GB2542405A

GB2542405A - Fluid-tight push-fit connector

Info

Publication number: GB2542405A
Application number: GB1516559.0A
Authority: GB
Inventors: James Dominic Fisher Martin; Maruthiah Palanivelrajen; Eastwood James
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2015-09-18
Filing date: 2015-09-18
Publication date: 2017-03-22
Also published as: GB201516559D0

Abstract

A push-fit connector for connecting a fluid supply to a body 16 comprises a tubular spigot 12 for connecting to the end of the pipe and a bore 14 in the body 16 for receiving the spigot 12. The spigot is a stepped cylinder having two axially spaced regions 22, 24 of different outside diameter, each region being formed with an annular groove 26, 28 receiving an O-ring 30, 32. The bore is a stepped bore 14 having two axially spaced sections 40, 42 of different inside diameter for receiving the regions of the spigot. The O-rings 30, 32 form axially spaced fluid-tight seals between the spigot 12 and the bore 14. The mouths of the two sections 40, 42 of the stepped bore 14 can be spaced apart by a distance that exceeds the length of the smaller diameter region of the spigot 12, and that is less than the distance between the O-ring receiving grooves 26, 28 in the different diameter sections of the spigot 12. The mouths of the sections of the bore 14 can be chamfered to assist in compressing the O-rings 30, 32 during insertion of the spigot 12 into the bore 14.

Description

FLUID-TIGHT PUSH-FIT CONNECTOR

Field of the invention

The present invention relates to a fluid-tight push-fit connector for connecting a fluid source, such as the end of a pipe carrying a fluid, to a body.

Background of the invention A turbocharger in a vehicle has bearings that support the rotor and that need to be oil lubricated. An oil feed line therefore needs to the connected to the body of the turbocharger. Because of the high temperature at which the turbocharger operates, it is critical that there should be no oil leak at the connection between the feed line and the body of the turbocharger.

It is known to use a push-fit connector constructed as a cylindrical spigot on the end of the feed line that plugs into a bore in the body of the turbocharger. An O-ring of a suitable material sits within an annular groove in the outer surface of the spigot and is compressed as it is pushed through a chamfered end of the bore to achieve an effective seal between the spigot and the inner surface of the bore.

To ensure that the O-ring is not damaged during insertion, it is important for the spigot to be accurately co-axial with the bore as the O-ring engages the chamfered end of the bore. The spigot therefore needs to have a substantial length forward of the annular groove that receives the O-ring (termed the piston lead) and both the piston and bore need to be machined with high accuracy. The very small machining tolerances add to the manufacturing cost and the aim of the present invention is to mitigate this disadvantage and to provide a more reliable seal.

Summary of the invention

According to the present invention, there is provided a push-fit connector for connecting a fluid source to a body, the connector comprising a tubular spigot for connecting to the fluid source and a bore in the body for receiving the spigot, wherein the spigot is in the form of a stepped cylinder having two axially spaced regions of different outside diameter, each region being formed with a respective annular groove receiving an O-ring, and the bore being a stepped bore having two axially spaced sections of different inside diameter for receiving the respective regions of the spigot, the O-rings forming axially spaced fluid-tight seals between the spigot and the bore.

Because the connector has two axially spaced seals, a defect in only one of the two seals will not result in a leakage as the other seal will remain effective. The twin seal system also provides a weather resistant feature in that corrosion is prevented from being present near the seal in the smaller diameter bore section that acts as the primary seal.

If two O-rings of the same diameter were to be used on a cylindrical spigot inserted into a bore of uniform diameter, then during insertion of the first O-ring into the bore, only the piston lead would assist in maintaining the spigot in accurate axial alignment with the bore and this can result in the leading O-ring being damaged during the installation. The use of a stepped bore ensures that the machining of each bore section is accomplished with different cutter tool surfaces, such that the likelihood of both being outside the permitted tolerance or faulty or affected by swarf, is significantly diminished.

In an embodiment of the invention, the mouths of the two sections of the stepped bore, that is to say their ends through which the O-rings are inserted, are spaced apart by a distance that exceeds the length of the smaller diameter region of the spigot. As a result, the larger diameter region of the spigot enters into the larger section of the bore before the leading O-ring enters the smaller diameter section of the bore. There are therefore two axially spaced piston leads, engaged in respective sections of the stepped bore before the leading O-ring is compressed into the smaller diameter section of the bore. This ensures accurate axial alignment of the spigot with the bore during insertion of the leading O-ring and minimises the risk of damage. An advantage of this method of alignment system is that it permits a reduction in the overall length of the joint, by avoiding the need for a long piston ahead of the primary O-ring.

In some embodiments, the distance between the mouths of the two sections of the stepped bore is different from and preferably less than the distance between the O-ring receiving grooves in the different diameter regions of the spigot. This ensures that the O-rings are compressed one at a time and not simultaneously, and reduces the amount of force required to push the spigot into the stepped bore.

In some embodiments, the mouths of the sections of the bore are chamfered to assist in compressing the O-rings during the insertion of the spigot into the bore.

Brief description of the drawings

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a section through a connector of the invention, at the commencement of insertion of the spigot into the stepped bore,

Figure 2 is a similar section to that of Figure 1 midway through insertion of the spigot, and

Figure 3 is a similar section to that of Figure 1 showing the connector in a fully assembled state.

