PISTON COFFEE MAKER FOR PREPARING COFFEE IN SMALL AMOUNTS

Abstract: With a piston coffee maker (1) with a cylindrical container (2), a lid (3), a piston (5) with piston rod (7) and a handle (8), where the piston (5) is made as a filter (6) for the ground coffee, it is the intention to make a piston coffee maker of the above mentioned kind, where with the piston coffee maker small portions for a single cup can be made, and where the piston coffee maker is capable of keeping the temperature of the infusion fluid on a suitable level during the preparation of the coffee, and where production costs for the piston coffee maker are small. This goal is achieved with a piston coffee maker according to the invention in, that the walls, the lid and the bottom in the cylindrical container (2) are made heat isolating and the upper rim is equipped with locking means (9), and that the lid (3) is provided with corresponding locking means with a view to that the lid (3) can be sealingly locked on the piston coffee maker (1).

Description: PISTON COFFE MAKER FOR PREPARING COFFEE IN SMALL AMOUNTS The present invention relates to a piston coffee maker with cy lindrical container, a lid, a piston with piston rod and a handle, where the piston is made as a filter for the ground coffee, where the piston coffee maker is particu larly suitable for preparing coffee in small amounts for, say, one person. It has for ages been known, that for preparing coffee different devices and methods could be applied, where the perspective reaches from a b lue, enamelled jug with matching fabric bag to espresso devices, where steam u n de r high pressure is lead through the ground coffee beans. From approximately mid 1970'es a piston coffee maker has been known and widely distributed in Den- mark, and such piston coffee makers have been made in varying sizes c o v e ri n g expected needs from 3 and up to 12 persons. However, it has never been possible - even in small piston coffee makers - to prepare smaller portions of coffee, as the dimensions result in an u n f a v o u r able relation between the total surface and the volume of the infusion fluid, taking into consideration that Stephan-Bolzmanns law for temperature emi s sion, where the radiated energy through a surface is reversed proportional to the volume of the body and proportional with the area of the surface and w i th the absolute temperature in fourth power, is also valid for such small bodies. This has. until now, caused that the infusion fluid during the p rep arati o n quickly delivered the heat to the environment, whereby the te mp erature deminished before the coffee had delivered its aromatic compounds to the i n f u sion fluid. This has obviously been to the disadvantage of drinking the coffee . Further, it has been uneconomic to produce a piston coffee maker for only o n e person, as the expenses for that have been exorbitant, as tools, assembling an d packaging by and large are independent of the size of a piston coffee maker. The inventor has therefore set his goal to make a piston coffee maker o f the above mentioned kind, where with the piston coffee maker small po rti o n s for a single cup can be made, and where the piston coffee maker is capable o f keeping the temperature of the infusion fluid on a suitable level during t h e preparation of the coffee, and where production costs for the piston coffee maker are small. This task is according to the invention solved by that the walls, the lid, a n d the bottom in the cylindrical container are made heat isolating and that the u p - per rim is equipped with locking means, and that the lid is provided with c o rre - sponding locking means with a view to that the lid can be sealingly locked o n the piston coffee maker. With a piston coffee maker according to the invention a favourable re l ation between the heat transmission of the outer surface and the volume of t h e infusion fluid is secured, whereby the temperature of the infusion fluid can b e optimally maintained during the infusion, i.e. over 96°C. Thereby, all essential aromatic oils for the coffee drink are extracted from the ground coffee. In an appropriate construction the walls and the bottom in the cy lindric al container are made as a double construction like double walls and double b o ttoms. Thereby, the container can be made by precision injection moulding o f plastics, whereby very small tolerances in the finished container are achieved. Thereby, a further advantage is achieved in that the sealing between the fil ter in the piston and the container wall can be established with simple and ec onomic propitious means so that the production cost for the finished piston c o ffee maker can be kept low. Further, such injection moulded construction allows, for further insulation of walls and bottom, introduction of insulating materi al between the double walls in the double constructions. Such insulating materi al can have either the same shape as the one injection moulding matrix, so that i t fits precisely to the space between the double walls and the bottom, or it can b e achieved by injecting