bearing seat. Thus, for similar pressure levels of liquid supplied into the nozzle, the rotational speed of the nozzle head support shaft and the nozzle head can be higher. Furthermore, the wear can be further reduced.

[0022] As an alternative, the fluid connection of the axial bearing seat can be omitted, resulting in a dry contact between the nozzle head support shaft and the axial bearing seat. This dry axial bearing can still provide a reduced wear compared to known nozzles, for example as explained above with respect to the axial bore of the axial bearing seat.

[0023] In embodiments, the axial bearing seat comprises two or more grooves in the axial bearing surface, which are equally spaced around the rotational axis. These grooves can provide a fluid connection between the axial bore of the axial bearing seat and the internal channel of the nozzle.

[0024] Thus, liquid can not only flow to the outer contour of the axial bearing seat, but can further flow inward to the axial bore. During use of the nozzle, the fluid film can be utilized along the entire axial bearing surface of the axial bearing seat and not only at the outer contour of the axial bearing seat.

[0025] Since the grooves are equally spaced around the rotational axis, a rotationally symmetric groove pattern can be obtained in the axial bearing surface, so as to facilitate a constant fluid film mass and / or fluid film thickness along the entire rotation and not a varying fluid film mass and / or fluid film thickness along the rotation.

[0026] Thus, a more uniform fluid film can be established between the nozzle head support shaft and the axial bearing seat and not possibly only to the outer contour of the axial bearing seat. This distributed fluid film can provide a further reduced amount of friction and wear of the nozzle.

[0027] Furthermore, the improved fluid film can provide a better cooling of the nozzle so as to compensate for heat generated due to the contact between the nozzle head support shaft and the axial bearing seat upon relative rotation between the nozzle head support shaft and the axial bearing seat.

[0028] In a further embodiment of the nozzle, each of the grooves is aligned in a radial direction, as seen with respect to the rotation axis. Such a radial orientation of the grooves can provide for a length of the grooves (e.g. from the outer profile of the axial bearing seat towards the axial bore) to be as short as possible. This short length can reduce a drop in pressure level between the outer profile of the axial bearing seat and the axial bore.

[0029] Alternatively, the grooves can be aligned in different directions, e.g. only having a component in a radial direction, as seen along the rotation axis, in order to obtain a helical groove pattern for example. Such a helical groove can have advantages e.g. in that the length of the groove is relatively long compared to a relatively short radial straight groove.

[0030] As a further alternative, the nozzle can comprise grooves that are offset with respect to the rotation axis. Thus, the grooves can extend in a direction that is parallel to a radial direction. However, this direction does not intersect the rotation axis, but is spaced a distance from the rotation axis. For example, the grooves can be aligned in line with a tangential direction of the central axial bore in the axial bearing seat.

[0031] In a further embodiment of the nozzle, the grooves comprise a rectangular cross-section. As seen in a plane perpendicular to a longitudinal direction of the grooves, e.g. in the radial direction in the above-described embodiment, the grooves have a shape of a rectangle, e.g. a shape of a square.

[0032] Alternatively, the grooves can comprise a triangular cross-section or a cross-section formed as a half-circle, such as a cross-section having a shape of a half-circle.

[0033] In embodiments in which the axial bearing seat is fluidly connected to the internal channel, the nozzle further comprises at least one discharge hole that is fluidly connected to the axial bearing seat so as to form a fluid connection with the surroundings of the nozzle.

[0034] According to this embodiment, during use of the nozzle, pressurized liquid can not only partially flow from the internal channel towards the axial bearing seat, but can further flow towards the discharge hole. At the discharge hole, the liquid can exit the nozzle towards the surroundings. Thus, an outflow of liquid can be established from the internal channel towards the surroundings of the nozzle. During use of the nozzle, at least a portion of the liquid supplied at the liquid inlet end can flow through the internal channel, back towards the axial bearing seat via the slit between the second housing part and the head end support shaft, and finally towards the surroundings of the nozzle via the discharge hole.

[0035] Thus, during use, the fluid film between the axial bearing surface and the support shaft end surface can be constantly replenished with new liquid. Since the liquid is discharged via the discharge hole, heat can be guided away from the axial bearing towards the surroundings, which can provide for a further improved cooling of the nozzle.

