GB2211258A - Cam-and-groove fluid transfer couplings with bayonet fitting - Google Patents

Abstract

A cam-and-groove coupling for connecting hoses is provided having a hollow male part (30) provided with a groove (36) around its outer circumference, a female part (10) having a bore (13) that can receive the male part (30). One or more arms (18) are provided on the female part that have a cam surface (27) that, in one position of the arms (shown in solid lines), can engage in the groove when the male part has been inserted into the female part. The arms (18) can be moved to another position (shown in dotted lines) to remove the cam surfaces (27), allowing the male and female parts (30, 10) to be disengaged. The coupling also includes a pin (38) in the male part that can be engaged in a channel (22) in the female part in the manner of a bayonet connection to prevent release of the coupling when the arms (18) disengage the cam surfaces (27) if there is still pressure in the hoses. <IMAGE>

Description

FILm) ###?#### The present invention relates to fluid transfer couplings, eq, hose couplings for connecting together the ends of two hoses or for connecting a hose to a fluid source, e.g. a tank, tanker or other vessel, in a leak-tight manner.

Cam-and-groove couplings have been known for 40 years and we have sold this type of coupling under the Registered Trade Mark 'Action' for several years. Such couplings have a female part, which may be secured to the end of one hose, and a male part, which may be secured to the end of another hose (or to the fluid source); the male part has a hollow generally cylindrical wall provided with a circumferential groove on its outer face while the female part has a hollow generally cylindrical wall enclosing a bore for receiving the male part. Two arms are secured in openings in the wall of the female part by pins about which the arms can be pivoted; in one position of the arms, cam surfaces on the arms extend into the bore of the female part and, when the male part is fully inserted in the female part, engage with the groove of the male part to hold the male and female parts together.In a second position of the arms, the cam surfaces are withdrawn from the groove and the male part is thus free to be withdrawn from the female part. The arms are so pivoted that when they are in their first position (i.e. the coupling is closed), internal pressure within the coupling, which tends to separate the male and female parts, urges the arms in the opposite direction to that required to open the coupling, thereby keeping the coupling closed. Hose couplings of this known type will be described in this specification as 'cam-and-groove' couplings.

One problem associated with cam-and-groove couplings is that, when the cam arms are moved to the second position in which the male part is released, the release is sudden and, if there is pressure in the hose line, there is no indication of this until the coupling has been fully opened but it is then too late to close the coupling before appreciable spillage occurs, which not only causes a loss of the contents (which could be expensive), but also, in the case of hazardous material, could give rise to damage to property and/or injury to personnel.

We have now devised a cam-and-groove hose coupling that can give advance warning of the fact that the hose line is under pressure and so will allow the coupling to be re-closed before it is fully released.

According to the present invention there is provided a fluid transfer coupling comprising: (a) a hollow male part having a recess in its outer circumference, (b) a hollow female part having an annular wall enclosing a bore capable of receiving the male part, the female part also including at least one arm extending through an opening in the annular wall, the or each arm being pivotable between a first position in which a cam surface on the or each arm extends into the bore to engage the recess of the male part (when the male part is present in the bore of the female part) thereby holding the male part in the female part, and a second position in which the cam surface is withdrawn from the bore thereby allowing the male part to move freely out from the female part, wherein the male and female parts are further secured by a bayonet connection, which preferably consists of one or more pins on the male part engaging with a channel in the bore of the female part, but the pins can be provided on the female part and the channel on the male part.

Preferably the coupling has at least two arms.

It is preferred that the dimensions of the pins and of the channel should be such that the bayonet connection, when made, should allow a limited amount of axial movement between the male and female parts.

As mentioned above, standard cam-and-groove couplings have a groove extending circumferentially around the outer surface of the male part and, in one embodiment of the present invention, the recess in the male member may be formed as such a groove.

The coupling may be such that it is possible to close the coupling by pivoting the arm(s) to the second position without engaging the bayonet connection, which is achieved by closing the arm(s) while the pins of the bayonet connection are simply located in the entrance to the bayonet channel so that, on release of the cam-and-groove coupling, the pins will not be held in the bayonet channel and so will not prevent the male and female parts being completely separated when the arm(s) are opened.However, when the fluid is hazardous or particularly valuable, it would desirable to prevent such an eventuality by the provision of means that prevent the coupling being closed by pivoting the arm(s) when the bayonet connection has not been secured, i.e. when the pins of the bayonet connection are merely located in the entrance into the bayonet channel; it would then be impossible to close the cam-and- groove coupling without first securing the bayonet connection and this measure would prevent the possibility of the coupling being fully opened merely by moving the arm(s) to the second position.Such means could be a key or protrusion on the male part that physically blocks the movement of the arm(s) when the bayonet connection has not been secured, e.g. the recess, instead of being a circumferential groove extending the whole way around the male part, may not be present in locations opposite the arm(s) when the bayonet connection is not engaged (thereby preventing closing of the arms when the bayonet connection is not engaged) but rather recesses are only present in locations that lie opposite the arm(s) when the bayonet connection is engaged.Alternatively, the bottom of the bayonet channel may have a protrusion opposite the channel entrance so that the bayonet pins cannot be seated properly at the bottom of the channel; the arrangement should be such that, on moving the arms towards the first position, the cam surface(s) on the arm(s) cannot engage properly with the recess thereby preventing the arm(s) being moved fully to the first position and thereby preventing the coupling being closed.

