Coupling element for a hydraulic coupling

Abstract

The invention relates to a coupling element, in particular a coupling sleeve (1) or coupling plug (6), for a hydraulic coupling on a pressure medium line, having a housing (2, 7) and a sealing unit (3, 8), wherein the housing (2, 7) has a flow channel (28, 75) for a pressure medium and a coupling axis (A), and is formed from a main body (21, 71) and at least one sleeve body (24, 25, 73) which is connected to the main body in a form-fitting and / or force-fitting manner, wherein the main body (21, 71) and one sleeve body (25, 73) of the at least one sleeve body delimit an annular channel (53, 93) with a preferably rectangular cross-section, in which a sealing ring, preferably an O-ring (51, 91) for sealing a sealing gap (55, 95) delimited between the main body (21, 71) and the sleeve body (25, 73) is arranged, and wherein the main body (21, 71) and the sleeve body (25, 73) each have an annular depression, as a result of which in each case one step (23, 26, 72, 741) is formed, the two flanks of which supplement one another to form a first side wall (531, 741) of the channel (531, 93), said side wall being arranged on the side of the sealing ring opposite the applied fluid pressure, and between which flanks the sealing gap (55, 95) to be sealed opens.

Description

[0001] Lawyer's file 26027

[0002] February 24, 2026

[0003] Coupling element for a hydraulic coupling

[0004] The invention relates to a coupling element, in particular a coupling sleeve for a hydraulic coupling on a pressure medium line according to the preamble of claim 1.

[0005] Hydraulic couplings consist of a coupling sleeve and a coupling plug that connects to it. They are used to connect two sections of a hydraulic line, through which hydraulically operated devices, such as tools or attachments, are connected to a hydraulic source, such as an agricultural or construction machine. Generally, a hydraulic coupling transfers fluid energy from a machine to a working device. This process generates high static and dynamic loads.

[0006] The amount of fluid energy depends on pressure and flow rate. Since high flow rates always lead to power losses due to friction, it is more efficient for the system to transmit high power at lower flow rates using high pressures. Against this background, the pressure resistance of a fluid coupling is of crucial importance.

[0007] Since fluid couplings are also used in bypasses, i.e., in a branch of a pipeline, they can be subjected to dynamic pressure loads even when uncoupled. Therefore, the couplings must exhibit high pressure resistance in both the coupled and uncoupled states.

[0008] Flat-sealing coupling sleeves and coupling plugs are known from the prior art. These are characterized by the fact that, in the unconnected (uncoupled) state, the components of the coupling plug or coupling sleeve form a flat and closed surface in the connection interface area. This prevents the ingress of dirt into the housing and between the components, and reliably prevents the loss of pressure medium.

[0009] Engaging a hydraulic coupling, i.e., creating a positive connection between a coupling sleeve and a coupling plug, is typically achieved by inserting the coupling plug into a coupling sleeve. The force applied during insertion opens a valve, connecting the flow channel of the coupling plug to the flow channel of the coupling sleeve. This simultaneously creates a positive connection between the coupling plug and coupling sleeve, stabilizing the connection and the engaged state. When disengaged, the flow channels of the coupling sleeve and coupling plug are sealed from the environment.

[0010] Figure 1 schematically depicts a coupling sleeve known in the prior art, and Figure 2 schematically depicts a coupling plug known in the prior art. One of the coupling elements, in this case the coupling sleeve, has a fixed plunger and a movable valve sleeve. In the closed state, the valve sleeve is sealed against the plunger and against the fluid-carrying flow channel of the coupling half. In the coupled state, the valve sleeve is sealed against the flow channels of both coupling elements. The fixed plunger is held in a plunger guide that includes at least two retaining elements. The other coupling element, in this case the coupling plug, has a movable valve plunger that is sealed against the flow channel in the closed state.

[0011] The flow channels of both coupling halves are delimited at their ends opposite the respective valve stems by a connecting element to which a fluid line can be attached. The two coupling elements are connected, as is known, by a screw sleeve rotatably mounted on one coupling element, which can be screwed onto a thread of the second coupling element. Alternatively, one coupling element has an axially displaceable sleeve and radially movable detent elements, for example, balls, with the other coupling element having a circumferential groove on its outer surface into which the detent elements engage when coupled.