[0036] In the environment surrounding the nozzle, the pressure level is at ambient pressure, while during nozzle use, the liquid pressure in the nozzle's internal channels can be relatively high. Therefore, a pressure drop may occur between the internal channels and the axial support, which could affect the flow of liquid from the internal channels to the axial support.

[0037] In addition, another pressure drop may occur between the axial support and the discharge port, resulting in a slight overpressure at the axial support compared to the ambient pressure level. During nozzle operation, this overpressure can force liquid to flow between the support shaft end surface and the axial support surface, thereby facilitating fluid film formation.

[0038] In one embodiment, the axial support comprises a plastic material. This plastic material may have a relatively low coefficient of friction, for example, when combined with a nozzle head support shaft made of a metallic material (such as stainless steel), which can result in relatively low frictional forces when the nozzle head support shaft rotates.

[0039] For example, plastic materials can be fiber-based self-lubricating plastic materials, such as... X. This self-lubricating plastic material may include components that function as lubricants within the material itself. Therefore, there is no need to provide a separate lubricant or fluid film, as the plastic material itself can act as a lubricant to reduce friction.

[0040] The use of this self-lubricating plastic can be particularly beneficial for dry axial supports, where there is no fluid film between the axial support and the nozzle head support shaft. Although the absence of a fluid film can typically lead to greater friction, the self-lubricating plastic material can provide reduced friction.

[0041] Another advantage of plastic materials is that, due to their relatively low hardness, the metal nozzle head support shaft may wear down in the plastic axial support surface until a smooth and uniform contact is achieved. Once this smooth contact is achieved, the support shaft end surface and the axial support surface can fit tightly together to provide the aforementioned uniformly distributed contact. At this point, the contact between the support shaft end surface and the axial support surface is distributed over a larger surface area, for example, over the remaining portion of the axial support surface surrounding the central hole. Due to this larger contact area, the pressure generated by the contact force forced by the nozzle head support shaft against the axial support seat is reduced. Because of this reduced contact force, the axial support seat may subsequently be less prone to wear.

[0042] In this embodiment, the axial support comprises a metallic material, such as brass. Due to the relatively high thermal conductivity of metallic materials, using such a material can provide improved cooling. Using brass as the material for the axial support can be particularly advantageous because it also has a self-lubricating effect, reducing friction between the axial support surface and the end surface of the support shaft during nozzle head rotation during nozzle use.

[0043] In embodiments of the nozzle, the axial bearing surface comprises a coating. Such a coating can for example be applied to reduce friction between the nozzle head support shaft and the axial bearing seat. Additionally or alternatively, the coating can comprise a relatively large hardness in order to improve wear resistance.

[0044] In embodiments of the nozzle, the support shaft end surface comprises a coating. Such a coating can for example be applied to reduce friction between the nozzle head support shaft and the axial bearing seat. Additionally or alternatively, the coating can comprise a relatively large hardness in order to improve wear resistance.

[0045] The coating can for example comprise tungsten carbide (WC) material, which is applied on the support shaft end surface to abut against the axial bearing surface of the axial bearing seat.

[0046] In embodiments, the axial bearing seat is provided as an insert, which is arranged within the axial bore of the nozzle. Thus, the axial bearing seat is separate from the housing of the nozzle and can therefore be replaced with another axial bearing seat. This can be beneficial when the first axial bearing seat has worn out, while the rest of the nozzle has not yet worn out. By replacing the initial axial bearing seat with a new axial bearing seat, the nozzle can be used again as if it were a brand new nozzle.

[0047] The axial bore in the nozzle can be provided as a blind bore in the housing, which is located in the vicinity of the nozzle head support shaft, as seen along the longitudinal axis of the nozzle. In case the axial bearing seat is provided as an insert in the axial bore of the nozzle, only the insert needs to be accurately machined to form the dimensionally accurate axial bearing seat. Thus, it is not necessary to machine the axial bearing surface within the tight limitations of the nozzle housing. Therefore, the manufacturing of the nozzle according to the present embodiments can be easier and thus less costly.

[0048] As an alternative to the above-mentioned blind bore, the axial bore in the housing can also be a through bore in the housing in order to achieve a direct fluid communication of the axial bore in the axial bearing seat with the liquid inlet end of the housing, so that during use of the nozzle, liquid can flow directly from the liquid inlet end to the axial bearing seat.

