Piping connection system for a pressurized fluid system

Abstract

The invention relates to a pipe connection system (1) for a pressure fluid system comprising a connecting body (3) for receiving a pipe (5) of a pressure fluid system, a leakage sealing device (7) to prevent fluid belonging to the pressure fluid system from entering the connecting body (3) via the pipe, a gripping device (9) for gripping the outer surface of the pipe (5) received in the connecting body (3), and an environmental sealing device (11) to prevent ingress from the outside of the connecting body (3), characterized in that the environmental sealing device (11) is at least partially movable and is prepared to be at least partially pressed out of a valve seat when internal fluid pressure prevails in the connecting body (3), which leads to a fluid flow out of the connecting body (3).and that the fluid flow into the outer space of the connecting body (3) indicates a leak from the pressurized fluid system.

Description

The present invention relates to a pipe connection system for a pressurized fluid system, comprising a connection part for receiving a pipe of a pressurized fluid system, a leak seal for preventing fluid from entering the connection part from the pressurized fluid system, a gripping device for gripping the outer surface of the pipe receivable in the connection part, and a surrounding sealing device for preventing entry from the vicinity of the connection part.In many applications, conduits must be connected to each other or to other components in such a way as to prevent leaks and to preclude unintentional detachment of the conduit. This is especially important in systems where failure of the line connection may be hazardous and may lead to severe damage, for example in a braking system of a vehicle. A typical line connector for such a purpose can be found in WO 2006 / 112726.The most common failures in the form of leaks and unintentional loosening are due to improper assembly when the conduit is connected to a connection system. The case that the pipe is not sufficiently inserted into a connection system is an example of such incorrect assembly. In particular, when the force for insertion is high due to tight gripping or sealing devices used in high pressure systems, the engagement of the conduit with a final stop region may not be easily perceptible to a user during manual assembly. In addition, the point of sufficient insertion may be unclear if the end of the lead is not cut at the proper angle, for example, because it has been manually shortened before assembly.Therefore, some form of feedback is needed that gives an indication to the assembler when the lead is sufficiently and correctly inserted into a connection body.It is known to provide visual markings on the outer surface of the lead which provide the assembler with a visual indication of when a predetermined depth of insertion has been reached. This can be, for example, a line which must be covered by the connecting body when the line is sufficiently inserted into the connecting system. This solution is disadvantageous, however, because the line cannot be shortened to a suitable length without losing the visual markers at one or both ends. Furthermore, there is an uncertainty in deciding on the positioning of the marker and the ability of the assembler whether or not the visual markers indicate the full introduction.Other common solutions provide the user with a perceptible plug-in feel that indicates when the lead is in the correct position. This requires the user to be able to feel discrimination, which is difficult when a tool for assembly is used, for example. Further, a perceptible plug-in feel is a highly subjective measure that different users can perceive in different ways.A line connection system is known from WO 2006 / 112726 A1. However, the problem of giving the assembler a feedback signal when the line is sufficiently and correctly inserted is not addressed therein.WO 2006 / 037962 A1 describes a line connection and addresses the feedback problem by giving an audible indication of the fully inserted position of the line. The connection system described therein comprises a line carrier part onto which a line is pushed. During the insertion of the conduit into the connection, the conduit pushes the conduit carrier part in, which is therefore forced to slide deeper into the connection body. A groove and protrusion configuration between the outer surface of the lead frame member and the inner surface of the connector body provides an audible click signal informing the user that the lead with the lead frame member has reached its fully inserted position.The solution described in WO 2006 / 037962 A1 has the disadvantage that the audible click signal only indirectly informs the user, namely that the line carrier part has reached a fully inserted position, instead of the line being fully inserted into the connection. Therefore, no information is provided as to whether the line is actually completely inserted into the line carrier