GB2195411A

GB2195411A - Pipe connectors

Info

Publication number: GB2195411A
Application number: GB8719394A
Authority: GB
Inventors: Kurt Stoll
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 1986-08-22
Filing date: 1987-08-17
Publication date: 1988-04-07
Also published as: FR2603084A1; GB8719394D0; DE3628543A1; DE3628543C2

Abstract

The invention relates to a connection fitting comprising a basic member (4) and a connection member (5) arranged thereon. The two members have a common passage (15) extending through them which in the connection member (5) is in the form of a female opening (18) for the male end (20) of a piece of piping (2) to be inserted into. The connection member (5) is in the form of a slotted gripping part adjacent to the female opening (18) and has an externally threaded section (35) and a gripping surface (34). There is also a gripping ring (37) which screws on the threaded section (35) and has a driving surface (36) which is able to cooperate with the gripping surface (34) for clamping into the inserted length of flexible piping (20). <IMAGE>

Description

SPECIFICATION A connection fitting The invention relates to connection fittings and more particularly but not exclusively to such a fitting for the connection of lengths of rigid or flexible piping together or with pneumatic components or devices, which has a basic member and at least one connection member arranged thereon, such members having a passage extending through them, whose one end part adjacent to the connection member is in the form of a female opening for the reception of the male end of flexible or rigid piping, the connection member having a slotted gripping part adjacent to the female opening with a gripping surface essentially surrounding the female opening and able to cooperate with a movable gripping ring for holding the inserted male end.

Such connection fittings generally have a connection member like a collet and the gripping part comprises at least four gripping fingers separated from each other by the slots so that they are circumferentially adjacent to each other. These gripping fingers are outwardly biased and slightly splayed outwards so that the male end of rigid or flexible piping may be introduced into the female opening widened in this manner. A gripping ring slides on the connection member in. an axial direction from a basic position adjacent to the basic member into an active position towards the inserted flexible piping so that it forces the originally outwardly splayed gripping fingers inwards onto the inserted male end, same accordingly being held fast.In order to provide not only free insertion of the male end but also a substantial gripping force, it is necessary that the gripping ring in this arrangement be able move a considerable distance so that the known fitting is unsuitable for many applications owing to the excessive overall length which means that it is only able to be used with difficulty if at all. Furthermore the assembly of such connection fittings is generally slow since the gripping ring has to be pushed externally onto the outwardly splayed gripping fingers with the result that the latter have to be manually or mechanically forced inwards when placing the gripping ring in position.A further point in this connection is that such a known design of connection fitting frequently makes it essential to provide the collet-like gripping fingers with internal barbs which bite into the male inserted end in the active position of the fitting, for the combination of the gripping surface and of the sliding gripping ring determines the maximum possible radially inward gripping motion of the gripping fingers possible in the design so that if the external diameter of the male end is smaller owing to inaccuracies of manufacture one may not be certain of the latter being securely retained simply owing to the barbless gripping fingers.

However the necessary barbs make the production# of the connection fitting mores expensive and if the fitting is frequently to be done up and undone they damage the material thereof.

Accordingly one object of the invention is to devise a connection fitting of the initially mentioned type which while having more compact external dimensions is simpler and cheaper to produce.

Another aim of the invention is to provide such a connection fitting which despite inconsistencies in the external diameters of the male piping end owing to inaccuracies of manufacture is able to ensure a firm clamping effect on the piping.

In order to achieve these or other aims the gripping surface of the gripping part is provided at the outer circumference of the connection fitting and extends radially outwards obliquely in the direction of insertion of the male end, it being directed radially outwards opposite to the direction of insertion, and opposite to the gripping surface as considered opposite to the direction of insertion there is an driving surface, which is located on the gripping ring, surrounds its annular opening and has essentially the same form and the gripping ring is a screw member arranged on a male thread section, running coaxial to the insertion opening, of the connection member, such screw member being able to be screwed to and fro in the longitudinal or axial direction of the female opening, and in the direction of screwing coincides with the direction of insertion the driving surface is able to act on the gripping surface so that the gripping part is able to clamp onto at least a part of the outer surface or a part thereof for holding the male end.

It is in this manner that only a relatively short axial motion of the gripping ring is sufficient to move it between a release position making possible insertion of the end of the piping and a gripping position securely clamping onto the inserted flexible or rigid piping.