[0049] Providing a separate insert can further provide that the axial bearing seat can be made of a different material than the housing of the nozzle. Thus, the nozzle housing can be made of a metallic material, such as stainless steel, while the axial bearing seat can be made of a plastic material, such as a fiber self-lubricating plastic material.

[0050] In another embodiment, the axial bore of the nozzle (e.g. an axial blind bore) can comprise a first bore section having a first bore diameter and a first bore length along the longitudinal axis, and a second bore section having a second bore diameter and a second bore length along the longitudinal axis. The second bore section is located deeper than the first bore section, as seen along the longitudinal axis, e.g. in a direction from the nozzle head support shaft towards the liquid inlet end. The first bore diameter is thus larger than the second bore diameter, and the first bore length is smaller than the second bore length, such that the axial bore comprises a first bore section which is relatively wide and shallow, and a second bore section which is relatively narrow and deep, as seen from the nozzle head support shaft towards the liquid inlet end.

[0051] According to an embodiment, the axial bearing seat comprises a first bearing seat section having a first seat diameter and a first seat length along the longitudinal axis, and a second seat section having a second seat diameter and a second seat length along the longitudinal axis. The first seat diameter substantially corresponds to the first bore diameter, and the second seat diameter substantially corresponds to the second bore diameter. Similarly, the first seat length substantially corresponds to the first bore length, and the second seat length substantially corresponds to the second bore length. The first bearing seat section comprises the axial bearing surface and is located inside the first bore section, and the second bearing seat section is located inside the second bore section, both optionally provided with a mating thread for securing the axial bearing seat in the axial bore.

[0052] This embodiment provides the advantage that the main body of the axial bearing seat (e.g. the second bearing seat section) is relatively narrow, thus involving a relatively small amount of material. However, the axial bearing surface on the first axial bearing seat section is relatively large, enabling a lower contact pressure and thus reduced wear, for the same contact force between the nozzle head support shaft and the axial bearing surface.

[0053] In an embodiment, the nozzle further comprises an axial pressure compensator arranged in the internal passage and configured to substantially compensate an axial pressure of the liquid entering the internal passage at the liquid inlet end of the housing. As the axial pressure is compensated by the axial pressure compensator, the contact force required at the axial bearing to prevent axial movement of the nozzle head support shaft in the housing is greatly reduced. Thus, the total amount of liquid required for cleaning a certain number of pipes is also reduced.

[0054] During use of the nozzle, the axial pressure compensator guides the liquid flowing through the internal passage of the housing, such that the axial force generated by the liquid entering the internal passage from an external pressure source is not transmitted to the nozzle head support shaft. The axial pressure compensator can be designed to transmit the liquid in a radial direction between the housing and the nozzle head support shaft, to prevent the axial pressure from being transmitted from the liquid to the nozzle head support shaft.

[0055] Further, the compensation of the axial force by the axial pressure compensator facilitates the use of different nozzle heads, for example nozzle heads having different exit angles for one or more jet channels provided in the nozzle head. The exit angle of the jet channel can be in the range of 0 degrees to 160 degrees with respect to the rotational axis of the nozzle head. Thus, the same combination of housing, axial pressure compensator and nozzle head support shaft can be used for different types of nozzle heads, including nozzle heads having an angle of less than 90 degrees with respect to the rotational axis and nozzle heads having an angle of more than 90 degrees with respect to the rotational axis of the nozzle head.

[0056] In a further embodiment, the axial bearing seat is arranged within an axial blind hole of the axial pressure compensator. Thus, the axial pressure compensator can be arranged centrally in the housing of the nozzle. The axial bearing seat in turn can be arranged centrally in the axial pressure compensator.

[0057] Thus, the axial bearing seat is separated from the axial pressure compensator and thus can be replaced with another axial bearing seat without the need to replace the axial pressure compensator. This can be beneficial when the first axial bearing seat has worn out, while the axial pressure compensator has not yet worn out. By replacing the initial axial bearing seat with a new axial bearing seat, the nozzle can be used again as if it was a brand new nozzle.