member. Therefore, there still remains the risk of leakage and accidental detachment due to improper installation of the conduit into the conduit support member. Further, no information is given as to whether the line remains in the correct, fully inserted position during normal use of the line connection system. Further, the force to push in during lead insertion is substantially increased by the resistance that the tongue and groove arrangement generates to generate an audible click signal. This resistance may be relatively large because an early click signal before the lead reaches a final stop region of the lead frame member would be detrimental. This resisting force adds to the friction caused by gripping or sealing means, which results in an inconveniently high overall force for pushing. A high total pushing force thus required can in turn easily result in a high frictional force between the conduit and the conduit support part, for example, when the conduit is fitted in a slightly inclined manner. If this frictional force exceeds the click resistance, an adverse overtime click signal may be triggered before the lead is fully inserted into the lead frame member.DE 691 05 655 T2 discloses a line connection system which has an environmental seal in the form of an O-ring between the outer wall of a connection body and a jacket surrounding the latter. When the fluid pressure in the pressure line exceeds a threshold value, the connecting body moves, so that openings in the connecting body establish a connection between the line passage and the interspace between the outer wall of the connecting body and the jacket. The environmental seal is then blown out of the space between the outer wall of the connecting body and the jacket by the increased fluid pressure, thereby effecting a permanent pressure relief.DE 195 24 934 A1 describes a conduit connection system for a pressurized fluid system having a connection body for receiving a conduit, leakage sealing means for preventing entry of fluid, which is supplied from the pressurized fluid system via the conduit, into the connection body, gripping means for gripping the outer surface of the conduit receivable in the connection body, and surrounding sealing means for preventing entry into the connection body from the surroundings thereof. The surrounding seal has a sealing sleeve inserted into a through-opening and a sealing lip formed integrally with the sealing sleeve and protruding therefrom, which lip rests with elastic pressure against an opposite wall surface of the sealing sleeve. When internal fluid pressure prevails in the connecting body, the sealing lip is thereby elastically deformed so that it is pivoted away from the wall surface of the sealing sleeve, which leads to a fluid flow through the sealing sleeve out of the connecting body, this fluid flow into the outer space of the connecting body indicating a leak. The surrounding sealing device is at least partially elastically deformable insofar as the sealing lip can move by elastic deformation and pivoting. Upon elastic deformation and pivoting away of the sealing lip, however, the lip is completely lifted from the wall surface of the sealing sleeve. If the internal fluid pressure in the connecting body falls again, the sealing lip pivots elastically back and comes back into contact with the valve seat surface. The construction of this environmental sealing device is relatively complicated with the integrally formed sealing lip and its sealing behavior can only be reproduced to a limited extent, since the elastic pressure of the sealing surface on an opposite wall surface of the sealing sleeve is not reproducible even with small tolerances or deviations in the production of the integrally formed sealing lip and, in this respect, the sealing behavior as a function of the internal pressure cannot be reliably predicted.It is an object of the present invention to overcome the disadvantages of the prior art and to provide a line connection system which ensures to a user that the line is inserted sufficiently and correctly after assembly and during normal use, while ensuring continuous inspection of the leak resistance.This object is achieved by the subject matter of claim 1. There is provided a conduit connection system for a pressurized fluid system, comprising a connection body for receiving a conduit of a pressurized fluid system, leak seal means for preventing fluid feedable from the pressurized fluid system via the conduit from entering the connection body, gripping means for gripping the outer surface of the conduit receivable in the connection body, and surrounding seal means for preventing entry from the outside of the surroundings of the connection body. The environmental seal device is at least partially slidable and is configured to be at least partially forced out of a seal seat when internal fluid pressure is present in the connection body, resulting in fluid flow out of the connection body. The fluid flow into the vicinity of the connecting body indicates a leak from the pressurized