Coupling element for a hydraulic coupling

Abstract

Coupling element, in particular a coupling sleeve (1) or coupling plug (6), for a hydraulic coupling on a pressure medium line, with 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 base body (21, 71) and at least one sleeve body (24, 25, 73) connected to the latter in a form-fitting and / or force-fitting manner, wherein the base body (21, 71) and a 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), characterized in that the base body (21, 71) and the sleeve body (25, 73) each have an annular recess, whereby a step (23, 26, 72,741), the two flanks of which complement each other 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.

Description

The invention relates to a clutch element, in particular a clutch sleeve for a hydraulic clutch on a pressure medium line according to the preamble of claim 1.Hydraulic couplings consist of a combination of a coupling sleeve and a coupling plug connectable to the latter. They are used to connect two sections of a pressure medium line, via which hydraulically operated devices, for example tools or attachments, are connected to a hydraulic source, for example an agricultural machine or a construction machine. Generally, flow energy is transmitted from a machine to a working device via a hydraulic clutch. High static and dynamic loads are thereby produced.The level of the flow energy is dependent on the pressure and volume flow. Since high volume flows always also lead to power losses due to friction, it is better for the efficiency of the system to transmit high powers due to high pressures at lower volume flows. Against this background, the pressure resistance of a fluid coupling is of decisive importance.Since fluid couplings are also used in bypasses, i.e. are used in a branch of a line, they can also be dynamically pressurized in the uncoupled state. It follows from this that the clutches must have a high pressure resistance both in the coupled and in the uncoupled state.From the prior art, so-called flat-sealing coupling sleeves and coupling plugs are known, which are characterized in that in the non-connected-uncoupled-state a planar and closed surface is formed by the components of the coupling plug or the coupling sleeve in the connection interface region. This prevents the entry of dirt into the housing and between the components and prevents the loss of pressure medium in a reliable manner.The coupling of a hydraulic coupling, i.e. the establishment of a positive connection between a coupling sleeve and a coupling plug, is usually effected by inserting the coupling plugs into a coupling sleeve, wherein the force applied during the insertion opens both a valve in each case in order to connect the flow channel of the coupling plug in terms of flow to the flow channel of the coupling sleeve. At the same time, this produces a positive connection between the coupling plug and the coupling sleeve in order to stabilize the connection or the coupled state. In the uncoupled state, the flow channels of coupling sleeve and coupling plug are sealed from the environment.FIG. 1 schematically shows a coupling sleeve known in the prior art, and FIG. 2 schematically shows a coupling plug known in the prior art. One of the coupling elements, in the present case the coupling sleeve, has a fixed tappet and a movable valve sleeve. In the closed state, the valve sleeve is sealed against the tappet and against the fluid-conducting 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 which comprises at least two holding elements. The other of the coupling elements, in the present case the coupling plug, has a movable valve tappet which is sealed against the flow channel in the closed state.The flow channels of both coupling halves are bounded at their end facing away from the respective valve jacks by a connecting part to which a fluid line can be connected. The connection of the two coupling elements is effected, as is known, via a screw sleeve which is rotatable on a coupling element and can be screwed onto a thread of the second coupling element. Alternatively, a coupling element has an axially displaceable sleeve and radially movable latching bodies, for example balls, wherein a circumferential groove is present on the outside of the other coupling element, in which groove the latching bodies engage in the coupled state.The seals between two components delimiting the flow channel are decisive for the pressure resistance of the hydraulic coupling. Soft seals are frequently used here as seals, which are produced, for example, from elastomers or else plastics such as thermoplastic polyurethane. In addition to the soft seal, support rings are frequently additionally used, which are made of harder material, such as PTFE, for example, or other plastics such as polyamide. Two embodiments which can be distinguished in principle are distinguished in the case of the seals.One form is axial sealing, in which a groove is introduced on the end face in one of the components to be sealed with respect to one another, in which groove at least one sealing element is positioned. The sealing elements seal against the groove base. 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 of the first component and of the flat surface of the second component form the sealing gap facing away from the pressure, the width of which gap is equal to zero by bracing the two components against one another. However, when a compressive load is applied, the width of this sealing gap can increase due to elastic deformation of the components.The second form is the radial seal, in which either a radial inner groove is introduced in the outer component or a radial outer groove in the inner component. In these grooves are positioned the sealing elements which seal against the groove base. The respective second part has, in the case of the radial inner groove, a cylindrical outer surface on which the sealing elements seal. In the case of the radially outer groove, the second part has a cylindrical inner surface on which the sealing elements seal. The sealing gap on the side facing away from the pressure is formed by the cylindrical inner or outer surface of the one component and a groove shoulder of the second component.In the case of high, in particular dynamic, pressure loads, in the case of both sealing molds, gap extrusion of the soft seals and, if appropriate, of the supporting rings into the sealing gap located on the side facing away from the pressure can occur. Gap extrusion is a progressive process that can ultimately result in leakage. This influences the pressure resistance and the maximum possible operating pressure.The invention seeks to remedy this. The invention is based on the object of providing a clutch element for a hydraulic