Axial flow control valve with annular discharge outlet into main fluid passage for fluid discharged from pilot valve

Abstract

The invention relates to an axial flow control valve (1) comprising a housing (2) with a fluid inlet (3), a fluid outlet (4), and a main fluid passage that extends from the fluid inlet (3) to the fluid outlet (4) at least substantially along a main axis (MA). It further comprises a main valve for opening and closing the main fluid passage, wherein the main valve includes a main valve seat (23) arranged in the main fluid passage and a main valve element (50) that is movable with respect to the main valve seat (23), a pilot valve (70) for inducing opening and closing of the main valve, and a discharge passage (91, 92, 93) extending from the pilot valve (70) to the main fluid passage, wherein a discharge outlet (93) of the discharge passage (91, 92, 93) opens into to the main fluid passage downstream of the main valve seat (23). For increased efficiency, the discharge outlet (93) is annular or intermittently annular about the main axis (MA).

Description

[0001]

[0002] Axial flow control valve with annular discharge outlet into main fluid passage for fluid discharged from pilot valve

[0003] The present invention relates to an axial flow control valve comprising a housing with a fluid inlet, a fluid outlet, and a main fluid passage that extends from the fluid inlet to the fluid outlet (at least substantially) along a main axis, and further comprising a main valve with a main valve seat arranged in the main fluid passage, and a pilot valve for inducing opening and closing of the main valve.

[0004] In such a flow control valve, the main valve is configured for opening and closing the main fluid passage. The main valve includes the main valve seat and a main valve element. The main valve element is movable parallel to the main axis with respect to the main valve seat.

[0005] When the flow control valve is closed, the main valve element sealingly abuts the main valve seat. Hence, the main fluid passage is blocked. Fluid cannot flow via the main fluid passage from the fluid inlet to the fluid outlet in this situation.

[0006] For opening the flow control valve, the main valve element is displaced away from abutting the main valve seat. As a consequence, the main fluid passage is not blocked any more but open. Fluid can flow through the main fluid passage from the fluid inlet to the fluid outlet via the main valve seat.

[0007] The pilot valve is used for inducing opening and closing the main valve, i.e. for inducing the switching between an open state and a closed state of the main valve (and hence of the flow control valve). A discharge passage extends from the pilot valve to the main fluid passage. In more detail, a discharge outlet of the discharge passage opens into the main fluid passage downstream of the main valve seat.

[0008] October 1 , 2025 D 200 P 2647 WO

[0009] When the flow control valve is closed, the main valve is closed. An inlet pressure of the fluid at the inlet port is higher than an outlet pressure of the fluid at the outlet port. The main valve element is partially subjected to a pilot pressure of fluid in a pilot pressure space. The pilot fluid pressure applies a pilot closing force on the main valve element, i.e. a force urging the main valve element towards abutting the main valve seat due to the pilot pressure. The pilot valve is closed and hence prevents fluid from being discharged from the pilot pressure space into the discharge outlet. Therefore, the pilot pressure remains on a high level, ensuring that the main valve element properly abuts the main valve seat-

[0010] For opening the flow control valve, first the pilot valve opens. Fluid is discharged from the pilot pressure space through the pilot valve into the discharge passage and, via the discharge outlet. The fluid flow of the fluid discharged from the pilot valve may be briefly referred to as pilot discharge flow. The pilot discharge flow enters through the discharge outlet into the main fluid passage, in particular downstream of the main valve seat.

[0011] Due to opening the pilot valve and discharging fluid from the pilot pressure space, the pilot pressure decreases. Accordingly, the pilot pressure force drops. Said drop is large enough such that total forces acting onto the main valve element are sufficient to displace the main valve element away from abutting the main valve seat. The main valve element hence opens the main fluid passage.

[0012] For closing the flow control valve, first the pilot pressure valve is opened. The pilot pressure and hence the pilot pressure force increase. As a consequence, the main valve element displaced towards the main valve seat and finally sealingly abuts the main valve seat.

[0013] The problem underlying the invention is to increase the efficiency of such a flow control valve.

[0014] October 1 , 2025 D 200 P 2647 WO

[0015] This problem is solved by an axial flow control valve according to the present invention.

[0016] The axial flow control valve comprises a housing with a fluid inlet, a fluid outlet, and a main fluid passage that extends from the fluid inlet to the fluid outlet (at least substantially) along a main axis; a main valve for opening and closing the main fluid passage, wherein the main valve includes a main valve seat arranged in the main fluid passage and a main valve element that is movable (e.g. parallel to the main axis) with respect to the main valve seat for opening and closing the main fluid passage; a pilot valve for inducing opening and closing of the main valve; a discharge passage extending from the pilot valve to the main fluid passage, wherein a discharge outlet of the discharge passage opens into to the main fluid passage downstream of the main valve seat; wherein the discharge outlet is annular or intermittently annular about the main axis.

[0017] For keeping the axial flow control valve open, the pilot valve stays open. Accordingly, there is an ongoing pilot discharge flow from the discharge outlet into the main fluid passage. It has been found that the pilot discharge flow into a main fluid flow (along the main fluid passage) seems to impair the efficiency of conventional axial flow control valves in operation. A main flow direction may refer to the intended flow of the fluid through the main fluid passage in operation when the axial flow control valve is open (from the inlet port to the outlet port through the main valve seat).

[0018] In operation, when the axial flow control valve is open, a main flow of fluid from the fluid inlet to the fluid outlet through the main valve seat is (at least

[0019] October 1 , 2025 D 200 P 2647 WO substantially) along the main axis. Hence, the main axis can be also referred to as main flow axis.

[0020] Typically, in existing axial flow control valves, the discharge outlet is a single, comparatively small opening at one side of the main fluid passage. The ongoing discharge of the pilot discharge flow when the axial flow control valve is open occurs from this small single opening and only along a single lateral direction perpendicular to the main fluid flow (the latter flowing substantially along the main axis). In other words, the pilot discharge flow is discharged (injected) into the main fluid flow laterally in a highly unsymmetric and non-uniform manner. This causes deflection of the main fluid flow and turbulences in the main fluid flow. Finally, this impairs the flow characteristics for the main fluid flow. Accordingly, in operation, an efficiency of the axial control valve in an open state is reduced.

[0021] The at least intermittently annular or especially annular discharge outlet leads to a more distributed and symmetrical discharge (injection) of a pilot fluid flow into the main fluid passage. The deflection of the main fluid flow by the pilot fluid flow is reduced or even avoided. Similarly, turbulences in the main fluid flow caused by the injection of the pilot fluid flow are reduced or even avoided. The flow characteristics of the axial flow control valve for the main fluid flow (i.e. the flow characteristics along the main fluid passage) are improved. This helps to obtain less energy losses and hence improves the efficiency of the axial flow control valve.