fluid system, wherein the vicinity sealing device is at least partially elastically deformable by an internal fluid pressure in the connecting body, and wherein at least a part of the vicinity sealing device is prepared to remain in contact with the sealing seat even if internal fluid pressure prevails in the connecting body.These features that at least a part of the surrounding seal device remains in contact with the valve seat when the surrounding seal device is opened and indicates leakage by the internal pressure are realized by the surrounding seal device being arranged in an annular groove in the form of an O-ring, the groove having a cutout lying on the outside in the axial direction, which cutout allows the surrounding seal device to form an opening of the valve by bulging the region of the O-ring lying in the region of the cutout into the cutout, while the O-ring remains held in the valve seat in the circumferential regions which do not lie opposite the cutout. In this way, with a valve element of very simple design in the form of an O-ring, an environmental sealing device can be realized which opens at a threshold pressure and which automatically closes elastically again when the internal pressure in the valve body falls below the threshold pressure.The pipe connection system according to the invention ensures that the fluid flow is always large enough to be noticeable to the user. Before the surrounding sealing device is at least partially pressed out of the sealing seat, a fluid pressure builds up in the interior of the connecting body. If the pressure exceeds a value necessary to force the environmental seal device out of the seal seat, a sufficiently high fluid flow is available to indicate leakage. The flexible and elastically deformable environmental sealing device is configured to come back into contact with the sealing seat when the internal fluid pressure in the connection body is below a certain threshold value. The environmental seal device comprises an O-ring disposed in an annular groove, the groove having a cut-out, which allows the environmental seal device to be at least partially forced out of the seal seat when internal fluid pressure is present in the connecting body. The seal seat of the environmental seal device is preferably an annular surface that lies at an axially inner region of the annular groove. Preferably, the fluid flow into the exterior of the connector body generates an audible feedback signal indicative of leakage from the pressurized fluid system. This audible feedback signal may be, for example, a whistle or hisston when the fluid is air or another gaseous fluid. If the fluid is a liquid or is optically distinguishable from air, the leak indication could also be an optical signal of the exiting fluid stream.As already said, the flexible and elastically deformable environmental sealing device is configured to come back into contact with the sealing seat when the internal fluid pressure in the connection body is below a certain threshold value. The environmental seal device is a flexible O-ring having restoring spring forces. The threshold value should then be far lower than the usual pressure of the pressurized fluid system, so that even a very small leakage still leads to a pressure build-up which is quickly indicated. The environmental sealing device can also be configured as a single-use, breaking-open component which is adapted to be pressed out of the sealing seat only once. A bore may also be provided which allows fluid flow from the interior of the connecting body into the exterior of the connecting body when the ambient sealing device is forced out of the sealing seat due to internal fluid pressure in the connecting body. Such a bore has the advantage that the fluid flow is guided through the bore in order to generate a better controlled and noticeable signal for the user. The bore size may be chosen to produce a warning whistle from the fluid stream or may be provided with further means for this purpose.Preferred embodiments of the invention will be described in more detail below with reference to Figs. 1 to 5. Figure 1 is a side view of a preferred line connection system, with one half shown in longitudinal cross-sectional view. FIG. 2 is an exploded view of a preferred line connection system. FIG. 3 is a side view of a preferred conduit connection system, with one half shown in longitudinal cross-sectional view, and with an insufficiently inserted conduit shown. FIG. 4 is a side view of a preferred conduit connection system, with one half shown in longitudinal cross-sectional view, showing a sufficiently inserted conduit. FIG. 5 is a detailed longitudinal sectional view of the environmental sealing device, with a part pushed out of the sealing seat.The pipe connecting system 1 shown in FIG. 1 comprises a connecting body 3 for accommodating a pipe 5 of a pressurized fluid system, a leak seal device 7 for preventing fluid from the pressurized fluid system from entering the connecting body 3, a gripping device 9 for gripping the outer surface