clutch on a pressure medium line, the pressure resistance of which and the maximum possible operating pressure are increased. According to the invention, this object is achieved by a coupling element having the features of claim 1.The invention provides a clutch element for a hydraulic clutch on a pressure medium line, the pressure resistance of which element and the maximum possible operating pressure are increased. Because the base body and the sleeve body each have an annular depression, as a result of which a step is formed in each case, the two flanks of which complement one another 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 and to be sealed by the sealing ring is not, as in the prior art, on an extension of the sealing surface against which the sealing ring seals, but offset with respect thereto.The step on the two sealing surfaces of the components ensures that the gap on the side facing away from the pressure does not directly connect to the sealing surface. This has the consequence that even in the case of slot extrusion no material of the sealing ring which seals towards the sealing surface extrudes into the sealing slot, which would directly result in an impairment of the prestress of the seal. Rather, only material of the seal or of the support ring can extrude into the sealing gap, which has a certain distance from the sealing surface. This effectively prevents the prestressing of the sealing ring against the sealing surface from being impaired.In a further development of the invention, the depression in the base body or the sleeve body is formed by a groove, the opposite flanks of which have a different height. This achieves an axial fixing of the sealing ring and an offset between the sealing surface and the sealing gap.In one embodiment of the invention, the second groove flank of the groove opposite the sealing gap has a greater height than the opposite first groove flank, wherein the height of the second groove flank preferably corresponds to the height of the first side wall of the channel. As a result, the axial contact surface for the sealing ring is maximized.In a further embodiment of the invention, the second groove flank is formed by an additional component. This allows damage-free mounting of the sealing ring.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 a pressure-induced deformation of the sealing ring.In one embodiment of the invention, the coupling element is a coupling sleeve, wherein the first side wall of the channel having the sealing gap to be sealed extends parallel to the coupling axis, wherein the second side wall of the channel is formed by a tappet guide which receives a tappet. This achieves a reliable sealing of the tappet guide against the housing of the coupling element. The plunger guide is preferably formed from at least two holding elements.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 the first groove flank facing away from the valve piston, in which the tappet guide engages, whereby the tappet guide and the valve tappet are connected in a positive-locking manner, wherein the second groove flank of the at least one groove facing away from the valve head of the valve tappet is designed to expand conically outwards. This results in a fixed mounting of the valve tappet, wherein stresses which can result from notch effects of the groove and which can lead to breakage at higher pressures or also dynamic loads are reduced. Due to the conical support, on the one hand, the support surface of the plunger on the holding elements is increased and, on the other hand, the force flow in the plunger is improved. The maximum stress can thus also be reduced in the holding elements.The second groove flank of the at least one groove preferably has a cone angle of between 50° and 140°, particularly preferably of between 60° and 130°, in particular of 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.In a further embodiment of the invention, the coupling element is a coupling plug, wherein the first side wall of the channel having the sealing gap to be sealed extends orthogonally to the coupling axis.Other developments and embodiments 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 following are shown: FIG. 1 shows the schematic representation of a coupling sleeve of a hydraulic coupling according to the prior art a) in longitudinal section; b) in detail section Z (sealing region); c) in detail section Y (tappet receptacle); FIG. 2 shows the schematic representation of a coupling plug of a hydraulic coupling according to the prior art a) in longitudinal section; b) in detail section Z (sealing region); FIG. 3 shows the schematic representation of a coupling sleeve of a hydraulic clutch a) in longitudinal section; b) in detail section Z (sealing region); c) in detail section Y (tappet receiving region Y) FIG. 4 shows the schematic representation of a coupling plug of a hydraulic coupling a) in longitudinal section; b) in detail section Y (sealing region); FIG. 5 shows the representation of a hydraulic coupling with a coupling sleeve and a coupling plug connected to the latter; FIG. 6 shows the detailed illustration of the detail X of the hydraulic clutch from FIG. 5.The coupling sleeve 1 selected as an exemplary embodiment according to FIG. 3 comprises a housing 2 with a sealing unit 3. the housing 2 delimits a flow channel 28 for a pressure medium, wherein the housing 2 extends substantially rotationally symmetrically about a coupling axis A.The housing 2 comprises a base body 21, a first sleeve body 24 connected thereto 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. Furthermore, a tappet guide 4 is axially clamped between the second sleeve body 25 and the base body 21, which is formed from two holding elements 41 in the exemplary embodiment and which accommodates the tappet 31 of the sealing unit 3.The base body 21 of the housing 2 is substantially hollow-cylindrical and has, at its end facing the first sleeve body 24, an inner-diameter-widened portion 211, which is provided with an internal thread 212. The inner diameter-widened section 211 delimits an end face 22, into which an annular first step 23 is introduced.The first sleeve body 24 has, on its inner side facing the valve tappet 31, an inner diameter-widened first shoulder 241, which merges at the end side into a second shoulder 242, which is again enlarged in the inner diameter. Opposite the second shoulder 242, the first sleeve body 24 is provided with an external thread 243.The second sleeve body 25 has, at its end facing the base body 21, an outwardly projecting annular flange 251, which has an annular second step 26 on its end. Opposite the annular flange 251, the second sleeve body 25 has a third shoulder 252 which is widened in the inner diameter and into which