The invention will be described in further detail with reference to the accompanying drawings, in which: Figure 1 is a part cut-away side view of a hollow female part of a coupling of the present invention; Figure 2 is a view along arrow A of Figure 1; Figure 3 is a part cut-away side view of a hollow male part of a coupling of the present invention, and Figure 3a is a detail of Figure 3.

Figures 1 and 2 show the hollow female part 10 of the coupling; it has a tail piece 11 that can be pushed into a hose and a generally cylindrical wall 12 enclosing a bore 13 and having two diametrically opposed openings 14, which are each flanked by two lugs 16. A cam arm 18 (not shown in Figure 2) is held in each opening 14 by a pin 20 that passes through the arm and is secured in lugs 16 so that the arms 18 can pivot about pins 20. There is a grooved channel 22 in the inner face of the wall 12 just below its outer rim 24 and, in addition, there are also two notches 26 (only one shown in Figure 1) in the outer rim 24 which communicate with the grooved channel 22; the grooved channel 22 and the notches 26 together form the socket of a bayonet connection as will be described in further detail below.

An annular gasket 28 is held in a seat at the base of the bore 13. At the bottom of the channel 22, there is a protrusion 29 which prevents the arms 18 from being closed when the bayonet coupling is not engaged, as will be described in detail below.

The hollow male coupling part 30, which is shown in Figure 3, has a male- or female-threaded end 32 for securing to a fluid source, e.g. a tank, tanker or other vessel or, when connecting two hoses together, for securing to a female threaded adaptor secured in the end of a hose; alternatively, in the latter application, the male coupling part 30 may have a tail piece similar to the tail piece 11 shown in Figure 1 which can be directly secured to its respective hose pipe. The male coupling part 30 has a cylindrical wall 34 having an external diameter slightly smaller than the diameter of the bore 13 of the female part 10. A groove 36 is machined around the perimeter of the wall 34 and, just behind the groove 36, two diametrically opposed bayonet pins 38 are tapped into blind holes in the wall (see Figure 3a). A land 42 may be provided along the length of the groove to prevent coupling being closed without the bayonet connection being engaged, as will be described in greater detail below.

In the following description, we will describe the connection between a hose and a vessel but it should be understood that the present invention is not limited to this application. In order to make the connection, the female part 10, which is secured to the hose, is pushed in the direction opposite to arrow A onto the male end 30, which is secured to the vessel, so that the male part 30 enters the bore 13; the action of the male part 30 entering into the bore 13 moves arms 13 into the position shown in dashed lines in Figure 1 (if the arms are not already in this position). During insertion, the female end should be orientated such that the pins 38 pass through access notches 26 into channel 22; in order to do this, the female part 10 must be turned by 900 about its longitudinal axis as compared to the orientation shown in Figure 1.The female coupling part 10 is then twisted so that the pins 38 move into grooved channel 22 but are no longer in register with notches 26 and thus the male and female parts are connected by a bayonet connection similar to that used in holding electric light bulbs. A pair of recesses (not shown) may be provided along the length of channel 22 to seat the bayonet pins 38 when the coupling is joined in this way.

The coupling is then fully closed by moving the arms 18 in the direction of arrows B to the position shown in solid lines in Figure 1 in which the cam surface 27 of each of the arms 18 extends into the groove 36 of the male part. When the arms have been moved to the position shown in solid lines, the leading face 40 of the male part is pressed against the gasket 28 to form a leakproof seal. The pressure in the hose tends to push the female part 30 off the male part 30 and thus to push the arms 18 in the direction of arrows B in Figure 1 but such movement is impossible because of the abutment of the arms 18 against the body of the female coupling part 10.

The coupling can be released by pivoting arms 18 in the direction opposite to arrows B to the position shown in dashed lines in Figure 1 in which the cam surfaces 27 are no longer located in groove 36. The coupling of the present invention differs from known cam-and-groove couplings in that the movement of the arms is not sufficient in itself to release the coupling fully because the male and female parts are still held together by virtue of pins 38 being located in channel 22. In order to release the coupling completely, the female part 10 is twisted until the pins 38 are in register with notches 26 and only when this is done can the two parts 10, 30 be separated.