This is because the driving surface of the gripping ring may be moved back or clamped in position by only a small amount of rotation of the ring. This leads to a substantially shorter overall length. Furthermore the gripping ring may be fitted in place quite simply on the connection member by screwing. A particular advantage is however the fact that owing to its design as a screw member the gripping ring may be screwed back steplessly in the direction of insertion so that the gripping force having to be exerted on the male, inserted end is practically able to be set to the desired amount whatever the external diameter of the male end. If the external diameter is slightly smaller in some cases owing to inaccuracies of manufacture, it is possible to provide compensation simply by screwing the gripping ring further onto the connection member.This makes it possible to dispense with internal barbs on the gripping part and this leads to a substantial increase in the life of the inserted male end.

Advantageous further developments of the invention are described in the claims.

In accordance with one such development of the invention the section with the external screw thread is arranged at least in part at the gripping part. This makes possible a fur ther shortening of the overall length of the connection fitting inasfar as the gripping part is able to perform a gripping function and fur thermore a retaining function with respect to the gripping ring.

The gripping part may be arranged to ex tend at least along the length of the female opening. Furthermore, the gripping part may be slotted along its full length. These features are intended for particular applications in which the connected flexible piping is continu ally moving for example, the fitting having a retaining effect since the male end is gripped along the whole of its length inserted into the fitting. .

It is possible for the gripping part to be provided at two radially opoposite positions with a respective slot extending from the outer end of the female opening in the length direction thereof and in the radial direction from the female opening to the outer surface, such slots being so arranged that the gripping surface and the gripping part are respectively divided into two radially opposite sections of the gripping surface and of the gripping part.

This design makes possible particularly cheap manufacture without a decrease in the gripping force of the gripping part able to be exerted on the male inserted end. In fact, in this case owing to the small number of gaps the gripp ing force actually acting on the male inserted end is substantially increased, something that also leads to an increase in the secure gripp ing effect.

It is possible to provide a tubular stabilizing section, surrounding and preferably resting on the flexible or rigid piping and furthermore ad joining the driving surface on the end remote from the connection member. This design fea ture precludes accidental kinking of the in serted flexible or rigid piping directly at the end of the female opening and thus also pre cludes leakage.

It is furthermore possible for the passage through the connection member to be made wider at the female opening in such a way that the difference between the diameters of the female opening and that of the passage section following is essentially equal to twice the wall thickness of the inserted male end of the piping. This feature is intended to ensure an eddy-free, low-loss flow through the con nection fitting.

The basic member and the connection member may be made integral with each other.

This feature means that there is a minimum number of parts and simplicity of manufacture, for example by injection molding.

The invention will now be explained in more detail with reference to the accompanying drawings.

Figure 1 shows a first possible form of the connection fitting in accordance with the invention in which the connection between pressure piping and a pneumatic component is shown, different gripping part positions being shown on the two sides of the center line.

Figure 2 is a cross section through the arrangement of Fig. 1 as taken on the line Il-Il therein.

Figure 3 is a section of the gripping part of a further embodiment of connection fitting of the invention.

In the working example of the invention to be seen in Figs. 1 and 2 the connection fitting is designed to connect pressure piping 2 with a pneumatic component 3. In this case the pressure piping 2 is made of plastic material, although this is not necessarily so and it might well be made of metal. In place of rigid pressure piping it would be possible to use flexible piping, i.e. pressure hose connected with the fitting. The piping is for instance fashioned of an elastomeric material and will in what follows simply be referred to as pressure piping. The pneumatic component 3 is for example the cylinder of a piston and cylinder actuator, although in place of this it might be a question of a pressure receiver.

The connection fitting 1 possesses a basic member 4 with a connection member 5 extending therefrom; the members 4 and 5 are preferably integrally joined together and are more especially produced by injection molding.

The basic member 4 in the working example possesses an end part remote from the connection member 5 with a cylindrical threaded part 6 having a male thread which is adjoined by a coaxial attachment part on the connection member end. This attachment part 7 is in the form of a hex nut for use with a wrench in order to screw the threaded part 6 as illustrated into a suitable tapped hole 8 in the wall 9 of the pneumatic component 3. The attachment part 7, which extends proud of the threaded part 6 like a collar, in the present case simultaneously serves as an abutment for limiting the amount by which the fitting may be screwed in; between the part 7 and the wall 9 it is possible if required to place a gasket ring 10 for sealing off the screw connection.

