GB2339010A

GB2339010A - Rotationally moulded tank

Info

Publication number: GB2339010A
Application number: GB9914112A
Authority: GB
Inventors: Patrick Joseph Feerick; Adrian Murtagh
Original assignee: Kingspan Research and Developments Ltd
Current assignee: Kingspan Research and Developments Ltd
Priority date: 1998-07-02
Filing date: 1999-06-18
Publication date: 2000-01-12
Also published as: GB9914112D0

Description

2339010 "A tank"

Introduction

The invention relates to hot water tanks for heating of water for delivery to a hot water distribution system, especially for domestic use. Conventional hot water cylinders are relatively expensive and, due to manufacturing defects and/or prolonged use, can over time become damaged by 10 corrosion, especially at welded joints or points of connection to pipework. Leaks from such tanks leads to major expense in repairing damage to the fabric and/or decor of the building. Such tanks are also heavy and difficult to re-process. Further, a thick insulating jacket is required. 15 There is therefore a need for an improved hot water tank which will overcome at least some of these difficulties. Statements of Invention

According to the invention there is provided a hot water tank which is formed by rotational moulding of a plastics material. In a preferred embodiment of the invention the tank has integrally formed support feet. 25 Preferably there are a number of integrally formed support feet which are arranged symmetrically about a base of the tank. In one case there are four integrally formed support feet substantially equi-spaced 30 at the base of the tank.

In another case there are six integrally formed support feet substantially equi spaced at the base of the tank.

In a preferred embodiment of the invention the support feet are interconnected by transition sections of the base.

Preferably the transition sections are of generally curvilinear shape.

In one embodiment of the invention the tank includes a number of integrally formed ports for connection to pipework and the like.

Preferably a port is defined by an insert having means for connection to pipework or the like.

Ideally, the insert is positioned in a tank mould on rotational moulding of the tank. In a preferred arrangement the insert includes keying means for interengagement with flowing plastics on rotational moulding of the tank. 20 In one embodiment of the invention the tank includes two ports communicating with a heating coil mounted in the tank. Preferably the coil is positioned within a mould during rotational moulding of the 25 tank.

The invention also provides a method for manufacturing a hot water tank comprising rotationally moulding plastics material to form a hot water tank.

Preferably the method includes the step of positioning inserts in the mould prior to rotational moulding, the inserts defining connection parts for pipework and the like.

In a preferred embodiment the method includes the step, prior to mou Iding, of positioning a heating coil in the mould.

In another aspect the invention provides a tank which is formed by rotational moulding of a plastics material, the tank having a base with an inwardly extending depressed reinforcing portion which is substantially continuous.

Preferably the reinforcing portion is of generally toroidal shape.

Most preferably the base of the tank includes transition portions to and from the reinforcing portion which are of generally curvilinear shape.

Typically the tank has a generally circular or eliptical base, preferably having a depressed generally toroidal shaped reinforcing portion extending inwardly of the base.

In a preferred embodiment the toroid extends for a depth of at least 25%, preferably 30 to 50%, ideally approximately 40% of the radius of the base.

Preferably the inner radius of the toroid is at least 25%, preferably 35% to 45% of the radius of the base.

In a preferred embodiment the outer radius of the toroid is at least 50%, ideally from 70% to 80% of the radius of the base.

In a fin-ther aspect the invention provides a tank which is formed by rotational moulding of a plastics material, the tank having an integrally formed top with a plurality of reinforcing ribs extending from a centre of the top towards the outer peripheral sidewall of the tank.

Preferably the top is of generally circular or eliptical shape in plan view and there are four reinforcing ribs arranged in a cruciform configuration on the top of the tank.

Usually the top is a domed top and the ribs extend both radially outwardly and axially downwardly along the dome top.

Preferably a port is located substantially at the centre of the dome top. Typically a port is also located along at least one of the ribs.

In a preferred embodiment a rib has a width which is at least 35%, preferably approximately 50% of the radius of the tank.

In a particularly preferred arrangement of these latter aspects of the invention the tank is a hot water tank.