[0022] In one embodiment, a circumferential direction in a plane perpendicular to the main axis at the discharge outlet is covered by the discharge outlet to at least 85 %. In other words, in said plane perpendicular to the main axis, the discharge outlet covers (all individual discharge segments together thereof cover) in total an angle range of at least 306° (around the main axis). The pilot fluid flow is injected (discharged) into the main fluid passage along various different lateral directions. For at least most of the lateral directions, the corresponding portions of the pilot

[0023] October 1 , 2025 D 200 P 2647 WO discharge flow cancel out each other such that they cannot deflect the main fluid flow.

[0024] According to one aspect, the discharge outlet includes discharge segments that are located (arranged) with a rotational symmetry of Nth order (e.g. with respect to the main axis), where N is at least two, maybe at least three, or even at least four. N is a natural number. The lateral impacts by the portions of the pilot fluid flow which are discharged by these discharge segments onto the main fluid flow (at least substantially) cancel out each other. Accordingly, said portions of the pilot fluid flow cannot contribute to deflecting the main fluid flow away from the main axis.

[0025] According to one aspect, the whole discharge outlet can consist of the discharge segments as defined above only.

[0026] Some or all adjacent ones of the discharge segments can merge seamlessly (i.e. transition into one another without interruption of the dis-charge outlet). For example, an annular discharge outlet can be considered including a number of n uniform discharge segments merging seamlessly into each other.

[0027] An axial position (i.e. a position along the main axis) of the discharge outlet may be located in a region with a maximum flow velocity of the main fluid flow in operation when the axial flow control valve is fully open.

[0028] In one embodiment, the main fluid passage includes a diffuser portion downstream of the main valve seat, wherein the discharge outlet opens into the main fluid passage

[0029] - between the main valve seat and an upstream end of the diffuser portion and / or

[0030] - within an upstream end portion of the diffuser portion.

[0031] October 1 , 2025 D 200 P 2647 WO

[0032] This refers to an axial position of the discharge outlet, i.e. along the main axis. The flow velocity of the main fluid flow in operation is typically particularly high in these regions in operation when the axial flow control valve is fully open.

[0033] The upstream end portion may be defined as extending from the upstream end of the diffuser (with regard to the main fluid passage) over 10 % of length of the diffuser portion along the main axis.

[0034] According to one aspect, the housing comprises an outlet component, wherein the outlet component forms the diffuser portion and the outlet port. This allow cost-efficient manufacturing and a small size.

[0035] Additionally or alternatively, seen along the axial direction, the outlet port can (directly) adjoin a downstream end of the diffuser portion.

[0036] According to one aspect, at an upstream end of the outlet port, a radial step may be formed between a diameter of the main fluid passage directly upstream of the outlet port and an inner diameter of the outlet port. The radial step can be configured to compensate for a wall thickness of a pipe end inserted into the outlet port, especially such that an inner diameter of the pipe end is flush with the inner diameter of the main fluid passage directly upstream of the outlet port. This reduces the flow resistance in operation.

[0037] Additionally or alternatively, at a downstream end of the inlet port, a radial step may be formed between a diameter of the main fluid passage directly downstream of the inlet port and an inner diameter of the inlet port. The advantages described in the preceding paragraph apply accordingly.

[0038] October 1 , 2025 D 200 P 2647 WO

[0039] In one embodiment, the housing includes a main valve body, in which the main valve seat is arranged, wherein the discharge outlet is formed between the main valve body and an end portion of the outlet component along the main axis that faces the main valve body. This allows for a cost-efficient and comparatively easy implementation of the discharge outlet. The axial flow control valve may comprise fixing means that fix the outlet component to the main valve body. The fixing means may include a threaded engagement between the outlet component and the main valve body.

[0040] The axial flow control valve may be configured to discharge the pilot fluid from the discharge outlet into the main fluid passage (at least substantially) symmetrically with respect to the main axis. This is particularly beneficial for a small flow resistance for the main fluid flow in operation when the axial flow control valve is open.

[0041] The fluid can be a refrigerant, e.g. carbon dioxide. The axial flow control valve can be configured for forming part of a refrigerant circuit.

[0042] In one embodiment, the discharge outlet is formed as a concentrical ring with respect to the main axis. This helps to obtain a particularly uniform discharge of the pilot fluid flow into the main fluid passage and hence a minimal disturbance of the main fluid flow.

[0043] According one aspect, a minimum flow cross-section of the discharge passage is located upstream of the discharge outlet. In other words, the minimum flow crosssection of the discharge is elsewhere than at the discharge outlet. A flow crosssection of the discharge outlet is larger than the minimum flow cross-section of the discharge outlet. This results in reduced flow velocity of the pilot fluid flow at the discharge outlet and hence less impact on the main fluid flow.

[0044] October 1 , 2025 D 200 P 2647 WO

[0045] Additionally or alternatively, wherein the discharge passage includes a distribution chamber, wherein the minimum flow cross-section of the discharge is arranged upstream of the distribution chamber. The distribution chamber can be formed (at least substantially) annular, e.g. around a circumferential wall section around the main fluid passage. Said wall section can be located upstream of the discharge outlet, e.g. between the main valve seat and the discharge outlet. The distribution chamber helps to uniformly distribute the pilot fluid flow over the whole discharge outlet (for example over all discharge segments).

[0046] The axial flow control valve can comprise an actuator for actuating the pilot valve. Especially, the axial flow control valve can comprise an electromagnetic actuator for actuating the pilot valve.

[0047] In one embodiment, the pilot valve is a multi-stage opening pilot valve. Accordingly, less actuation forces a needed for actuating the pilot valve. The actuator can be less powerful, cheaper, and smaller.

[0048] The axial flow control valve may include a pilot pressure chamber. The pilot pressure chamber may be in fluid connection with (an inlet of) the pilot valve. The axial flow control valve may be configured such that a pilot pressure in the pilot pressure chamber causes a pilot force onto the main valve element, especially a pilot closing force that urges the main valve element towards abutting the valve seat. The pilot valve may be configured for influencing the pilot pressure by opening and closing of the pilot valve.

[0049] According to one aspect, the axial flow control valve comprises at least one fluid bleed from the main fluid passage upstream of the main valve seat towards the pilot valve and / or to the pilot pressure chamber. Especially, (the inlet of) the pilot valve may be fluidly connected with the at least one fluid bleed via the pilot pressure chamber. Accordingly, the pilot pressure chamber can be supplied with a

[0050] October 1 , 2025 D 200 P 2647 WO limited maximum flow of fluid from the main fluid passage upstream of the main valve seat (and hence independently from an opening degree of the main valve, in particular also when the main valve is closed). Additionally or alternatively, the axial flow control valve can comprise an additional fluid inlet (i.e. in addition to the fluid inlet for the main fluid passage) for supplying fluid to the pilot pressure chamber.

[0051] In one embodiment, the at least one fluid bleed, the pilot valve, and the discharge passage form part of a fluid bypass for bypassing the main valve seat when the pilot valve is open.

