GB2196080A - Pressure coupling - Google Patents

Abstract

A female fluid coupling member adapted to receive and retain a male fluid coupling member, each of which members is provided with a check valve to prevent egress of fluid in its unconnected state, each check valve being provided with a projection, the projections being adapted to interengage with one another and by means of which the valves can be opened, the female member being provided with means to permit its check valve to open when coupled to a male member with a higher residual pressure therein causing its check valve to remain closed, the said opening of the female member being effected while avoiding any detrimental quantity of fluid leaking and subsequently permitting fluid under pressure to be applied through the female member to cause the male check valve to open against the higher residual pressure, the male check valve being prevented from reseating when the members are coupled together. <IMAGE>

Description

SPECIFICATION Fluid coupling This invention relates to a fluid coupling and is more particularly concerned with a fluid coupling for connecting fluid from a pressure power source to a line to a fluid operated implement.

Such couplings are commonly used in tractor/trailer couplings where a fluid operated implement on a trailer is coupled with a fluid power source on a tractor.

Such couplings comprise a female member adapted to receive a male member, the members being connected respectively to the fluid power source and to the implement, each of the members being provided with a check valve to prevent egress of fluid in its unconnected state, each check valve being provided with a projection, the projections being adapted to interengage with one another to open the valves.

The male and female couplings are normally retained against separation in the connected condition by a plurality of locking balls contained in the female coupling which engage in an external groove on the male coupling. The locking balls are situated in a spring centred housing which is arranged to move inwards to permit radial outward movement of the balls during connection. The balls then return to the locked position by movement of the housing to the centre position. When a separating force is applied externally to the male coupling the spring centred housing moves outwardly so the balls can move radially outwards allowing disconnection of the two coupling halves.

The spring centred housing then returns to the centre position.

The pressure in the line behind the male coupling may have a load induced pressure which may be present at the time of disconnection or may be generated after disconnection by the subsequent application of an external load to the equipment behind the male coupling. In either case some load induced pressure can be present within the male cou pling member which usually requires the release of a substantial volume of fluid before it can be relieved.

Where the force generated by the application of this pressure acting over the nose of the male coupling member in engagement with the corresponding seal provided in the female member exceeds the force exerted by the centering spring the spring centred housing cannot return to the central locked position until the male coupling has been disengaged.

Connection under this condition is impossible.

A strong centering spring increases the load induced pressure under which connection can be made but even where this spring strength renders the coupling difficult for the operator to connect relatively modest load induced pressures still prevent the opening of the male coupling member.

Moreover male coupling members of the most widely used in agricultural implements are the subject of an international standard which specifies the maximum spring load of the internal check valve and an internal stop to prevent excessive value movement.

Also if a high force is used to overcome this residual pressure leakage can occur which then forms a barrier between the male and female members thus preventing any further insertion and preventing the coupling being connected.

It is an object of the present invention to enable coupling to take place where there is a residual pressure in the line to the implement.

According to the present invention a female fluid coupling member for a coupling of the type set forth is provided with means to permit its check valve to open when coupled to a male member with a higher residual pressure therein causing its check valve to remain closed, the said opening of the female member being effected while avoiding any detremental quantity of fluid leaking and subsequently permitting fluid under pressure to be applied through the female member to cause the male check valve to open against the higher residual pressure, the male check valve being prevented from reseating when the members are coupled together.

The reference to any detremental quantity of fluid above means that when the check valve in the female member or in some circumstances in the male member is cracked no fluid will escape therefrom which would in any way form a fluid barrier and prevent coupling.

In one construction the means for preventing the male check valve from reseating comprise means for limiting the opening movement of the female check valve in the fully coupled position. Conveniently the means for limiting the opening movement of the female check valve are rendered inoperative during the coupling operation.

Preferably the check valve in the female member is biassed into the closed position by means of a spring. There may be two such springs operating in sequence.

The check valve is preferably located in a movable sleeve which is itself adapted to move in the check valve opening direction when the check valve is opened. Preferably the check valve is carried by a further body member itself slidable in a bore in the sleeve member and the valve being biassed with respect to the further body member into a closed position.

