Tube couplings

The disclosure relates to a tube coupling having a body with a throughway open at one or both ends to receive a tube. A collet is located in the throughway and a plurality of resilient fingers which engage an internal cam surface tapering in one direction towards said one end of the throughway to compress the fingers against the tube to grip and hold the tube when the collet is drawn in said one direction with the tube. An end of the collet projects from the throughway and can be depressed into the throughway to release a tube therefrom and an end cap is detachably mounted on the body to cover said open end of the throughway. The end cap has manually operable radially movable presser members for engaging the end of the collet projecting from the throughway for urging the collet into the throughway to release a tube from the body.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to tube couplings. 
2. Background Prior Art 
U.K. Patent Publication No. 2132296 discloses a tube coupling having a body 
part with a bore containing an axially tapered portion co-operating with 
arms of a collet extending into the bore, the tapered portion being such 
that axially outward movement of the collet arms to be pressed inwardly to 
grip a tube in the bore, wherein there is provided an end cover extending 
around the axially outer end of the collet and adapted to engage 
resiliently a part of the coupling body, the end cover having an aperture 
portion through which the tube can extend into the collet, said end cover 
and coupling body further having mutually engaging portions limiting 
axially inward movement of the end cover so as to prevent the collet being 
pressed inwardly to release the tube by pressure on the end cover and the 
end cover and coupling body being shaped so that the end cover can be 
disengaged from the body by an axially outward pull. 
Whilst that arrangement provides adequate protection for the collet against 
inadvertent release of a tube from the coupling body, it does also prevent 
ready intentional release of a tube from the coupling body when required 
since the end cap must first be detached from the coupling body. 
SUMMARY OF THE INVENTION 
This invention provides a tube coupling comprising a body having a 
throughway open at one end to receive a tube, a sleeve in the throughway 
projecting from said one end of the throughway, and through which a tube 
may extend into the throughway, gripping means in the throughway arranged 
to be releasable by depressing the projecting end of the sleeve into the 
throughway to allow a tube to be withdrawn from the body and an end cap 
detatchably mounted on the body to cover said open end of the throughway, 
the end cap having a aperture through which a tube can extend into the 
throughway and having manually operable means for engaging the projecting 
end of the sleeve to depress the sleeve into the throughway and thereby 
release the tubing, gripping means to allow the tube to be withdrawn. 
By way of example the sleeve and gripping means may comprise a collet 
extending into one end of the throughway, and having a plurality of 
resilient fingers extending along the throughway, and the throughway may 
have an internal cam surface tapering in one direction towards said one 
end thereof to compress the fingers against a tube within the collet to 
grip and hold the tube when the collet is drawn towards said one end of 
the throughway and to release the tube when the collet is depressed into 
the throughway by said means on the end cap. 
This invention also provides a tube coupling comprising a body having a 
throughway open at one end to receive a tube, a collet in said one end of 
the throughway through which a tube may extend into the throughway, the 
collet having a plurality of resilient fingers and the throughway having 
an internal cam surface tapering in one direction towards said one end of 
the throughway to compress the fingers against the tube to grip and hold 
the tube when the collet is drawn in said one direction with the tube, the 
collet having an end part which projects from said one end of the 
throughway to release a tube therefrom and an end cap detachably mounted 
on the body to cover said open end of the throughway, the end cap having 
an aperture thorugh which a tube can extend into the throughway and having 
manually operable means for engaging the end of the collet projecting from 
the throughway for urging the sleeve into the throughway to release a tube 
from the body. 
The cap may have a skirt closed at one end by an end wall having an 
aperture through which a tube may extend and adapted at the other end to 
mount on the body and the manually operable release means are mounted on 
the skirt of the cap. 
In a preferred construction the manually operable release means comprise a 
presser member or members extending through the skirt, the or each member 
having a cam face at the end within the skirt to engage said projecting 
end of the collet and having an end projecting outwardly of the skirt to 
which pressure may be manually applied to force the member inwardly to 
cause the cam surface thereof to engage and depress the collet end 
inwardly into the throughway of the body. 
More specifically two presser members may be provided at opposite locations 
around the skirt. 
Furthermore the or each presser member may be formed integrally with the 
wall of the skirt and the skirt may have a pair of slots extending around 
the skirt by the side of the presser member to provide webs supporting the 
presser member between the slot, the webs being resilient flexible to 
permit the presser member to be depressed inwardly of the skirt to act on 
the collet. 
In a further construction, the or each presser member is mounted in 
cantilever manner in the wall of the skirt. 
In a preferred construction, the cam face at the inner end of the presser 
member may be formed by an angled face between the side of the presser 
member adjacent the open end of the throughway and the inner end of the 
presser member to bear against the end of the sleeve projecting from the 
throughway. 
Also in a preferred construction the inner end of the presser member may be 
concavely curved to fit around the tube within the end cap when the 
presser member is depressed inwardly to act on the sleeve. 
In any of the above arrangements the open end of the cap may be formed with 
an inwardly projecting lip around its inner periphery to engage in a 
corresponding groove in the outer periphery of the body to locate the cap 
on the body with the end wall of the cap spaced from the end of the body. 
In addition the upstanding projection may be formed on the end cap adjacent 
the or each pressor member to protect the latter against inadvertent 
operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, there is shown a double ended coupling body 10 for 
effecting a coupling between two lengths of tubing 11. The coupling 
comprises an injection moulded plastics hollow generally tubular body 12 
having a central throughway 13 and open ends 14 and 15. Midway along the 
throughway 13 the body has an integral annular wall 16 encircling the 
throughway to define a stop against which the ends of the tubes 11 
inserted from either end of the throughway engage. Partway along the 
throughway from the annular wall 16 towards each end 14, 15 of the 
throughway, the wall of the throughway is stepped out at 17, 18 to form 
enlarged bores 19, 20 extending towards the open ends 14, 15 of the 
throughway. The steps or shoulders 17, 18 thus formed in the bore face 
towards the open end 14, 15 of the throughway. Annular resilient seals 21, 
22 are disposed in the enlarged bores 19, 20 against the shoulders 17, 18 
to seal with the outer surfaces of the tubes inserted into the throughway. 