Detailed description of the drawings

The figures show a push-fit connector 10 at different stages of insertion. The connector 10 is formed of a tubular spigot 12 that is fitted to the end of a pipe, or other gas or liquid supply, and a bore 14 in a body 16 for receiving the spigot 12 to establish a fluid-tight connection between a gallery 18 in the body 16 and the pipe to which the spigot 12 is fitted, through the inner bore 20 of the spigot 12.

The outer surface of the spigot 12 is formed as a stepped cylinder with a larger diameter region 22 and a smaller diameter region 24. Each region is formed with a respective groove 26, 28 that receives a respective O-ring 30, 32. At their leading ends, i.e. their ends facing downwards in the drawings, the two regions 22, 24 have respective tapers 36, 38 to assist in aligning the spigot 12 with the bore 14.

The bore 14 is also stepped, being formed with a larger diameter section 40 and a smaller diameter section 42. The two regions 22, 24 of the spigot 12 are dimensioned to be a nice fit in the sections 40, 42 of the bore, respectively. When the spigot 12 is fully inserted in the bore 14, in the manner shown in Figure 3, the O-rings 30, 32 are compressed and form a fluid-tight seal around the spigot 12.

The mouths 44, 46 of the two bore sections 40 and 42 are chamfered or tapered so that the O-rings 30, 32 are compressed as the spigot 12 is advanced axially into the bore 14.

To establish a connection between the pipe connected to the spigot 12 and the body 13, the spigot is first offered up to the stepped bore and urged axially into it. The conical tapers 36, 38, the front end of the regions 22, 24 and the chamfered mouths 44, 46 of the bore sections 40 and 42 act to centre the spigot 12 relative to the axis of the bore 14 and, until the spigot reaches the position shown in Figure 1, no significant resistance is encountered when pushing the spigot 12 into the bore 14.

In the position shown in Figure 1, the O-ring 32 has reached the tapering mouth 46 of the narrower bore section 42 and starts to be compressed. Because, as shown in the drawings, the mouths 44, 46 of the two sections 40, 42 of the bore 14 are spaced apart by a distance that is greater the length of the smaller diameter region 24 of the spigot 12, the larger diameter region 22 of the spigot 12 is already engaged in the larger section 40 of the bore by the time the O-ring 32 reaches the mouth 46 of the smaller diameter bore section 42. This engagement ensures that the spigot is perfectly aligned with the bore 14 when force is applied to the spigot 12 to push the O-ring 32 into sealing contact with the bore section 42. As a result, the O-ring 32 is compressed from all sides at the same time and this avoids any risk of damage to the O-ring 32.

It will be seen from Figure 2 that even after the O-ring 32 has been pushed into the smaller diameter section 42 of the bore 14, the O-ring 30 still lies outside the larger diameter section 40 of the bore 14. Further force applied to the spigot now compresses the O-ring 30 into the bore but because the two O-rings are compressed sequentially, rather than simultaneously, less resistance is encountered in pushing the spigot 12 into the bore 14 albeit that resistance is encountered over a greater range of movement of the spigot 12.

Once the spigot 12 is fully inserted into the stepped bore 14, it may be held in place by means a retaining plate or bracket that engages the protruding end of the spigot and is separately bolted to the body. As an alternative, a nut fitted to the end of the pipe may engage an externally screw threaded tubular formation on the body 16. The nut is not however required to apply compression to establish a seal; it serves only for retention of the spigot in the bore.

The term “O-ring” has been used herein to describe the compressible annular sealing elements but it should be noted that the cross-section of the sealing elements need not be a perfect circle. For example, if the sealing elements may be chamfered on their forward facing side, whereupon it may not be necessary for the mouths of the bore sections to be chamfered.

The invention has been described by reference to an embodiment having only two staggered seals but it will be clear that a greater number of seals may be employed in situations where avoiding leakage is critical.

The connector described herein is designed for connecting an oil feed line to an engine turbocharger but it will be clear to the person skilled in the art that it has application in any situation where any fluid supply is to be connected to a housing. The connector is inexpensive to manufacture because it does not rely heavily on components manufactured to exacting tolerances. It is quick and easy to assemble with less risk of its being damaged during assembly. Furthermore, the connector can be used in hostile environments, as it is able to withstand high temperature and vibrations.

The design of the above described embodiment results in a very robust connector that does not need to be leak checked before the engine is run for the first time in cold/Hot test. The design offers the following important advantages, namely: • A reduction in overall package length resulting from a reduction in the length of the piston lead feature, • A reduction of the assembly force by avoiding the need to compress two O-rings simultaneous, and • Improved resistance to corrosion, such as by weather.

Claims

1. A push-fit connector for connecting a fluid source to a body, the connector comprising a tubular spigot for connecting to the fluid source and a bore in the body for receiving the spigot, wherein the spigot is in the form of a stepped cylinder having two axially spaced regions of different outside diameter, each region being formed with a respective annular groove receiving an O-ring, and the bore being a stepped bore having two axially spaced sections of different inside diameter for receiving the respective regions of the spigot, the O-rings forming axially spaced fluid-tight seals between the spigot and the bore.

2. A connector as claimed in claim 1, wherein mouths of the two sections of the stepped bore are spaced apart by a distance that exceeds the length of the smaller diameter region of the spigot.

3. A connector as claimed in claim 1 or 2, wherein the distance between the mouths of the two sections of the stepped bore is less than the distance between the O-ring receiving grooves in the different diameter regions of the spigot.

4. A connector as claimed in any preceding claim, wherein the mouths of the sections of the bore are chamfered to assist in compressing the O-rings during the insertion of the spigot into the bore.

5. A connector constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.