of the pipe 5 accommodated in the connecting body 3, and a surrounding seal device 11 for preventing intrusion from the vicinity of the connecting body 3. The end of the connecting body 3 which is not intended to receive the conduit 5 is provided with a threaded connecting end 13 and a seal 15. The connecting body 3 further comprises a portion with an outer shape 17 suitable for receiving a wrench for screwing the conduit connection system 1 with its threaded connection end 13 into another component of the pressurized fluid system.In this embodiment, the line connection system 1 comprises a line retaining sleeve 19 inserted from the end in the connection body 3 provided for receiving the line 5. The inner shape of the connecting body 3 is adapted to receive the outer sleeve of the pipe retaining sleeve 19 to retain the pipe retaining sleeve 19 secured in the radial direction. The line retaining sleeve 19 is pressed into the connecting body 3 until a flange portion of the line retaining sleeve 19 abuts an inner shoulder in the connecting body 3 which forms a final stop for the line retaining sleeve 19 to be pressed into the connecting body 3. The inner sleeve of the conduit retaining sleeve 19 is adapted to fit within a conduit 5 to be received by the connection system 1. The outer sleeve of the conduit retaining sleeve 19 is adapted to fit over the outer surface of the conduit 5 such that an end portion of the conduit 5 is enclosed by the conduit retaining sleeve 19. The conduit retaining sleeve 19 fixed in the connecting body 3 therefore provides a guide for the conduit 5 during insertion and a stabilization of the conduit 5 in the connecting body 3 once it is inserted. The internal shape of the connecting body 3 provides a cavity portion to receive sealing and gripping means which are inserted into the connecting body 3 after the line retaining sleeve 19 has been inserted. As a result, the line-holding sleeve 19 is prevented from becoming detached from the connecting body 3 by the sealing and gripping devices.The sealing and fastening means comprise a leak-sealing means 7 for preventing fluid from the pressurized fluid system from entering the cavity portion of the connecting body 3. The leak seal means fits in tight communication between the inner surface of the joint body 3 and the outer surface of an inserted conduit 5. the leak seal means 7 is preferably an O-ring of rubber material which, prior to insertion of the conduit, partially protrudes into the cavity which is to receive the conduit 5. When the conduit 5 is inserted deep enough into the conduit connection system 1 to reach the leakage sealing device 7, the leakage sealing device 7 is deformed into a sealing fit between the conduit 5 and the connection body 3.In the cavity portion of the connection body 3 there are further outside the means for securing the conduit 5 inside the conduit connection system 1. Further, the securing means may comprise an insert 21 provided at an axially inner portion preferably with a plurality of inner protrusions 24 spaced along the inner periphery of the insert 21, the protrusions 24 having a segmented conical inner portion of decreasing diameter towards the axially outer end of the insert 21. The gripping means 9 has a radially outer conical surface substantially corresponding to the segmented inner conical portion of the insert 21. The securing means are a combination of features of the insert 21 and the gripping means 9. The configuration of the insert 21 and the gripping device 9 is such that an axially outward force exerted on the line 5 held in the line connection system 1 is converted into an increase in a compressive force exerted by the gripping device 9 on the outer surface of the line 5. Any unintentional pulling force on the conduit 5 therefore causes the gripping device 9 to react with an increased gripping force on the conduit 5, so that the pulling force does not lead to an actual release of the conduit 5.The axially outer portion of the insert 21 is preferably provided with an annular groove for receiving an environmental sealing means 11, namely an O-ring, for example of rubber material, to prevent any intrusion from the environment of the connecting body 3. Alternatively, the environmental seal means 11 could be located between an axially outer surface of the inner protrusions 24 of the insert 21 and an axially outer flange 28 of the insert 21. The environmental seal means 11 is not axially secured in the annular groove or space between the projections 24 and the flange 28 of the insert 21. Preferably, the groove or space has a greater axial extent than the surrounding seal means 11. Alternatively, the groove or space has an axially outward cut-out which allows the surrounding seal means 21 to move axially outward out of the seal seat when internal fluid pressure is present in the connecting body. The seal seat of the surrounding seal device 11 is the surface of the axially inner portion of the groove or space. When an internal fluid pressure builds up in the cavity portion of