the retaining elements 41 of the plunger guide 4 extend.The first sleeve body 25 is screwed with its external thread into the internal thread 212 of the base body 21, wherein the first sleeve body 25 clamps the annular flange 251 of the second sleeve body 25 extending into its second shoulder 242 against the end face 22 of the base body 21. At the same time, the sections of the holding elements 41 projecting into the third shoulder 252 widened in the inner diameter are braced against the end face 22 of the base body 21.In this case, the second step 26 of the second sleeve body 25 is arranged opposite the first step 23 of the base body 21, wherein the two flanks of the two steps 23, 26 complement one another to form a first side wall 531, between which a sealing gap 55 opens out. Arranged parallel to this first side wall 531 are the holding elements 41, which form a second side wall 532 of the annular channel 53 formed between the base body 21, the second sleeve body 25 and the holding elements 41 of the plunger guide 4. In the channel 53, a support ring 52 is arranged resting against the first side wall 531 and an O-ring 51 resting against this. Support ring 52 and O-ring 51 are prestressed against the sealing surface 54 of the base body 21 delimited by the first step 23 and the two holding elements 41. The sealing surface 54 is arranged axially offset with respect to the sealing gap 55. The sealing arrangement 5 formed in this way is shown in FIG. 3 b).The sealing unit 3 comprises the valve tappet 31 received by the tappet guide 4, a valve sleeve 36 arranged displaceably between the second sleeve body 25 and the valve tappet for sealing contact with a piston seal 35 arranged on the valve piston 32 of the valve tappet 31 and fixed via a chamber sleeve 351, and a pressure sleeve 37 arranged displaceably between the first sleeve body 24 and the second sleeve body 25. The pressure sleeve 37 has, at its end facing away from the plunger guide 4, an annular collar 371 which forms a common plane with the outwardly directed 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 web bears against the first shoulder 241 of the first sleeve body 24, against which it is prestressed by a further compression spring 38.In an end-side region of the valve tappet 31, a circumferential groove 34 is formed in the tappet shank 33, into each of 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 plunger shaft 33. The second groove flank 342 of the groove 34 opposite the first groove flank 341 is formed to be inclined outwards and forms a cone which in the exemplary embodiment has a cone angle α of 130°. The outer contour of the sections of the holding elements 41 inserted into the groove 34 are designed here corresponding to the inner contour of the groove 34 (cf. FIG. 3 c )). The valve tappet 31 is held in a fixed position in the housing 2 via the tappet guide 4. Instead of the circumferential groove 34, a plurality of grooves arranged offset from one another circumferentially in the tappet shank 33 can also be arranged, which grooves each receive a retaining element and the second groove flank of which grooves are each formed inclined outwards and lie on a common imaginary cone.The coupling plug 6 selected as an exemplary embodiment according to FIG. 4 comprises a housing 7 with a sealing unit 8, the housing 7 delimiting a flow channel 75 for a pressure medium, wherein the housing 7 extends substantially rotationally symmetrically about a coupling axis A.The housing 7 is formed from a base body 71 onto which a plug sleeve 73 is screwed. The base body 71 is substantially hollow-cylindrical and has, on the end side, an outer diameter-reduced section 711 with an external thread 712, which is adjoined on the end side by a first step 72. The plug sleeve 73 has, at its end facing the base body 71, an inner diameter-widened portion 731 which is provided with an internal thread 732. The internal thread is adjoined by a groove 74 which is bounded by a first groove flank 743 and a second groove flank 744 opposite it and by which a second step 741 and a third step 742 opposite it are formed. At its end opposite the inner diameter widened section 731, an annular groove 76 is formed in the plug sleeve, into which an profiled seal prestressed by two O-rings 761 is formed for sealing with respect to the valve piston 81 of the sealing unit 8.The plug sleeve 73 is screwed with its internal thread 732 onto the external thread 712 of the base body 71. In this case, the second step 741 of the plug sleeve 73 is arranged opposite the first step 72 of the base body 71, wherein the two flanks of the two steps 72, 741 complement one another to form a first side wall 931, between which a sealing gap 95 opens out.The third step 742 formed by the groove 74 is arranged parallel to this first side wall 931, wherein the second groove flank 744 of the groove 74 forms a second side wall 932 of the annular channel 93 formed between the reduced-diameter section 711 of the base body 71 and the enlarged-diameter section 731 of the plug sleeve 71. The width of the third step 742 corresponds to the width of the first side wall 931 of the channel 93 formed by the first step 72 of the base body 71 and the second step 741 of the plug sleeve.In the channel 93, a support ring 92 is arranged resting against the first side wall 931 and an O-ring 91 resting against this. Support ring 92 and O-ring 91 are prestressed against sealing surface 94 of base body 71 delimited by first step 72 of base body 71 and second step 741 of plug sleeve 73. The sealing surface 94 is arranged radially offset with respect to the sealing gap 95. The sealing arrangement 9 formed in this way is shown in FIG. 4 b).The sealing unit 8 comprises a valve piston 81 which is displaceably guided in the housing 7 and is prestressed into the closed position by means of a compression spring 83. In the valve piston 81, passage openings 82 are provided 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 plug sleeve 73 and prestressed via the two O-rings 761 bears sealingly against the valve piston 81.FIG. 5 schematically shows a coupling with a coupling sleeve 1 and a coupling plug 6. By inserting the coupling plug 6 into the coupling sleeve 1, on the one hand the pressure sleeve 37 of the coupling sleeve 1 is moved by the plug sleeve 73 of the coupling plug 6 counter to the prestress of the compression spring 38 in the direction of the base body 21, wherein it drives the valve sleeve 36 with it. On the other hand, the valve piston 81 of the coupling plug 6 is moved by the fixed valve tappet 31 of the coupling sleeve 1 counter to the prestress of the compression spring 38, as a result of which the flow duct 28 of the coupling sleeve 1 is connected to the flow duct 75 of the coupling plug 6.