The connection member 5 is directly adjacent to the attachment part 7 in the longitudinal direction and is coaxial in relation to it and to the threaded part 6, the common logitudinal axis being provided with the reference numeral 14.

The basic member 4 and the connection member 5 have a pasage 15 extending through them coaxially in the longitudinal direction. At one end this passage 15 opens at the free axial end of the basic member 4 (at 16) and at the other end it opens at the opposite end part of the connection member 5 (at 17).

The end part, adjacent to the connection member 5, of the passage 15 is in the form of a female opening 18 into which the male end 20 of pressure piping 2 may be inserted from the end 17 as marked by the arrow 19.

Fig. 1 shows the connection fitting 1 with the male end 20 in the inserted condition so as to produce a connection between the passage 21 of the piping and the space 22 delimited by the wall 9, such space 22 being, as noted earlier, the space within a cylinder.

The connection member 5 has a generally cylindrical outer surface and the female opening 18 extends essentially from the end 17 thereof or port as far as a point right on the transition 22 adjoining the basic member 4. A particular feature thereof is that the passage 15 adjacent thereto has a diameter generally the same as the external diameter of the pressure piping 2, whereas the passage section adjoining the female opening adjacent to the end 16 of the opening has a smaller diameter.

In the present working example the difference in diameter is equal to generally twice the thickness of the wall of the piping so that there is generally a stepless transition from the passage 21 to the passage section with a smaller diameter. This serves to preclude back pressure and eddying so that there is a lowloss flow.

The annular collar 23 present at the transition between the two passage sections at the same time forms an abutment for limiting the depth of insertion of the male end 20, it being possible to have a gasket ring 25 between the end and the free end 24 of the male end 20. Such gasket ring seals off the passages 15 and 21 at the transition between the connection fitting and the pressure piping 2 to prevent leakage of fluid to the outside. It is preferred for the male end 20 to be introduced to such an extent into the female opening 18 that its end 24 rests against the gasket ring 25 as shown in Fig. 1 and the ring 25 then rests on the collar 23.

For securing the male end 20 located in the female opening 18 the connection member 50 comprises a gripping part 30 which in the present working example extends from the end 17 of the opening as far as the opposite end of the female opening 18 at the annular collar 23. The gripping part 30 is in this case practically identical to the connection member 5.

The gripping part 30 is slotted and has two slots 31 and 31' (see Fig. 2) which are opposite to each other radially in relation to the longitudinal axis 14. On the one hand they extend along the entire length of the gripping part 30 and on the other hand extend in the radial direction so that they open on the one hand in the female opening 18 and on the other hand on the outer periphery or collar 23 of the gripping part 30. As seen in the cross section shown in Fig. 2 they thus subdivide the connection member 5 into two annular segments 33 and 33'.

It is naturally possible for the length as measured in the longitudinal direction 14 of the gripping part 30 and of the slots 31 and 31' to be less than that of the female opening 18; in any case the gripping part and the slots begin at the free end of the female opening adjacent to its end.

The gripping part 30 furthermore comprises a gripping surface 34 which is arranged so as to be coaxial to the female opening 18 and surrounds the latter in the manner of a ring.

The only interruptions in the gripping surface 34 are at the two slots 31 and 31'. The gripping surface 34 is arranged at the outer periphery 32 of the gripping part 30, preferably adjacent to the passage opening or end 17 at the free end of the connection member 5. Starting at the passage opening 17 it thus extends in the direction 19 of insertion obliquely radially outwards in relation to the longitudinal axis 14 so that apart from the slots 31 and 31' it is in the form of the outer surface of the frustum of a cone, whose base side with the larger diameter faces the direction 19 of insertion and whose base side with a smaller diameter faces in a direction opposite to the direction 19 of insertion. Thus the gripping surface 34 faces in a direction opposite to the direction 19 of insertion radially outwards.

As shown in Fig. 1 the gripping surface 34 forms a sort of bevel at the end of the gripping part 30 at the maximum distance of the gripping surface 34 from the longitudinal axis 14 there is the remaining part of the gripping part 30 at the outer periphery 23. Here the gripping surface 34 directly adjoins a male thread section 35 which extends as far as the attachment part 7 and is essentially completely at the gripping part 30. Accordingly it is not only a question of the gripping surface 34 being subdivided by the slots 31 and 31' into two gripping surface sections arranged opposite to each other in the radial direction but furthermore of the male threaded section 35 having corresponding interruptions.