the connecting body 3 due to leakage of the leak seal device 7, the internal fluid pressure forces the environmental assurance device 11 at least partially out of the seal seat. Once the ambient sealing device 11 has at least partially lost contact with the sealing seat, fluid flow passes the ambient sealing device 11 into the exterior of the joint body 3.Preferably, the fluid is air and the flow of air into the vicinity of the connecting body 3 generates an audible feedback signal indicative of a leak in the pressurized fluid system. In a preferred embodiment, a bore 22 is provided in the insert 21 which allows passage of fluid flow from the cavity portion of the connecting body 3 to the environment of the connecting body 3 when the environmental sealing device 11 is forced out of the sealing seat due to internal fluid pressure in the connecting body 3. Such a bore has the advantage that the fluid flow is guided through the bore 22 in order to generate a better controlled and perceptible signal.FIG. 2 shows an exploded view of the line connection system 1 with all its components separated from one another. This illustration is particularly useful to describe the manner in which the line connection system 1 is assembled. The seal 15 for the end which is not intended to receive the conduit 5 is slid over the threaded connection end 13 into a sealing position at the starting point of the thread. The line carrier sleeve 19 is inserted into the connecting body 3 through the opening of the connecting body 3 which is intended to receive the line 5. Next follows the leakage sealing means 7 which, once sufficiently inserted, abuts the inner sleeve of the lead carrier sleeve 19. The gripping device 9 in the form of a conical gripping ring is then introduced. The insert 21 has a special configuration so that it is seated in the connecting body 3 once it is correctly inserted. The insert 21 has a bulge 23 on its radially outer surface, which corresponds to an annular recess 25 along the radially inner periphery of the cavity portion of the connecting body 3. In order to facilitate the insertion of the insert 21, the projection or the bulge 23 has an inclinedly rising region on the side which lies on the inside in the axial direction. Once the insert 21 is pressed into the connecting body 3, the bulge-and-recess arrangement secures the insert 21 itself and all those components within the connecting body 3 that are arranged axially further inward. The environmental seal means 11 in the form of a flexible O-ring of rubber material may then be inserted into the annular groove within the insert 21 to be in contact with the sealing seat.FIG. 3 illustrates a situation in which a line 5 is not sufficiently inserted into the line connection system 1. The conduit 5 is not inserted so deeply that the leakage sealing device 7 could establish a tight fit between the outer surface of the conduit and the inner surface of the connecting body 3. In this situation, there is no fluid pressure in the conduit 5. Once there is fluid pressure in the pressurized fluid system and in the conduit 5, there is a leakage of fluid into the cavity portion of the connecting body 3 and fluid pressure builds up therein. Figure 3 shows the environmental seal device 11 in contact with the seal seat as long as no pressure is applied in the system. Since there is frictional contact between the duct 5 and the surrounding seal device 11 during insertion, the surrounding seal device 11 is pressed into the inner portion of the annular groove during insertion of the duct 5 to come into contact with the seal seat. Once the fluid pressure in the cavity portion of the connecting body 3 is above a threshold value, the pressure is strong enough to push the environmental seal device 11 axially outward out of the seal seat.Alternatively, the outer flange 28 of the insert 21 is provided with one or more stopper projections 26 spaced along the inner periphery, the stopper projections 26 extending axially inwardly to form contact surfaces 30 for keeping the surrounding seal device 11 partially in contact with the seal seat even when fluid pressure is present within the connecting body 3. However, those parts of the surrounding seal device 11 which are not in contact with the stopper projections 26 are pushed out of the seal seat by internal fluid pressure because the surrounding seal device 11 is flexible. Preferably, an axial bore 22 is provided in the insert 21 which extends axially from the annular groove or space in which the environmental sealing device 11 is located to the exterior of the conduit connection system 1. It is advantageous if the bore 22 is located at the inner periphery centrally between two stopper projections 26 which are arranged at distances from one another along the inner periphery on the outer flange 28 of the insert 21. In the middle between two stopper protrusions 26, the outward deflection of the flexible surrounding seal device 11 by the internal fluid pressure is the greatest. As soon as the flexible sealing device 11 