GB2027599A - Capsules for separately containing materials to be mixed - Google Patents

Abstract

A dental mixing capsule 11 usable for separately containing quantities of metal alloy powder 39 and mercury 37 and subsequently enabling intermixing of these components comprises a plunger 15 which is located in a first position relative to the capsule body 11 to define a mercury cavity 33 and an alloy powder chamber 35; the plunger 15 being movable to a second position placing the cavity 33 in communication with the chamber 35 thereby enabling intermixing of the alloy 39 and mercury 37. <IMAGE>

Description

SPECIFICATION Capsule structure The present invention relates to a capsule for separately containing quantities of materials and subsequently enabling combination of these materials. More particularly the present invention relates to a dental mixing capsule for separately containing quantities of metal alloy and mercury and subsequently enabling combination and intermixing of the alloy and the mercury.

In the prior art numerous arrangements of such dental mixing capsules have been proposed and used.

One type of prior art arrangement has utilized a mixing chamber containing one ingredient and a cooperating plunger, the plunger having a separate compartment formed therein. The mixing chamber and plunger compartment are arranged to be placed in communication with each other by various means, for example through a narrow capillary type passage (e.g. Australian Patent No.

407,235) or through a frangible diaphragm (e.g.

Australian Patent No. 455,975).

Other prior art arrangements have utilized separate compartments within a capsule body which compartments are isolated, each from the other, by either a frangible diaphragm (e.g.

Australian Patent No. 426,471) or a separable sealing member (e.g. Australian Patent Nos.

465,849 and 472,910) which separable sealing member becomes intermixed together with the combined materials.

Elimination of the use of such frangible diaphragms, separate sealing members and capillary passages to provide an alternate capsule construction is desired.

In one aspect the present invention provides a capsule comprising: a body member having an opening communicating with a passage, said passage extending inwardly into said body, and a plunger receivable by said passage, said plunger having first and second portions spaced apart from each other; said plunger being locatable with said body member in a first position whereat said plunger portion closes-said opening, and said second plunger portion is spaced inwardly from said opening in sealing engagement with said passage; said body and said plunger thereby defining: a cavity extending at least in part between said first and second plunger portions, and a chamber located inwardly of said second portion, and arranged such that said sealing engagement prevents communication of said cavity with said chamber thereby, in use, enabling separate containment of materials therein; said plunger being movable from said first position to a second position whereat said first portion closes said passage and said cavity communicates with said chamber, thereby, in use, enabling intermixing of said materials.

In another aspect the present invention provides a capsule comprising: a body member having a cylindrical passage which has an opening at one end and which is closed at the other end, said passage extending inwardly into said body member and being divided into a first section extending from said opening to a second section, said first section having a lesser diameter than said second section, and a plunger receivable by said passage, said plunger having first and second portions interconnected by a shaft, said shaft having a lesser cross-section than said second plunger portion; said plunger being locatable with said body member in a first position whereat:: said first plunger portion is at least partially located in said first passage section and closes said opening, and said second plunger portion is spaced inwardly from said opening and is located within said first passage section whereat said second portion sealingly engages said first passage section; said cylindrical passage and said plunger thereby defining:: a cavity extending at least in part between said first and second plunger portions, and a chamber extending at least in part between said second plunger portion and said closed end of said passage; said sealing engagement of said second portion with said first passage section preventing communication of said cavity with said chamber thereby, in use, enabling separate containment of materials therein;; said plunger being movable from said first position to a second position whereat said first plunger portion is at least partially located in said first passage section and thereby closes said passage, said second plunger portion is located within said second passage portion such that at least a part of said second portion is spaced apart from said second passage section thereby placing satd cavity in communication with said chamber, and thereby in use, enabling intermixing of said materials.

Preferred embodiments of the present invention will be described hereinafter with reference to the accompanying drawings, wherein: Figure 1 is a side sectional view of a first preferred embodiment of the capsule of the present invention; Figure 2 is a side sectional view of a second preferred embodiment of the capsule of the present invention; Figure 3 is a side part-sectional view of the capsule of Figure 2 in which the plunger has been moved downwardly relative to Figure 2; Figure 4 is a side sectional view of the capsule of Figure 3 after mixing of the materials and subsequent separation of the bottom end cap; Figure 5 is a side part-sectional view of a third preferred embodiment of the capsule of the present invention; and Figure 6 is a side part-sectional view of the capsule of Figure 5 in which the plunger has been moved downwardly relative to Figure 5.

The capsules shown in the preferred embodiments of the accompanying drawings are specifically adapted for use as dental mixing capsules which separately contain mercury and metal alloy powder and then enable subsequent intermixing of these constituents.

Referring firstly to Figure 1 there is shown a mixing capsule 11 which comprises a body member 13 and a plunger 15. The body member 13 includes a passage 17 having an opening 19 and a closed end 21.