[0052] The housing can comprise an inlet component including the inlet port. The inlet component can be fixed (directly) to the main body. The axial flow control valve may comprise fixing means that fix the inlet component to the main valve body. The fixing means may include a threaded engagement between the inlet component and the main valve body.

[0053] The present disclosure also relates to a refrigerant circuit including at least one axial fluid control valve according to the present invention. The refrigerant circuit may comprise one of, several of, or all of the following: a compressor, a condenser, an expansion valve, and an evaporator.

[0054] Additional features, advantages and possible applications of the invention result from the following description of exemplary embodiments and the drawings. All the features described and / or illustrated graphically here form the subject matter of the invention, either alone or in any desired combination, regardless of how they are combined in the claims or in their references back to preceding claims.

[0055] Preferred embodiments of the invention will now be described with reference to the drawings, in which:

[0056] October 1 , 2025 D 200 P 2647 WO

[0057] Fig. 1 shows a longitudinal cross-section of an embodiment of an axial flow control valve according to the present invention in a fully open state;

[0058] Fig. 2 shows a magnified section of Fig. 1 ;

[0059] Fig. 3 shows a longitudinal cross-section of the axial flow control valve of Fig. 1 in a closed state; and

[0060] Figs. 4A to 4C schematically show examples of different shapes of a discharge outlet.

[0061] Fig. 1 shows a longitudinal cross-section of an axial flow control valve 1 for controlling a flow of a fluid, e.g. a refrigerant in a fully open state. Fig. 3 shows the same longitudinal cross-section of the axial flow control valve 1 in a closed state.

[0062] The axial flow control valve 1 comprises a housing 2. The housing 2 includes a fluid inlet 3 for a main fluid passage and a fluid outlet 4 for the main fluid passage.

[0063] The housing 2 includes a (main) valve body 20 with a guiding chamber 21 having an (inner) circumferential surface 22. The housing 2 further includes an inlet component 30 with the inlet port 3 and an outlet component 40 with the outlet port 4. The inlet component 30 is fixed to the valve body 20, e.g. by a threaded engagement. The outlet component 40 is fixed to the valve body 20, e.g. by a threaded engagement.

[0064] A main fluid passage through the axial flow control valve 1 extends from the fluid inlet 3 to the fluid outlet 4 along a main axis MA. An intended main flow direction MFD in operation when the axial flow control valve 1 is open is from the inlet port 3

[0065] October 1 , 2025 D 200 P 2647 WO to the outlet port 4. The (intended) main flow direction MFD is parallel to the main axis MA. When the axial flow control valve 1 is open in operation, a main fluid flow through the main fluid passage may be coaxial with the main axis MA. An axial direction AD is parallel to the main axis CA.

[0066] A main valve is arranged in the main flow passage. The main valve includes a main valve seat 23 and a main valve element 50.

[0067] The main valve seat 23 is located in the valve body 20.

[0068] The main valve element 50 is inserted into the housing 2. The main valve element 50 is axially movable within the housing 2 along the axial direction AD (and hence along the main flow direction MFD) with respect to the main valve seat 23. A resilient closing force of a resilient element, e.g. a main valve spring 59, biases the main valve element 50 towards abutting the main valve seat 23.

[0069] When the axial flow control valve 1 is closed as shown in Fig. 3, a sealing section 51 of a central portion 55 of the main valve element 50 sealingly abuts a main valve seat 23 in the valve body 20. Thereby, a main fluid passage is closed. The main valve element 50 is in a most downstream position along the axal direction AD.

[0070] Figs. 1 and 2 show the axial flow control valve 1 in the fully open state. The main valve element 50 is axially moved away from abutting the main valve seat 23 by a maximum displacement. The main fluid passage is fully open and the fluid (e.g. the refrigerant) easily flow from the inlet port 3 to the outlet port 4 along the main flow direction MFD through the main fluid passage.

[0071] The terms "upstream" and "downstream" may refer to the axial direction AD in view of the intended main flow direction MFD if not stated otherwise.

[0072] October 1 , 2025 D 200 P 2647 WO

[0073] The main valve element 50 includes a sliding portion 52, a flow guide skirt 53, and a central portion 55.

[0074] The valve body 20 can be made, as an example, of aluminum or an aluminum- based alloy. The main valve seat 23 may be formed integrally with the valve body 20.

[0075] The inlet component 30 and / or the outlet component 40 can be made of the same or other material(s) than the valve body 20. For example, the inlet component 30 and / or the outlet component 40 can be made copper-plated steel (including the case of copper-plated stainless steel), brass, copper and / or of bronze.

[0076] The sliding portion 52 can be made of aluminum or an aluminum-based alloy.

[0077] The valve body 20 and the sliding portion 52 can be made of the same material.

[0078] In more detail, the main valve element 50 comprises an insert element that includes the flow guide skirt 53, a sealing head holder 56 forming part of the central portion 55, and several lateral struts 54. The struts 54 fix the sealing head holder 56 to the flow guide skirt 53. Seen along a lateral direction LD (which is perpendicular the axial direction AD), the sealing head holder 56 forms an inner part of the insert element, the flow guide skirt 53 forms an outer part of the insert element, and the struts 54 connects the inner part with said outer part.

[0079] Actually, in this embodiment, the lateral direction LD is a radial direction with respect to the main axis MA. Correspondingly, for example, the struts 54 can be also referred to as "radial" struts 54.

[0080] October 1 , 2025 D 200 P 2647 WO

[0081] In this exemplary embodiment, the insert element includes four struts 54. Due to the perspective, only one of the struts 54 can be seen in the figures, especially in Fig. 1.

[0082] In general, the struts 54 can be formed integrally with the flow guide skirt 53 and / or the sealing head holder 56.

[0083] Especially, the insert element can be formed in one piece. In other words, the flow guide skirt 53, the struts 54, and the sealing head holder 56 are formed in one part. The insert element can be formed by injection molding. There may be, for example, four injection points for the injection molding. Additionally or alternatively, a number of the injection points can correspond to a number of the struts 54.

[0084] The insert element can be made of fiber-reinforced plastics, e.g. from polyether ether ketone reinforced with long carbon fibers.

[0085] In this embodiment, the central portion 55 includes the sealing head holder 56, a sealing head including the sealing section 51 , and a screw fixing the sealing head to the sealing head holder 56. The screw can be a metal screw. A threaded engagement is formed between the sealing head and the screw. A screw-head of the screw is arranged at an upstream end of the central portion 55. A shaft of the screw is inserted through a central hole of the sealing head holder 56 for allowing the threaded engagement between a downstream portion of the screw and the sealing head.

[0086] At an outer circumferential surface of the central portion 55, there is a smooth transition from the sealing head holder 56 to the sealing head. This improves the flow characteristics.