[0058] The axial blind hole in the axial pressure compensator can be provided as a blind hole in the housing, which blind hole is located near the nozzle head support shaft, as seen along the longitudinal axis of the nozzle. During use of the nozzle, liquid supplied into the nozzle at the liquid inlet end of the housing can be guided radially outward by the axial pressure compensator, so that the liquid does not need to pass through the axial bearing seat.

[0059] In case the axial bearing seat is provided as an insert in the axial blind hole of the axial pressure compensator, only the axial bearing seat itself needs to be accurately machined, without the need to machine the axial pressure compensator. Thus, the manufacturing of the nozzle according to the present embodiment can be easier and thus less costly.

[0060] Further, the provision of a separate axial bearing seat can provide that the axial bearing seat can be made of a different material than the axial pressure compensator. Thus, the axial pressure compensator housing can be made of a metallic material, such as stainless steel, while the axial bearing seat can be made of a plastic material, such as a fiber self-lubricating plastic material.

[0061] In an embodiment, the axial pressure compensator is an integral part of the longitudinal housing. The axial pressure compensator can comprise a plurality of liquid guiding channels extending through the housing, wherein an inlet opening of each liquid guiding channel is in fluid communication with the liquid inlet end of the housing, and wherein an outlet opening of each liquid guiding channel is in fluid communication with the liquid channel of the nozzle head support shaft.

[0062] To allow liquid to pass from the liquid inlet end to the nozzle head support shaft during use of the nozzle, the liquid guiding channels can guide the liquid, while axial forces resulting from the liquid pressure of the liquid entering the nozzle at the liquid inlet end are not transmitted to the nozzle head support shaft. Instead, these axial forces are guided through the axial pressure compensator which forms part of the housing.

[0063] The axial pressure compensator can comprise any suitable number of liquid guiding channels, for example 10 to 30 liquid guiding channels, which are preferably equally distributed over the circumference of the axial pressure compensator.

[0064] In alternative embodiments, the axial pressure compensator and the housing can be separate components, such that the axial pressure compensator can be replaced independently of the housing.

[0065] The nozzle can for example comprise a housing having a first housing part and a second housing part, wherein the axial pressure compensator is clamped between the first housing part and the second housing part. By clamping the axial pressure compensator between the first housing part and the second housing part, the relative position of the axial pressure compensator with respect to the housing is guaranteed. The clamping force can also be used to create a circumferential seal between the housing and the axial pressure compensator.

[0066] The invention further provides an axial pressure compensator for a high-pressure nozzle, the high-pressure nozzle comprising an axial bearing seat as described above. The axial pressure compensator is configured to be located within a housing of the nozzle, and the axial bearing seat comprises an axial bearing surface configured to face an end surface of a nozzle head support shaft of the nozzle.

[0067] The axial bearing seat comprises an axial bore in the axial bearing surface that is concentrically aligned with a rotational axis of the nozzle. The axial bore is centrally located in the axial bearing surface and can provide that the support shaft end surface and the axial bearing seat do not contact at a central portion of the axial bearing surface, for example at or near the rotational axis, after being arranged in the nozzle.

[0068] The axial bearing seat of the axial pressure compensator according to the invention can further comprise one or more features of the axial bearing seat described above with respect to embodiments of the high-pressure nozzle according to the invention.

[0069] Since the support shaft end surface and the axial bearing surface cannot contact each other at the rotational axis, it is no longer possible to have a theoretical center point contact or a flat planar contact between them. Instead, the contact between the support shaft end surface and the axial bearing surface is distributed over a larger surface, for example over the remaining portion of the axial bearing surface that surrounds the central bore.

[0070] Due to this larger contact area, the pressure resulting from the contact force of the nozzle head support shaft being forced against the axial bearing seat is reduced.

[0071] Thus, the axial bearing seat of the axial pressure compensator according to the present application is less prone to wear, which means that the lifetime of the axial bearing seat is also increased. Furthermore, the reduced wear can provide a reduction of heat generated by relative rotation between the nozzle head support shaft and the axial bearing seat, which contributes to the reliability and lifetime of the axial bearing seat.

