Jordaan, Pieter Willem (34 Richfield, 3 Berlandia Street, 1447 Meyersdal, ZA)
Stephen, Bruce (19 Fiona Road, Discovery, 1709 Roodepoort, ZA)
Scorgie, Robert Kenneth Hewson (7 Bontebok Avenue, Nyala Park, 3880 Empangeni, ZA)
Jordaan, Pieter Willem (34 Richfield, 3 Berlandia Street, 1447 Meyersdal, ZA)
Stephen, Bruce (19 Fiona Road, Discovery, 1709 Roodepoort, ZA)
| 1. | A liner for a pump including first and second liner sections each having an abutting surface, with the abutting surface of the first liner section being provided with a projection and the abutting surface of the second liner section being made of a softer material than the projection so that when the two liner sections are clamped together the projection abuts the softer material to form a seal between the two liner sections. |
| 2. | The liner section of claim 1 wherein the softer material is provided in the form of a layer on the second liner section, with the remainder of the second liner section being made of a harder material. |
| 3. | The liner of claim 2 wherein the layer of softer material is bonded to the remainder of the second liner section. |
| 4. | The liner of any one of the above claims wherein two spaced projections are provided on the abutting surface of the first liner section. |
| 5. | The liner of any one of the above claims wherein the liner sections are made of a polymeric material which has a Shore hardness greater than about 60 (A), except for the softer material which has a Shore hardness less than about 60 (A). |
| 6. | The liner of claim 5 wherein the polymeric material is polyurethane. |
| 7. | The liner of any one of the above claims wherein the projection is integrally formed with the remainder of the first liner section. |
| 8. | A liner section for a pump including an abutting surface for abutting another liner section to form a liner, the abutting surface containing a groove for a seal so that in use a seal located within the groove forms a seal between the two liner sections. |
| 9. | A liner for a pump including first and second liner sections each having an abutting surface, with the abutting surface of the first liner including a projection made of a softer material than the abutting surface of the second liner so that when the two liner sections are clamped together the projection forms a seal between the two liner sections. |
| 10. | The liner of claim 9 wherein the abutting surface of the first liner is provided by a layer of material from which the projection projects, the layer being bonded to, and being softer than, the remainder of the first liner. |
| 11. | A liner for a pump including first and second liner sections, with the abutting surface of one of the liner section being provided with a layer of softer material than the abutting surface of the other liner section, and with one of the abutting surfaces being provided with a projection so that when the two liner sections are clamped together the projection forms a seal between the two liner sections. |
| 12. | A liner for a pump substantially as herein described and illustrated with reference to the accompanying drawings. |
BACKGROUND TO THE INVENTION A liner for a pump consists of two liner sections which are clamped together between plates. The liner sections are made of a polymeric material which may be an elastomeric material or a harder material such as polyurethane.
The applicant has found that if the Shore hardness of the liner material exceeds about 60 (A), it becomes increasingly difficult to form a seal between the two liner sections as the pressure of liquid within the liner increases. In addition because of the very poor memory of polyurethane, repeated opening and closing of pumps lined with polyurethane liners causes the abutting sections of the liners to lose their ability to form a seal rendering the liners useless, albeit that the remainder of the liners is in good condition.
SUMMARY OF THE INVENTION According to the invention a liner for a pump includes first and second liner sections each having an abutting surface, with the abutting surface of the first liner section being provided with a projection and the abutting surface of the second liner section being made of a softer material than the projection so that when the two liner sections are clamped together the projection abuts the softer material to form a seal between the two liner sections.
The softer material may be provided in the form of a layer on the second liner section, with the remainder of the second liner section being made of a harder material.
The layer of softer material is preferably bonded to the remainder of the second liner section.
In one form of the invention two spaced projections are provided on the abutting surface of the first liner section.
The liner sections may be made of a polymeric material which has a Shore hardness greater than about 60 (A), except for the softer material which has a Shore hardness less than about 60 (A).
The polymeric material is preferably polyurethane.
The projection may be integrally formed with the remainder of the first liner section.