[0087] October 1 , 2025 D 200 P 2647 WO

[0088] The flow guide skirt 53 (and hence the insert element and with it the whole central portion 55) are secured to the sliding portion 52 of the main valve element 50. In the exemplary embodiment, the insert element includes an annular flange formed at an upstream end of the flow guide skirt 53. Said flange protrudes laterally outward from an outer circumferential surface of the flow guide skirt 53. The sliding portion 52 includes a mount for mounting the insert element, in particular for receiving the annular flange. The upstream end of the flow guide skirt 53 axially abuts an annular upstream end face of the mount. Further, an outer circumference of the flange of the flow guide skirt 53 laterally circumvented by an annular wall of the mount that protrudes downstream with respect to the annular upstream end face of the mount. In this exemplary embodiment, said mount also include an annular groove that is formed in an inner circumferential surface of the annular wall. A spring ring (expanding ring) 57 is snapped into the annular groove . It secures the annular flange at the flow guide skirt 53 within the mount.

[0089] The sliding portion 52 - and hence the rest of the main valve element 50 that is axially secured to the sliding portion 52 - is guided within the guiding chamber 21 . An outer circumferential surface of the sliding portion 52 engages the inner circumferential surface 22 of the guiding chamber 21 .

[0090] In addition, an upstream portion 58 of the sliding portion 52 protrudes into the inlet component 30. The upstream portion 58 has a reduced outer diameter (compared to a main part of the sliding portion 52 engaging with the guiding chamber 21 of the valve body 20). A part of an outer circumference of the upstream portion 58 engages an inner circumferential surface 32 of a guiding chamber 31 in the inlet component 30. When the axial flow control valve 1 is fully open, said part (and an axial overlap between the upstream portion 58 and the guiding chamber 21 ) is larger since the upstream portion 58 is moved farther into the inlet component 30 compared to the case when the axial flow control valve 1 is closed.

[0091] October 1 , 2025 D 200 P 2647 WO

[0092] The main fluid passage can be explained best referring to Fig. 1 where the axial flow control valve 1 is fully open. The main fluid passage extends from the inlet port 3 along the main flow direction MFD (which coincidences with the main axis MA) to the outlet port 4. Firstly, it extends along the main axis MA from the inlet port 3 through the inlet component 30 up to the upstream portion 58. Then, it extends along the main axis MA through the sliding portion 52.

[0093] The central portion 55 of the main valve element 50 is inserted into the main fluid passage.

[0094] The main fluid passage includes a circumventing flow passage for passing the fluid alongside the central portion 55. The circumventing flow passage includes a main fluid flow section space formed between the flow guide skirt 53 and an outer circumferential surface of the central portion 55, and further a flow space that is formed between the central portion 55 and the valve body 20 downstream of the flow guide skirt 53.

[0095] In cross-sections perpendicular to the main axis MA, the circumventing flow passage is substantially annularly around the outer circumference of the central portion 55, locally interrupted by the struts 54.

[0096] When the axial flow control valve 1 is open, the main fluid passage "reunites" downstream of the central portion 55. The main valve seat 23 is arranged at the main fluid passage such that the latter is blocked when the axial flow control valve 1 is closed.

[0097] Downstream of the main valve seat 23, the main fluid passage may include a diffuser portion 41 .

[0098] The main fluid passage ends at the outlet port 4.

[0099] October 1 , 2025 D 200 P 2647 WO

[0100] A downstream end portion of the guiding chamber 21 is used as displacement space 25 for the sliding portion 52. When comparing Fig. 3 showing the main valve element 50 when the axial flow control valve 1 is closed and Fig. 1 showing the main valve element 50 when the axial flow control valve 1 is fully open, it appears that the sliding portion 52 partly occupies the displacement space 25 in Fig. 3.

[0101] The flow guide skirt 53 shields a laterally outer space between the flow guide skirt 53 and the valve body 20 from the main fluid flow section space that is defined between the flow guide skirt 53 and the central portion 55.

[0102] In more detail, the flow guide skirt 53 shields the laterally outer space between the outer circumferential surface of the flow guide skirt 53 and an inner circumferential surface of the valve body 20 from the main fluid flow section space that is defined between an inner circumferential surface of the flow guide skirt 53 and the outer circumferential surface of the central portion 55.

[0103] The laterally outer space includes the displacement space 25. In the exemplary embodiment, the flow guide skirt 53 shields the complete displacement space 25 from direct impact of the main fluid flow independently of an (axial) position of the main valve element 50 (i.e. in any opening degree of the axial flow control valve 1 ).

[0104] At least when the axial flow control valve 1 is closed, a downstream end of the flow guide skirt 53, here in the form of a free annular tip, may protrude into an inner space of the valve body 20 between the guiding chamber 21 and the main valve seat 23. Said inner space might be referred to as intermediate space. The "laterally outer space" shielded by the flow guide skirt 53 hence includes (in addition to the displacement space 25) an outer channel 26 formed between the outer

[0105] October 1 , 2025 D 200 P 2647 WO circumferential surface of the flow guide skirt 53 and the inner circumferential surface of the valve body 20 in the intermediate space. The outer channel 26 is, in this embodiment, annular.

[0106] According to one aspect, a downstream end of the flow guide skirt 53 (e.g. the annular tip) protrudes over a downstream end of the guiding chamber 21 even when the axial flow control valve 1 is fully open.

[0107] The flow guide skirt 53 hence helps to ensure a smooth flow of the fluid (refrigerant) alongside the central portion 55, especially adjacently alongside the outer circumferential surface of the central portion 55. In addition, it reduces the risk that particles entrained by the main fluid flow accumulate in the displacement space 25 and finally enter into the engagement area between the inner circumferential surface 22 of the guiding chamber 21 and the outer circumferential surface of the sliding portion 52.

[0108] The outer channel 26 allows an inlet pressure and some fluid to propagate from the main fluid passage to the displacement space 25. The inlet pressure is a fluid pressure of the fluid (e.g. the refrigerant) at the inlet port 3. The outer channel 26 opens to the main fluid passage upstream of the main valve seat 23. In other words, although being shielded from direct impact of the main fluid flow by the flow guide skirt 53, the displacement space 25 is in fluid connection with the main fluid passage upstream of the main valve seat 23.

[0109] An inlet-pressure zone within the axial flow control valve 1 includes all spaces for accommodating / receiving the fluid to which unimpaired pressure-propagation (within the axial flow control valve 1 ) of the inlet pressure is possible even when the axial flow control valve 1 is closed. Additionally or alternatively, the inlet-pressure zone within the axial flow control valve 1 may include all spaces for accommodating the fluid that have an unimpaired fluid communication (within the axial

[0110] October 1 , 2025 D 200 P 2647 WO flow control valve 1 ) to the inlet port 3 even when the axial flow control valve 1 is closed. In this embodiment, the inlet-pressure zone includes the inlet port 3 itself, an interior of the inlet component 30 upstream of the sliding portion 52, an interior of the sliding portion 52 (including the interior of its upstream portion 58), the main fluid flow space (between the outer circumferential surface of the central portion 55 and the inner circumferential surface of the flow guide skirt 53), the intermediate section, the outer channel 26, and the displacement space 25.

