Pipe joints or couplings – Nonmetal to metal – Internal member
Reexamination Certificate
2001-12-04
2004-08-10
Bagnell, David (Department: 3672)
Pipe joints or couplings
Nonmetal to metal
Internal member
C285S255000, C285S242000, C285S342000, C285S339000
Reexamination Certificate
active
06773039
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a plug-in coupling comprising a base body, a sealing ring, a locking ring, and an annular body connectable with the base body, in which a pipe end can be locked in position by the locking ring.
European Patent Application No. EP 587,131 describes such a plug-in coupling, which is constructed as a double coupling and comprises a base body and a holding device or locking device for the corresponding ends of the pipes to be connected, which can be inserted into the coupling body. The holding device comprises a locking ring, which has a locking cone on the outside and at least one locking rib on the inside, which can engage with the corresponding pipe end. By means of a union nut, which can be screwed onto the coupling body, an opposite cone can be locked in position using said locking ring. Furthermore, along the interior of the coupling body, a sealing ring is provided, which fits tightly against the exterior surface of the inserted pipe end.
The pipe end must have sufficient rigidity, so that it does not yield toward the interior due to the radial locking force components, which would jeopardize the axial fixation of the pipe end within the plug-in coupling. When the connection is established, care must be taken that the pipe end is inserted far enough into the coupling body, so that the locking ring as well as the sealing ring can perform their function. If the pipe end is incompletely inserted into the plug-in coupling, there is a risk that the connection is either not being made at all or is being made incorrectly. Furthermore, especially in pressure pipes, there is the problem that the pipe end may be partially moved out of the plug-in coupling due to relative movements of the pipe end in relation to the plug-in coupling, so that the required seal and/or axial fixation can no longer be assured.
SUMMARY OF THE INVENTION
It is the object of the invention to provide an improved plug-in coupling for connecting pipes with which a connection can be made with at least one pipe end with little effort and high functional reliability.
Another object of the invention is to provide a plug-in coupling which permits functionally suitable handling during mounting.
A further object of the invention is to provide a plug-in coupling which prevents mounting errors in coupling installation.
It is also an object of the invention to provide a plug-in coupling which is equally suitable for pipes of different materials, such as plastic or metal or a composite thereof (composite pipes made of plastic with a metal interlayer).
A still further object of the invention is to provide a plug-in coupling which can provide a secure connection over many years even for comparatively soft materials, particularly polyethylene, for example.
Yet another object of the invention is to provide a plug-in coupling which is especially suitable for plumbing applications, particularly for hot water and cold water installations.
An additional object of the invention is to provide a plug-in coupling which can reliably absorb any changes in the material, especially with respect to dimensions or rigidity, resulting particularly from temperature changes of the flowing medium.
These and other objects of the invention have been achieved by providing a plug-in coupling comprising a base body, a sealing ring, a locking ring, and an annular body which can be connected with the base body, in which a pipe end can be locked into position by the locking ring, wherein the pipe end can be inserted into an axial annular gap between the base body and the annular body, the sealing ring fits tightly against the interior surface of the pipe end, and the annular gap accommodates the locking ring, which fits under initial stress against a locking surface of the annular body and against the exterior surface of the inserted pipe end.
The plug-in coupling according to the invention is characterized by a functionally reliable design and little complexity in production and assembly. The base body, which partly engages with the interior of the pipe end, assures secure radial support of the pipe end, so that the locking forces of the holding means are reliably absorbed and transmitted even under changing operating conditions. An annular body or cap, which radially surrounds the exterior of the pipe end, is coupled together with the base body. The pipe end is locked into position in an annular space between the base body and the cap. The interior surface of the annular body or the cap is preferably conical.
The locking ring, which is coupled on either side in a non-positive and/or a positive fit with both the interior surface of the annular body and the exterior surface of the pipe, is arranged between said interior surface of the annular body and the exterior surface of the pipe end. The sealing element is preferably arranged on the portion of the base body that engages with the pipe end and fits tightly against the interior surface of the pipe end. The locking or holding ring has at least one holding claw each radially on the inside and radially on the outside, which claws are respectively pressed into the exterior surface of the pipe end and into the interior surface of the annular body.
In one specific embodiment of the invention, the locking ring comprises at least one additional integrally formed clamping element, which is used to produce initial stress on the pipe in the mounted state. This improves and/or accelerates claw fixation of the pipe. The cap comprises at least one projection and/or annular collar associated with the locking ring and/or the clamping element to support the clamping element or the locking ring. The clamping element is seated against the annular collar such that the locking ring preferably contacts the corresponding locking surface of the cap under initial stress. When the pipe end is inserted into the plug-in coupling, the locking ring can yield in axial direction against the prestressing force of the clamping element, while the insertion resistance preferably remains essentially unchanged.
After complete insertion of the pipe end, the locking ring is pressed against the especially conical locking surface of the cap or the annular body by means of the clamping element, so that the pipe end is quickly and securely fixed in the plug-in coupling. Manufacturing tolerances of the plug-in coupling, particularly of the annular body and the locking ring, are thus compensated just as reliably as manufacturing tolerances of the pipe end and particularly its outside diameter. There is no risk that the locking ring mounted inside the cap will already be radially deformed to such an extent that the pipe end can be inserted into the plug-in coupling only by overcoming a large insertion resistance. Advantageously, several, preferably three, such elastic clamping elements are provided. They are connected with the locking ring along one of its axial end faces, particularly via short ribs oriented in substantially axial direction, and form an integral unit with the locking ring. The cap or the annular body preferably comprises radially inwardly pointing projections that can engage with the clamping element to produce radial prestressing and reliable claw fixation and bracing with the pipe end, which is inserted into the plug-in coupling.
Advantageously, the cap or the annular body is provided with at least one inspection window, which is designed particularly in the form of a radial port or opening or an at least partially transparent area. This makes it possible to check at any time by visual inspection whether the pipe end is properly inserted into the plug-in coupling, particularly up to a predefined limit stop. This visual inspection is simple to perform either during or after assembly, including after prolonged operation, so that any impending detachment of the connection can be detected at any time and suitably corrected. The cap is preferably made of a completely transparent material; production problems are avoided due to the one-piece design.
Furthermore, the cap can have at
Friedrich Peter
Luz Oliver
Muenster Wilfried
Bagnell David
Collins G M
Crowell & Moring LLP
Friatec Aktiengesellschaft
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