DESCRIPTION

The present patent application for industrial invention relates to a coffee grinder with a device for ejecting the residues of ground coffee.

As it is known, traditional coffee grinders comprise a hopper in upper position, which is suitable for containing coffee beans. The hopper is closed with a plastic lid.

The coffee beans falls from the hopper by gravity into a grinding chamber disposed under the hopper.

A grinding unit is disposed in the grinding chamber. The grinding unit comprises two blades to grind the coffee beans and obtain coffee powder. Generally speaking, one blade is rotary and one blade is fixed. The two blades are spaced out in such a way as to form an air space, wherein the coffee beans pass in order to be ground.

The coffee grinder of the prior art comprises a conveying duct in communication with the grinding chamber and with the exterior. The conveying duct is suitable for receiving the coffee powder that is ground by the blades. A receptacle, such as a filter holder, is disposed under the conveying duct in order to collect the coffee powder. The ground coffee is ejected from the grinding chamber by means of two or more wings. By rotating, said wings force the coffee to pass through a lateral slot provided in the grinding chamber, which ends in the conveying duct.

The coffee grinders of the prior art are impaired by a drawback caused by the fact that the ground coffee is not ejected from the coffee grinder completely. In fact, when the delivery of one dose of ground coffee is completed, the ground coffee is not completely ejected from the coffee grinder and a quantity of ground coffee remains inside the grinding chamber and/or in the conveying duct. Such a drawback is technically defined as "retention" of the ground coffee. The retention is caused by the fact that the wings used for ejecting the ground coffee from the grinding chamber are not capable of completely ejecting the ground coffee from the grinding chamber, especially because the slot used by the coffee to come out of the grinding chamber is obtained in lateral position with respect to the grinding chamber. In view of the above, the ground coffee remains inside the grinding chamber.

Moreover, the retention is caused by the fact that the coffee acquires an electrostatic charge during the grinding process. Said electrostatic charge cannot be discharged to the ground and therefore remains in the ground coffee until it reaches the filter holder. The electrostatic charge of the ground coffee causes the adhesion of the ground coffee to the walls of the grinding chamber and of the conveying duct.

The ground coffee that remains in the grinding chamber and in the conveying duct is mixed with the coffee of the following dose. The mixing of previously ground coffee and freshly ground coffee reduces the quality of the coffee. Obviously, the longer the time between two successive doses of ground coffee, the worse the drawback will be. Such a drawback is especially relevant in the case of instantaneous coffee grinders, which should instantaneously grind the coffee beans in order to make good quality coffee.

It must be noted that dosers are known which are used to dose the coffee beans before grinding, in order to always deliver the same dose of ground coffee. The fact that not all the ground coffee is ejected from the coffee grinder involves that the weighed quantity of ground coffee does not correspond to the quantity of ground coffee that is ejected from the coffee grinder. Therefore, the dose of ground coffee is not always the same.

The purpose of the present invention is to overcome the drawbacks of the prior art by devising a coffee grinder that is capable of ejecting the freshly ground coffee completely and rapidly, in such a way that the ground coffee does not remain inside the coffee grinder and the dose of ground coffee is always the same.

Another purpose is to disclose such a coffee grinder that is inexpensive, practical and simple to make. These purposes are achieved according to the invention with the characteristics of the appended independent claim 1 .

Advantageous embodiments appear from the dependent claims.

The coffee grinder of the invention is defined by the independent claim 1 .

The advantages of the coffee grinder according to the invention are evident, wherein because of the provision of the ejection device, compressed air can be generated in the air space between the blades towards the conveying duct in such a way as to eject the residues of ground coffee.

Additional features of the invention will appear manifest from the detailed description below, which refers to a merely illustrative, not limiting embodiment, as illustrated in the attached figures, wherein Fig. 1 is a sectional view of a coffee grinder according to the invention, taken along a vertical plane.

With reference to Fig. 1 , a coffee grinder according to the invention is disclosed, which is generally indicated with numeral (100).

The coffee grinder (100) comprises a hopper (1 ) suitable for containing coffee beans and a body (20) connected in lower position to the hopper (1 ).