[0111] The axial flow control valve 1 includes a pilot valve 70. The pilot valve 70 is configured to induce opening and closing of the axial flow control valve 1 .

[0112] The axial flow control valve 1 includes a pilot fluid supply for limited fluid supply of the fluid (e.g. the refrigerant) from the inlet-pressure zone to the pilot valve 70. For example, the pilot fluid supply can include at least one fluid bleed 61 , 62 from the inlet-pressure zone, a pilot pressure chamber 63, and at least one bleed fluid channel 64 for passing fluid from the pilot pressure chamber 63 towards the pilot valve 70. The exemplary embodiment shown includes two bleed fluid channels 64, wherein only one is visible in the Figs. 1 to 3 due to the perspective.

[0113] In more detail, a fluid bleed 62 from the inlet-pressure zone is formed in the engagement area between the outer circumferential surface of the sliding portion 52 and the inner circumferential surface 22 of the guiding chamber 21 of the valve body 20 (also referred to as downstream fluid bleed 62). In the figures, the downstream fluid bleed 62 includes a labyrinth seal. However, the downstream fluid bleed 62 can alternatively or additionally include one or more piston rings.

[0114] Additionally or alternatively, a fluid bleed 61 is formed in an engagement area between the outer circumferential surface of the upstream portion 58 and the inner circumferential surface 32 of the guiding chamber 31 in the inlet component 30 (also referred to as upstream fluid bleed 61 ). In the figures, the upstream fluid

[0115] October 1 , 2025 D 200 P 2647 WO bleed 61 includes a labyrinth seal. However, the upstream fluid bleed 61 can alternatively or additionally include one or more piston rings.

[0116] Both the upstream fluid bleed 61 and the downstream fluid bleed 62 are configured to bleed fluid from the inlet-pressure zone to the pilot pressure chamber 63. A maximum amount of fluid provided by the fluid bleeds 61 , 62 is limited.

[0117] The pilot pressure chamber 63 is arranged at a side of the main part of the sliding portion 52 that faces away from the main valve seat 23. In other words, the pilot pressure chamber 63 is arranged at an upstream axial side of the main part of the sliding portion 52.

[0118] Depending on the opening degree of the main valve, the pilot pressure chamber can partly extend into an upstream end of the guiding chamber 21 (see Fig. 3).

[0119] The pilot pressure chamber 63 is configured to be filled with fluid (e.g. refrigerant) in operation of the axial flow control valve 1 . A fluid pressure in the pilot pressure chamber 63 is briefly referred to as pilot pressure.

[0120] The pilot pressure in the pilot pressure chamber 63 causes a pilot force onto the main valve element 50. The pilot force urges the main valve element 50 towards abutting the valve seat. In other words, the pilot force applied to the main element 50 is parallel to the main flow direction in this embodiment.

[0121] The pilot pressure chamber 63 is (via the bleed fluid channels 64) fluidly connected with the pilot valve 70. The pilot force can be changed by switching the pilot valve 70 between a closed state and an open state thereof. This is used for switching the main valve (and hence the axial flow control valve 1 ) between the open state and the closed state.

[0122] October 1 , 2025 D 200 P 2647 WO

[0123] A discharge passage extends from the pilot valve 70 to the main fluid passage downstream of the main valve seat 23. In more detail, the discharge passage includes a pilot valve outlet channel 91 , a distribution chamber 92, and a discharge outlet 93. These elements arrange in this order along an intended flow direction of a pilot fluid flow from the pilot valve 70 to the main fluid passage in operation when the pilot valve 70 is open.

[0124] The operation of the axial flow control valve 1 is explained starting from the situation shown in Fig. 3 where the axial flow control valve 1 is closed. The main valve is closed. The sealing section 51 of the main valve element 50 sealingly abuts the main valve seat 23. The main fluid passage is blocked.

[0125] The inlet-pressure zone is subject to the inlet pressure. Since the main fluid passage is blocked at the main valve seat 23, a fluid pressure in the main fluid passage downstream of the main valve seat 23 corresponds to an outlet pressure. The outlet pressure is a fluid pressure at the fluid outlet 4. When the main valve is closed, the outlet pressure is lower than the inlet pressure.

[0126] Due to the fluid bleeds 61 , 62, the pilot pressure is supplied with fluid (e.g. refrigerant) from the inlet-pressure zone. In Fig. 3, the pilot valve 70 is also completely closed. No fluid can escape from the pilot pressure chamber 63 through the closed pilot valve 70. There is no pilot fluid flow from the pilot valve 70 to the main fluid passage. The pilot pressure in the pilot pressure chamber 63 (at least substantially) corresponds to the high inlet pressure. The high pilot pressure result in a strong pilot force acting onto the main valve element 50. This ensures that the main valve remains closed.

[0127] Starting from the situation shown in Fig. 3, for opening the axial flow control valve 1 , initially the pilot valve 70 is opened. Since the main valve is still closed, the outlet pressure in the main fluid passage downstream of the main valve

[0128] October 1 , 2025 D 200 P 2647 WO seat 23 is still lower than the inlet pressure. A fluid connection from the pilot pressure chamber 63 to the main fluid passage downstream of the main valve seat 23 is opened. A pilot fluid flow from the pilot valve 70 into the main fluid passage downstream of the main valve seat 23 starts. The pilot pressure in the pilot pressure chamber 63 decreases. Accordingly, the pilot force onto the main valve element 50 decreases. A downstream side of the main valve element 50 (including the downstream end of the sliding portion 52 facing the displacement chamber 23) is - except an area encircled by the main valve seat 23 - still subjected to the higher inlet-pressure. The resilient closing force of the resilient element (e.g. the main valve spring 59) is overcome. The main valve element 50 displaces away from abutting the main valve seat 23 to a fully open position as shown in Fig. 1. The main fluid passage is open.

[0129] Starting from the situation shown in Fig. 1 , for closing the axial flow control valve 1 , initially the pilot valve 70 is closed. Due to the fluid bleeds 61 , 62, the pressure in the pilot pressure chamber 63 increases. Accordingly, the pilot force increases. The pilot force and the resilient closing force push the main valve element 50 axially back into abutment with the main valve seat 23 and the axial flow control valve 1 is closed while the pilot pressure chamber 63 is filled up with fluid via the fluid bleeds 61 , 62.

[0130] In general, the pilot valve 70 can be of any type. According to one aspect, the pilot valve 70 can be configured to open in at least two stages. For example, the pilot valve 70 shown in Figs. 1 and 3 is configured to open in two stages (i.e. the pilot valve 70 is a two-stage opening pilot valve). For the sake of a readability, some of the reference signs related to the pilot valve 70 are only shown in Fig. 2, although it is also referred to them for describing the situations in Figs. 1 and 3.