[0012] The seals between two components that define the flow channel are crucial for the pressure resistance of the hydraulic coupling. Soft seals, made of materials such as elastomers or plastics like thermoplastic polyurethane, are frequently used. In addition to the soft seal, backup rings made of harder materials like PTFE or other plastics such as polyamide are often employed. Two fundamentally different types of seals are distinguished.

[0013] One type of seal is axial sealing, in which a groove is machined into the end face of one of the components to be sealed against each other. At least one sealing element is positioned in this groove. The sealing elements seal against the bottom of the groove. The second component has a flat surface at the location of the axial groove of the first component, against which the sealing elements seal. The outer shoulder of the groove in the first component and the flat surface of the second component form the sealing gap on the side opposite the pressure. The width of this sealing gap is zero due to the tension between the two components. However, under pressure, the width of this sealing gap can increase due to elastic deformation of the components.

[0014] The second type is the radial seal, in which either a radial inner groove is incorporated into the outer component or a radial outer groove is incorporated into the inner component. The sealing elements are positioned in these grooves, sealing against the groove base. In the case of the radial inner groove, the second part has a cylindrical outer surface against which the sealing elements seal. In the case of the radial outer groove, the second part has a cylindrical inner surface against which the sealing elements seal. The sealing gap on the side opposite the pressure is formed by the cylindrical inner or outer surface of one component and a groove shoulder of the second component. Under high, especially dynamic, pressure loads, gap extrusion of the soft seals and, if applicable, the support rings into the sealing gap on their side opposite the pressure can occur in both sealing types. Gap extrusion is a progressive process that can ultimately lead to leakage.This affects the pressure resistance and the maximum possible operating pressure.

[0015] The invention aims to remedy this problem. The invention is based on the objective of providing a coupling element for a hydraulic coupling on a pressure medium line, the pressure resistance and maximum possible operating pressure of which are increased. According to the invention, this objective is achieved by a coupling element with the features of claim 1.

[0016] The invention provides a coupling element for a hydraulic coupling on a pressure medium line, the pressure resistance and maximum possible operating pressure of which are increased. Because the base body and the sleeve body each have an annular recess, thereby forming a step whose two flanks combine to form a first side wall of the channel, which is arranged on the side of the sealing ring opposite the applied fluid pressure and between which the sealing gap to be sealed opens, the sealing gap facing away from the pressure, which is to be sealed by the sealing ring, is not located, as in the prior art, on an extension of the sealing surface against which the sealing ring seals, but offset from it.

[0017] The step on both sealing surfaces of the components ensures that the gap on the side facing away from the pressure does not directly adjoin the sealing surface. This means that even in the event of gap extrusion, no material from the sealing ring that seals against the sealing surface is extruded into the sealing gap, which would directly impair the preload of the seal. Instead, only material from the seal or the support ring that is at a certain distance from the sealing surface can extrude into the sealing gap. This effectively prevents any impairment of the preload of the sealing ring against the sealing surface. In a further development of the invention, the recess in the base body or the sleeve body is formed by a groove whose opposing flanks have different heights. This achieves axial fixation of the sealing ring and an offset between the sealing surface and the sealing gap.

[0018] In one embodiment of the invention, the second groove flank opposite the sealing gap has a greater height than the opposite first groove flank, the height of the second groove flank preferably corresponding to the height of the first side wall of the channel. This maximizes the axial contact area for the sealing ring.

[0019] In a further embodiment of the invention, the second groove flank is formed by an additional component. This enables damage-free installation of the sealing ring.

[0020] In a further development of the invention, a support ring is arranged axially next to the sealing ring, preferably on its side facing the sealing gap. This counteracts pressure-induced deformation of the sealing ring.

[0021] In an embodiment of the invention, the coupling element is a coupling sleeve, wherein the first side wall of the channel, which contains the sealing gap to be sealed, extends parallel to the coupling axis, and wherein the second side wall of the channel is formed by a plunger guide that receives a valve plunger. This ensures a reliable seal between the plunger guide and the housing of the coupling element. Preferably, the plunger guide is formed from at least two retaining elements.

[0022] In a further embodiment of the invention, the valve tappet has at least one groove with a first groove flank facing the valve piston and a second groove flank opposite it, facing away from the valve piston, into which the tappet guide engages, thereby forming a positive connection between the tappet guide and the valve tappet. The second groove flank of the at least one groove, facing away from the valve head of the valve tappet, is conically widening outwards. This provides a fixed mounting of the valve tappet, reducing stresses that can arise from notch effects in the groove and that can lead to breakage at higher pressures or dynamic loads. The conical bearing surface increases the contact area of ​​the tappet on the mounting elements and improves the force transmission within the tappet. The maximum stress in the mounting elements can also be reduced in this way.