[0072] The axial pressure compensator according to the present application can be further retrofitted in an existing high-pressure nozzle having the axial pressure compensator. This can provide that an existing high-pressure nozzle (which originally did not comprise an axial bearing seat for forming an axial bearing with a nozzle head support shaft of the nozzle) can now be equipped with an axial bearing. Thus, wear of the existing high-pressure nozzle can also be reduced by the axial pressure compensator according to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0073] Further features of the present application will be explained below with reference to the embodiments shown in the drawings, in which:

[0074] Figure 1 schematically depicts an embodiment of a high-pressure nozzle according to the present application;

[0075] Figure 2 schematically depicts a cross-sectional view in a plane along the rotational axis of the nozzle of Figure 1

[0076] Figure 3 depicts an exploded view representation of the cross-section in Figure 2

[0077] Figure 4A depicts an isometric view of the axial bearing seat of the nozzle in Figure 1

[0078] Figure 4B depicts a front view of the axial bearing surface of the axial bearing seat in Figure 4A

[0079] Figure 4C depicts a cross-sectional view of the axial bearing seat along the line G-G in Figure 4B

[0080] Figures 5A-5K schematically depicts various different axial bearing seats.

[0081] Throughout the drawings, same reference numerals are used for corresponding or similarly- functioning parts. DETAILED DESCRIPTION

[0082] Figure 1 ​​​​​An embodiment of a high-pressure nozzle according to the present invention is schematically depicted, the high-pressure nozzle being indicated by reference numeral 1. The nozzle 1 includes a longitudinal housing having a first housing portion 11 and a second housing portion 12. The nozzle 1 further includes a nozzle head support shaft 20 partially rotatably arranged within the housings 11 and 12, and a rotating nozzle head 30 attached to the nozzle head support shaft 20 and arranged outside the housings 11 and 12. According to this embodiment, at least the housings 11 and 12, the nozzle head support shaft 20, and the nozzle head 30 are made of a metallic material, such as stainless steel.

[0083] Figure 2 schematic depiction Figure 1 Cross-sectional view of nozzle 1. Figure 2 The plane is parallel to the longitudinal rotation axis AA inside the housings 11 and 12 of the nozzle head support shaft 20. Figure 2 As can be seen, housings 11 and 12 include a liquid inlet end 13 and a liquid outlet end 14 opposite to the liquid inlet end 13. Nozzle 1 further includes an internal channel 15 extending from the liquid inlet end 13 to the liquid outlet end 14. During use of nozzle 1, the liquid inlet end 13 can be connected to a pressure source through which pressurized liquid can be supplied to nozzle 1. Thus, liquid enters nozzle 1 at the liquid inlet end 13 and flows through the internal channel 15 to the liquid outlet end 14 of housings 11 and 12. At the liquid outlet end 14 of housings 11 and 12, the liquid is then configured to flow into nozzle head support shaft 20.

[0084] The nozzle head support shaft 20 includes a liquid passage 21 that is in fluid communication with an internal passage 15 at a liquid outlet end 14. During use, this fluid communication allows pressurized liquid in the nozzle 1 to flow from the internal passage 15 to the liquid passage 21 in the nozzle head support shaft 20. The rotating nozzle head 30 and the nozzle head support shaft 20 are thus configured to rotate about a rotation axis AA relative to the housings 11, 12 to provide a rotational jet of liquid ejected from the rotating nozzle head 30.

[0085] The nozzle 1 further comprises an axial pressure compensator 16 arranged in the inner channel 15 and configured to substantially compensate an axial pressure of liquid entering the inner channel 15 at the liquid inlet end 13 of the housing 11, 12. In the present embodiment, the axial pressure compensator 16 is an integral part of the housing 11, 12 and comprises a plurality of liquid guiding channels 17 extending through the housing 11, 12. Each liquid guiding channel 17 comprises an inlet opening 18’ in fluid communication with the liquid inlet end 13 of the housing 11, 12 and an outlet opening 18” in fluid communication with the liquid outlet end 14 of the housing 11, 12 and the liquid channel 21 of the nozzle head support shaft 20. In order to allow liquid to pass from the liquid inlet end 13 to the nozzle head support shaft 20 during use of the nozzle 1, the liquid guiding channels 17 can guide the liquid while an axial force resulting from a liquid pressure of the liquid entering the nozzle 1 at the liquid inlet end 13 is not transmitted to the nozzle head support shaft 20. In particular, since the liquid flows from the inner channel 15 into the liquid channel 21 of the nozzle head support shaft 20 in a radially inward direction (visible with respect to the rotational axis A-A), an axial pressure is prevented from acting on the nozzle head support shaft 20.