The bore in the sleeve member may be formed as a bore and counter bore joined by a chamfer, the further body member having respectively portions of larger and smaller diameter slidable therein. Furthermore the stem of the check valve may be slidable in a bore in the further body member, and in this case radial openings may be provided in the further body member between the two different diameter bores, the radial openings leading into the bore in which slides the check valve, and balls provided in the radial openings and movable between a retracted position in which the stem of the check valve can slide freely and an operative position in which the balls are engaged in the smaller diameter bore, said operative position limiting opening movement of the check valve.

Where there are two springs operating in sequence one of the springs preferably provides less than half the force necessary to overcome the male check valve coupling spring, whilst at the same time providing sufficient force to engage the balls in the operative position. This function may be formed by an inner spring while an outer spring may act on a webbed guide member restrained by retaining ring so that this additional spring load is only transmitted to the valve after initial opening movement of the female member when the internal static pressure has been released.

This construction is particularly applicable where there are only modest pressures in the line behind the male member.

The male check valve projection reseats the female check valve against the slight residual pressure in the female member allowing fluid to escape to atmosphere before the male member engages the seal.

The atmospheric air which is displaced on the movement of the sleeve number is preferably vented by one or more passages in the sleeve member leading from the rear thereof.

Movement of the sleeve member preferably causes movement of the balls into the large diameter bore thus releasing the check valve for further movement.

The sleeve member has means preferably biasing it in the closing direction of the check valve, and a sleeve member is preferably adapted to be moved on entry of the male coupling member. In this case the sleeve member is provided with means for sealing the male coupling member with respect thereto, as well as means for retaining it therein.

The invention may be performed in various ways and one specific embodiment and a modification thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional side elevation of a coupling member according to the present invention; Figure 2 is a similar view to Figure 1 with a second coupling member about to be coupled thereto and in the initial insert position; and, Figures 3 to 5 are views similar to Figure 2 showing the disposition of th various parts as the members are progressively coupled together.

Figure 6 is a similar view to Figure 1 of a modified construction.

In the arrangement to be described and as shown in the drawings the coupling member is for connecting a fluid line from an agricultural vehicle to a fluid operated implement and comprises a body member indicated generally at 1 adapted to be connected to a body member 2 (shown in Figures 2 to 5). Each of the body members 1 and 2 has respective means (not shown) for connection to conduits at their rearward ends indicated at 3 and 4 respectively, leading to the fluid pressure source and the implement.

The body member 1 is a female member and comprises a rear generally cylindrical member 5 and a generally cylindrical member 6 which are secured together by screw threaded portions indicated at 7 and with a fluid seal indicated at 8, the member 6 extending into the interior of the rear member 5 to a position adjacent its rear end.

The member 6 is provided with four stepped bores 10, 11, 12 and 13. Secured in the outer stepped bore 10 and retained therein by a retaining ring 9 is a coupling ring 15 and having an internal groove 16 therein in which retaining balls 17 are receivable.

Located within the body member 1 is an internal sleeve member indicated generally at 18 adapted to slide with respect thereto. An outer portion 20 is adapted to slide in an internal bore 19 of the coupling ring 15 while a smaller external diameter portion 21 is spaced from the bore 11 and in the space between the two diameters is located a compression spring 22. The portion 21 is rigidly secured to a further portion 24 of the sleeve member 18 and which is adapted to slide in the bore 13 in body member 1 and is provided with a radially directed flange 25 the outer end of which abuts the portion 21 and which flange slides in the bore 12.

The sleeve member 24 is provided with seals 26 and 27 between which are a series of radial stepped bores 28 which are adapted to provide communication between corresponding openings 30 in the body member 1 and the interior of portion 24.

A passage 31 communicates a space 32 to the rear of the peripheral flange 25 with space 34 to the rear of internal portion 24.

Portion 21 carries at its forward end an internally directed annular flange 35 housing a valve seat 36 against which seats a poppet valve 37 the stem of which is centrally located and slidable in a bore 38 in an inner body member 40. The poppet valve 37 has an outwardly projecting projection 39.

The poppet valve 37 is biased by one end of a compression spring 41 against its seat, the other end of which engages a body member 40. The body member 40 has a rearwardly-extending portion 42 which is axially slidable in a bore 43 in a member 44 rigid with the sleeve member 24. The body member 40 has a narrower diameter portion 45 adapted to slide in a bore 46 of corresponding diameter in the member 44, the two portions 42 and 45 being interconnected by a chamfered shoulder 47. Balls 48 are housed in openings adjacent the shoulder on the internal body member and are slidable between the position shown in Figure 1 and the positions shown in the other Figures. The internal member 44 has a further stepped bore 50 in which slides the stem 51 of a pusher 52 the head 53 of which slides in bore 46.