The plunger 1 5 is proportioned to be receivable by the passage 1 7 and comprises a first portion 23 and a second portion 25 spaced apart from each other and interconnected by a shaft 27.

Shaft 27 has a lesser cross-section than the second portion 25.

Referring now to Figures 2 to 6 there are shown capsules 11 which have an exactly analogous structure to that of the capsule of Figure 1 except that the embodiments of Figures 2 to 6 are provided with a removable end cap 29. After intermixing this end cap 29 may be removed from the remainder of capsule 11 to enable convenient access to the mixture contained therein.

It should be noted that the provision of end cap 29 is only a convenience and is not essential to the working of the invention. For example, in the embodiment of Figure 1 access to the interior of the capsule 11 could be obtained by severing the capsule along line A-A or alternatively by extraction of plunger 1 5 from passage 17 for example by inserting a screw-threaded device (not shown) into the first portion 23 and using this device to pull the plunger 15 upwardly out of passage 17.

Hereinafter this description will be directed to the preferred embodiments shown in Figures 2 to 6; however it should be understood that with the exception of end cap 29 this description will relate equally to the embodiment of Figure 1.

Referring once again to Figure 2, plunger 1 5 is shown located in a first position wherein the first portion 23 closes the opening 19 of the passage 17. In the embodiments shown in the accompanying drawings this closure of opening 1 9 is achieved by location of the first member 23 at least partially within passage 17. However it should be understood that this closure may be achieved by other means, for example the abutment (not shown) of the first member 23 against the end face 24 of passage 1 7. In such an arrangement the top portion 14 of body member 13 and/or the first member 23 would need to be deformable to accommodate insertion of first member 23 during downward movement of plunger 15.

Referring once again to Figure 2, the second portion 25 is located within passage 17 between closed passage end 21 and first member 23 so dividing the passage 17 into a cavity 33 and a chamber 35 each of which may contain a quantity of material for subsequent combination.

In the preferred embodiments of the invention shown in Figures 1 to 4, passage 17 has a circular cross-section which results in chamber 35 having a substantially cylindrical shape and further results in cavity 33 having a substantially annular shape.

With this configuration cavity 33 is located within passage 17 and thus within the cross-sectional confines of first and second plunger portions 23 and 25 respectively. Similarly chamber 35 is located inwardly of second portion 25 within the cross-sectional confines thereof, and at the same time chamber 35 is located further into body 13 (relative to the inward extent of passage 17) than cavity 33.

It should be understood that it is by no means essential that passage 17 have a circular cross section nor that the configurations of cavity 33 be restricted, whilst extending between first and second plunger portions 23 and 25 respectively, to lie within the cross-sectional configuration of first and second plunger portions 23 and 25 respectively, nor is it necessary that chamber 35 be restricted to lying within the cross-sectional configuration of second plunger portion 25.

In this regard attention is firstly directed to the possibility (not shown) of the inward extent of passage 1 7 being terminated after the point of enagagement of second portion 25 therewith (when plunger 1 5 is in its first position), whereby chamber 35 may extend from the termination of passage 17 and may have any desired configuration.

Attention is secondly directed to the embodiment of Figures 5 and 6 in which the side walls 55 and 57 and consequently cavity 33 and chamber 35, have a bulbous configuration. In this embodiment, whilst extending between first and second plunger portions 23 and 25 respectively, cavity 33 also extends beyond the width of first and second plunger portions 23 and 25 respectively. Similarly, whilst chamber 35 extends between second plunger portion 25 and the closed end 21 of passage 17, chamber 35 also extends beyond the width of second plunger portion 25.

Referring once again to Figure 2, a small quantity of mercury 37 is shown contained in cavity 33 and a relatively larger quantity of alloy powder 39 is shown contained in the chamber 35.

The engagement of the second portion 25 with passage 1 7 should be arranged such that during the normal shelf life of the capsule, this engagement prevents communication of the mercury 37 contained in cavity 33, with the alloy powder 39 contained in chamber 35, to an extent that substantial interaction of these ingredients would occur. Consequently the engagement of second portion 25 with passage 1 7 is a sealing engagement to the extent that communication of the respective materials is sufficiently prevented to provide a reasonable shelf life for the capsule 11.

As above described the first portion 23 is arranged to close the opening 19 of passage 1 7. It should be understood that this closure may, if desired, be a sealing engagement of first portion 23 with passage 1 7. If, for example for safety reasons, it is desired to prevent the escape of mercury vapour from capsule 11 such vapour can be sealed within capsule 11 by ensuring that a suitable sealing engagement of first portion 23 with passage 1 7 is achieved. Alternatively the location of the mercury 37 and the alloy powder 39 may be interchanged (not shown in the drawings) so that the mercury 37 is located in chamber 35 and mercury vapour is prevented from escaping from capsule 11 by arranging a suitable sealing engagement of second portion 25 with passage 17.