If the female member is not twisted to locate the pins 38 in the channel 22 prior to the arms 18 being pivoted to secure the cam-and-groove coupling, then the coupling can be released merely by moving the arms to the position shown in dotted lines in Figure 1. To prevent the coupling being closed without the bayonet connection being engaged, the land 42 may be provided that prevents the arms being moved to close the coupling unless the female member has been twisted to locate the pins in the channel 22. If seats were provided in the channel 22 for the pins 38, the groove 36 could be present only in places opposite to the location of the arms when the pins are located in the seats; this arrangement is not shown in Figure 1.Instead of providing the land 42, the arms 18 may be prevented from being closed when the bayonet connection has not been engaged by protrusions 29 as follows: if the pins 38 were positioned in notches 26 instead of in the channel 22, the protrusions prevent the female part being pushed fully onto the male part and in this position the cam surfaces 27 on the arms 28 cannot engage properly in the groove 36 and so cannot be moved to their closed position. When the protrusions 29 are present, the clearance between them and the top of the channel 22 must be large enough to allow the pins 38 to pass into the channel 22.

The relative dimensions of the pins 38 and the channel 22 are such that a limited amount of axial movement is possible between the male and female parts when the bayonet connection has been secured but before the coupling is fully closed by moving arms 28 in the direction of arrow B. Thus the bayonet connection allows a small movement by the female member to enable the gasket 28 and the end face 40 of the male member to be urged together to form a leak-tight seal when the arms 18 are moved in the direction of arrow B to close the coupling fully. When the arms 18 are released, the leading face 40 of the male part is no longer urged against gasket 28 and the play of the pins 28 in the channel 22 allows a limited amount of axial movement between the male and female parts which provides leak path between these parts. If there is pressure in the hose line when arms 18 are released, the leakage along the leak path will be observed by the operator who can then re-seal and secure the coupling by moving arms 18 in the direction of arrows B. When the operator has checked that there is no leakage following the release of the arms 18, he can fully release the coupling by twisting the female part so that the pins 38 are located opposite notches 26 and the female part can then be pulled off the male part.

When not in use, the end of a hose provided with a female coupling part can be sealed off by means of a male part that is as shown in Figure 3 with the exception that it is not hollow or the end of the male part is blanked off. Likewise the end of a hose fitted with a male coupling part can be sealed by a blanked off female part.

Claims (10)

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1. A fluid transfer coupling comprising: (a) a hollow male part having a recess in its outer circumference, (b) a hollow female part having an annular wall enclosing a bore capable of receiving the male part, the female part also including at least one arm extending through openings in the annular wall, the or each arm being pivotable between a first position in which a cam surface on the or each arm extends into the bore to engage the recess of the male part (when the male part is present in the bore of the female part) thereby holding the male part in the female part, and a second position in which the cam surface is withdrawn from the bore thereby allowing the male part to move freely out from the female part, wherein the male and female parts are further secured by a bayonet connection.

2. A coupling as claimed in claim 1, wherein the coupling includes means for preventing the arms being moved from the second position to to the first position when the bayonet connection is not engaged.

3. A coupling as claimed in claim 2, wherein the recess is provided only in those parts of the outer circumference of the male member lying opposite the arm(s) when the bayonet connection is engaged thereby preventing the arm(s) being moved from the second position to the first position when the bayonet connection is not engaged.

4. A coupling as claimed in claim 2, wherein the recess is a groove extending around the outer circumference of the male part but lands are provided in the groove in places opposite the arm(s) when the bayonet connection is not engaged thereby preventing the arm(s) from being moved from their second to their first positions when the bayonet connection is not engaged

5. A coupling as claimed in claim 2, wherein a protrusion is formed at the bottom of the channel of the bayonet connection opposite to the entrance into the channel for the bayonet pins, which protrusion is such that it prevents the cam surface on the or each arm from engaging the recess and thereby prevents the arm(s) being moved to the first position.

6. A coupling as claimed in claim 1 or claim 2, wherein the recess is a groove extending the whole way around the outer circumference of the male part.

7. A coupling as claimed in any one of claims 1 to 5, wherein two or more arms are provided.

8. A coupling as claimed in any one of claims 1 to 7, wherein the bayonet connection is formed by one or more pins on the male part engaging with a channel in the bore of the female part.

9. A coupling as claimed in any one of claims 1 to 8, wherein the bayonet connection, when engaged, allows limited axial movement between the male and female parts to allow pressurised contents of the coupling to leak when the arm(s) are in the second position.

10. A coupling substantially as hereinbefore described in connection with and as shown in the accompanying drawings.