The hopper (1 ) is shaped like a funnel and comprises a wall (14) that defines a compartment (15) that can be accessed by means of an upper opening (12) suitable for introducing the coffee beans in the hopper (1 ). The hopper (1 ) comprises a lower opening (13) suitable for delivering the coffee beans from the hopper towards a grinding chamber (2). The coffee grinder (100) comprises a lid (5) disposed in the upper opening (12) of the hopper (1 ) to close the upper opening (12) of the hopper. The lid (5) is advantageously made of a rigid material, such as for example plastics.

The grinding chamber (2) is obtained in the body (20). The grinding chamber (2) is disposed under the hopper (1 ) and communicates with the hopper (1 ).

The coffee grinder (100) comprises a grinding unit (3) comprising two blades (30) disposed inside the grinding chamber (2). At least one of the blades is a rotary blade. Actuation means (31 ) are connected to at least one of said blades (30) to rotate said at least one blade (30). Both blades (30) can be moved. In such a case, the blades (30) are contra-rotating.

The actuation means (31 ) comprise an electric motor (32) disposed in the body (20) under the grinding chamber (2), and a shaft (33) that enters the grinding chamber (2) from below. The shaft (33) is connected to a blade (30) in order to rotate it, whereas the other blade is fixed. Alternatively, transmission means connect the shaft (33) to a second shaft that is connected to the second blade, in such a way that the second blade rotates in opposite direction with respect to the first blade.

The two blades (30) have a disc-like shape. The two blades (30) are parallel and spaced out in such a way as to create an air space (34) for grinding the coffee beans. The air space (34) communicates with the hopper (1 ).

The coffee beans that descend from the hopper (1 ) enter the air space (34) between the blades (30). The coffee beans that are contained in the hopper (1 ) descend towards the air space (34) between the blades (30) by gravity or are moved by means of a conveyor (10) disposed in the outlet of the hopper (1 ).

By rotating, the blades (30) grind the coffee. The ground coffee is delivered radially from the air space (34), which communicates with the grinding chamber (2), in such a way as to disperse the ground coffee in the grinding chamber (2).

The blades shown in Figs. 1 and 2 are of planar type. Alternatively, conical blades can be provided. In such a case, the ground coffee would be delivered from the air space (34) passing through non-radial slots with respect to the axis of rotation of the blades.

The ground coffee in the grinding chamber (2) is moved by means of rotating wings (not shown in the figures) towards an opening (21 ) obtained on a lateral wall of the grinding chamber (2). In view of the above, the ground coffee is ejected from the grinding chamber (2).

The coffee grinder (100) comprises a conveying duct (4) obtained in the body (20) and in communication with the grinding chamber (2) by means of the opening (21 ) obtained on the lateral wall of the grinding chamber (2). The conveying duct (4) communicates with the exterior by means of an outlet (40) for the delivery of the ground coffee. A receptacle, such as for example a filter holder, is suitable for being positioned under the outlet (40) of the conveying duct (4), in such a way that the ground coffee is supplied towards the filter holder.

The coffee grinder (100) comprises an ejection device (6) disposed upstream the air space (34) between the blades (30).

Such an ejection device (6) is suitable for generating compressed air in the air space (34) between the blades (30) towards the conveying duct (4) in such a way as to eject the residues of ground coffee.

According to a first embodiment of the invention, the ejection device (6) can comprise the lid (5) that is mounted with possibility of sliding axially and in air tight mode with respect to the hopper (1 ), in such a way as to act as piston to push compressed air inside the hopper.

The lid (5) can be compressed manually by the operator o mechanically, after grinding the coffee beans. The compression of the lid (5) causes a volume reduction of the compartment (15) of the hopper. Consequently, the air inside the compartment (15) of the hopper is compressed and is pushed towards the air space between the blades and towards the conveying duct (4), in such a way as to eject the residues of ground coffee that are not ejected by the coffee grinder outside the conveying duct (4).

Return means (R) can be provided to return the lid to the initial position after being pressed.

For example, the return means can be a membrane of compressible material or a spring.

With reference to Fig. 1 , the return means (R) comprise a membrane (60) of compressible air-tight type, connected to the lid (5) and to the hopper

(1 )- Advantageously, the membrane (60) is of bellows-type and has a tubular shape with vertical axis. In view of the above, the membrane (60) and lid (5) assembly acts as bellows for pushing air from the hopper towards the air space between the blades and towards the conveying duct (4).