To enable intermixing of the materials contained in cavity 33 and chamber 35 adownward force, as shown by arrow F in Figures 2 or 5, is applied to displace plunger 1 5 downwardly from the first position shown in Figures 2 or 5 to a second position as shown in Figures 3 or 6. During this downward movement first portion 23 preferably maintains a suitable sealing engagement with passage 17.

As can be most clearly seen in Figure 2, first portion 23 preferably has a length from its end 47 to its point of interconnection 49 with shaft 27 which is greater than the displacement between the first plunger position shown in Figure 2 and the second plunger position shown in Figure 3 such that the downward movement of plunger 1 5 from the first plunger position shown in Figure 2 to the second plunger position shown in Figure 3 enables first plunger portion end 47 to be positioned flush with passage end face 24 as shown in Figure 3.

In the second plunger position shown in Figure 3, the first portion 23 closes the opening 1 9 of passage 1 7. Additionally, cavity 33 is placed in communication with chamber 35 thereby enabling mercury 37 to pass downwardly, as shown by arrows D, into chamber 35 to mix with alloy powder 39. Subsequent agitation of capsule 11 enables intermixing of mercury 37 and alloy powder 39 to form a mixture 31 which is usable as a dental amalgam. The above referred closure of opening 19 by first portion 23 whilst plunger 1 5 is in the second position shown in Figure 3 should be such as to minimize and preferably completely prevent leakage of mercury 37, powder 39 and the resultant amalgam, during this agitation.In the embodiment shown in Figure 3 prevention of leakage is achieved by suitable sealing engagement of first portion 23 with passage 17.

It should be noted that in the embodiments of Figures 1 to 4 passage 1 7 is divided into a first cylindrical passage section 43 and a second cylindrical passage section 45 with the first passage section 43 having a lesser cross-section than second passage section 45. Consequently when plunger 1 5 is located in the first plunger position as shown in Figure 2, the second sealing portion 25 engages first passage section 43 whereas when plunger 1 5 is moved into the second plunger position as shown in Figure 3, the second plunger portion 25 no longer engages passage 1 7 because of the larger cross-section of second passage section 45 into which second plunger portion 25 has been inserted.

The resultant clearance 44 between second plunger portion 25 and second passage section 45 enables the above referred downward movement of mercury 37 and further enables free movement of the mercury 37 and the alloy powder 39 during agitation and mixing thereof. Additionally clearance 44 should be dimensioned such that neither the unmixed materials nor the resultant mixture 31 becomes trapped in the space between second plunger portion 25 and second passage section 45 during the agitation of the capsule used to effect intermixing of the mercury 37 and alloy powder 39.

In order to further promote this free movment the transition in cross-section of the first passage section 43 to the larger second passage crosssection 45 is effected in a streamlined manner to reduce dead spots in the mixing operation. This streamlining is achieved by providing a bevelled portion 46 in the embodiments of Figures 1 to 4 and by the smooth contour 56 of the bulbous sidewalls 55 and 57 of the embodiment of Figures 5 and 6.

Additionally this free movement is still further promoted by providing a conical shaft portion 49 which interconnects shaft 27 with second plunger portion 25. This conical portion 49 ensures a streamlined transition from shaft 27 to second plunger portion 25 thereby promoting free movement of materials during mixing and so avoiding a dead spot where mixing would be suppressed at the location where shaft 27 and second sealing plunger portion 25 interconnect (i.e. similar to corner 51 at the interconnection of shaft 27 with first plunger portion 23).Thus during agitation bevel portion 46, conical portion 49 and clearance 44 enable and promote ready movement of the ingredients arid amalgam between cavity 33 and chamber 35 thereby ensuring intimate intermixing of the mercury 37 and the alloy powder 39 and ensuring that entrapment of these materials in the clearance 44 is avoided.

As may be appreciated from Figures 1 to 4, these preferred.embodiments utilize a body member 13, plunger 15, passage 17 and shaft 27 which have a substantially circular cross-sectional configuration. Plunger 15 and shaft 27 desirably are also concentrically located in passage 1 7 whereby cavity 33 has substantially uniform annular configuration. It should be noted however that these configurational features are not essential to the invention.

After intermixing has been achieved the resultant mixture is gathered (e.g. by falling of the mixture aided by tapping of the capsule) into the endcap 29.

Figure 4 illustrates the separation of endcap 29 from the rest of capsule 11 thereby enabling access to the chamber 35 and thus to the mixture 31 gathered at the bottom of the endcap 21.

The above described preferred embodiments of the present invention achieve the following advantage relative to prior art structures. The plunger 15 may be fabricated in one piece only, yet in its first position, it still maintains separation of the two quantities of materials until mixing is desired. Relative to prior art capsules this structure is exceedingly simple.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this application is not limited to theparticular embodiment described by way of example hereinabove.

