GB2138101A

GB2138101A - Spring supports

Info

Publication number: GB2138101A
Application number: GB08402858A
Authority: GB
Inventors: Anthony John Salter
Original assignee: B I E HOLDINGS Ltd
Current assignee: B I E HOLDINGS Ltd
Priority date: 1983-02-03
Filing date: 1984-02-03
Publication date: 1984-10-17
Also published as: GB8402858D0

Abstract

A spring support of the kind as are used for supporting pipes which in use are subjected to movement, comprises a frame 1, a bell-crank lever 2 pivotally mounted on the frame, spring means 6 acting on the lever, and load connecting means 27 acting on the lever. Compensating means 8, (comprising a pivotally mounted link 9) operates to vary the position at which the load connecting means 27 acts on the lever in such a manner as to maintain a constant load moment on the lever despite variations in the load applied thereto. One end of the link 9 is pivoted to the frame, the other end is connected to a toothed carrier wheel which carries the load turnbuckle 27 and can roll in a toothed slot 25 in the lever. <IMAGE>

Description

SPECIFICATION Spring Supports This invention is concerned with spring supports, particularly of the kind (hereinafter referred to as being of the kind specified) as are used for supporting pipes which, in use, are subject to movement caused, for example, by temperature variations.

A conventional spring support of the kind specified comprises a frame, a lever member pivoted on the frame, load connecting means attached to the lever at a position spaced from the pivot and which is adapted to connect a load to be supported to the lever, a draw bar which is also attached to the lever at a position spaced from the pivot, and spring means which acts on the draw bar and applies thereto, and hence to the lever, a predetermined force which counterbalances the load connected to the lever.

Conventionally, such spring supports are arranged so as to transmit a substantially constant force to the lever throughout its range of normal movement, and are thus known as spring supports of the constant load type.

However, in cases particularly of extensive pipe works, such as those comprisin,g lengths of vertically extending pipes, whilst by the use of conventional spring supports the pipes will be adequately supported in use, over a period of time there occurs what is referred to as "creep" (alternatively known as "pipe ratchet"). Thus, whilst a constant load is applied to support the pipe, allowing it to move due to expansion, on cooling of the pipe it does not in fact return completely to its original position. Whilst the extent of such movement is small, over a length of time the cumulative effect may cause problems, particularly undesirable stresses to which the pipes are subjected if they are not returned to their original cold supported positions.

A further difficulty is that over a period of time, cake or scale may adhere to the pipe, producing a change in loading, and this will affect the capability of a conventional spring support such as of the constant load type to function adequately.

In both such circumstances, replacement of the spring support, or the spring means thereof, to compensate, either for creep or the build-up of scale or cake, can be difficult and expensive to carry out.

Alternatives which have been suggested involve the provision of separate auxiliary spring units which are arranged to act in conjunction with the spring support to support the pipe when subjected to creep, and to assist return of the pipe to its original cold supported position. However, such arrangements are also expensive because of the additional equipment and fixings required.

According to this invention, there is provided a spring support of the kind specified, comprising a frame, a member mounted for pivotal movement relative to the frame, spring means acting to move the member about its pivot, load connecting means acting to move the member about the pivot, and compensating means operative on variation in the load applied to said member to vary the moment of the spring means about said pivot in relation to the moment of the load connecting means about said pivot.

Preferably, the construction and arrangement is such that the load moment on the pivoted member remains substantially in counterbalance with the spring moment on the pivoted member.

Thus, where pipe creep occurs, resulting (e.g.) in the application of an increased loading to the pivoted member, the effect of the counterbalancing means is to apply an increased force to the pipe to tend to restore it to its datum position. In this manner, the cumulative effect of pipe creep may be reduced.

Additionally, where the load applied to the pivoted member increases due, for example, to the build-up of cake or scale, the compensating means will act effectively to increase the force applied by the spring means to the pipe, to compensate for such build-up.

The compensating means may be operative to change the position of the pivot of the pivotally-mounted member relative to the positions at which the spring means and the load connecting means act on it. Alternatively, the compensating means may be operative to change the position at which the spring means acts on the pivoted member relative to the position of the pivot. Preferably however, the compensating means is operative to change the position at which the load connecting means acts on the pivoted member relative to the position of the pivot.

Preferably, the compensating means comprises link which is pivotally connected to the frame, or a part fixed relative thereto in the use of the support, at a position spaced from the pivot of the member, and: (a) to a part attaching the load connecting means to the member; or (b) to a part attaching the spring means to the member, as the case may be, such part being movable to the member radially of the pivot.

In such circumstances, as the pivotal axis of the link is fixed relative to the pivotal axis of the pivoted member, and the length of the link is fixed, at least when in operation, when the member pivots relative to the frame, the link causes the load connecting means to move radially along the pivoted member, either towards or away from the member's pivot depending upon the direction of pivoting movement of the member. The position at which a load supported by the spring support in use is applied to the pivoted member by the load connecting means therefore changes to maintain the load moment constant event though the load may vary.