polyurethane foam in the cavity, which latter method seems to be the most economic and appropriate method for insulating the p i s to n coffee maker. In an appropriate elaboration the piston coffee maker has the form of a drinking cup, where in the lid can be found partly a depression, the size o f which is sufficient for containing the pressure handle on the piston rod in t h e piston coffee maker, and partly a drinking edge and a drinking o pen in g . Thereby it is secured, that the piston coffee maker can be stabled during s torage, and that its need for space has deminished. It is favourable, if the drinking opening in the lid can be closed by a cover. Thereby, after preparation, further drop in the temperature caused b y evaporation from the coffee drink can be avoided. In that connection it is a practical arrangement, if the cover is pivotably fastened on the pressure h a n dle of the piston rod. Thereby, it can be avoided, that the cover will be mislaid, and it is thereby present at any time, when the need for closure arise. With a view to opening and closure of the cover this is equipped with an o peratin g handle reaching out over the drinking edge. Thereby, the use of the cover i s substantially eased, and as it is pivotably fastened, it can be operated with o n e hand, which might be practical in some situations. In an embodiment of the piston coffee maker the depression in the lid c a n be gradually decreased from the area around the drinking opening until it i s flush with the drinking edge opposite the area around the drinking o peni n g Thereby, there is a possibility of fastening the pressure handle on the piston i n a safe way, so that it is sealing the lid and does not drop out, when the user o f the piston coffee maker is drinking of the drinking edge When the piston b e lifted, the cover of the drinking opening can be used as handle for pulling u p the piston from the depression A most favourable embodiment of the piston coffee maker is provided b y the cylindrical container having an elliptic cross section, and by having t h e piston rod connected to a not shown closing device on top of the filter, and b y the piston rod being pivotable around its axis Thereby, it is secured, that t h e filter is secured from rotating relative to the container, and that by turning t h e piston rod an infusion barring between the coffee drink and the degenerated coffee grounds can be established, whereby further infusion is avoided It c an , in this connection, be suitable, if the eccentricity of the piston cross section i s not too large, as a too large eccentricity will present a more unfavourable re l ation between the volume and the surface The invention together with further embodiments is disclosed more s pe- cifically in the following specification with reference to the examples of e m bodiments shown in the drawing, which is showing on fig 1 a piston coffee maker according to the invention in a partly sectional view, fig 2 the piston coffee maker with elevated piston, i 3 the piston coffee maker seen from above with closed cover, fig 4 the piston coffee maker seen from above with o p e n cover, and F Fiigg 5 5 a sectional view of a different embodiment of the pi s ton coffee maker according to the invention A piston coffee maker 1 according to the invention is shown on fig 1 wi th the container 2, the lid 3 together with its cover 4 Further, the piston 5 with the filter 6 sealing against the cylindrical container wall by a seal ring 16, and a piston rod 7 being fastened in the piston 5 by retaining devices 17, 18, a n d reach up through the lid 3 through a hole in a depression 15, and over the lid 3 is provided with a pressure handle 8. From the sectional drawing it is seen, th at the pressure handle ? can be guided down below the upper limitation of the lid 3. In this position the piston rod 7 or the pressure handle 8 can be locked to t h e lid 3 by a not shown snap lock, so that the piston does not unintentionally slide 5 out. The piston coffee maker is in the presently shown embodiment at the top equipped with a bead 9 round about the outside, where the lid 3 can engage w i th the bead 9 through a groove 10 all the way round on the inside of the skirt 14 o f the lid. The specific shape of the locking means is immaterial in this c o nn ec - ιo tion, as such locking means can be worked out in many ways. Also, in fig. 1 a cover 4 is shown being capable of closing the dri n k i n g opening 12 and thereby impede evaporation of the contents in the piston c offee maker 1. The cover 4 is here pivotably fastened on the pressure handle 8 for t h e piston 5. Thereby it is secured, that the cover is always present when needed, i5 and that the cover also favourably can be used as a pulling handle, when t h e piston 5 should be lifted up from its lowest position. This is particularly needed, if the piston is held in its lowest position by a snap lock not shown in t h e drawing, preventing that the piston slides into the face of the person drinking , when the piston coffee maker shaped as a drinking cup is almost empty. It goes 20 without saying that the cover cannot be used during the infusion itself, but a s soon as the piston has been pressed down to its lowest position, the cover 4 c a n swing down and close the drinking opening 12. In an embodiment of the piston coffee maker, where the piston e.g. has a n elliptical cross section, the cover can, after the infusion, further serve as a r o - 25 tary handle for the rotation of the piston rod around its own axis, whereby a n infusion barring can be achieved between coffee grounds and coffee dri nk . Here, it would be practical if the cover's 4 position over the drinking o p e n i n g 12 corresponds to the situation that the infusion barring between c offee grounds and coffee drink has been established. 