As is more clearly shown in Figure 2 the coupling ring 15 is adapted to receive the end of a second body member 2 which is provided with a conventional head comprising a central axially directed projection 59 adapted to engage projection 39 on valve 37, the projection 59 being an extension of a conventional poppet valve in this part of the coupling.

The valve behind projection 59 is housed in a housing containing a nose end 61 adapted to slide in smaller internal diameter portion 62 of body portion 20 and has a shoulder 63 joining it to a larger diamter portion 64 adapted to slide in a larger internal diameter bore 65 of the body portion 20.

In the position shown in Figure 1 the body member 1 is closed with the poppet valve 37 engaged against its seat 36. In the position of Figure 2 the nose 61 is engaged in bore 62 with the shoulder 63 in bore 65 and about to engage balls 17. In this position projection 59 engages projection 39 causing it to crack poppet valve 37.

The pressure acting on the valve behind projection 59 is greater than that acting on poppet valve 37, i.e. greater than the force of the spring 41 and the residual pressure within the body member 24.

At the same time as valve 37 is moved to the rear the entry of the body member 2 by engagement of shoulder 63 against balls 17 causes the sleeve member 18 to move to the left against the force of the compression spring 22 which in turn causes sleeve portion member 24 to move to the left until the end of pusher 51 engages the rear end 58 of the body member 6, further movement moving stem 51 to the right with respect to member 44 so that the head 53 moves to the right thus engaging narrower diameter portion 45 of body member 40 moving it to the right and causing balls 48 to move into the larger diameter portion 43.

Also in the position of Figure 2 the balls 17 have been engaged and have moved from the position of Figure 1 into that of Figure 2 where they can enter groove 16.

In the position of Figure 3 the body 2 is fully engaged in the body member 1, the balls 17 being fully moved into the groove 16. In this position the poppet valve 37 is moved to the rear against compression spring 41 and the balls 48 now permitting the valve stem 38 to pass therebetween. Also in this position "0" ring seal 66 in ring 15 engages nose 61 and seals body member 2 with respect of body member 1. While this movement has been taking place and which has caused the sleeve to move to the right any fluid to the rear of the sleeve member 18 is vented to atmosphere through passage 31 there being provided appropriate clearances between the various subsequent parts, i.e. between the flange 25 and bore 12 and between ring 15 and bore 19.

In the position of figure 4 the operator has removed his grip from body member 2 which was causing it to be in the fully engaged position as shown in figure 3. This enables spring 22 to move body member 18 to the right so that the parts now move to the position as shown in figure 4. In this position the projection 59 on the male member holds the check valve 37 open but the parts otherwise return to the position of figure 1, except for the relative disposition of the further body member 40 and the retaining balls and their associated parts. The operator now applied presure to the fluid line connected to the female member to cause a rise in pressure in the female member to a point where this exceeds the residual pressure and any biasing force behind the male check valve causing this to open.

The check valve 37 moves to the right against the bias of spring 41 which also moves body member 40 to the left, balls 48 moving into bore 46 thus limiting movement of the check valve to the left and hence preventing it from opening beyond a certain distance so that the male check valve cannot reseat, the coupling thus remaining open as shown in Figure 5 until the operator closes it by retracting the male member in which case the parts return to the position in Figure 1.

A modified construction is shown in Figure 6.

In this construction in place of spring 41 there are two coaxial springs, an outer spring 70 and an inner spring 71. The left hand end of the outer spring 70 abuts against member 44 which is rigid with the sleeve member 24, whilst its right hand end acts on a webbed guide member 73 which slides in a bore 74 in member 24. The axially outer part 75 of guide member 73 is biassed against a retaining ring 76 limiting its movement to the right. Its axially inner portion is generally wedge shaped and extends to the right to form seating shoulder 77 for the spring 70. The right hand end of the webbed guide member is shaped inwardly from the poppet valve 37 so that it is not engaged until this has opened after predetermined distance.