Adjacent the ends 14, 15 of the body 12 the throughway is formed with 
tapering cam surfaces 23, 24 reducing towards the end of the body and 
collets 25, 26 are disposed in the ends of the body and formed with metal 
insert grips partway along the inner sides of the fingers for gripping the 
tubes which extend through the collets. The resilient fingers of the 
collets are compressed in engagement with the tubes extending through the 
collets by engagement with the tapering cam surfaces 23, 24 by movement of 
the collets outwardly of the coupling body to lock the tubes in the 
throughway. 
The collets 25, 26, extending outwardly of the open ends 14, 15 of the 
coupling body and the ends of the collets are formed with radially 
outwardly extending heads 25a, 26a. In order to release the tubes from the 
coupling, the collets are pressed inwardly by pressure on the heads 25a, 
26a to relese the camming action of the cam surfaces 23, 24 on the 
resilient fingers 27, 28 and with the collet held inwardly, the tubes 11 
can then be withdrawn. 
In order to prevent accidental release of the tube, end covers 30, 31 are 
provided. Each cover comprises a cylindrical skirt 32 having an end wall 
33 at one end thereof with an aperture 34 through which a respective tube 
11 extends. The other end of the skirt extends around an outer end of the 
coupling body and has a radially inturned flange 35 which engages in an 
encircling groove 36 on the body. Each cap is thus detachably held on the 
body and the skirt is so dimensioned that the end wall 33 of the cap is 
spaced well clear of the head of the collet projecting from the adjacent 
end of the throughway. 
The skirt of each cap is formed with integral radially extending presser 
members 37, 38 at diametrically spaced locations across the cap which have 
parts 37a, 38a extending radially outwardly of the skirt of the cap and 
parts 37b, 38b extending radially inwardly of the cap. The latter, 
inwardly extending parts have concavely curved ends 37c, 38c shaped to 
extend around the tube 11 passing through the cap. The corners of the 
inwardly extending parts 37b, 38b of the presser members are bevelled 
between the inner ends 37c, 38c and the sides of the presser members 
adjacent the ends of the coupling body to provide inclined cam surfaces 
37d, 38d to engage the head of the collet 25a, projecting from the 
adjacent end of the coupling body encircled by the cap. 
On either side of the presser members 37, 38, the wall of the skirt is 
formed with elongage slots 40, 41 extending around the skirt and beyond 
each presser member as best seen in FIGS. 2 and 4. The wall of the skirt 
between adjacent ends of the slots forms webs 42 supporting the presser 
members and the material of the cap and thickness is such that the webs 
are resiliently flexible to permit the presser members to be depressed 
inwardly of the cap by radial pressure on the outer ends of the presser 
members 37, 38 as depicted in the left hand part of FIG. 1. Forcing the 
presser members radially inwardly engages the inclined cam surfaces 37d, 
38d with the enclosed head 25a, 26a of the collet to press the collet 
axially inwardly and thereby to release the gripping action of the 
resilient fingers on the tube within the collet permitting the tube to be 
extracted. When inward pressure on the presser members is released, the 
presser members are restored to their outer positions as illustrated in 
the right hand end of FIG. 1 and a tube can then be re-inserted in the 
coupling body and by slight movement outwardly of the body locked in place 
by the jamming action of the resilient fingers of the collet on the tube 
as aforesaid. 
The arrangement of the invention thus provides protection against 
inadvertent release of the tube from the coupling body by accidental 
impact on the end of the collet projecting from the coupling whilst 
readily permitting release of the tube by actuating the presser members of 
the cap when it is required to extract the tube. 
Reference is now made to FIGS. 5 and 6 of the drawings which illustrate a 
modified version of the end cap. For the sake of simplicity, like parts 
have been allotted the same reference numerals as in the previously 
described embodiment. In the embodiment of FIGS. 5 and 6, the skirt 32 is 
formed with generally rectangular openings 45 at diametrically spaced 
locations around the skirt and the presser members 37, 38 are mounted in 
the openings 45 in cantilever fashion on short webs 46 formed in the skirt 
wall adjacent the open end of the skirt. 
There is a clearance between the periphery of the apertures 45 and the 
pressure members 37, 38 to provide free movement of the presser members 
through the apertures. The end wall 33 of the skirt has raised lugs 47, 48 
disposed opposite the presser members 37, 38 to provide some protection 
against accidental operation of the presser members. 
In the embodiment of FIGS. 1 to 4, the bevelled faces 37d, 38d on the inner 
edges of the presser members terminated in end faces 37.degree., 
38.degree.. In the embodiment of FIGS. 5 and 6, the bevelled faces 37d, 
38d extend fully across the inner ends of the presser members. Finally, 
the in-turned lip or flange 35 around the open end of the skirt 32 has an 
inclined inner face 35a as shown in FIG. 6 to facilitate removal of the 
end cap from the coupling body. 
In the above described embodiments the tube is gripped in the body member 
of the tube coupling by means of a collet having resilient arms which are 
pressed against the tube by a tapered cam surface on the body. Other 
gripping devices may however be utilised for holding the tube and a sleeve 
provided in the throughway projecting from the open end thereof to receive 
the tube and arranged to release the gripping action by depressing the 
sleeve into the coupling body by means of the presser members on the end 
cap.