According to a further aspect of the invention a liner section for a pump includes an abutting surface for abutting another liner section to form a liner, the abutting surface containing a groove for a seal so that in use a seal located within the groove forms a seal between the two liner sections.
According to another aspect of the invention a liner for a pump includes first and second liner sections each having an abutting surface,. with the abutting surface of the first liner including a projection made of a softer material than the abutting surface of the second liner so that when the two liner sections are clamped together the projection forms a seal between the two liner sections.
The abutting surface of the first liner is preferably provided by a layer of material from which the projection projects, the layer being bonded to, and being softer than, the remainder of the first liner.
According to another aspect of the invention a liner for a pump includes first and second liner sections, with the abutting surface of one of the liner section being provided with a layer of softer material than the abutting surface of the other liner section, and with one of the abutting surfaces being provided with a projection so that when the two liner sections are clamped together the projection forms a seal between the two liner sections.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a liner section according to the invention; Figure 2 is an enlarged view of the circled part of figure 1; Figure 3 is a cross-sectional side view of the liner section of figures 1 and 2 abutting another liner section to form a liner ; Figure 4 is an enlarged view of the circled part of figure 3; Figures 5 to 10 are cross-sectional end views of parts of liners illustrating further embodiments of the invention; and Figures 11 is a cross-sectional end view of parts of liners according to yet another embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS Referring firstly to figures 1 to 4, a liner or volute 10 consists of two polyurethane liner or volute sections 12 and 14. The liner sections 12 and 14 are known as frame plate and cover plate liners respectively.
Each liner section 12 and 14 has a planar abutting or clamping surface 16.1 and 16.2 respectively. The abutting surface 16.1 of the liner section 12 has an integrally moulded projection or bead 18.
The abutting surface 16.2 of the liner section 14 comprises a layer 20 of polyurethane which is softer than the polyurethane of the remainder of the liner sections 12 and 14. The layer 20 is bonded to the remainder of its liner section 14 by being cast or moulded into position. The layer 20 has a Shore hardness of 65 (A) and the remainder of the liner section 14 has a Shore hardness of 85 (A) to 90 (A). The liner section 12 has a Shore hardness of 85 (A) to 90 (A).
In use, the liner sections 12 and 14 are clamped together to form the liner between pump casing members comprising a frame plate and a cover plate (not shown). The projection 18 of liner section 12 abuts the layer 20 of softer polyurethane of liner section 14 to form a seal between the two liner sections 12 and 14. In this regard the projection 18 forms an indentation in the layer 20. The applicant has found that this seal enables a pump incorporating the liner to achieve a pressure of greater than 2,1 Mpa without leakage occurring from the abutting or clamping surfaces 16.1 and 16.2. The applicant has also found that the softer layer 20 of the liner section 14 has a better elastic memory than harder polyurethane in that the softer layer 20 is less affected by permanent set when clamped.
Referring now to figures 5 to 8, different embodiments of the projection, indicated by reference numerals 18.1 to 18.4, are illustrated.
In figure 9 the liner section 12 has a groove 20 in its abutting surface 16.1 which groove contains an O-ring 22. The O-ring 22 forms a seal between the liner sections 12 and 14. In this embodiment of the invention the softer layer 20 may be omitted.
In figure 10 two grooves 20 are provided, one in each of the abutting surfaces 16.1 and 16.2 of the liner sections 12 and 14. An O-ring 22.1 is located in the two grooves 20 to form a seal between the two liner sections 12 and 14.
Referring now to figure 11, liner sections 12.1 and 14.1 each have abutting surfaces 16.1 and 16.2. The abutting surface of liner section 12.1 has a layer 20.1 of polyurethane which is softer than the remainder of liner section 12.1 and softer than liner section 14.1. The layer 20.1 is bonded to the remainder of liner section 12.1 by being cast or moulded into position.
The layer 20.1 has a projection 18. 1. When the two liner sections 12.1 and 14.1 are clamped together, the projection 18.1 forms a seal between the two liner sections by being deformed between the two liner sections. The layer 20.1 has a Shore hardness of 65 (A), and the remainder of the liner section 12.1, and the liner section 14.1, have a Shore hardness of 85 (A) to 90 (A).
It will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention.