GB2250609A

GB2250609A - Fluid flow circuits

Info

Publication number: GB2250609A
Application number: GB9014018A
Authority: GB
Inventors: Alfred John Bailey
Original assignee: GREENLAND DISTRIBUTION UK LIMI
Current assignee: GREENLAND DISTRIBUTION UK LIMI
Priority date: 1990-06-23
Filing date: 1990-06-23
Publication date: 1992-06-10
Anticipated expiration: 2010-06-23
Also published as: GB2250609B; GB9014018D0

Abstract

A method of providing a fluid flow circuit with a predetermined flow restriction by clamping a restrictor member (14) between co-operating surfaces (11b, 12b) of a union (11, 12) provided in the circuit. The flow restrictor member is provided with one or more orifices (17, 18) whose cross-sectional dimensions are chosen to provide the required flow restriction in the circuit. The flow restrictor member may provide the same flow restriction through the union in both directions or may provide different flow restrictions in each direction by the use, for example, of a valve member (19) which is carried by the restrictor member and is moved axially relative to the orifice or orifices by the flow in one direction through the union to modify the flow through the union in that direction. <IMAGE>

Description

FLUID FLOW CIRCUITS This invention relates to fluid flow circuits and in particular to such circuits which include one or more unions, defined below as being "of the type specified", for providing a fluid flow connection between at least one pair of adjacent components in the circuit.

A union of the type specified for connecting together flow passages in adjacent components comprises a pair of co-operating surfaces one surrounding an open end of the flow passage in each component and clamping means for clamping the co-operating surfaces into fluid-tight sealed relationship around the ends of the passages thus connecting the passages for fluid-tight flow therebetween. Typically, the clamping means comprises a screwthread fastening acting between the two components and the cooperating surfaces are frusto-conical in form.

It is an object of the present invention to provide a simple, cheap and effective method of providing a fluid flow circuit (eg an hydraulic circuit) which includes a union of the type specified with a predetermined flow characteristic.

Thus according to the present invention there is provided a method of supplying a predetermined flow restriction in a fluid flow circuit containing a union of the type specified comprising clamping in the union in a fluid-tight manner between the cooperating surfaces a restrictor member having one or more flow orifices therein whose cross-sectional dimensions are chosen to provide the required flow restriction.

The invention also provides a flow restrictor member for use in the above method comprising an outer body portion for clamping between the co-operating surfaces of the union and a restricting portion projecting into the flow through the union and provided with one or more flow orifices whose cross-sectional dimensions are chosen to provide the required flow restriction.

The restrictor member may provide the same restriction to flow in both directions or may have different flow characteristics in each direction.

For example, the restrictor member may provide one rate of flow towards a fluid operated component and a higher or lower flow away from the component.

This variable flow rate in the two directions of flow may be provided by a valve member carried by the restricting portion of the member which is moved axially relative to the orifice or orifices of the member by the flow in one direction through the restrictor member to modify the overall flow rate through the orifice or orifices in that direction.

The restrictor member could also be designed to provide flow at a predetermined rate in one direction of flow and no flow (ie to operate as a non-return valve) in the other direction.

One embodiment of the present invention as applied to an hydraulic restrictor member for use in an hydraulic circuit on a seed drill will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-section through a restrictor member in accordance with the present invention clamped in position in an hydraulic union of an hydraulic cylinder supply line; Figure 2 shows an end view of part of the restrictor member of Figure 1; and Figure 3 shows an end view of part of an alternative restrictor member.

Referring Figure 1, this shows a cross-section through a union 10 between adjacent components in an hydraulic circuit. The union has a male portion 11 and a female portion 12, each having flow passages lia and 12a respectively. The male and female portions are held together by a screw-threaded connection 13 and are provided with co-operating frusto-conical surfaces lib and 12b respectively.

In conventional use of the union, the male portion 11 is screwed into the female portion 12 to bring the frusto-conical cooperating surfaces lib and 12b into contact and hence ensure a good fluid-tight joint.

In accordance with the present invention, a pre-determined flow restriction can easily and cheaply be incorporated in the union by the use of a restrictor member 13 of general frusto-conical form. The restrictor member has an outer body portion 15 of general frusto-conical form arranged to be clamped between cooperating surfaces lib and 12b and a central restricting portion 16 which, in the arrangement shown in Figures 1 and 2, is provided with two orifices 17 at the same radial spacing from the longitudinal axis X-X of the flow passage and a third orifice 18 disposed radially further away from axis X-X. Also mounted on the central portion 16 of the restrictor member is a valve member i9 which comprises a bolt 20 inserted as a sliding fit-in, a central aperture 21 of the restrictor member and a nut 22 which is locked on the bolt 20.The radial extent R of the nut 22 is arranged to be such when the valve member is forced to the left as viewed in Figure 1 by the presence of a higher pressure in passage lla than in passage 12a, the nut covers orifices 17 whilst leaving orifice 18 uncovered. When a higher pressure exists in passage 12a than passage lla, valve member 19 is forced to the right thus uncovering orifices 17.