[0086] The nozzle 1 further comprises an axial bearing seat 40 located within the first housing part 11 and arranged as an insert within an axial blind hole of the axial pressure compensator 16. The axial bearing seat 40 comprises an axial bearing surface 41 facing a corresponding end surface 22 of the nozzle head support shaft 20 located in the housing 11, 12 and positioned opposite an end of the attached nozzle head 30 of the nozzle head support shaft 20.

[0087] In Figure 3 is best shown in the exploded view representation, during use, the axial bearing surface 41 and the support shaft end surface 22 cooperate with each other, e.g. are in contact with each other, to form an axial bearing for the nozzle head support shaft 20. The axial bearing is configured to prevent displacement of the nozzle head support shaft 20 along the longitudinal rotational axis A-A.

[0088] The axial bearing seat 40 is fluidically connected to the inner channel 15. Thereby, the nozzle 1 is configured to establish a fluid film between the axial bearing surface 41 and the support shaft end surface 22 to form an axial fluid bearing for the nozzle head support shaft 20. During use of the nozzle 1, liquid can flow between the axial bearing surface 41 and the support shaft end surface 22, which means that the axial bearing seat 40 and the nozzle head support shaft 20 are not in direct mechanical contact with each other, but are indirectly in contact via the fluid film.

[0089] The nozzle 1 further comprises a plurality of discharge holes 19 arranged in the second housing part 12. The discharge holes 19 form fluid passages through the wall of the second housing part 12 and fluidically interconnect the axial bearing seat 40 and the surrounding environment of the nozzle 1. At the discharge holes 19, liquid can exit the nozzle 1 and an outflow of liquid can be established towards the surrounding environment of the nozzle 1. In particular, at least a portion of the liquid supplied to the nozzle 1 at the liquid inlet end 13 can flow through the inner channel 15, via the liquid guiding channel 17 in the axial pressure compensator 16, back towards the axial bearing seat 40 via the slit between the second housing part 12 and the head end support shaft 20, and finally to the surrounding environment of the nozzle 1 via the discharge holes 19. A pressure drop can exist at the discharge holes 19, resulting in a slight overpressure at the axial bearing seat 40 compared to the ambient pressure level. During use of the nozzle 1, this overpressure can force liquid between the support shaft end surface 22 and the axial bearing surface 41 in order to facilitate the formation of a fluid film.

[0090] Between the first housing part 11 and the second housing part 12, the nozzle 1 comprises a first sealing ring 51 and a second sealing ring 52. Both rings 51, 52 are configured to seal the joint between the housing parts 11, 12 against passage of fluid therebetween. The first sealing ring is embodied as a rubber O-ring 51 and the second sealing ring is embodied as a backup sealing ring 52 made of PTFE. The second sealing ring 52 can be relatively rigid and can thus be configured to provide additional mechanical rigidity to the O-ring 51 which is relatively weak by itself.

[0091] Figures 4A-4C An embodiment of the axial bearing seat 40 is shown in more detail. The axial bearing seat 40 comprises an axial bore 42 in the axial bearing surface 41 which is concentrically aligned with the rotational axis A-A. This axial bore 42 is centrally located in the axial bearing surface 41 and provides that the support shaft end surface 22 and the axial bearing seat 40 do not contact at a central portion of the axial bearing surface 41. In contrast, the contact between the support shaft end surface 22 and the axial bearing surface 41 is distributed over the remaining portion of the axial bearing surface 41 which surrounds the central axial bore 42.

[0092] The axial bearing surface 41 has a concave shape and the support shaft end surface 22 has a matching convex shape. The radius of curvature of the concave axial bearing surface 41 is identical to the radius of curvature of the convex support shaft end surface 22. Thus, the axial bearing surface 41 and the support shaft end surface 22 can closely fit into each other to provide a uniformly distributed contact therebetween, thereby providing a fluid film of constant thickness therebetween during use of the nozzle 1.

[0093] Since the axial bearing seat 40 is provided as a separate insert in the metal axial pressure compensator 16, it can be made of a different material, for example a material other than a metal material. Thus, the axial bearing seat 40 comprises a plastic material which is a fiber self-lubricating plastic material. According to the present embodiment, the entire axial bearing seat 40 is made of X, which is a specific type of self-lubricating plastic material.

