CA1155004A - Porting faces of hydraulic pumps and motors - Google Patents
Porting faces of hydraulic pumps and motorsInfo
- Publication number
- CA1155004A CA1155004A CA000364968A CA364968A CA1155004A CA 1155004 A CA1155004 A CA 1155004A CA 000364968 A CA000364968 A CA 000364968A CA 364968 A CA364968 A CA 364968A CA 1155004 A CA1155004 A CA 1155004A
- Authority
- CA
- Canada
- Prior art keywords
- barrel
- motor
- hydraulic pump
- cylinder
- port
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/122—Details or component parts, e.g. valves, sealings or lubrication means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
- F04B1/2014—Details or component parts
- F04B1/2021—Details or component parts characterised by the contact area between cylinder barrel and valve plate
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Hydraulic Motors (AREA)
- Reciprocating Pumps (AREA)
Abstract
IMPROVEMENTS IN OR RELATING TO THE
PORTING FACES OF HYDRAULIC PUMPS AND MOTORS
Abstract of the Disclosure The service life of hydraulic pumps and motors of the kind in which a rotary cylinder barrel rotatable within a body chamber containing a number of pistons having a ported face bearing against a stationary surface containing the inlet and delivery ports is improved by reducing port face leakages resulting from deformation or from wear at the mating port faces. At least one passage is provided in each barrel and port block.
Each passage extends radially inside the cylinder port face and permits fluid to flow from the chamber. At least the passage in the barrel communicates with a region closely adjacent the radially innermost edge of the cylinder port face.
PORTING FACES OF HYDRAULIC PUMPS AND MOTORS
Abstract of the Disclosure The service life of hydraulic pumps and motors of the kind in which a rotary cylinder barrel rotatable within a body chamber containing a number of pistons having a ported face bearing against a stationary surface containing the inlet and delivery ports is improved by reducing port face leakages resulting from deformation or from wear at the mating port faces. At least one passage is provided in each barrel and port block.
Each passage extends radially inside the cylinder port face and permits fluid to flow from the chamber. At least the passage in the barrel communicates with a region closely adjacent the radially innermost edge of the cylinder port face.
Description
~5S~)04 This invention relates to hydraulic pumps and motors of the kind in which a rotary cylinder barrel containing a plurality of pistons has a ported face bearing against a stationary surface containing the inlet and delivery ports.
The invention particularly relates to the port faces, which are usually flat, but may be of part spherical or of conical form.
The port faces are usually substantially hydro-statically balanced and are spring loaded together, so that there is intimate contact and negligible leakages from the high pressure portings. Usually the face of the cylinder barrel is in the form of an annular ring pierced by openings into the cylinders, so that the openings are bounded by narrow annular sealing lands.
Because of the intimate sealing contact at the narrow annular sealing lands, if there is zero leakage, the surfaces run very hot and it is necessary to employ proved bearing materials, such as one hard surface and one having a lower melting point.
The major limitation to the service lives of these forms of pumps and motors is port face leakages resulting from deformation, or from wear at the mating port faces. The purpose of the invention is to provide means for reducing this limitation to service life.
The closed inside edge of each of the two confronting annular sealing lands is well cooled by the flow of liquid to and from the portings. The outer edges of the outer sealing lands are also well cooled, in this case by the liquid in the pump housing, but the inner edges of the inner sealing lands '~
l~SS004 are in contact with a very small volume of substantially static liquid surrounding the axis of the cylinder barrel.
Because of this, the confronting inner sealing lands run at a considerably higher temperature than the outer lands and this results in thermal deformation, causing the two opposing surfaces to become slightly convex. This results in increased leakages at the outer sealing land, which is further cooled by this flow while the increased surface loading at the inner lands, with zero leakage, results in a further increase in temperature.
An -object of the invention is to provide an adequate cooling flow to the inside of the inner sealing land, thereby promoting substantially uniform temperatures across the whole surface of the port face and minimising thermal deformations.
The main cause of abrasive wear between the port faces is small solid particles in the liquid being forced into the interface, where they become imbedded in the soft surface and produce abrasive wear at the hard counterface. The flow of liquid through the portings serves to flush abrasive particles away from the adjacent inside edges of the sealing lands and solid particles are centrifuged away from the outer edges of the outer sealing lands. However, ~olid particles are centrifuged into the interface at the inner edges of the ~inner sealing lands and this results in a high rate of abrasive wear.
A secondary object of preferred embodiments of the invention is to so direct a cooling flow to the inner edges of the inner sealing lands that it purges solid particles from this zone, thereby substantially eliminating a major 1~55004 cause of abrasive wear.