30 In fig. 2 the piston coffee maker is shown with elevated piston. Here, t h e piston coffee maker is shown as seen by an observer, whereas fig. 1 is a sec tional view. In the figure the piston is seen in an elevated position, where t h e infusion normally takes place. The cover 4 is here swung up so that it will n o t close the drinking opening 12, when the piston is pressed down. 35 Figs. 3 and 4 show the piston coffee maker as seen from above with closed and open cover, respectively, whereby it can be seen that this embodiment r e fers to the embodiment with a cylindrical container having a circular c y l i nde r cross section. However, the cylinder cross section, which can also elliptical, i s immaterial for showing the cover 4 and its opening and closing. Fig. 5 shows a sectional view of a different embodiment of the piston c offee maker according to the invention, where the drinking opening is arranged a t s an elevation of the lid's drinking edge, and where the cover is hinged directly on top of the lid. Here the locking means between the lid and the container a re achieved by a threaded closure, whereby the lid easily can be mounted or r e moved. This has, however, as a consequence that the cross section of the c o n tainer 2 at the upper rim must be circular. As a result of the large precision a t ιo injection moulding the sealing of the piston against the container wall c an , however, also here be a simple seal ring. From the so disclosed invention it will be clear, that this can be varied i n many ways. Such variations shall not be considered as departing from the s pi ri t and scope of the invention, and the intention is, that all such changes are c o v - i5 ered by the following claims.

Claims: PATENT CLAIMS 1. Piston coffee maker (1) with a cylindrical container (2), a lid (3), a piston (5) with piston rod (7) and a handle (8), where the piston (5) is made as a filter (6) for the ground coffee, characterized in, that the walls, the lid and the bottom in the cylindrical container (2) are made heat isolating and the upper rim is equipped with locking means (9), and that the lid (3) is provided with corresponding locking means with a view to that the lid (3) can be sealingly locked on the piston coffee maker (1). 2. Piston coffee maker according to claim 1, characterized in, that the piston coffee maker has the form of a drinking cup, where in the lid (3) can b e found partly a depression (13), the size of which is sufficient for containing the pressure handle (8) on the piston rod (7) in the piston coffee maker (1), and partly a drinking edge (11) and a drinking opening (12). 3. Piston coffee maker according to claim 1, characterized in, that the walls and the bottom in the cylindrical container (2) are made as a double con- i struction like double walls and double bottoms. 4. Piston coffee maker according to claim 2, characterized in, that insulating material is introduced between the double walls in the double construc- tions. 5. Piston coffee maker according to any of the preceding claims, characterized in, that the drinking opening in the lid (3) can be closed by a cover (4). 6. Piston coffee maker according to claim 5, characterized in, that the 5 cover (4) is pivotably fastened on the pressure handle (8) of the piston rod (7). 7. Piston coffee maker according to any of the preceding claims, characterized in, that the cover (4) is equipped with an operating handle (19) reaching out over the drinking edge (11). 8. Piston coffee maker according to any of the preceding claims, charac- o terized in, that the depression in the lid (3) can be gradually decreased from the area around the drinking opening (12) until it is flush with the drinking edge opposite the area around the drinking opening (12). 9. Piston coffee maker according to any of the preceding claims, characterized in, that the cylindrical container (2) has an elliptic cross section and 5 the piston rod (7) being pivotable around its axis, and by having the piston rod connected to a not shown closing device on top of the filter. 10. Piston coffee maker according to claim 1 - 3, 5 and/or 7, characterized in, that the cover f/4) is pivotably fastened on the lid (3).

Inventors: JOERGENSEN CARSTEN, JOERGENSEN, CARSTEN
Applicants: JOERGENSEN CARSTEN, PI DESIGN AG, JOERGENSEN, CARSTEN, PI-DESIGN AG
Application year: 1998
Main classification: A47J31
IPC codes: A47J31