[0094] According to the embodiment in Figures 4A-4C , the axial bearing seat 40 comprises four grooves 43 in the axial bearing surface 41 which are equally spaced around the rotation axis A-A. These grooves 43 provide a fluid connection between the axial bore 42 in the axial bearing seat 40 and the inner passage 15 of the nozzle 1. Thus, liquid can flow not only to the outer contour 44 of the axial bearing seat 40, but further inwards to the axial bore 42. During use of the nozzle 1, a fluid film can be utilized along the entire radius R of the axial bearing seat 40, and not only at the outer contour 44 of the axial bearing seat 40.

[0095] Each of the grooves 43 is aligned in the radial direction R, as seen with respect to the rotation axis A-A. This radial orientation of the grooves 43 provides that the length of the grooves 43, for example from the outer contour 44 of the axial bearing seat 40 towards the axial bore 42, is as short as possible.

[0096] Furthermore, the grooves 43 comprise a rectangular cross-section. As seen in a plane perpendicular to the radial direction R of the axial bearing seat 40, the grooves 40 thus have the shape of a rectangle.

[0097] In Figures 5A-5F , various different axial bearing seats are schematically depicted, which all comprise a different number of grooves. In Figures 5A-5F , the left side shows an elevation view of the axial bearing surface of the respective axial bearing seat, and the right side shows an isometric view of the respective axial bearing seat.

[0098] Figure 5A An axial bearing seat is shown, which comprises no grooves in its axial bearing surface. The axial bearing seat comprises only an axial bore in the axial bearing surface, and the remaining axial bearing surface has a smooth and annular shape to contact the nozzle head support shaft.

[0099] Figure 5B An axial bearing seat is shown, which comprises one axial bore and two grooves in the axial bearing surface. The grooves are equally spaced around the rotation axis at 180°.

[0100] Figure 5C An axial bearing seat is shown, which comprises one axial bore and three grooves in the axial bearing surface. The grooves are equally spaced around the rotation axis at 120°.

[0101] Figure 5D An axial bearing seat is shown which also comprises Figures 4A-4C an axial hole and four grooves in the axial bearing surface. The grooves are equally spaced around the rotation axis at 90°.

[0102] Figure 5E An axial bearing seat is shown which also comprises an axial hole and five grooves in the axial bearing surface. The grooves are equally spaced around the rotation axis at 72°.

[0103] Figure 5F An axial bearing seat is shown which also comprises an axial hole and six grooves in the axial bearing surface. The grooves are equally spaced around the rotation axis at 60°.

[0104] Figures 5A-5F The axial bearing seats in Figure 5G and Figure 5H schematically depict two further different axial bearing seats which both comprise grooves of different cross-sectional shape. In Figure 5G and Figure 5H the left-hand side shows a side view of the respective axial bearing seat and the right-hand side shows an isometric view of the respective axial bearing seat.

[0105] Thus, Figure 5G An axial bearing seat is shown which also comprises four grooves with triangular cross-section.

[0106] Figure 5H An axial bearing seat is shown which also comprises four grooves with semi-circular cross-section.

[0107] It is to be understood that other embodiments of axial bearing seats can be envisaged which for example comprise a different number of grooves with triangular cross-section or semi-circular cross-section.

[0108] With respect to the rotation axis, Figures 5A-5H the axial bearing seats in Figure 5I and Figure 5J schematically depict two further different axial bearing seats which both comprise grooves which extend in different directions of different type. In Figure 5I and Figure 5J the left-hand side shows a side view of the respective axial bearing seat, the middle shows an elevation view of the axial bearing surface of the respective axial bearing seat and the right-hand side shows an isometric view of the respective axial bearing seat.

[0109] Thus, Figure 5IAn axial bearing seat is shown which comprises four grooves having a rectangular cross section and being arranged offset with respect to the rotation axis. Thus, the grooves extend in a direction parallel to the radial direction. However, this direction does not intersect the rotation axis but is spaced apart from the rotation axis by a distance. According to Figure 5I the grooves are arranged in line with the tangential direction of the central axial bore in the axial bearing seat.