Thus, as will be appreciated, flow from passage lla to passage 12a can only occur through orifice 18 while flow from passage 12a to passageway lla can occur through orifice 18 and both orifices 17 also. The restrictor member thus provides a different restriction to the flow of fluid in each direction. Such a flow characteristic is particularly useful, for example, when wishing to extend an hydraulic ram at a predetermined rate (dependent on the flow characteristics of orifice 18) whilst wishing the ram to retract at a higher rate (dependent on the flow characteristics of orifice 18 and also orifices 17) under the action of the weight of a component which has previously been raised by the extension of the ram.An example of such an application is the use of an hydraulic ram to raise an outer beam portion or wing of a pneumatic seed drill as described in UK Patent Application No. 8625976.

The frusto-conical portion of the restrictor member can conveniently be manufactured as a pressing from metal sheet (eg brass or steel) with the angle of the outer frusto-conical body portion 15 chosen to ensure good sealing contact with the cooperating surfaces lib and 12b. The angle of the frusto-conical body portion 15 may be the same as the angle(s) of the surfaces lib and 12b or it may be designed to be different so that a small amount of deflection of the body portion 15 occurs when the restrictor member is clamped between surfaces llb and 12b thus ensuring good sealing contact.

Figure 3 shows a cross-section through an alternative form of restrictor member in which no valve member is used and the frusto-conical component has a single, central orifice 20. Such a restrictor member provides an equal restriction to the flow of fluid through the union in both directions.

Although the present invention has been described above in relation to an hydraulic union with an incompressible fluid, it will be appreciated that it is equally applicable to compressible fluid and can be used, for example, with a pneumatic union.

As will be appreciated, the present invention provides a cheap but efficient method for adjusting the flow rate through a fluid pressure line which is both predictable in its effect and easily varied by fitting a different flow restrictor member. The crosssectional dimensions of the orifice or orifices provided in the restricted member and the constructional details of any required valve member are all readily determined by those skilled in the art by the use of standard fluid flow considerations.

Claims

i. A method of providing a predetermined flow restriction in a fluid flow circuit containing a union of the type specified comprising clamping in the union in a fluid-tight manner between the co-operating surfaces a restrictor member having one or more flow orifices therein whose cross-sectional dimensions are chosen to provide the required flow restriction.
2. A flow restrictor member for use in the method of Claim 1 comprising an outer body portion for clamping between the co-operating surfaces of the union and a restricting portion projecting into the flow through the union and provided with one or more flow orifices whose cross sectional dimensions are chosen to provide the required flow restriction.
3. A flow restrictor member according to Claim 2 which provides the same restriction to flow through the union in both directions.
4. A flow restrictor member according to Claim 2 which provides different flow characteristics through the union in each direction.
5. A union of the type specified fitted with a flow restrictor member according to any one of Claims 1 to 4
6. A seed drill including a union according to Claim 5.

5. A flow restrictor member according to Claim 4 in which a valve member is carried by the restricting portion of the member, the valve member being moved axially relative to the orifice or orifices of the member by the flow in one direction through the restrictor member to modify the overall flow rate through the orifice or orifices in that direction.

6. A flow restrictor member according to Claim 4 which provides flow at a predetermined rate in one direction of flow through the union and no flow in the other direction.

7. Aunion of the type specified fitted with a flow restrictor member according to any one of Claims 2 to 6.

8, A seed drill including a union according to Claim
7.

9. A union of the type specified fitted with a flow restrictor member constructed and arranged substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 or Figure 3 of the accompanying drawings.

1. A unitary fluid flow restrictor adapted to be held between mating elements of a standard fluid conducting union and consisting of an outer body portion contoured to form a seal between the two parts of the standard union and having one or more or orifices, an inner body portion adapted to obturate flow through the said orifices to different degree depending on the direction of flow through the union.

2. A restrictor as claimed in claim 1 wherein at least one orifice is permanently open whilst at least one other orifice is subject to closure on reversal of flow.

3. A restrictor as claimed in claim 2 in which a valve member is carried by the inner body portion, the valve member being movable axially relative to the orifice or orifices of the inner body by the flow through the restrictor to modify the overall flow rate through the union.

4. A restrictor as claimed in claim 3 which provides flow at a predetermined rate in one direction of flow through the union and no flow in the other direction.