In the embodiment the external diameters of the two threaded parts or sections 6 and 35 are identical to each other.

In a direction opposite to the direction 19 of insertion there is a driving surface 36 opposite to the gripping surface 34, that is to say the gripping surface halves separated by the slots, such surface being arranged on a gripping ring 37. This gripping ring 37, which is essentially cylindrical and if required is formed as a hex nut, has a through opening 39 extending in the axial direction. The end part of this opening adjacent to the connection member 5 is provided with an internal thread section 38 complementary to the external thread section 35. It is in this manner that the gripping ring 37 may be screwed as a sort of union nut in the direction 19 of insertion onto the threaded section of the connection member 5 and may be moved to and fro in the longitudinal direction by corresponding actuation.

As considered in the screwed on state of the gripping ring 37 (all the present description assumes this condition) the threaded section 38 is adjacent to the annular driving surface 36, and its form and more especially its slope in relation to the longitudinal axis 14 are the same as that of the gripping surface 34.

Whatever the position into which the gripping ring 37 has been screwed in the length direction 14 the driving surface 36 is opposite to the gripping surface 34; when the gripping ring 37 is screwed to change its position the only effect is a parallel displacement of the driving surface in relation to the gripping surface.

The connection of the pressure piping 2 may accordingly take place as follows: When the male end 20 is to be inserted into the opening 18, the gripping ring 37 is screwed in a direction opposite to the direction 19 of insertion until its driving surface 36 no longer exerts any thrust on the gripping surface 41. This may take place even when the two surfaces are still in contact, but it may be necessary to unscrew the gripping ring 37 so far that the two surfaces come clear of each other. Such a condition is shown in an exaggerated manner in the section of Fig. 1 above the longitudinal axis 14 in order to make things clear. In this position of the gripping ring 37 the pressure piping 2 may be inserted through the gripping opening 39 into the male opening 18 for the depth as mentioned above.Following this the gripping ring 37 is screwed onto the connection member 5, because its driving surface 36 moves in the direction 19 of insertion towards the gripping surface 34 and finally rests on it. By further screwing of the gripping ring 37 the driving surface 36 will then exert a thrust on the gripping surface 34 with the result that the two annular segments 33 and 33' of the gripping part 30 will be pressed together radially inwards and onto each other, their clearance in the slots being accordingly decreased.

The two surfaces 36 and 34 then slide somewhat on each other. The screwing operation is at an end when the gripping force exerted by the gripping ring 37 via the corresponding surface 34 and 36 and the annular segments 33 and 33' on the outer face of the male end 20 is so large that the male end 20 is securely clamped in the female opening 18. This condition is indicated in Fig. 1 beneath the longitudinal axis 14.

For disengaging the male end 20 the gripping ring 37 has to be moved in the opposite and as the driving surface 36 is moved further and further opposite to the direction 19 of insertion the thrust exerted thereby on the gripping surface 34 will decrease accordingly so that the annular segments 33 and 33' of the gripping part 30 will be able to return into their spread out position. The male end 20 may now be removed without any difficulty.

A particular advantage of the connection fitting in accordance with the invention is to be seen in the fact that the male end 20 may be securely retained in position simply by the force as opposed to any interlocking effect.

Any irregularities in the external diameter of the male, inserted end may be readily allowed for by modifying the distance along which the gripping ring 37 is screwed. A further point in this connection is that since there is no interlocking effect the piping is not damaged.

However if required it is possible for the annular segments 33 and 33' to be provided with one or more circumferential barbs 40 more especially adjcent to the end 17 in order in this manner to produce a force fit or an interlocking connection with the piping 2 As will be clear from Fig. 1 there is a cylindrical opening section 44 adjoining the driving surface 36 as seen in a direction opposite to the direction 19 of insertion. This section 44 opens on the side of the gripping ring 37 facing away from the connection fitting. The length of this section 44 is relatively small and it may be dispensed with so that the connection fitting will then be even shorter. Furthermore, it is however also possible for this opening section 44 to have a relatively long length so that it forms a stabilizing section (not illustrated) which locates the piping 2 in the part following on the male end 20.

It is furthermore to be noted that the connection fitting in accordance wit the invention may also be used for the connection together of two lengths of pressure piping, in which case the threaded part 6 would be replaced by a further connection member and gripping ring of the type described (not shown). The attachment part 7 is then preferably kept as it is in order to hold the connection fitting while screwing on the gripping rings by means of a tool.