[0110] Figure 5J An axial bearing seat is shown which comprises four grooves having a rectangular cross section and extending helically away from the central bore. The grooves do not extend along a straight line but along a curve to obtain a helical groove pattern.

[0111] It is to be understood that other embodiments of the axial bearing seat can be envisaged which for example comprise a different number of grooves and / or a different cross section while being arranged offset with respect to the rotation axis or helically.

[0112] Figures 5A-5J The axial bearing seats in Figs. 1-3 each comprise a concave axial bearing surface. In Figure 5K a further different axial bearing seat is schematically depicted in Fig. 4 which comprises a flat axial bearing surface. In Figure 5K in Fig. 5 the left side shows a side view of the respective axial bearing seat, the middle shows an elevation view of the axial bearing surface of the respective axial bearing seat, and the right side shows an isometric view of the respective axial bearing seat.

[0113] Thus, Figure 5K An axial bearing seat is shown which comprises four grooves having a rectangular cross section. The axial bearing surface has a flat shape in order to be associated with a support shaft end surface having a matching flat shape. The flat shape of the axial bearing surface can provide that the axial bearing surface and the nozzle head support shaft can fit closely to each other to provide a uniformly distributed contact between them.

[0114] It is to be understood that other embodiments of the axial bearing seat can be envisaged which for example comprise a different number of grooves and / or a different cross section and / or a different extension direction while comprising a flat axial bearing surface.

Claims

1. A high-pressure nozzle comprising: a longitudinal housing comprising a liquid inlet end and a liquid outlet end opposite the liquid inlet end and comprising an internal passage extending from the liquid inlet end to the liquid outlet end, a nozzle head support shaft being partially rotatably arranged in the housing and arranged in a portion of the internal passage, and comprising a liquid passage in fluid communication with the internal passage, a rotational nozzle head being attached to the nozzle head support shaft and arranged outside the housing, an axial pressure compensator being arranged in the internal passage and configured to substantially compensate for axial pressure of liquid entering the internal passage at the liquid inlet end of the housing, and an axial bearing seat being located within the housing and comprising an axial bearing surface facing an end surface of the nozzle head support shaft, wherein the rotational nozzle head and the nozzle head support shaft are configured to rotate relative to the longitudinal housing about a longitudinal rotation axis to provide rotational ejection of liquid ejected from the rotational nozzle head, and wherein the axial bearing surface and the support shaft end surface cooperate with each other during use to form an axial bearing for the nozzle head support shaft, characterized in that the axial bearing seat is arranged within an axial blind hole of the axial pressure compensator, and the axial bearing seat comprises an axial hole in the axial bearing surface concentrically aligned with the rotation axis.

2. The high-pressure nozzle according to claim 1, wherein the axial bearing surface has a shape matching a shape of the support shaft end surface.

3. The high-pressure nozzle according to claim 2, wherein the axial bearing surface has a concave shape, and wherein the support shaft end surface has a matching convex shape.

4. The high-pressure nozzle according to claim 2, wherein the axial bearing surface has a flat shape, and wherein the support shaft end surface has a matching flat shape.

5. The high-pressure nozzle according to any one of the preceding claims, wherein the axial bearing seat is fluidically connected to the internal passage, and wherein the nozzle is configured to establish a fluid film between the axial bearing surface and the support shaft end surface to form an axial fluid bearing for the nozzle head support shaft.

6. The high-pressure nozzle according to claim 1, wherein the axial bearing seat comprises two or more grooves in the axial bearing surface, the two or more grooves being equally spaced around the rotation axis.

7. The high-pressure nozzle according to claim 6, wherein each of the grooves is aligned in a radial direction as seen relative to the rotation axis.

8. The high-pressure nozzle according to claim 6 or 7, wherein the grooves comprise a rectangular cross-section.

9. The high-pressure nozzle according to claim 1, further comprising at least one drain hole fluidically connected to the axial bearing seat so as to form a fluid connection with a surrounding environment of the nozzle.

10. The high-pressure nozzle according to claim 1, wherein the axial bearing seat comprises a plastic material.

11. The high-pressure nozzle according to claim 1, wherein the axial bearing seat is provided as an insert arranged within an axial blind hole of the axial pressure compensator.

12. The high-pressure nozzle according to claim 1, wherein the axial pressure compensator is an integral part of the longitudinal housing.

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