[0131] In this embodiment, the pilot valve 70 includes a larger valve seat 72 and a corresponding larger sealing section 74 as well as a smaller valve seat 76 and a

[0132] October 1 , 2025 D 200 P 2647 WO corresponding smaller sealing section 77. The smaller sealing section 77 is formed on a member that is movable by an actuator, in this example on a movable armature member 83. The larger sealing section 74 and the smaller valve seat 76 are formed at opposite sides of a valve member 75 along a longitudinal direction LDP of the pilot valve 70. The smaller valve seat 76 is located on a side facing an the movable armature member 83 (an actuator-side). The larger sealing section 74 is located on the opposite side (a lower side) of the valve member 75.

[0133] The larger valve seat 72 is formed around an inlet of pilot valve outlet channel 91 that forms part of the discharge passage for discharging fluid from the pilot valve 70.

[0134] The valve member 75 is movable along the longitudinal direction LDP of the pilot valve 70 (into abutment and out of abutment on the larger valve seat 72). The valve member 75 includes an inner fluid channel 79 extending from the smaller valve seat 76 to the lower side (i.e. to a surface of the valve element 75 that is surrounded by the larger sealing section 74). In other words, the smaller valve seat 76 is formed around a first opening of the inner fluid channel 79 and a second opening of the inner fluid channel 79 is in the middle of the larger sealing section 74 and faces towards the pilot valve outlet channel 91

[0135] The axial flow control valve 1 may include the actuator for actuating the pilot valve 70. In general, all kinds of actuators are feasible. The actuator can, for example, comprise an electromagnetic actuator (e.g. including a permanent magnet), a wax actuator, a shape memory alloy actuator, and / or a solenoid actuator.

[0136] In this exemplary embodiment, the axial flow control valve 1 includes a solenoid actuator. There is a coil 87, the movable armature member 64, and a static armature member 85. By applying an electric current to the coil 87, the movable armature member 64 can be drawn along the longitudinal direction LDP of the pilot

[0137] October 1 , 2025 D 200 P 2647 WO valve 70 in a direction away from the larger valve seat 72. In other words, by applying the electric current to the coil 87, the movable armature member 64 can be moved towards the static armature member 85. The static armature member 85 is fixed with respect to the valve body 20 via a pilot valve housing 82.

[0138] When the pilot valve 70 is closed as in Fig. 3, the larger sealing section 74 of the valve member 75 sealingly abuts the larger valve seat 72 and the smaller sealing section 77 sealingly abuts the smaller valve seat 76. A pilot fluid bleed 81 allows for a limited flow of fluid from the outlets of the bleed fluid channels 64 to a fluid space 78 at the actuator-side of the valve member 75. The pilot fluid bleed 81 can be formed between a sliding sleeve 80 (arranged about the valve member 75) and the pilot valve housing 82. According to one aspect, the sliding sleeve 80 may form part or can be considered part of the valve member 75. Both a fluid space 71 at the lower side of the valve member 75 and the fluid space 78 at the actuatorside are subject to the inlet pressure in this situation. However, at the lower side of the valve member 75, a first central section encircled by the larger sealing section is not subject to the inlet pressure in this situation. Further, at the actuatorside of the valve member 75, a second central section encircled by the smaller valve seat 72 is not subject to the inlet pressure in this situation. As noted above, in operation, the outlet pressure in the main fluid passage downstream of the main valve seat 23 is lower than the inlet pressure while the axial flow control valve 1 is closed. Further, in Fig. 3, the pilot valve outlet channel 91 and the inner channel 79 of the valve member 75 are in fluid connection with part of the main fluid passage downstream of the main valve seat 23. As the second central section is smaller than the first central section, the inlet pressure keeps the valve member 75 (in particular the larger sealing section 74) in abutment with the larger valve seat 72.

[0139] Furthermore, a resilient element of the pilot valve 70 (e.g. a pilot valve spring 84) keeps the movable armature member 64 into abutment with the smaller valve

[0140] October 1 , 2025 D 200 P 2647 WO seat 76. Additionally or alternatively, the inlet pressure may propagate to a longitudinal end face of the movable armature member 83 facing away from the valve member 75. Since the second central section is not subjected to the inlet pressure in the closed stat as shown in Fig. 3, the inlet pressure also keeps the movable armature member 64 into abutment with the smaller valve seat 76.

[0141] Due to arrangement with the pilot valve 70, only a small actuation force is needed to induce opening of the axial flow control valve 1 . The actuation force has to be sufficient to open the smaller pilot valve 70 only. The forces for opening and closing the main valve are provided by the pressure differences of the refrigerant that are influenced by switching the pilot valve 70 between the open state and the closed state of the pilot valve 70. Accordingly, the requirements for the power of the actuator lower. The actuator can be less powerful. It can be smaller and cheaper. The pilot valve arrangement allows opening of a large orifice of the main valve, which is subjected to a large pressure differential, with a minimum actuator force and hence a minimum energy consumption.

[0142] Opening of the pilot valve 70 occurs in two stages. In other words, the axial flow control valve 1 opens in three stages, wherein the third stage is that the main valve opens. In a first stage, an actuator retracts the movable armature member 64 away from abutting the smaller valve seat 76. Fluid escapes from the fluid space 78 at the actuator-side of the valve member 75 through the inner fluid channel 79. It flows through the pilot valve outlet channel 91 , the distribution chamber 92 and is discharged by the discharge outlet 93 into the main fluid passage (downstream of the main valve seat 23 with regard to the main flow direction MFD). As only limited fluid flow to the fluid space at the actuator-side is possible, the pressure in said fluid space 78 decreases.

[0143] Accordingly, in a second stage, the high inlet pressure at its lower side (see fluid space 71 in Figs. 2 and 3) pushes the valve member 75 and the sliding sleeve 80

[0144] October 1 , 2025 D 200 P 2647 WO away from abutting the larger valve seat 72 such that the pilot valve 70 is completely open. Fluid provided to the pilot valve 70 (via the pilot fluid supply) passes between the larger sealing section 74 and the larger valve seat 72 into the pilot valve outlet channel 91 .

[0145] For closing the pilot valve 70, the coil 87 is not powered (supplied with electrical current) anymore and the fluid pressure in the fluid space 78 at the actuator-side of the valve element 66 pushes the valve member 75 (together with the movable armature member 64) back towards abutting the larger valve seat 72.

[0146] The (larger) valve seat 72 of the pilot valve 70 can be formed integrally with the valve body 20.

[0147] A pilot valve assembly 73 may be fixed to the valve body 20, e.g. via a union nut 86. The pilot valve assembly 73 forms together with the (larger) valve seat 69 the (two-stage) pilot valve 70.