There may be sliding engagement between the load connecting means or a part attaching the means to the pivoted member, and the pivoted member. There may be rolling engagement of the load connecting means, or attachment part, with the pivoted member.

In this latter arrangement, the load connecting means, or attachment part, and the pivoted member may have co-operating toothed formations. For example, the pivoted member may have toothed formations extending linearly as a rack radially of, or parallel to a radius from the pivot of the member, and the load connecting means or attachment part may have complementary toothed formations on a pitch circle. As a further possibility, there may be rocking engagement of the load connecting means or attachment part with the pivoted member which allows alteration of the distance from the pivot to the position at which the load supported by the spring support in use acts on the pivoted member.

Again, the load connecting means or attachment part and pivoted member may have cooperating toothed formations. Thus the pivoted member may have toothed formations extending linearly as a rack and the load connecting means or attachment part may have complementary toothed formations disposed in an arc for the rocking engagement.

Suitable stops may be provided to limit the extent of the rocking movement. For example, if the pivoted member has a slot in which the load connecting means or attachment part rocks, the means or part may have abutment surfaces which move into contact with an edge or edges of the slot to define limits of the rocking movement.

In a preferred form of the invention, the pivoted member, in accordance with that of the spring support which is the subject of United Kingdom Patent Specification 1,601,217, has a slot extending radially of the pivot, and the load connecting means is attached to a carrier which is movable along the slot. The link is connected to the carrier.

The carrier may be slidable along the slot but preferably to reduce friction between the carrier and the pivoted member, the carrier is adapted to have rolling engagement with the pivoted member at the slot, or rocking engagement. Where there is rolling or rocking engagement, the slot and carrier may or may not have intermeshing toothed formations, as desired.

The position of the pivot connection of the link to the frame of the spring support, or part fixed relative to the frame in the use of the spring support, may be adjustable to vary the attitude of the link relative to the pivoted member to suit various initial angular positions of the pivoted member relative to the frame. Adjustment of the position may be made on site to suit a required initial setting of the pivoted member.

It is possible that alternatively, or in addition, the link may be adapted for adjustment of its effective length to allow for various initial angular positions of the pivoted member relative to the frame.

The frame preferably has at least one suspension point whereby the frame can be suspended from a support for use, and which is variably positionable on the frame such that it can be adjusted to position it in vertical alignment with the load connecting means in the position at which the pivoted member is disposed initially relative to the frame for use of the spring support.

According to this invention, there is also provided a spring support comprising a frame, a lever pivoted to the frame, load connecting means attached to the lever and adapted to connect a load to be supported to the lever at a position spaced from the pivot, a draw bar attached to the lever at a position spaced from the pivot, and spring means which act on the draw bar and thereby applies a predetermined force to the lever which counterbalances the load connecting to the lever, comprising compensating means adapted to alter automatically relative to the pivot of the lever the position of attachment of the load connecting means to the lever, and thereby alter the distance from the pivot of the position at which a load supported by the spring support in use acts on the lever, to compensate for a variation from an initial value of the load exerted on the lever in use, such that the load moment on the lever remains constant and counterbalanced by the spring moment on the lever resulting from the force exerted on the lever by the spring means.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a side view of a spring support in accordance with the present invention for supporting a pipe in suspension; and Figure 2 is a section on the line 2-2 of Fig.

1.

The spring support comprises a frame 1, a member pivotally mounted on the frame and which is afforded by twin horizontally-spaced bell crank levers 2 joined together and acting as a single lever pivoted by a common pivot pin 3 about a horizontal axis to the frame (the levers having front and rear arms 2', 2" respectively), load connecting means for attaching a pipe to be supported to the front arms 2' of the levers, a draw bar 5 attached to the rear arms 2" of the levers, a compression spring 6 which acts on the draw bar and is housed in a body 7 rigid with the frame, and compensating means 8 mounted on the body 7 and connected to the load connecting means 4. Except for the compensating means 8 and modifications to the load connecting means 4, the spring support is substantially in accordance with that described and illustrated in United Kingdom Patent Specification 1,601,217.Accordingly, the compensating means will be described in detail here and the modifications to the load connecting means, and reference to the other parts of the spring support will be confined to such as may be necessary for the compensating means and its operation to be understood.

The compensating means 8 comprises a pair of identical parallel links 9 each pivoted at one end to a respective bracket 10 and pivoted at the opposite end to an extended pin 11 of the load connecting means 4.