partially deflects outwards out of the sealing seat, a channel is opened through the bore 22, so that a fluid flow from the interior of the connecting body 3 into the exterior of the connecting body 3 is produced through this channel.FIG. 4 illustrates a situation in which a line 5 is completely inserted into the line connection system 1. In this situation, fluid pressure is applied in the conduit 5. The conduit 5 is correctly inserted and there should be no fluid leakage from the system. However, the surrounding seal device 11 is partially pushed out of the seal seat because a fluid pressure is present in the cavity portion of the connecting body 3. This indicates fluid leakage in the leakage sealing devices 7. The leakage can be caused, for example, by wear, abrasion, aging or damage to the leakage sealing devices 7. The flow of fluid into the vicinity of the connecting body 3 indicates the leakage by an audible feedback signal in the form of a whistle or hisston if the fluid is air or another gaseous fluid.Figure 5 provides a more detailed view of the function of the environmental seal device 11. The upper part of the longitudinal sectional view shows a section through a region of the system in which a stopper protrusion 26 arranged on the outer flange 28 of the insert 21 with its inner contact surface 30 keeps a part of the environmental seal device 11 in contact with the seal seat, even if fluid pressure is present within the connecting body 3. The lower part of the longitudinal sectional view shows a section through a region of the system in which an axial bore 22 is provided in the insert and no stopper protrusion 26 prevents the environmental sealing device 11 from flexing outwards due to internal fluid pressure. The bore 22 extends from the exterior of the line connection system 1 to the annular groove in which the surrounding sealing device 11 is arranged. When internal fluid pressure prevails in the cavity portion of the connecting body 1, as shown in the lower part of Fig. 5, a channel opens up to the axial bore 22, which leads to a fluid flow out of the connecting body 3, the fluid flow into the outer space of the connecting body 3 indicating a leakage from the pressure fluid system.

Claims

A conduit connection system (1) for a pressurized fluid system, comprising - a connection body (3) for receiving a conduit (5) of a pressurized fluid system, - leakage sealing means (7) for preventing entry of fluid, which can be supplied from the pressurized fluid system via the conduit (5), into the connection body (3), - gripping means (9) for gripping the outer surface of the conduit (5) receivable in the connection body (3), and - surrounding sealing means (11) for preventing entry into the connection body (3) from its surroundings, wherein the surrounding sealing means (11) is at least partially displaceable and is configured to be at least partially pushed out of a sealing seat when an internal fluid pressure prevails in the connection body (3), which leads to a fluid flow out of the connection body (3), and wherein this fluid flow into the vicinity of the connecting body (3) indicates a leak from the pressurized fluid system, wherein the surrounding sealing device (11) is at least partially elastically deformable by an internal fluid pressure in the connecting body (3) and wherein at least a part of the surrounding sealing device (11) is prepared to remain in contact with the sealing seat even when internal fluid pressure prevails in the connecting body (3), wherein the surrounding sealing device (11) is arranged in the form of an O-ring in an annular groove, wherein the groove has an axially outer cutout which allows the surrounding sealing device (11) to be at least partially pressed out of the sealing seat when internal fluid pressure prevails in the connecting body (3).A conduit connection system according to claim 1, wherein the fluid flow into the exterior of the connection body (3) generates an audible feedback signal indicative of leakage from the pressurized fluid system.A line connection system according to claim 1, wherein the axially outer cutout is the space between two stopper protrusions (26) spaced apart from each other along the axially inner periphery, the stopper protrusions (26) extending axially inward to form contact surfaces (30) for keeping the surrounding sealing device (11) partially in contact with the sealing seat.A pipe connection system according to any preceding claim, wherein a bore (22) is provided which allows fluid flow from the interior of the connection body (3) to the vicinity of the connection body (3) when the surrounding sealing device (11) is at least partially forced out of the sealing seat due to internal fluid pressure in the connection body (3).The line connection system according to claim 4, wherein the bore (22) runs in the axial direction from the annular groove to the outer space of the line connection system (1).The conduit connection system of claim 1 or 2, wherein the fluid is air.

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