The inner spring 71 has its right hand end directly engaging poppet valve 37 and its left hand end abuts against a shoulder 78 on inner body member 40 which has been slightly modified in this construction to take account of the two coaxial springs.

In operation in this construction when the male coupling member is coupled the male projection meets female projection 39 it does not encounter the combined resistance of the fluid pressure in the female member and the whole of the spring force biasing the valve 37. Where there are only modest pressures in the line behind the male member such a spring force would tend to cause the male coupling member to open and thus release hydraulic fluid which would form a fluid barrier between the two check valves and thus prevent engagement of the male coupling member in the female member. Thus the female member opens initially against the bias of spring 71 and permits the fluid which would otherwise be blocked to flow in to the female coupling member and enable coupling to take place.

At greater load induced pressures the male coupling valve is more heavily biassed towards its seat and is less susceptible to dislodgement which would otherwise release pressurized fluid into the female coupling. This construction is particularly suitable where the load induced pressure range is below 20 bar.

Claims (19)

1. A female fluid coupling member adapted to receive and retain a male fluid coupling member, each of which members being provided with a check valve to prevent egress of fluid in its unconnected state, each check valve being provided with a projection, the projections being adapted to interengage with one another and by means of which the valves can be opened, the female member being provided with means to permit its check valve to open when coupled to a male member with a higher residual pressure therein causing its check valve to remain closed, the said opening of the female member being effected while avoiding any detrimental quantity of fluid leaking and subsequently permitting fluid under pressure to be applied through the female member to cause the male check valve to open against the higher residual pressure, the male check valve being prevented from reseating when the members are coupled together.

2. A fluid coupling member as claimed in Claim 1 in which the means for preventing the male check valve reseating comprise means for limiting the opening movement of the female check valve.

3. A coupling member as claimed in Claim 2 in which the means for limiting the opening movement of the female check valve are rendered inoperative during the coupling operation;

4. A coupling member as claimed in any one of Claims 1 to 3 in which the check valve in the female member is biassed into the closed position by means of a spring.

5. A check valve as claimed in Claim 4 in which there are two springs operating in sequence.

6. A coupling member as claimed in any one of Claims 1 to 5 in which the check valve is located in a movable sleeve which is itself adapted to move in the check valve opening direction when the check valve is opened.

7. A coupling member as claimed in any one of Claims 1 to 6 in which the check valve is carried by a further body member itself slidable in a bore in the sleeve member and the valve is biassed with respect to the further body member towards a closed position.

8. A coupling member as claimed in Claim 7 in which the bore in the sleeve member is formed as a bore and counter bore joined by a chamfer, the further body member having respectively portions of larger and smaller external diameter slidable therein.

9. A coupling member as claimed in Claims 8 in which the stem of the check valve is slidable in a bore in the further body member.

10. A coupling member as claimed in Claim 9 in which radial openings are provided in the further body member between the two different diameter bores and the radial openings lead into the bore in which slides the check valve, and balls in the radial openings movable between a retracted position in which the stem of the check valve can slide freely and an operative position when the balls are engaged in the smaller diameter bore said operative position limiting opening movement of the check valve.

11. A coupling member as claimed in Claim 10 in which one of the sequential springs provides less than half the force necessary to overcome the male check valve coupling spring.

12. A coupling member as claimed in Claim 11 in which the sequential springs comprise inner and outer springs, the inner spring providing the reduced force.

13. A coupling member as claimed in Claim 12 in which the outer spring acts on a webbed guide member restrained by a retaining ring so that this additional spring load is only transmitted to the valve after initial opening movement when the internal static pressure in the female member has been released.

14. A coupling member as claimed in any one of Claims 6 to 10 when dependent upon Claim 6 in which the displaced fluid is vented via one or more passages in the sleeve member in the rear thereof.

15. A coupling member as claimed in Claims 10 to 14 in which the movement of the sleeve member in the check valve opening direction causes the balls to engage in the larger diameter bore.

16. A coupling member as claimed in Claim 15 in which the sleeve member is adapted to move on entry of the male coupling member.

17. A coupling member as claimed in Claim 16 in which the sleeve member is provided with means for sealing the male coupling member and means for retaining it therein.

18. A female coupling member substantially as described herein with reference to and as shown in the accompanying drawings.

19. A fluid coupling incorporating a female member as claimed in any one of the preceding claims.