The need to employ one surface having a low melting point results in other causes of failure, such as cavitation erosion of the soft surfaces, or when leakage begins at a small radial scratch, it rapidly increases due to erosion from the flow of high pressure liquid. Ideally, both surfaces should be of hard abrasive resistant materials, but this is possible only if the surfaces are continually cooled over the whole of their areas.
A further object of preferred embodiments of the inven-tion is to permit the use of two hard materials running together for the port faces.
An aspect of the invention is as follows:
A hydraulic pump or motor of the type having a rotary cylinder barrel rotatable within a body chamber adapted to be filled with fluid, said barrel containing a plurality of cir-cumferentially spaced pistons and having a cylinder port face containing a like plurality of circumferentially spaced cylinder ports, said cylinder port face bearing against a stationary port surface on a port block containing circumfe-rentially spaced inlet and delivery ports, characterised in that at least one passage is provided in each of said barrel and port block, each passage extend~ng substantially radially from said chamber to a region radially inside said cylinder port face such that rotation of the barrel centrifugally causes fluid to flow continuously from the said chambex to and from said region through said passages, at least said passage in said barrel communicating with said region closely adjacent the radially inner most edge of said cylinder port face.
.
~ 5500~
Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 is a sectional side-elevation illustrating a fixed displacement pump or motor according to the invention;
Figure 2 is an enlarged view of part of the cylinder barrel and port block interface region of the barrel shown in Figure 1;
Figure 3 is a view of the cylinder barrel port faces taken on line 3-3 of Figure 2;
Figure 4 is an enlarged view similar to Figure 2 but illustrating another embodiment of the invention.
Figure 5 is a view similar to Figure 3 but showing a different arrangement of the cylinder barrel port faces; and Figure 6 is a view of the stationary port block surface complimentary to the moving surface shown in Figure 5.
Referring to the drawings, the pump or motor illustrated in Figures 1 and 2 includes a stationary port block 10 aga1nst which a cylinder barrel 11 rotates. The cylinder barrel is urged against~the port block by a spring 12 and as it rotates, a plurality of cyIinder ports 13 are successively brought into communication with an inlet port 8 and an outlet port 9 provided in the stationary port block. The basic structure and operation of these hydraulic pumps or motors is well known and need not be described further.
In a preferred embodiment of the invention, radial holes 15 are drilled between each cylinder of the cylinder barrel 11 and axial drillings 16 are provided to these radial drillings. Preferably the axial drillings should cut ~ ................................................. .
l~SSoO4 slightly into the inner edge 17 of the inner sealing land 18, so that they collect all abrasive matter centrifuged to that zone. One or more drillings or passages 19 are also provided in the stationary port block 10, providing a connection from the liquid in the body cavity 20 to a region 21 inside the inner sealing lands 18. The drillings 19 may, for example, be arranged at an angle to the mating port surfaces as shown in Figures 1 and 2 or parallel as shown in Figure 4.
Because of the rotation of the liquid in the housing, there is a centrifugal pressure gradient in this liquid during operation. -This causes a flow to the inside of the inner sealing lands 18, which is then centrifuged through the rotor drillings 15, providing a continuous cooling flow circulation and purging solid particles from the region 21 inside of the inner sealing lands. This preferred arrangement thereby meets the first two objectives-stated above.
In a further preferred embodiment, the inner and outer rotating sealing lands 22 and 23 respectively are of a radially wavy form as shown in Figure 5, so that there is no continuous circumferential line of contact between the counterfaces during rotation. In this way, all areas of the eotating sealing faces are continuously cooled by passing over freshly wetted areas of the stationary,surface.
When applied to the preferred radially wavy sealing lands, the previously described axial drillings 16, leading to the radial drillings 15 in the rotor 11 are preferably drilled to the outermost radius of the inside wavy edge 24 where solid particles would otherwise accumulate.
' :,-1~55004 Preferably, the stationary surface should be shot peened, as shown in Figure 6, or minute pockets 25 should be formed by other means, so that these small pockets of liquid enter the interface. Any rise of temperature causes the liquid in these pockets to expand, or to vaporise thereby forcing the surfaces very slightly apart and avoiding the formation of metal junctions.
Preferably one or both the sealing faces should be surfaced with a very hard material of high melting point, ~hl~g~6~J
~ such as tungc~an carbide.
,. .~, Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.
.
~ `
The invention particularly relates to the port faces, which are usually flat, but may be of part spherical or of conical form.