[0023] Preferably, the second groove flank of the at least one groove has a cone angle of between 50° and 140°, particularly preferably between 60° and 130°, and especially between 70° and 120°. The cone angle is the angle of an imaginary cone on which the first groove flank of the at least one groove lies.

[0024] In a further embodiment of the invention, the coupling element is a coupling plug, wherein the first side wall of the channel, which has the sealing gap to be sealed, extends orthogonally to the coupling axis.

[0025] Other embodiments and configurations of the invention are specified in the remaining dependent claims. An exemplary embodiment of the invention is illustrated in the drawings and is described in detail below. The drawings show:

[0026] Figure 1 shows a schematic representation of a coupling sleeve of a hydraulic coupling according to the prior art.

[0027] a) in longitudinal section;

[0028] b) in detail section Z (sealing area);

[0029] c) in detail section Y (piston receptacle);

[0030] Figure 2 shows a schematic representation of a coupling plug of a hydraulic coupling according to the prior art a) in longitudinal section;

[0031] b) in detail section Z (sealing area);

[0032] Figure 3 shows a schematic representation of a coupling sleeve of a hydraulic coupling.

[0033] a) in longitudinal section; b) in detail section Z (sealing area);

[0034] c) in detail section Y (ram receiving area Y)

[0035] Figure 4 shows a schematic representation of a coupling plug of a hydraulic coupling.

[0036] a) in longitudinal section;

[0037] b) in detail section Y (sealing area);

[0038] Figure 5 shows a hydraulic coupling with a coupling sleeve and a coupling plug connected to it;

[0039] Figure 6 shows a detailed view of section X of the hydraulic coupling from Figure 5.

[0040] The coupling sleeve 1 selected as an embodiment according to Figure 3 comprises a housing 2 with a sealing unit 3. The housing 2 defines a flow channel 28 for a pressure medium, wherein the housing 2 extends substantially rotationally symmetrically about a coupling axis A.

[0041] The housing 2 comprises a base body 21, a first sleeve body 24 connected to it, and a second sleeve body 25 surrounded by the first sleeve body 24 and axially clamped between the base body 21 and the first sleeve body 24. A closure sleeve 27 is slidably arranged on the outside of the first sleeve body 24. A plunger guide 4, which in the exemplary embodiment is formed from two retaining elements 41 and which receives the valve plunger 31 of the sealing unit 3, is also axially clamped between the second sleeve body 25 and the base body 21.

[0042] The base body 21 of the housing 2 is essentially hollow cylindrical and has an internally enlarged section 211 at its end facing the first sleeve body 24, which is provided with an internal thread 212. An end face 22 is defined by the internally enlarged section 211, into which an annular first step 23 is inserted.

[0043] The first sleeve body 24 has, on its inner side facing the valve tappet 31, a first shoulder 241 with an increased inner diameter, which transitions at its end into a second shoulder 242, also with an increased inner diameter. Opposite the second shoulder 242, the first sleeve body 24 is provided with an external thread 243.

[0044] The second sleeve body 25 has an outwardly projecting annular flange 251 at its end facing the base body 21, which has an annular second step 26 at its end. Opposite the annular flange 251, the second sleeve body 25 has a third shoulder 252 with an increased inner diameter, into which the retaining elements 41 of the plunger guide 4 extend.

[0045] The first sleeve body 25 is screwed with its external thread into the internal thread 212 of the base body 21, whereby the first sleeve body 25 clamps the ring flange 251 of the second sleeve body 25, which extends into its second shoulder 242, against the end face 22 of the base body 21. At the same time, the sections of the retaining elements 41 projecting into the internally enlarged third shoulder 252 are clamped against the end face 22 of the base body 21.