In the case of further working examples which are not shown of the connection fitting it is possible to have more than two possibilities of connection, there then being a larger number of connection members and/or basic members as may be needed.

Claims

1. A fitting for the connection of piping, the fitting comprising two members, at least one of which is a connection member, the members having a passage extending therethrough, one end part of the passage adaja cent to the connection member being in the form of a female opening for the reception of a male end of piping, the connection member having a slotted gripping part adjacent to the female opening with a gripping surface substantially surrounding the female opening and being arranged to cooperate with a movable gripping ring for holding the inserted male end, the gripping surface of the gripping part being provided at the outer circumference of the connection fitting and extending radially outwards obliquely in the direction of insertion of the male end, being directed radially outwards opposite to the direction of insertion, and, opposite to the gripping surface relative to the direction of insertion, a driving surface, which is located on the gripping ring, surrounds an opening in the latter and has substantially the same form as the gripping surface, the gripping ring comprising a screw member arranged on a male thread section which extends coaxial to the insertion opening of the connection member, the screw member being arranged to be screwed to and fro in the axial direction of the female opening, and as the direction of screwing coincides with the direction of insertion the driving surface is able to act on the gripping surface so that the gripping part is able to clamp onto at least a part of the outer surface of piping or a part thereof for holding the male end.

2. A connection fitting as claimed in claim 1 wherein the gripping surface surrounds the female opening at the end thereof furthest from the other of the two fitting members.

3. A connection fitting as claimed in claim 1 or claim 2 wherein as seen in the direction of insertion the externally threaded section is arranged following the gripping surface.

4. A connection fitting as claimed in claim 3 wherein the externally threaded section directly adjoins the gripping surface.

5. A connection fitting as claimed in any one preceding claim wherein the section with the external screw thread is arranged at least in part at the gripping part.

6. A connection fitting as claimed in any one preceding claim wherein the gripping part is arranged to extend at least along the length of the female opening.

7. A connection fitting as claimed in any one preceding claim wherein the gripping part is provided at two radially opposite positions with a respective slot extending from the outer end of the female opening in the length direction thereof in the radial direction from the female opening to the outer surface, such slots being so arranged that the gripping surface and the gripping part are respectively divided into two radially opposite sections of the gripping surface and of the gripping part.

8. A connection fitting as claimed in any one preceding claim wherein the gripping part is slotted along its full length.

9. A connection fitting as claimed in any one preceding claim wherein the gripping ring is similar to a union nut and has an internal thread section complementary to the external thread section of the connection member, said driving surface being adjacent thereto in the direction opposite to the direction of screwing in.

10. A connection fitting as claimed in any one of the preceding claims wherein the driving surface is in the form of a circumferentially complete annular surface with frusto-conical form.

11. A connection fitting as claimd in claim 10 wherein said frusto-conical form is complementary to the form of the gripping surface.

12. A connection fitting as claimed in any one preceding claim wherein as seen in a longitudinal section of the gripping ring and of the connection member the driving member is parallel to the gripping surface.

13. A connection fitting as claimed in any one preceding claim having a tubular stabilizing section, surrounding and resting on the piping and furthermore adjoining the driving surface on the end remote from the connection member.

14. A connection fitting as claimed in any one preceding claim wherein the passage through the connection member is made wider at the female opening in such a way that the difference between the diameters of the female opening and that of the passage section following is essentially equal to twice the wall thickness of the inserted male end of the piping.

15. A connection fitting as claimed in any one preceding claim having an inwardly projecting collar forming an abutment for the inserted end of the piping at the end of the female opening adjacent to the basic member.

16. A connection fitting as claimed in any one preceding claim wherein the other fitting member has a threaded part arranged coaxially in relation to the through passage for the connection of a fluid power component.

17. A connection fitting as claimed in any one preceding claim having at least two such connection members on the other fitting member, each such connection member having such a gripping ring thereon.

18. A connection fitting as claimed in any one preceding claim wherein the other fitting member and said connection member are arranged coaxially to the passage extending therethrough.

19. A connection fitting as claimed in any one of the preceding claims wherein the other fitting member and said connection member are integral with each other.

20. A connectior fitting substantially as hereinbefore described with reference to Figs.

1 and 2 of the accon ,anying drawings.

21. A connection fitting substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.

22. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.