Brief Description of the Drawinp-

The invention will be more clearly understood from the following description thereof, given by way of example only, with reference to the accompanying drawings, in which:-

Fig. I is a perspective view of a hot water tank according to the invention; Fig. 2 is a front elevational view of the tank; Fig. 3 is a side elevational. view of the tank; -5Fig. 4 is a top plan view of the tank; Fig. 5 is an underneath plan view of the tank; Fig. 6 is a perspective view of the tank, from a base thereof; Fig. 7 is a cross sectional view of a detail of a tank, during moulding; Fig. 8 is a side view of an insert used in forming the tank; Fig. 9 is a plan view of the insert of Fig. 8; Fig. 10 is a front elevational view of a tank according to another aspect of the invention; Fig. I I is a side elevational view of the tank of Fig. 10; Fig. 12 is a top plan view of the tank of Fig. 10; Fig. 13 is an underneath plan view of the tank of Fig. 10; Fig. 14 is a part cross sectional view on the line A-A in Fig. I I Fig. 15 is a part cross sectional view on the line B-B in Fig. 11.

Fig. 16 is a part cross sectional view on the line C-C in Fig. 12; and Fig. 17 is a part cross sectional view on the line D-D in Fig. 12.

Detailed Desgdption Referring to the drawings and initially to Figs. I to 9 thereof there is illustrated a hot water tank I which is formed by rotational moulding of a suitable plastics material such as a polyarnide formed by anionic polyrnerisation of laurolactam which may contain an inert filler.

The tank 1 has a generally cylindrical main body section 2, a base 3 and a domed top 4 which are integrally rotationally moulded in one piece with the main body section 2. A central hot water outlet port 6 is provided in the domed top 4 and an inlet/drain port 7 is provided in the main section 2 adjacent to the base 3.

Another port 9 is provided in the top 4 for reception of an immersion heater element, not shown. Water in the tank is also heated by a coil 10 which is positioned within the tank 1, during moulding as illustrated in Fig. 1. The coil 10 extends from a heated water entry port 11, for example from a central heating system, to an outlet port 12.

The base 3 of the tank I has a number, in this case four, integrally formed support feet 15 which are substantially equi-spaced at the base 3 to support the tank 1, in use. The support feet 15 are interconnected by transition sections 16 which are of generally curvilinear shape.

Referring in particular to Figs. 8 and 9 there is illustrated an insert 20 which is used to form the various ports, during rotational moulding. The insert comprises a central ring portion 21 and a circurnferentially extending flange 22 having a plurality of spaced-apart keying holes 23. In use, as particularly illustrated in Fig.

7, the insert 20 is held in position by a fixing head part 25 and bolt 26 which tie the insert 20 to a mould 30. During rotational moulding plastics material 35 takes up the shape illustrated and, in the molten state, is keyed to the insert 20 which is thus retained to form an opening or port in the finished tank.

The invention provides a hot water tank which is relatively easy to manufacture to required use specifications, while providing an integrally formed structure which is not subject to corrosion and the like. Further, the tank is relatively light weight and may be readily re-processed for recycling.

The design of the base of the tank facilitates ease of removal from a tool while allowing the tank to be free-standing.

The rotornoulding technique allows a wide range of size and shapes of hot water tanks to be easily manufactured. The insulating effect of the plastics material should also provide a greater heat efficiency to be achieved than with conventional copper hot water cylinders. In addition, it is envisaged that a foam layer may be rotomoulded within the tank to provide an additional insulating effect. 15 Referring to Figs. 10 to 17 there is illustrated another tank 50 according to the invention. This tank 50 is especially suited for hot fluids such as hot water. The tank 50 has some features in common with the tank referred to in Figs. I to 9 and like parts are identified by the same reference numerals. For clarity, items such as 20 a heating coil have been ornitted from Figs. 10 to 17. The tank 50 has a domed top 51 with reinforcing ribs 52 arranged in a ciruciform shape when viewed from above. The tank 50 has a base 55 which has an inwardly extending depressed toroidal portion 60 to strengthen and stabilise the tank 50, in 25 use, especially with hot fluids. The toroidal depressed area of the base has transition portions to and from the main wall of the base 55 which are of generally smooth curved shape to ensure even load distribution. The toroid extends inwardly for a depth of at least 25%, 30 ideally 30 to 50%, and most preferably approxiinately 40% of the radius of the base. Preferably the inner radius of the toroid is at least 25%, usually 35 to 45% of the radius of the base. The outer radius of the toroid is at least 50%, ideally 70% to 80% of the radius of the base.

Each of the reinforcing ribs 52 has a width which is at least 35% and preferably approximately 50% of the radius of the tank.

The tanks, especially the tank of Figs. 10 to 17 is particularly suitable for hot fluids. It will be appreciated that the tank may be of any suitable shape and configuration. For "ample it may be of elliptical shape or of a shape to fit snugly into a comer.

The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail.