Claims (14)

1. A capsule comprising: a body member having an opening communicating with a passage, said passage extending inwardly into said body, and a plunger receivable by said passage, said plunger having first and second portions spaced apart from each other; said plunger being locatable with said body member in a first position whereat: said first plunger portion closes said opening, and said second plunger portion is spaced inwardly from said opening in sealing engagement with said passage; said body and said plunger thereby defining:- a cavity extending at least in part between said first and second plunger portions, and a chamber located inwardlv of said second portion, and arranged such that said sealing engagement prevents communication of said cavity with said chamber thereby, in use, enabling separate containment of materials therein; said plunger being movable from said first position to a second position whereat said first portion closes said passage and said cavity communicates with said chamber, thereby, in use, enabling intermixing of said materials.

2. A capsule comprising: a body member having a cylindrical passage which has an opening at one end and which is closed at the other end, said passage extending inwardly into said body member and being divided into a first section extending from said opening to a second section, said first section having a lesser diameter than said second section, and a plunger receivable by said passage, said plunger having first and second portions interconnected by a shaft, said shaft having a lesser cross-section than said second plunger portion;; said plunger being locatable with said body member in a first position whereat said first plunger portion is at least partially located in said first passage section and closes said opening, and said second plunger portion is spaced inwardly from said opening and is located within said first passage section whereat said second portion sealingly engages said first passage section; said cylindrical passage and said plunger thereby defining:: a cavity extending at least in part between said first and second plunger portions, and a chamber extending at least in part between said second plunger portion and said closed end of said passage; said sealing engagement of said second portion with said first passage section preventing communication of said cavity with said chamber thereby, in use, enabling separate containment of materials therein;; said plunger being movable from said first position to a second position whereat said first plunger portion is at least partially located in said first passage section and thereby closes said passage, said second plunger portion is located within said second passage portion such that at least a part of said second portion is spaced apart from said second passage section thereby placing said cavity in communication with said chamber, and thereby, in use, enabling intermixing of said materials.

3. A capsule as claimed in claim 1 wherein said passage is divided into first and second sections, said first section having a lesser cross-section than said second section, said first Plunger position locating said second plunger portion in sealing engagement with said first passage section and said second plunger position locating said second plunger portion in said second passage section whereat at least a part of said second portion no longer engages said passage thereby enabling said communication of said cavity with said chamber.

4. A capsule as claimed in claims 1 or 3 wherein said first and second portions are interconnected by a shaft having, along at least a part of its length, a lesser cross-section than said second portion.

5. A capsule as claimed in claim 4 wherein both ,said first passage section and said shaft have a substantially uniform cirdular cross-section over at least a corresponding part of their length whereby said cavity includes an annular space between said passage and said shaft.

6. A capsule as claimed in claims 2 or 5 wherein said passage and said shaft are substantially concentric whereby, when said plunger is located in said second position, said second portion is entirely disengaged from said passage thereby enabling ready intermixing of said materials.

7. A capsule as claimed in any one of claims 2, ' 5 or 6 wherein said second plunger portion is interconnected with the portion of said shaft having a substantially uniform circular crosssection, by a conical shaft portion having a substantially circular cross-section, which crosssection decreases from said second portion to said uniform circular cross-section shaft portion.

8. A capsule as claimed in any one of claims 1 to 7 wherein, when said plunger is located in said first position said first portion sealingly closes said open end by engagement with said passage.

9. A capsule as claimed in any one of claims 1 to 8 wherein, when said plunger is located in said second position said first plunger portion sealingly closes said passage.

10. A capsule as claimed in claims 2, 8 or 9 wherein said first plunger portion sealingly engages said passage during the movement of said plunger from said first to said second position.

11. A capsule as claimed in any one of claims 2, 4, 5, 6, 7, 8, 9 or 10 wherein said first portion has a length extending from the remote end thereof to its interconnection with said shaft, which length is greater than the distance between said first and second positions of said plunger, whereby, in use, when said plunger is located in said first position a part of said first portion is located in and sealingly engages said passage and a length of said first portion substantially corresponding to said distance protrudes beyond the opening of said passage; whereafter movement of said plunger to said second position locates said passage opening and said remote end of said second portion, in a position where they are substantially flush each with the other.

12. A capsule as claimed in any preceding claim wherein a portion of said body member is removable to thereby enable access to said chamber.

13. A capsule as claimed in claim 2 wherein said removable portion is an end cap located opposite said opening.

14. A capsule as claimed in any preceding claim wherein the width of said cavity extends beyond the width of said first or second plunger portions.

1 5. A capsule substantially as hereinbefore described with reference to Figures 1 or 2 to 4 or 5 and 6 of the accompanying drawings.