Claims

Coupling element, in particular 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 duct (28, 75) for a pressure medium and a coupling axis (A) and is formed from a base body (21, 71) and at least one sleeve body (24, 25, 73) connected thereto in a positive-locking and / or non-positive-locking manner, wherein the base body (21, 71) and a sleeve body (25, 73) of the at least one sleeve body delimit an annular duct (53, 93) with a preferably rectangular cross section, in which a sealing ring, preferably an O-ring (51, 91), is arranged for sealing a sealing gap (55, 95) delimited between the base body (21, 71) and the sleeve body (25, 73), characterized in that, the base body (21, 71) and the sleeve body (25, 73) each have an annular depression, whereby a step (23, 26, 72, 741) is formed in each case, the two flanks of which complement one another 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.Coupling element according to claim 1, characterised in that the depression in the base body (21, 71) or the sleeve body (25, 73) is formed by a groove (74), the opposite groove flanks (743, 744) of which have a different height.Coupling element according to Claim 2, characterized in that the second groove flank (744) of the groove (74), which flank is 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).Coupling element according to Claim 3, characterized in that the second groove flank (744) is formed by a separate component.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 resting on its side facing the sealing gap (55, 95).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), which has 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 tappet guide (4) which accommodates a tappet (31).Coupling element according to claim 6, characterised in that the plunger guide (4) is formed from at least two retaining elements (41).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 the latter and facing away from the valve piston (32), in which groove flank the tappet guide (4) engages, as a result of which the tappet guide (4) and the valve tappet (31) are connected in a positive-locking manner, 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 designed such that it widens conically outwards.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 of between 60° and 130°, particularly preferably of between 70° and 120°.Coupling element according to one of Claims 1 to 5, characterized in that it is a coupling plug (6), the first side wall (931) of the duct (93) having the sealing gap (95) to be sealed extending orthogonally with respect to the coupling axis (A).

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