GB2260971A - A vent plug for an enclosure - Google Patents

Abstract

A vent plug 10 for an enclosure 12 comprises two nested insert members 13, 14 defining a tortuous duct by which air can pass into and out of the enclosure but contaminants, such as water, are prevented from entering the enclosure. Insert member 12 nests within insert member 14 and each insert member may include a helical groove 13c, 14c forming part of the duct and directing air flow in two opposite directions A and B. A cross bore 14e in the inner member connects the interior of the enclosure to the groove 14c, while recesses 15 connect the exterior to groove 13c, the grooves being connected via notches in the end surface of side wall 13a, (13d, Fig 2a). The plug may push fit or snap fit in the enclosure opening and the enclosure may contain electrical or electronic circuitry for an internal combustion engine. <IMAGE>

Description

A VENT FOR AN ENCLOSURE This invention relates to a vent for an enclosure, and the invention relates particularly, though not exclusively, to a vent for an enclosure which houses electrical or electronic circuitry, such as the electronic control unit (e.c.u) for an internal combustion engine.

Hitherto, it has been customary to protect electrical and electronic circuitry from contaminants, such as water, by sealing the circuitry inside an enclosure using a potting material. However, in the case of relatively complex (and expensive) circuitry, such as the e.c.u. for an internal combustion engine, the circuitry must be accessible for repair or servicing and so the afore-mentioned potting technique cannot be used. In the absence of potting material, air will be present inside the enclosure and so some form of vent is needed in order to accommodate the expansion and contraction of the air which occurs as a result of internal and external temperature changes. The vent usually has the form of a tube connected to an opening in the wall of the enclosure.However, this arrangement has proved unsatisfactory because contaminants, and in particular water, can enter the enclosure via the tube.

Therefore, it is an object of the invention to provide a vent for an enclosure which at least alleviates the aforementioned problem.

According to a first aspect of the invention, there is provided a vent for an enclosure, comprising insert means located in an opening formed in a wall of the enclosure and defining a duct by which air can pass into and out of the enclosure, the duct being configured to follow a tortuous path so as to substantially prevent contaminant from entering the enclosure.

The insert means may be a push fit in said opening.

Alternatively, the insert means may be a snap fit in said opening.

Preferably, the insert means comprises an insert assembly having two or more insert members arranged in a nested configuration, and said duct comprises a first part located at an interface of the insert assembly and the enclosure wall, and a respective further part located at an interface of the or each pair of adjacent said nested insert members.

Said first and further parts of the duct may be so arranged and interconnected that successive parts of the duct define flow paths extending in generally opposed directions. This arrangement assists in preventing movement of contaminant along the duct.

Each said nested insert member may comprise a tubular side wall and an end wall, and each said part of the duct may be defined by a respective helical groove, which may be of V-shaped cross-section, formed in a surface of a said tubular side wall.

In a preferred embodiment of the invention, the insert assembly comprises an inner said insert member dimensioned to be a push or snap fit into an outer said insert member, wherein the inner and outer insert members each comprises a tubular side wall, an end wall and a helical groove formed in the outer surface of the tubular side wall, the tubular side wall of the outer insert member is adapted to interconnect said helical grooves and the tubular side wall of the inner insert member has a cross-bore for connecting the helical groove formed in its outer surface to the interior of the enclosure.

The cross-bore is preferably located away from the end wall of the inner insert member. This reduces the possibility of the cross-bore becoming blocked by an accumulation of dust or like debris on the end wall.

The wall of the enclosure may be formed with one or more recesses disposed around the opening therein, whereby to expose two or more turns of the helical groove formed in the side wall of the outer insert member, and so enable air to pass into and out of the duct.

According to a further aspect of the invention, there is provided an enclosure for housing electrical or electronic circuitry, such as the electronic control unit (e.c.u.) of an internal combustion engine, the enclosure incorporating a vent as defined in accordance with the first aspect of the invention.

A vent in accordance with the invention is now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a sectional view through the vent; and Figures 2(a) and 2(b) show respective sectional views through an outer insert member and an inner insert member of which the vent shown in Figure 1 is comprised.

Referring now to Figure 1, the vent comprises an insert assembly 10 which is a push fit in a cylindrical opening 11 formed in a wall 12 of an enclosure, of which only a part is shown in the drawing.

As will be explained, the insert assembly defines a duct which allows air to pass into and out of the enclosure and which follows a tortuous path whereby to prevent contaminant, such as water, from entering the enclosure.

The insert assembly 10 comprises outer and inner insert members 13,14 which are arranged in a nested configuration, as shown in Figure 1.

The outer insert member 13 (which is also shown in Figure 2a) has a tubular side wall 13a dimensioned to be a push-fit in opening 11, an end wall 13b and a helical groove 13c, of V-shaped cross-section, formed in the outer surface of the side wall 13a.