The port faces are usually substantially hydro-statically balanced and are spring loaded together, so that there is intimate contact and negligible leakages from the high pressure portings. Usually the face of the cylinder barrel is in the form of an annular ring pierced by openings into the cylinders, so that the openings are bounded by narrow annular sealing lands.
Because of the intimate sealing contact at the narrow annular sealing lands, if there is zero leakage, the surfaces run very hot and it is necessary to employ proved bearing materials, such as one hard surface and one having a lower melting point.
The major limitation to the service lives of these forms of pumps and motors is port face leakages resulting from deformation, or from wear at the mating port faces. The purpose of the invention is to provide means for reducing this limitation to service life.
The closed inside edge of each of the two confronting annular sealing lands is well cooled by the flow of liquid to and from the portings. The outer edges of the outer sealing lands are also well cooled, in this case by the liquid in the pump housing, but the inner edges of the inner sealing lands '~
l~SS004 are in contact with a very small volume of substantially static liquid surrounding the axis of the cylinder barrel.
Because of this, the confronting inner sealing lands run at a considerably higher temperature than the outer lands and this results in thermal deformation, causing the two opposing surfaces to become slightly convex. This results in increased leakages at the outer sealing land, which is further cooled by this flow while the increased surface loading at the inner lands, with zero leakage, results in a further increase in temperature.
An -object of the invention is to provide an adequate cooling flow to the inside of the inner sealing land, thereby promoting substantially uniform temperatures across the whole surface of the port face and minimising thermal deformations.
The main cause of abrasive wear between the port faces is small solid particles in the liquid being forced into the interface, where they become imbedded in the soft surface and produce abrasive wear at the hard counterface. The flow of liquid through the portings serves to flush abrasive particles away from the adjacent inside edges of the sealing lands and solid particles are centrifuged away from the outer edges of the outer sealing lands. However, ~olid particles are centrifuged into the interface at the inner edges of the ~inner sealing lands and this results in a high rate of abrasive wear.
A secondary object of preferred embodiments of the invention is to so direct a cooling flow to the inner edges of the inner sealing lands that it purges solid particles from this zone, thereby substantially eliminating a major 1~55004 cause of abrasive wear.
The need to employ one surface having a low melting point results in other causes of failure, such as cavitation erosion of the soft surfaces, or when leakage begins at a small radial scratch, it rapidly increases due to erosion from the flow of high pressure liquid. Ideally, both surfaces should be of hard abrasive resistant materials, but this is possible only if the surfaces are continually cooled over the whole of their areas.
A further object of preferred embodiments of the inven-tion is to permit the use of two hard materials running together for the port faces.
An aspect of the invention is as follows:
A hydraulic pump or motor of the type having a rotary cylinder barrel rotatable within a body chamber adapted to be filled with fluid, said barrel containing a plurality of cir-cumferentially spaced pistons and having a cylinder port face containing a like plurality of circumferentially spaced cylinder ports, said cylinder port face bearing against a stationary port surface on a port block containing circumfe-rentially spaced inlet and delivery ports, characterised in that at least one passage is provided in each of said barrel and port block, each passage extend~ng substantially radially from said chamber to a region radially inside said cylinder port face such that rotation of the barrel centrifugally causes fluid to flow continuously from the said chambex to and from said region through said passages, at least said passage in said barrel communicating with said region closely adjacent the radially inner most edge of said cylinder port face.
.
~ 5500~
Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 is a sectional side-elevation illustrating a fixed displacement pump or motor according to the invention;
Figure 2 is an enlarged view of part of the cylinder barrel and port block interface region of the barrel shown in Figure 1;
Figure 3 is a view of the cylinder barrel port faces taken on line 3-3 of Figure 2;
Figure 4 is an enlarged view similar to Figure 2 but illustrating another embodiment of the invention.
Figure 5 is a view similar to Figure 3 but showing a different arrangement of the cylinder barrel port faces; and Figure 6 is a view of the stationary port block surface complimentary to the moving surface shown in Figure 5.
Referring to the drawings, the pump or motor illustrated in Figures 1 and 2 includes a stationary port block 10 aga1nst which a cylinder barrel 11 rotates. The cylinder barrel is urged against~the port block by a spring 12 and as it rotates, a plurality of cyIinder ports 13 are successively brought into communication with an inlet port 8 and an outlet port 9 provided in the stationary port block. The basic structure and operation of these hydraulic pumps or motors is well known and need not be described further.