Claims

1. A hot water tank which is formed by rotational moulding of a plastics material.

2. A hot water tank as claimed in claim I having integrally formed support feet.

3. A hot water tank as claimed in claim 2 wherein there are a number of integrally formed support feet which are arranged symmetrically about a base of the tank.

4. A hot water tank as claimed in claim 2 or 3 wherein there are four integrally formed support feet substantially equi-spaced at the base of the tank.

5. A hot water tank as claimed in claim 2 or 3 wherein there are six integrally formed support feet substantially equi-spaced at the base of the tank.

6. A tank as claimed in any of claims 2 to 5 wherein the support feet are interconnected by transition sections of the base.

7. A tank as claimed in claim 6 wherein the transition sections are of generally curvilinear shape.

8. A tank as claimed in any preceding claim wherein the tank includes a number of integrally formed ports for connection to pipework and the like.

9. A tank as claimed in claim 8 wherein a port is defined by an insert having means for connection to pipework or the like.

10. A tank as claimed in claim 9 wherein the insert is positioned in a tank mould on rotational moulding of the tank.

11. A tank as claimed in claim 9 or 10 wherein the insert includes keying means for interengagement with flowing plastics on rotational moulding of the tank.

12. A tank as claimed in any of claims 8 to 11 including two ports communicating with a heating coil mounted in the tank.

13. A tank as claimed in claim 12 wherein the coil is positioned within a mould during rotational moulding of the tank.

is

14. A hot water tank substantially as hereiribefore described with reference to the accompanying drawings.

15. A method for manufacturing a hot water tank comprising rotationally moulding plastics material to form a hot water tank.

16. A method as claimed in claim 15 including the step of positioning inserts in the mould prior to rotational moulding, the inserts defining connection ports for pipework and the like.

17. A method as claimed in claim 15 or 16 including the step, prior to moulding, of positioning a heating coil in the mould.

18. A method for manufacturing a hot water tank substantially as hereinbefore described with reference to the accompanying drawings.

- I I -

19. A hot water tank whenever manufactured by a method as claimed in any of claims 15 to 18.

20. A tank which is formed by rotational moulding of a plastics material, the tank having a base with an inwardly extending depressed reinforcing portion which is substantially continuous.

21. A tank as claimed in claim 20 wherein the reinforcing portion is of generally toroidal shape.

22. A tank as claimed in claim 20 or 21 wherein the base of the tank includes transition portions to and from the reinforcing portion which are of generally curvilinear shape.

23. A tank as claimed in any of claims 20 to 22 which has a generally circular or eliptical base.

24. A tank as claimed in claim 23 having a depressed generally toroidal shaped reinforcing portion extending inwardly of the base.

25. A tank as claimed in claim 24 wherein the toroid extends inwardly for a depth of at least 25% of the major radius of the base.

26. A tank as claimed in claim 25 wherein the toroid extends inwardly to a depth of from 30 to 50% of the radius of the base.

27. A tank as claimed in claim 26 wherein the toroid extends inwardly to a depth of approximately 40% of the radius of the base.

28. A tank as claimed in any of claims 24 to 27 wherein the inner radius of the toroid is at least 25% of the radius of the base.

29. A tank as claimed in claim 28 wherein the inner radius of the toroid is from 35 to 45% of the radius of the base.

30. A tank as claimed in any of claims 24 to 29 wherein the outer radius of the toroid is at least 50% of the radius of the base. -

31. A tank as claimed in claim 30 wherein the outer radius of the toroid is from 70% to 80% of the radius of the base.

32. A tank which is formed by rotational moulding of a plastics material, the tank having an integrally formed top with a plurality of reinforcing ribs extending from a centre of the top towards the outer peripheral sidewall of the tank.

33. A tank as claimed in claim 32 wherein the top is of generally circular or eliptical shape in plan view and there are four reinforcing ribs arranged in a cruciform configuration on the top of the tank.

34. A tank as claimed in claim 32 or 33 wherein the top is a domed top and the ribs extend both radially outwardly and axially downwardly along the dome top.

35. A tank as claimed in claim 34 wherein a port is located substantially at the centre of the dome top.

36. A tank as claimed in claim 34 or 35 wherein a port is located along at least one of the ribs.

37. A tank as claimed in any of claims 32 to 36 wherein a rib has a width which is at least 35% of the radius of the tank.

38. A tank is claimed in claim 37 wherein a rib has a width of approximately 50% of the radius of the tank.

39.A tank as claimed in any of claims 20 to 38 which is a hot water tank.

40. A tank substantiaffy as hereinbefore described with reference to Figs. 10 to 17 of the drawings.