[0148] The pilot valve assembly 73 can include at least one of, several of, or all of the following: The pilot valve housing 82, the valve member 75, the movable armature member 64, the (optional) resilient element of the pilot valve 70 (e.g. the pilot valve spring 84), the static armature member 85, and the coil 87.

[0149] The movable armature member 83 can be (at least partly) made of a metal material that is configured to be moved by an electromagnetic force generated by the actuator.

[0150] The fluid bleeds 61 , 62, the pilot pressure chamber 63, the bleed fluid channel(s) 64, the pilot valve 70, and the discharge passage with its discharge outlet 93 form part of a fluid bypass for bypassing the main valve seat 23 when the pilot valve 70 is open.

[0151] October 1 , 2025 D 200 P 2647 WO

[0152] The discharge passage is explained in more detail with respect to Fig. 2.

[0153] The discharge passage begins at the pilot valve 70 with the pilot valve outlet channel 91 . An opening of the pilot valve outlet channel 91 at the pilot valve 70 is surrounded by the larger valve seat 72.

[0154] The pilot valve outlet channel 91 includes a minimum flow cross-section Adm of the discharge passage. Accordingly, when the pilot valve 70 is open in operation, a flow velocity of the pilot fluid flow is the highest in the pilot valve outlet channel 91.

[0155] The discharge outlet 93 is the end of the discharge passage. It is located between the main valve seat 23 and an upstream end 42 of the diffuser portion 41 .

[0156] In the exemplary embodiment shown in Figs. 1 to 3, the discharge outlet 93 is formed annular. In more detail, the discharge outlet 93 is formed as a concentrical ring with respect to the main axis MA. The discharge outlet 93 is configured to discharge the pilot fluid flow laterally into the main fluid passage and at least substantially symmetrically with respect to the main axis MA.

[0157] As a consequence, the main fluid flow in the main fluid passage (that occurs in operation when the axial flow control valve 1 is open) is not deflected by the discharge of the pilot flow valve into the main fluid passage. This improves the flow characteristics and hence a pressure drop from the inlet port 3 to the outlet port 4 in operation when the axial flow control valve 1 is open. This means less energy losses and hence better efficiency.

[0158] In this example, the discharge outlet 93 is formed at an interface between the valve body 20 and the outlet component 40.

[0159] October 1 , 2025 D 200 P 2647 WO

[0160] In more detail, the discharge outlet 93 is formed between a recessed axial end face 43 at an upstream end (i.e. the end facing the valve body 20) of the outlet component 40 and an axial end face of circumferential wall section 24 of the valve body 20. Said circumferential wall section 24 encircles a portion of the main fluid passage downstream of the main valve seat 23 and directly upstream of the discharge outlet 93. An annular wall 44 around the recessed axial end face 43 axially protrudes from the recess axial end face 43 towards the valve body 20.

[0161] It is noted that flow cross-section of the main fluid passage directly downstream the discharge outlet 93 is a bit larger than a flow cross-section of the main fluid passage directly upstream of the discharge outlet 93 (see Fig. 2). This is advantageous to compensate for the increase of the main fluid flow due to injection the pilot fluid flow into the main fluid passage by means of the discharge outlet 93.

[0162] A minimum flow cross-section Amm of the main fluid passage downstream of the valve seat 23 is defined by the circumferential wall section 24. In operation when the main valve is fully open, a flow velocity of the main fluid flow (at least downstream of the main seat 23) is the highest in an interior of the circumferential wall section 24. The discharge outlet 93 opens into the main flow passage directly at the circumferential wall section 24 and hence in a region with the highest flow velocity of the main fluid flow (at least downstream of the main valve seat 23) in operation when the main valve is fully open. By having the outflow from the pilot valve 70 at this position, the main valve can open and stay open at the lowest possible pressure difference.

[0163] The pilot fluid flow discharged from the discharge outlet 93 into the main fluid passage passes the complete diffuser portion 41.

[0164] October 1 , 2025 D 200 P 2647 WO

[0165] The discharge passage also includes the distribution chamber 92. The distribution chamber 92 can be formed annularly around the circumferential wall section 24. Along the intended flow direction of the pilot fluid flow in operation, the distribution chamber 92 is arranged between the pilot valve outlet channel 91 and the discharge outlet 93. The distribution chamber 92 is configured for distributing the pilot fluid flow uniformly over the discharge outlet 93. A flow cross-section for the pilot fluid flow in the distribution chamber 92 is larger than the minimum flow crosssection Adm in the pilot valve outlet channel 91 . It is also larger than a flow crosssection of the discharge outlet. The pilot fluid flow entering the distribution chamber 92 flows along the lateral direction LD towards the outer circumferential surface of the circumferential wall section 24. A flow velocity of the pilot fluid flow is reduced. Further, the pilot fluid flow is distributed along a circumferential direction. The flow cross-section of the discharge outlet 93 being smaller than the flow- cross-section in the distribution chamber 92 can help that the pilot fluid valve distributes well along the circumferential direction in the distribution chamber 92.

[0166] Other shapes of the discharge outlet 93 are possible. Fig. 4A to 4D schematically shows some possible modifications of the discharge outlet 93 in a plane perpendicular to the main axis MA at an axial position of the discharge outlet 93.

[0167] Fig. 4A corresponds the discharge outlet 93 with an annular shape as described above. This discharge outlet 93 has circular symmetry. This might be understood as a rotational symmetry of Nth order, wherein N is infinite. Naturally, the annual discharge outlet 93 shown in Fig. 4A also has rotational symmetry for any other N that is at least 2. For example, the discharge outlet 93 might be conceptually split in to three discharge segments 93A, 93B, 93C that are uniformly arranged along a circumferential direction about the main axis MA, wherein adjacent discharge segments 93A, 93B, 93C along the circumferential direction merge seamlessly into each other. Assuming this, the discharge outlet 93 includes (even

[0168] October 1 , 2025 D 200 P 2647 WO consists of) three discharge segments 93A, 93B, 93C that are located with a rotational symmetry of third order with respect to the main axis MA.

[0169] Fig. 4B shows a modification where the discharge outlet 93 consist of four discharge segments 93A to 93D that are arranged with a rotational symmetry of fourth order with respect to the main axis MA. Adjacent discharge segments 93A to 93D are separated by walls 45. In this case, the discharge outlet 93 is intermittently annular. However, the discharge segments 93A to 93D cover in total an angle range of about 320° to 330° around the main axis MA.

[0170] Fig. 4C shows a further modification. Again, the discharge outlet 93 is intermittently annular. Along the circumferential direction around the main axis MA, it is only interrupted by one wall 45. It covers approximately and angle range of 351 ° to 352° around the main axis MA. In addition, it includes two discharge segments 93A and 93B that are arranged with a rotational symmetry of second order with respect to the main axis MA (and together cover in total an angle range of about 342° to 344°). An angle range covered by the wall 45 and the "non-compensated" third discharge segment 93C are comparatively small. In operation, the main fluid flow is not impaired excessively by the pilot fluid flow discharged into the main fluid passage.