[0046] Here, the second stage 26 of the second sleeve body 25 is arranged opposite the first stage 23 of the base body 21, with the two flanks of the two stages 23, 26 forming a first side wall 531, between which a sealing gap 55 opens. Parallel to this first side wall 531, the retaining elements 41 are arranged, forming a second side wall 532 of the annular channel 53 formed between the base body 21, the second sleeve body 25, and the retaining elements 41 of the plunger guide 4. A support ring 52 and an O-ring 51 are arranged in the channel 53 against the first side wall 531. The support ring 52 and the O-ring 51 are pre-tensioned against the sealing surface 54 of the base body 21, which is bounded by the first stage 23 and the two retaining elements 41. The sealing surface 54 is arranged axially offset from the sealing gap 55. The sealing arrangement 5 thus formed is shown in Figure 3 b).The sealing unit 3 comprises the valve tappet 31, which is received by the tappet guide 4; a valve sleeve 36, which is slidably arranged between the second sleeve body 25 and the valve tappet, for sealing contact with a piston seal 35, which is arranged on the valve piston 32 of the valve tappet 31 and fixed by a cam sleeve 351; and a pressure sleeve 37, which is slidably arranged between the first sleeve body 24 and the second sleeve body 25. The valve sleeve 36 is preloaded against the piston seal 35 by a compression spring 38. The pressure sleeve 37 has an annular collar 371 at its end facing away from the tappet guide 4, which forms a common plane with the outwardly facing side of the valve piston 32. At its end facing away from the collar 371, a circumferential outwardly projecting web 372 is arranged on the pressure sleeve 37, which rests against the first shoulder 241 of the first sleeve body 24, against which it is pre-tensioned by a further compression spring 38.

[0047] In an end region of the valve tappet 31, a circumferential groove 34 is formed in the tappet shaft 33, into which two retaining elements 41 of the tappet guide 4 are inserted. The first groove flank 341 of the groove 34, facing the valve piston 32, is arranged orthogonally to the central axis of the tappet shaft 33. The second groove flank 342 of the groove 34, opposite the first groove flank 341, is inclined outwards and forms a cone, which in the exemplary embodiment has a cone angle oc of 130°. The outer contour of the sections of the retaining elements 41 inserted into the groove 34 corresponds to the inner contour of the groove 34 (see Figure 3c). The valve tappet 31 is held stationary in the housing 2 by the tappet guide 4.Instead of the circumferential groove 34, several grooves can also be arranged circumferentially in the plunger shaft 33, offset from each other, each receiving a retaining element and whose second groove flank is inclined outwards and lies on a common imaginary cone.

[0048] The coupling plug 6 selected as an embodiment according to Figure 4 comprises a housing 7 with a sealing unit 8. The housing 7 defines a flow channel 75 for a pressure medium, wherein the housing 7 extends substantially rotationally symmetrically about a coupling axis A.

[0049] The housing 7 is formed from a base body 71 onto which a connector sleeve 73 is screwed. The base body 71 is essentially hollow and cylindrical and has at its end a section 711 with a reduced outer diameter and an external thread 712, to which a first stage 72 adjoins. The connector sleeve 73 has at its end facing the base body 71 an internally enlarged section 731, which is provided with an internal thread 732. Adjoining the internal thread is a groove 74, which is bounded by a first groove flank 743 and a second groove flank 744 opposite it, and which forms a second stage 741 and, opposite this, a third stage 742.At its end opposite the internally diameter-enlarged section 731, an annular groove 76 is provided in the plug sleeve, into which a profile seal pre-tensioned with two O-rings 761 is provided for sealing against the valve piston 81 of the sealing unit 8.

[0050] The connector sleeve 73 is screwed onto the external thread 712 of the base body 71 with its internal thread 732. The second stage 741 of the connector sleeve 73 is arranged opposite the first stage 72 of the base body 71, with the two flanks of the two stages 72, 741 forming a first side wall 931, between which a sealing gap 95 opens.

[0051] Parallel to this first side wall 931, the third stage 742, formed by the groove 74, is arranged, wherein the second groove flank 744 of the groove 74 forms a second side wall 932 of the annular channel 93 formed between the outer diameter-reduced section 711 of the base body 71 and the inner diameter-expanded section 731 of the connector sleeve 71. The width of the third stage 742 corresponds to the width of the first side wall 931 of the channel 93 formed by the first stage 72 of the base body 71 and the second stage 741 of the connector sleeve. A support ring 92 and an O-ring 91 are arranged in the channel 93, abutting the first side wall 931. The support ring 92 and the O-ring 91 are pre-tensioned against the sealing surface 94 of the base body 71, which is bounded by the first stage 72 of the base body 71 and the second stage 741 of the connector sleeve 73. The sealing surface 94 is arranged radially offset from the sealing gap 95.The sealing arrangement 9 thus formed is shown in Figure 4 b).