The inner insert member 14 (which is also shown in Figure 2b) has a structure similar to that of the outer insert member 13, being comprised of a tubular side wall 14a, an end wall 14b and a helical groove 14c, again of V-shaped cross-section, formed in the outer surface of the side wall 14a. In this case, the side wall 14a is dimensioned to be a push-fit into the tubular side wall 13a of the outer insert member 13, and it also has a circumferential flange 14d which abuts the open end of side wall 13a when the inner and outer insert members 13,14 are in the assembled condition, as shown in Figure 1.

Semi-circular notches 13d formed in the end surface of side wall 13a interconnect the two helical grooves 13c,14c and cross-bores 14e connect the innermost groove 14c to the interior of the enclosure.

The helical grooves 13c,14c, the notches 13d and the cross-bores 14e define a duct in the insert assembly which allows air to pass into and out of the enclosure.

However, as will be apparent from Figure 1, the duct follows a tortuous path through the structure of the insert assembly and is effective to substantially prevent contaminant, such as water, from entering the enclosure via the duct. In this regard, it will be noted from Figure 1 that the grooves 13c and 14c define respective flow paths which extend in generally opposed directions; that is to say, air passing in one direction along the section of duct defined by groove 13c (in the direction of arrow A, say) must subsequently pass along the downstream section of the duct, defined by groove 14c, in the opposite direction (as indicated by arrow B).

The duct can be made more or less tortuous in dependence on the required flow of air into and out of the enclosure, and the required degree of protection against ingress of contaminant and, to that end, the configuration of the duct could be modified by varying such parameters as the number and/or pitch of the grooves and by provision of one or more additional nested insert members.

The outer surface of the enclosure wall 12 is formed with four recesses 15 disposed at regular intervals around the cylindrical opening 11 whereby to expose the helical groove 13c formed in the side wall 13a of the outer insert member 13, allowing air to pass into and out of the duct.

In order to reduce the risk of a blockage occuring, the depth of the recesses 15 is sufficient to expose at least two complete turns of groove 13c, and the end wall 13b of the outer insert member 13 is arranged to overhang the recesses.

Similarly, the cross-bores 14e are positioned away from the end wall 14c in order to reduce the possibility that they become blocked by an accumulation of dust or the like on the end wall.

It will be appreciated that because the insert assembly 10 is a push fit in opening 11 it is a relatively straightforward procedure to fit a replacement insert assembly.

Alternatively, the insert assembly 10 could be designed to be snap fit in opening 11.

Typically, the described vent can be used in association with enclosures that are used to house electrical or electronic circuitry e.g. circuitry, such as an e.c.u., associated with an internal combustion engine. However, it will be appreciated that the invention is not restricted to such applications, and has general applicability to enclosures from which contaminant is to be excluded.

Claims (14)

1. A vent for an enclosure, comprising insert means located in an opening formed in a wall of the enclosure and defining a duct by which air can pass into and out of the enclosure, the duct being configured to follow a tortuous path so as to substantially prevent contaminant from entering the enclosure.

2. A vent as claimed in claim 1, wherein the insert means is a push fit in said opening.

3. A vent as claimed in claim 1, wherein the insert means is a snap fit in said opening.

4. A vent as claimed in any one of claims 1 to 3, wherein the insert means comprises an insert assembly having two or more insert members arranged in a nested configuration, and said duct comprises a first part located at an interface of the insert assembly and the enclosure wall, and a respective further part located at an interface of the or each pair of adjacent said nested insert members.

5. A vent as claimed in claim 4, wherein said first and further parts of the duct are so arranged and inter connected that successive parts of the duct define flow paths extending in generally opposed directions.

6. A vent as claimed in claim 4 or claim 5, wherein each said nested insert member comprises a tubular side wall and an end wall.

7. A vent as claimed in claim 6, wherein each said part of the duct is defined by a respective helical groove formed in a surface of a said tubular side wall.

8. A vent as claimed in claim 7, wherein the helical groove is of V-shaped cross-section.

9. A vent as claimed in any one of claims 4 to 8, wherein the insert assembly comprises an inner said insert member dimensioned to be a push or snap fit into an outer said insert member, wherein the inner and outer insert members each comprises a tubular side wall, an end wall and a helical groove formed in the outer surface of the tubular side wall, the tubular side wall of the outer insert member is adapted to interconnect said helical grooves and the tubular side wall of the inner insert member has a cross-bore for connecting the helical groove formed in its outer surface to the interior of the enclosure.

10. A vent as claimed in claim 9, wherein the cross-bore is located away from the end wall of the inner insert member.

11. A vent as claimed in claim 9 or claim 10, wherein the wall of the enclosure is formed with one or more recesses disposed around the opening therein, whereby to expose two or more turns of the helical groove formed in the side wall of the outer insert member, and so enable air to pass into and out of the duct.

12. An enclosure for housing electrical or electronic circuitry, the enclosure incorporating a vent as claimed in any one of claims 1 to 11.

13. A vent for an enclosure substantially as herein described with reference to the accompanying drawings.

14. An enclosure for housing electrical or electronic circuitry substantially as herein described with reference to the accompanying drawings.