[0171] October 1 , 2025 D 200 P 2647 WO

[0172] Reference signs:

[0173] 1 Axial flow control valve

[0174] 2 housing

[0175] 3 inlet port

[0176] 4 outlet port

[0177] 20 main valve body

[0178] 21 guiding chamber

[0179] 22 inner circumferential surface

[0180] 23 main valve seat

[0181] 24 circumferential wall section

[0182] 25 displacement chamber

[0183] 26 outer channel

[0184] 30 inlet component

[0185] 31 guiding chamber

[0186] 32 inner circumferential surface

[0187] 40 outlet component

[0188] 41 diffuser portion

[0189] 42 upstream end (of the diffuser portion)

[0190] 43 end face

[0191] 44 annular wall (of the outlet component)

[0192] 50 main valve element

[0193] 51 sealing section

[0194] 52 sliding portion

[0195] 53 flow guide skirt

[0196] 54 strut

[0197] 55 central portion

[0198] 56 sealing head holder

[0199] 57 spring ring

[0200] 58 upstream portion

[0201] 59 main valve spring

[0202] October 1 , 2025 D 200 P 2647 WO

[0203] 61 , 62 fluid bleed

[0204] 63 pilot pressure chamber

[0205] 64 bleed fluid channel

[0206] 70 pilot valve

[0207] 71 fluid space

[0208] 72 larger valve seat

[0209] 73 pilot valve assembly

[0210] 74 larger sealing section

[0211] 75 valve member

[0212] 76 smaller valve seat

[0213] 77 smaller sealing section

[0214] 78 (actuator-side) fluid space

[0215] 79 inner channel

[0216] 80 sliding sleeve

[0217] 81 fluid bleed

[0218] 82 pilot valve housing

[0219] 83 movable armature member

[0220] 84 pilot valve spring

[0221] 85 static armature member

[0222] 86 union nut

[0223] 87 coil

[0224] 91 pilot valve outlet channel

[0225] 92 distribution chamber

[0226] 93 discharge outlet

[0227] 93A, 93B, 93C, 93D discharge segments

[0228] AD axial direction

[0229] Adm minimum flow cross-section

[0230] Amm minimum flow cross-section

[0231] LDP longitudinal direction (of the pilot valve)

[0232] LD lateral direction

[0233] October 1 , 2025 D 200 P 2647 WO

[0234] MA main axis

[0235] MFD main flow direction

[0236] October 1 , 2025 D 200 P 2647 WO

Claims

Claims:1 . An axial flow control valve (1 ), comprising: a housing (2) with a fluid inlet (3), a fluid outlet (4), and a main fluid passage that extends from the fluid inlet (3) to the fluid outlet (4) at least substantially along a main axis (MA); a main valve for opening and closing the main fluid passage, wherein the main valve includes a main valve seat (23) arranged in the main fluid passage and a main valve element (50) that is movable with respect to the main valve seat (23); a pilot valve (70) for inducing opening and closing of the main valve; a discharge passage (91 , 92, 93) extending from the pilot valve (70) to the main fluid passage, wherein a discharge outlet (93) of the discharge passage (91 , 92, 93) opens into to the main fluid passage downstream of the main valve seat (23); characterized in that the discharge outlet (93) is annular or intermittently annular about the main axis (MA).

2. The axial flow control valve (1 ) according to claim 1 , wherein a circumferential direction in a plane perpendicular to the main axis (MA) at the discharge outlet (93) is covered by the discharge outlet to at least 85 %.

3. The axial flow control vale (1 ) according to any one of the preceding claims, wherein the discharge outlet (93) includes discharge segments (93A, 93B, 93C, 93D) that are located with a rotational symmetry of Nth order about the main axis (MA), where N is at least two.

4. The axial flow control valve (1 ) according any one of the preceding claims, wherein the main fluid passage includes a diffuser portion (41 ) downstream of the main valve seat (23), and wherein the discharge outlet (93) opens into the main fluid passageOctober 1 , 2025 D 200 P 2647 WO- between the main valve seat (23) and an upstream end (42) of the diffuser portion (41 ) and / or- within an upstream end portion of the diffuser portion (41 ).

5. The axial flow control valve (1 ) according to claim 4, wherein the housing (2) comprises an outlet component (40), wherein the outlet component (40) forms the diffuser portion (41 ) and the outlet port (4).

6. The axial flow control valve (1 ) according to claim 5, wherein housing (2) includes a main valve body (20), in which the main valve seat (23) is arranged, wherein the discharge outlet (93) is formed between the main valve body (20) and an end portion of the outlet component (40) along the main axis (MA) that faces the main valve body (20).

7. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the axial flow control valve (1 ) is configured to discharge a pilot fluid from the discharge outlet (93) into the main fluid passage at least substantially symmetrically with respect to the main axis (MA).

8. The axial flow control valve (1 ) according to any one of the preceding claims, wherein a minimum flow cross-section (Adm) of the discharge passage (91 , 92, 93) is located upstream of the discharge outlet (93).

9. The axial flow control valve (1 ) according to claim 8, wherein the discharge passage (91 , 92, 93) includes a distribution chamber (92), wherein the minimum flow cross-section (Adm) of the discharge passage (91 , 92, 93) is arranged upstream of the distribution chamber (92).

10. The axial flow control valve (1 ) according to any one of the preceding claims, wherein a flow cross-section of the discharge outlet (93) is smaller than aOctober 1 , 2025 D 200 P 2647 WOminimum flow cross-section (Amm) of the main fluid passage downstream of the main valve seat (23).

11. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the discharge outlet (93) opens into the main fluid passage where the main fluid passage has its minimum flow cross-section (Amm) downstream of the main valve seat (23).

12. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the pilot valve (70) is a multi-stage opening pilot valve.

13. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the axial flow control valve (1 ) comprises a solenoid actuator for actuating the pilot valve (70).

14. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the axial flow control valve (1 ) comprises at least one fluid bleed (61 , 62) from the main fluid passage upstream of the main valve seat (23) towards the pilot valve (70).

15. The axial flow control valve (1 ) according to claim 14, wherein the at least one fluid bleed (61 , 62), the pilot valve (70), and the discharge passage (91 , 92, 93) form part of a fluid bypass for bypassing the main valve seat (23) when the pilot valve (70) is open.

16. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the housing (2) comprises an inlet component (30) including the inlet port (3).October 1 , 2025 D 200 P 2647 WO17. The axial flow control valve (1 ) according to any one of the preceding claims, wherein the main valve element (50) is movable parallel to the main axis (MA) with respect to the main valve seat (23).October 1 , 2025 D 200 P 2647 WO

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