Each link 9 comprises a connecting rod 12 and a clevis 13 adjustably connected together for varying the length of the link. The connecting rod 12 is formed with an integral eye 14 at one end by which the link is pivoted to the pin 11. An external screw thread 15 at the opposite end of the connecting rod engages with a complementary internal screw thread in the web 16 of the clevis 13, thereby providing the adjustable connection between the two components. The bracket 10 to which each link is pivoted is of L-shape. A first limb 10' of the bracket is triangular and is straddled at its apex by the clevis 13 of the link which is pivotally connected to that limb by a pivot pin 17.A second limb 10" of the bracket is retangular, being joined at one longer side to the base of the triangular limb 10' at the heel of the bracket, and having two aligned, closed-ended, slots 18 extending along its central longitudinal axis parallel to the heel of the bracket.

The brackets 10 of the two links 9 are mounted on a front end plate 19 of the body 7 at opposite side of the frame 1 and horizontally outwardly of the bell-crank levers 2. They are mounted in horizontal alignment, so that the pivot pins 17 are horizontally co-axial, by their second limbs 10" which are secured to the front end plate 19 by bolts 20 engaged with the slots 18 and tightened into tapped bores 21 in the end plate. The second limbs are disposed with their longitudinal axes extending vertically and so the slots 18 extend vertically and allow some vertical adjustment of the brackets, and accordingly the clevis ends of the links, relative to the pivot pin 3 of the bell crank levers 2.

The pin 11 of the load connecting means 4 is headed at one end 22 to retain one of the links to the pin and at its opposite end is fitted with a split pin 23, or other suitable applied retainer, to retain the other link.

Included in the load connecting means is a pair of pin carriers 24 through and between which the pin 11 extends, the links being conected to the pin laterally outwardly of the pin carriers. The pin carriers are formed as gear wheels axially through which the pin extends. They are located in slots 25 in the front arms 2' of the bell-crank levers 2 extending radially of the pivot pin 3. The slots 25 of the two bell-crank levers are parallel and directly opposite one another. A bottom longitudinal edge of each slot 25 is formed with teeth 26 with which the respective pin carrier meshes. A turnbuckle 27 is connected to the pin 11 between the pin carriers 24 by an eye bolt 28. In use, the pipe to be supported is suspended from the turnbuckle 27.The carriers can roll along the toothed slots 25, thereby altering the position of the connection of the turnbuckle to the bell-crank levers along their front arms 2'.

The pivot pin 3 of the bell-crank levers, the co-axial pivot pins 17 of the links 9 and the pin 11 are at corners of a national triangle of which, in use of the spring support, two sides are of fixed lengths, i.e. the sides between the pivot pin 3 and the co-axial pivot pins 17 and between the latter pins and the pin 11, and the positions of two of the corners are fixed, i.e. the corners at pivot pin 3 and the co-axial pivot pins 17. Any relative angular movement between the links and the front levers 2' of the bell-crank levers, therefore, alters the length of the third side of the triangle between the pivot pin 3 and the pin 11.

For use of the spring support in supporting a pipe in suspension, the lengths of the links and the vertical positions of the brackets 10 on the front end plate 19 of the body 7 are adjusted to suit the initial cold set angular position of the bell-crank levers relative to the frame 1 with the pipe suspended from the turnbuckle 27. The moment on the bell-crank levers due to the load of the pipe is counterbalanced by the moment on the levers due to the force of the compression spring 6.

If the load applied to the bell-crank levers by the pipe should increase during use as the result of pipe ratchet, the bell-crank levers pivot under the load about the pivot pin 3, anti-clockwise as viewed in Fig. 1. However, as the bell-crank levers pivot, the position of the pin 11 and pin carriers 24 relative to the front arms 2' of the levers is automatically adjusted by virtue of the triangle arrangement described to reduce the distance at which the load is applied to the bell-crank levers. In consequence, in spite of the increased load, the load moment remains constant and counterbalanced by the spring moment, and the pipe can be returned to its initial cold supported position.

It will be appreciated that in the angular position of the bell-crank levers as shown in Fig. 1, and indeed in any angular position in which the front arms 2' are inclined upwardly away from the pivot pin 3, the links act as struts resisting rolling of the pin carriers 24 down the slots 25 towards the pivot pin 3. If the bell-crank levers should occupy an angular position in which the front arms 2' are inclined downwardly away from the pivot pin 3 then, of course, the links act as ties to resist rolling of the pin carriers down the slots 25 away from the pivot pin.

The rolling engagement of the pin carriers with the front arms 2' at the slots minimises frictional resistance to relative movement between the pin carriers and the arms.

Whilst in the preferred embodiment above described, the compensating means is operative to maintain the load moment an the lever 2 substantially in counterbalance with the spring moment on the lever, it is to appreciated that this effect can alternatively be achieved, either by varying the effective position at which the spring means is connected to the pivoted member, or varying the position at which the lever is pivotally mounted, in relation to the points of connection of the load connecting means and the spring means.