In a preferred embodiment of the invention, radial holes 15 are drilled between each cylinder of the cylinder barrel 11 and axial drillings 16 are provided to these radial drillings. Preferably the axial drillings should cut ~ ................................................. .
l~SSoO4 slightly into the inner edge 17 of the inner sealing land 18, so that they collect all abrasive matter centrifuged to that zone. One or more drillings or passages 19 are also provided in the stationary port block 10, providing a connection from the liquid in the body cavity 20 to a region 21 inside the inner sealing lands 18. The drillings 19 may, for example, be arranged at an angle to the mating port surfaces as shown in Figures 1 and 2 or parallel as shown in Figure 4.
Because of the rotation of the liquid in the housing, there is a centrifugal pressure gradient in this liquid during operation. -This causes a flow to the inside of the inner sealing lands 18, which is then centrifuged through the rotor drillings 15, providing a continuous cooling flow circulation and purging solid particles from the region 21 inside of the inner sealing lands. This preferred arrangement thereby meets the first two objectives-stated above.
In a further preferred embodiment, the inner and outer rotating sealing lands 22 and 23 respectively are of a radially wavy form as shown in Figure 5, so that there is no continuous circumferential line of contact between the counterfaces during rotation. In this way, all areas of the eotating sealing faces are continuously cooled by passing over freshly wetted areas of the stationary,surface.
When applied to the preferred radially wavy sealing lands, the previously described axial drillings 16, leading to the radial drillings 15 in the rotor 11 are preferably drilled to the outermost radius of the inside wavy edge 24 where solid particles would otherwise accumulate.
' :,-1~55004 Preferably, the stationary surface should be shot peened, as shown in Figure 6, or minute pockets 25 should be formed by other means, so that these small pockets of liquid enter the interface. Any rise of temperature causes the liquid in these pockets to expand, or to vaporise thereby forcing the surfaces very slightly apart and avoiding the formation of metal junctions.
Preferably one or both the sealing faces should be surfaced with a very hard material of high melting point, ~hl~g~6~J
~ such as tungc~an carbide.
,. .~, Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.
.
~ `
Claims (12)
1. A hydraulic pump or motor of the type having a rotary cylinder barrel rotatable within a body chamber adapted to be filled with fluid, said barrel containing a plurality of cir-cumferentially spaced pistons and having a cylinder port face containing a like plurality of circumferentially spaced cylinder ports, said cylinder port face bearing against a stationary port surface on a port block containing circumfe-rentially spaced inlet and delivery ports, characterised in that at least one passage is provided in each of said barrel and port block, each passage extending substantially radially from said chamber to a region radially inside said cylinder port face such that rotation of the barrel centrifugally causes fluid to flow continuously from the said chamber to and from said region through said passages, at least said passage in said barrel communicating with said region closely adjacent the radially inner most edge of said cylinder port face.
2. A hydraulic pump or motor as claimed in claim 1 wherein said passage in said barrel intrudes at least partly into said cylinder port face.
3. A hydraulic pump or motor as claimed in claim 1 wherein a plurality of said passages are provided.
4. A hydraulic pump or motor as claimed in claim 3 wherein the passages in said barrel are defined by radial drillings extending into said barrel between said cylinder ports, each radial drilling communicating with an axial drilling opening into said region.
5. A hydraulic pump or motor as claimed in claim 4 wherein said axial drilling intrudes at least partly into said cylinder port face.
6. A hydraulic pump or motor as claimed in claim 3 wherein said passages in said port block are each defined by two intersecting drillings each extending at an angle to the axis of said barrel.
7. A hydraulic pump or motor as claimed in claim 1 wherein the radially inner most edge of the cylinder port face bearing against said stationary port surface is non-circular thereby repeatedly covering and uncovering part of said port surface.
8. A hydraulic pump or motor as claimed in claim 7 wherein the radially outer most edge of said cylinder port face bearing against said stationary port surface is also non-circular thereby repeatedly covering and uncovering part of said port surface.
9. A hydraulic pump or motor as claimed in claim 8 wherein said edges are sufficiently non-circular to uncover in at most one revolution of said barrel the entire bearing region of said port surface extending from the radially inner most and outer most edges of said port surface respectively to the radially inner most and outer most extent of said cylinder ports.
10. A hydraulic pump or motor as claimed in claim 7 wherein a plurality of said passages are provided and said passages in said barrel communicate with said region closely adjacent the radially outer most portions of the radially inner most edge of said cylinder port face.
11. A hydraulic pump or motor as claimed in claim 10 wherein said passages in said barrel intrude at least partly into said cylinder port face.