[0052] The sealing unit 8 comprises a valve piston 81, which is slidably guided in the housing 7 and pre-tensioned into the closed position by a compression spring 83. The valve piston 81 has through-openings 82 for the passage of pressure medium from the flow channel 75. In the closed position of the valve piston 81, the profile seal, arranged in the annular groove 76 of the connector sleeve 73 and pre-tensioned by the two O-rings 761, abuts the valve piston 81 in a sealing manner.

[0053] Figure 5 schematically shows a coupling with a coupling sleeve 1 and a coupling plug 6. When the coupling plug 6 is inserted into the coupling sleeve 1, the pressure sleeve 37 of the coupling sleeve 1 is moved by the plug sleeve 73 of the coupling plug 6 against the preload of the compression spring 38 towards the base body 21, thereby carrying the valve sleeve 36 with it. Simultaneously, the valve piston 81 of the coupling plug 6 is moved by the stationary valve tappet 31 of the coupling sleeve 1 against the preload of the compression spring 38, thus connecting the flow channel 28 of the coupling sleeve 1 with the flow channel 75 of the coupling plug 6.

Claims

Patent claims 1. Coupling element, in particular coupling sleeve (1) or coupling plug (6), for a hydraulic coupling on a pressure medium line, comprising a housing (2, 7) and a sealing unit (3, 8), wherein the housing (2, 7) has a flow channel (28, 75) for a pressure medium and a coupling shaft (A) and is formed from a base body (21, 71) and at least one sleeve body (24, 25, 73) positively and / or force-fit connected to it, wherein the base body (21, 71) and a sleeve body (25, 73) of the at least one sleeve body define an annular channel (53, 93) with a preferably rectangular cross-section, in which a sealing ring, preferably an O-ring (51, 91), is located for sealing a space between the base body (21, 71) and the sleeve body (25, 73). sealing gap (55, 95) is arranged, characterized in that the base body (21, 71) and the sleeve body (25, 73) each have an annular recess, whereby each has a step (23,26, 72, 741) is formed, the two flanks of which combine to form a first side wall (531, 931) of the channel (53, 93), which is arranged on the side of the sealing ring opposite the applied fluid pressure and between which the sealing gap (55, 95) to be sealed opens.

2. Coupling element according to claim 1, characterized in that the recess in the base body (21 , 71 ) or the sleeve body (25, 73) is formed by a groove (74) whose opposing groove flanks (743, 744) have different heights.

3. Coupling element according to claim 2, characterized in that the second groove flank (744) of the groove (74) opposite the sealing gap (55, 95) has a greater height than the opposite first groove flank (743), wherein the height of the second groove flank (743) preferably corresponds to the height of the first side wall (531, 931) of the channel (53, 93).

4. Coupling element according to claim 3, characterized in that the second groove flank (744) is formed by a separate component.

5. Coupling element according to one of the preceding claims, characterized in that a support ring (52, 92) is arranged axially next to the sealing ring, preferably on its side facing the sealing gap (55, 95).

6. Coupling element according to one of the preceding claims, characterized in that it is a coupling sleeve (1), wherein the first side wall (531) of the channel (53) having the sealing gap (55) to be sealed extends parallel to the coupling axis (A), wherein the second side wall (532) of the channel (53) is formed by a plunger guide (4) which receives a valve plunger (31).

7. Coupling element according to claim 6, characterized in that the plunger guide (4) is formed from at least two retaining elements (41).

8. Coupling element according to claim 6 or 7, characterized in that the valve tappet (31) has at least one groove (34) with a first groove flank (341) facing the valve piston (32) and a second groove flank (342) opposite this, facing away from the valve piston (32), into which the tappet guide (4) engages, whereby the tappet guide (4) and the valve tappet (31) are positively connected, wherein the second groove flank (342) of the at least one groove (34) facing away from the valve piston (32) of the valve tappet (31) is conically widening outwards.

9. Coupling element according to claim 8, characterized in that the second groove flank (342) of the at least one groove (34) has a cone angle of between 50° and 140°, preferably between 60° and 130°, particularly preferably between 70° and 120°.

10. Coupling element according to one of claims 1 to 5, characterized in that this is a coupling plug (6), wherein the first side wall (931) of the channel (93) having the sealing gap (95) to be sealed extends orthogonally to the coupling axis (A).

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