In addition to alleviating the problems hereinbefore described particularly pipe creep and build-up of scale or cake, the present invention may be used to compensate for a poor quality spring which otherwise might be of unacceptable performance. Thus, where the load characteristics of a spring are outside the normal tolerances, a compensating means may be utilised to vary the effective characteristics of the spring. Thus, by variation of the position of the pivot 17 (e.g. by selection of the position of the bracket 10) the force applied by the spring to the lever may be increased or decreased, as is desired, to provide a desired moment to the lever 2.

Claims

1. A spring support of the kind specified, comprising a frame, a member mounted for pivotal movement relative to the frame, spring means acting to move the member about its pivot, load connecting means acting to move the member about the pivot, and compensating means operative on variation in the load applied to said member to vary the moment of the spring means about said pivot relative to the moment of the load connecting means about said pivot.

2. A spring support according to Claim 1 wherein the compensating means acts in a manner such that the load moment on the pivoted member remains substantially in counterbalance with the spring moment on the pivoted member.

3. A pipe support according to one of Claims 1 and 2 wherein the compensating means is operative to change the position of the pivot relative to the positions at which the spring means and the load connecting means act.

4. A spring support according to one of Claims 1 and 2 wherein the compensating means is operative to change the position at which the spring means acts on the pivoted member relative to the position of the pivot.

5. A spring support according to one of Claims 1, 2 and 4 wherein the compensating means comprises a link which is pivotally connected to the frame, or a part fixed relative thereto in the use of the support, at a position spaced from the pivot of the member, and a part attaching the spring means to the pivoted member, such part being movable relative to the member radially of the pivot.

6. A spring support according to one of Claims 1 and 2 wherein the compensating means is operative to change the position at which the load connecting means acts on the pivoted member relative to the position of the pivot.

7. A spring support according to any one of Claims 1, 2 and 6 wherein the compensating means comprises a link which is pivotally connected to the frame, or a part fixed relative thereto in the use of the support, at a position spaced from the pivot of the member, and a part attaching the load connecting means to the member, such part being movable relative to the member radially of the pivot.

8. A spring support according to Claim 7 wherein the construction and arrangement is such that there is sliding engagement between the load connecting means, or a part attaching the means to the pivoted member, and the pivoted member.

9. A spring support according to Claim 7 wherein the construction and arrangement is such that there is rolling engagement of the load connecting means, or attachment part, with the pivoted member.

10. A spring support according to Claim 9 wherein the load connecting means, or attach ment part, and the pivoted member are provided with co-operating toothed formations.

11. A spring support according to Claim 10 wherein the pivoted member is provided with toothed formations extending linearly as a rack radially of, or parallel to a radius from, the pivot of the member, and the load connecting means or attachment part is provided with complementary toothed formations on a pitch circle.

12. A spring support according to Claim 7 wherein the construction and arrangement is such that there is rocking engagement of the load connecting means or attachment part with the pivoted member which allows alteration of the distance from the pivot to the position at which the load supported by the spring support in use acts on the pivoted member.

13. A spring support according to Claim 12 wherein the load connecting means or attachment part and pivoted member have cooperating toothed formations.

14. A spring support according to any preceding claim which is appendant to Claim 7 wherein the position of the pivot connection of the link to the frame of the spring support, or part fixed relative to the frame in the use of the spring support, may be adjusted to vary the attitude of the link relative to the pivoted member to suit various initial angular positions of the pivoted member relative to the frame.

15. A spring support according to any preceding claim which is appendant to Claim 7 wherein the link is adapted for adjustment of its effective length to allow for various initial angular positions of the pivoted member relative to the frame.

16. A spring support according to any one of the preceding claims wherein the frame has at least one suspension point whereby the frame can be suspended from a support for use, and which is variable positionally on the frame such that it can be adjusted to position it in vertical alignment with the load connecting means in the position at which the pivoted member is disposed initially relative to the frame for use of the spring support.

17. A spring support comprising a frame, a lever pivoted to the frame, load connecting means attached to the lever and adapted to connect a load to be supported to the lever at a position spaced from the pivot, a draw bar attached to the lever at a position spaced from the pivot, and spring means which act on the draw bar and thereby applies a predetermined force to the lever which counterbalances the load connected to the lever, comprising compensating means adapted to alter automatically relative to the pivot of the lever the position of attachment of the load connecting means to the lever, and thereby alter the distance from the pivot of the position at which a load supported by the spring support in use acts on the lever, to compensate for a variation from an initial value of the load exerted on the lever in use, such that the load moment on the lever remains constant and counter balanced by the spring moment on the lever resulting from the force exerted on the lever by the spring means.

18. A spring support constructed and arranged substantially as hereinbefore described, with reference to the accompanying drawings.

19. Any novel feature or novel combination of features disclosed herein and/or shown in the accompaning drawings.