The membrane (60) comprises a wall (67) made of compressible material, such as for example rubber or soft plastics, and a compartment (61 ) defined by said wall (67) and in communication with the compartment (15) of the hopper (1 ). The compartment (61 ) of the membrane (60) can be accessed through an upper opening (62) defined by an upper edge (64) of the membrane and through a lower opening (63) defined by a lower edge (65) of the membrane.

The lid (5) is disposed on an upper opening (62) of the membrane (60) to close the upper opening (62) of the membrane (60). In fact, the upper edge (64) of the membrane (60) is slightly smaller than the lid (5), in such a way that the lid (5) can be forcedly positioned on the upper opening (62) of the membrane (60).

The lower edge (65) of the membrane (60) comprises a perimeter groove suitable for receiving the upper edge of the hopper (1 ). In view of the above, by closing the lid (5) on the membrane (60), air is prevented from entering the hopper (1 ).

Although not shown in the figures, the lid (5) and the membrane (60) can be made in one piece. Moreover, the membrane (60) can comprise a lower rigid frame to favor the coupling of the membrane (60) with the hopper (1 ).

According to a second embodiment, which is not shown in the figures, the ejection device (6) can provide for mounting the lid (5) on the hopper (1 ) in air-tight mode and for mounting the hopper (1 ) with possibility of sliding axially in air-tight mode relative to the body (20), in such a way that the hopper and lid assembly acts as piston to push compressed air towards the air space between the blades.

Otherwise said, the lid (5) can be permanently mounted in the hopper and the entire hopper (1 ) is mounted with possibility of axially sliding with respect to the body (20). In view of the above, by pushing the hopper (1 ) downwards, the air volume in the air space between the blades is reduced and the compressed air pushes the residues of ground coffee towards the conveying duct.

Also in such a case, the ejection device (6) can comprise return means to restore the hopper to the initial position after being pressed. The return means can comprise a membrane of compressible material or a spring.

For example, when the return means comprise the membrane (60), said membrane (60) is advantageously connected to the hopper (1 ) and to the body (20) upstream the air space (34) between the blades (30). In such a case, the hopper (1 ) is provided with conveyor means that stop the delivery of coffee beans from the hopper. The upper opening of the membrane (60) communicates with the compartment (15) of the hopper (1 ) and the lower opening of the membrane (60) communicates with the air space (34) between the blades. In view of the above, by exerting a downward force on the hopper (1 ), the membrane (60) is compressed and the air in the compartment of the hopper is pushed towards the air space (34) between the blades (30) and towards the conveying duct (4), causing the ejection of the residues of ground coffee from the coffee grinder.

According to a third embodiment of the invention, which is not shown in the figures, the ejection device (6) comprises a conduit connected to a pneumatic system and to the compartment (15) of the hopper, in such a way as to send compressed air into the compartment (15) of the hopper. When the hopper is air-tightly closed by the lid (5), compressed air is introduced in the compartment of the hopper and is forced towards the air space between the blades and towards the delivery duct, in such a way as to eject the residues of ground coffee.

Although it is shown in the figures, the lid (5) is optional because the upper opening of the hopper (1 ) can be closed by the user's hand or with any other element that acts as a lid.

The only essential characteristic of the invention is represented by the provision of the ejection device (6) suitable for generating a flow of compressed air inside the coffee grinder in order to eject the residues of ground coffee from the coffee grinder.

Although it is not shown in the figures, the grinding machine may be omitted and the blades (30) may be disposed directly in the conveying duct (4), in such a way that the air space (34) between the blades (30) is in direct communication with the conveying duct (4). In fact, the coffee that is ground by the blades (30) comes out of the air space (34) between the blades (30) and falls by gravity into the conveying duct (4), which acts as funnel for conveying the ground coffee in the filter holder. In such a case, the air pushed by the ejection device (6) passes through the air space (34) between the blades disposed directly in the conveying duct.

Moreover, it must be noted that the coffee grinder (100) may comprise a doser (which is not shown in the figures) installed upstream the air space (34) between the blades (30) in order to weigh the coffee beans before grinding, in such a way as to always obtain the same quantity of ground coffee. Because of the ejection device (6) that ejects the ground coffee completely, the quantity of ground coffee obtained from the preset quantity of coffee bean will be always the same because no coffee ground residues remain in the coffee grinder.

Numerous variations and modifications can be made to the present embodiment of the invention, which are within the reach of an expert of the field, falling in any case within the scope of the invention as disclosed by the appended claims.