12. A hydraulic pump or motor as claimed in claim 10 or claim 11 wherein said radially inner most edge is wave-like in form, having a plurality of equally spaced radially outwardly extending crests and radially inwardly extending troughs extending circum-ferentially around said edge, said barrel being provided with a like plurality of said passages corres-ponding with said crests, each said passage communi-cating with said region closely adjacent its respec-tive crest.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPE1427/79 | 1979-11-21 | ||
| AU64082/80A AU536164B2 (en) | 1979-11-21 | 1979-11-21 | Hydraulic pump or motor |
| AUPE142779 | 1979-11-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1155004A true CA1155004A (en) | 1983-10-11 |
Family
ID=25634205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000364968A Expired CA1155004A (en) | 1979-11-21 | 1980-11-19 | Porting faces of hydraulic pumps and motors |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5696180A (en) |
| AU (1) | AU536164B2 (en) |
| CA (1) | CA1155004A (en) |
| DE (1) | DE3043436A1 (en) |
| FR (1) | FR2470265B1 (en) |
| GB (1) | GB2064673B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5133562A (en) * | 1989-04-24 | 1992-07-28 | Eg&G Sealol, Inc. | Drained face seal |
| US5143384A (en) * | 1989-04-14 | 1992-09-01 | Eg&G Sealol, Inc. | Bi-directional, non-contact face seal |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2123093B (en) * | 1982-06-03 | 1985-10-23 | Ifield Eng Pty | Hydraulic pumps |
| JPS60141486U (en) * | 1984-02-29 | 1985-09-19 | 株式会社島津製作所 | piston pump or motor |
| JPS60141487U (en) * | 1984-02-29 | 1985-09-19 | 株式会社島津製作所 | piston pump or motor |
| US4532855A (en) * | 1984-04-04 | 1985-08-06 | Stirling Thermal Motors, Inc. | Two-part drive shaft for thermal engine |
| JPS6257779U (en) * | 1985-09-30 | 1987-04-10 | ||
| JPS6360080U (en) * | 1986-10-03 | 1988-04-21 | ||
| DE3721698A1 (en) * | 1987-07-01 | 1989-01-19 | Hauhinco Maschf | RADIAL PISTON PUMP FOR CONVEYING WATER |
| DE4126640B4 (en) * | 1991-08-12 | 2005-06-16 | Robert Bosch Gmbh | Pump arrangement with a prefeed pump and a radial piston pump |
| JP4540750B1 (en) * | 2010-06-01 | 2010-09-08 | 株式会社小坂研究所 | Oil motor cooling mechanism for submerged pump drive |
| JP5063823B1 (en) * | 2012-04-13 | 2012-10-31 | 株式会社小松製作所 | Oblique shaft type axial piston pump / motor |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3249061A (en) * | 1963-07-01 | 1966-05-03 | Sundstrand Corp | Pump or motor device |
| US3304885A (en) * | 1965-04-30 | 1967-02-21 | Int Harvester Co | Piston pump lubrication structure |
| GB1266155A (en) * | 1968-07-05 | 1972-03-08 | ||
| US3633463A (en) * | 1968-12-25 | 1972-01-11 | Komatsu Mfg Co Ltd | Plunger pump or motor |
| DE2241204A1 (en) * | 1971-08-30 | 1973-03-08 | Advanced Prod Pty | MULTI-CYLINDER HYDRAULIC MACHINE |
-
1979
- 1979-11-21 AU AU64082/80A patent/AU536164B2/en not_active Ceased
-
1980
- 1980-11-17 GB GB8036840A patent/GB2064673B/en not_active Expired
- 1980-11-18 DE DE19803043436 patent/DE3043436A1/en active Granted
- 1980-11-19 CA CA000364968A patent/CA1155004A/en not_active Expired
- 1980-11-19 FR FR8024840A patent/FR2470265B1/en not_active Expired
- 1980-11-20 JP JP16448480A patent/JPS5696180A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5143384A (en) * | 1989-04-14 | 1992-09-01 | Eg&G Sealol, Inc. | Bi-directional, non-contact face seal |
| US5133562A (en) * | 1989-04-24 | 1992-07-28 | Eg&G Sealol, Inc. | Drained face seal |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5696180A (en) | 1981-08-04 |
| FR2470265B1 (en) | 1987-03-20 |
| DE3043436A1 (en) | 1981-06-04 |
| GB2064673A (en) | 1981-06-17 |
| FR2470265A1 (en) | 1981-05-29 |
| GB2064673B (en) | 1983-07-20 |
| AU536164B2 (en) | 1984-04-19 |
| AU6408280A (en) | 1981-05-28 |
| JPH0134305B2 (en) | 1989-07-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |