A typical conventional beverage extraction apparatus is shown in FIG. 1. This beverage extraction apparatus is provided with cylinder 20 for stirring a mixture of a raw material in the form of powder and hot water, paper filter 21 for filtration of the mixture discharged from cylinder 20 and beverage receiver 22 for receiving the beverage through paper filter 21. Cylinder 20 is supported by a guide rail not shown, to be movable up and down. Paper filter 21 is arranged under cylinder 20 so that the mixture prepared in and discharged from cylinder 20 is supplied to paper filter 21, in which the extract of the raw material is separated from the mixture.
Cylinder 20 consists of mixing chamber 20b for mixing the powdered raw material and hot water supplied from inlet 20a provided upward and discharging the mixture from conduit 20e provided at the bottom, extraction chamber 20d for producing the beverage by extraction process connected with mixing chamber 20b by conduit 20e.
Conduit 20e is allowed to open or close by means of valve 23 connected rotatably by pin 32a to the distal end of lever 32. Extraction chamber 20d has inlet 20f for introducing pressurized air thereto through air pipe 52 from an air pump not shown.
Paper filter 21 is supplied in the form of a roll and the used portion is transferred to the left in FIG. 1.
Beverage receiver 22 is provided with inlet 22a for receiving the beverage extracted by paper filter 21, beverage transporting tube 22C for supplying the beverage received by inlet 22a to a cup, and drain tube 22D for draining the beverage received by inlet 22a. Beverage transporting tube 22C is provided with beverage supply valve 53 operated electromagnetically. Pressurized air is supplied to inlet 22a through air pipe 52 from an air pump not shown during agitation process and cleaning process. Drain tube 22D is closed by the action of pressure plate 46 which is pressed by rotating cam 48 so as to pinch drain tube 22D between pressure plate 46 and stationary plate 47.
The beverage extraction apparatus operates on demand for the beverage. At first, rotating cam 48 is rotated, so that pressure plate 46 is pressed by a projection of rotating cam 48, thereby drain tube 22D is pinched between pressure plate 46 and stationary plate 47 to be closed. Next, cylinder 20 and valve 23 are descended from the stand-by position shown so that the lower end of cylinder 20 comes into contact with beverage receiver 22, and conduit 20e is opened. Thereafter, the powdered raw material and hot water are supplied from inlet 20a, and beverage supply valve 53 is closed in accordance with the supply. At the same time, pressurized air is supplied to beverage receiver 22 from the air pump through air pipe 52. The pressurized air flows into extraction chamber 20d through paper filter 21, whereby the air bubbles agitate the mixture of powdered raw material and water in extraction chamber 20d, accelerating the dissolution of beverage components into the hot water.
After agitation for a predetermined period, valve 23 is elevated to close conduit 20c, and pressurized air is supplied from the air pump through air pipe 52 to inlet 20f at the top of extraction chamber 20d. The mixture in extraction chamber 20d is transported downward by pressure of the air supplied, filtered with paper filter 21 and supplied to the serving cup as the beverage through beverage receiver 22 and beverage supply tube 22C. After extraction for a predetermined period, cylinder 20 and valve 23 are elevated, paper filter 21 is advanced, the residue left on paper filter 21 is discarded together with paper filter 21, and a new portion of paper filter 21 is set over beverage receiver 22.
Meanwhile, cylinder 20 in the beverage extraction apparatus is cleaned in the time when frequency of serving is very small, such as night. A typical operation of the cleaning is as follows. At first, rotating cam 48 is rotated, so that pressure plate 46 is pressed by a protrusion of rotating cam 48, thereby drain tube 22D is pinched between pressure plate 46 and stationary plate 47 to be closed. Next, cylinder 20 and valve 23 are descended from the stand-by position shown so that the lower end of cylinder 20 comes into contact with beverage receiver 22, and conduit 20e is opened. Then, the powdered raw material and hot water are supplied from inlet 20a, and beverage supply valve 53 is closed in accordance with the supply. At the same time, pressurized air is supplied to beverage receiver 22 from an air pump through air pipe 52. The air flows into extraction chamber 20d so as to agitate the hot water in extraction chamber 20d, thereby the inside of extraction chamber 20d is cleaned.
FIG. 2 shows extraction chamber 20d in the state of cleaning. The air supplied to beverage receiver 22 flows through air filter 21 into extraction chamber 20d (as shown by an arrow) to form air bubbles, by which the hot water in extraction chamber 20d is agitated whereby the residue left inside extraction chamber 20d is removed.
After the cleaning by agitation for a predetermined period is finished, rotating cam 48 is rotated again so as to release pressure plate 46 from the pressure by a protrusion of rotating cam 48, thereby drain tube 22D is opened. Valve 23 is elevated to close conduit 20e, and pressurized air is supplied from the air pump through air pipe 52 to inlet 20f. The water used for the cleaning in extraction chamber 20d is transported downward by the pressure of air, passes through paper filter 21, and is discarded through beverage receiver 22 and drain tube 22D. After a predetermined period, cylinder 20 is elevated, paper filter 21 is advanced, the residue left on paper filter 21 is discarded together with paper filter 21, and a new portion of paper filter 21 is set over beverage receiver 22.
Cleaning in the conventional beverage extraction apparatus, however, is only applied to the extraction chamber. Thus, the raw material left inside the mixing chamber is not removed in the cleaning, resulting in imparting the cleanness of the mixing chamber. The maintenance of the beverage extraction apparatus is mandatory to keep the apparatus always clean, because the quality of the beverage to be served is deteriorated if the cleanness of the mixing chamber is lowered.