TECHNICAL FIELD

The present invention relates to a coffee machine, and more particularly, to a water tank connector in a coffee machine. The invention is intended for use particularly but not exclusively in a coffee machine of the type in which hot water is passed through a filter under pressure, such as an espresso type coffee machine.

BACKGROUND

Generally, an espresso coffee machine consists of a water tank unit, a water tank connector, a pump, a self priming valve, a boiler for heating the water, a brewing unit and a waste water container. At the beginning of the pump working the self priming valve releases air that may be present in the tube system of a coffee machine. The air in the system has to be removed in order to have the pump working properly. During this priming operation some clean water is pumped out together with the air.

In many coffee machines the clean water from the self priming action is lead to the waste water container. However, this causes the waste water container to relatively quickly be filled up and the user has to empty it. Furthermore, the water tank needs to re-filled with fresh water. These emptying and filling actions may be considered annoying by a user of the machine. in some coffee machines the water ejected from the self priming valve is lead back to the water tank, either through the opening in the top of the water tank or through a second connection port in the bottom of the water tank. A drawback with these known solutions is that they are relatively bulky and incorporates several parts. Also, the assembling process is more complicated and time consuming the more parts the machine consists of.

As may be realized from the above there is a need for improvements in the area of coffee machines with aspect to the water tank connectors and to the housekeeping of water in the appliance. SUMMARY

An object of the present invention is to overcome at least one of the above mentioned drawbacks. A further object is to provide an effective and yet robust solution for utilising the water in the water tank in an effective way.

A still further object is to provide an improved solution for effective circulation of water in a coffee machine.

According to an aspect of the invention, at least one of these objects is achieved by a water tank connector for a coffee machine comprising a first end adapted to be connected to a valve opening in a water tank and a second end adapted to be connected to a pump and to a self priming valve, to allow water to pass from the water tank to a brewing unit in the coffee machine. The water tank connector comprises a first channel leading water from the water tank to the pump in the coffee machine and a second channel leading water and air from the self-priming valve back to the water tank.

Since the water tank connector has two channels, the leading of water to the pump and the leading back of water and air from the self-priming valve can take place from the same connection point on the water tank. Therefore, the construction and assembling of a coffee machine provided with the suggested water tank connector is simplified and more cost effective. Also the water usage in the coffee machine provided with the suggested water tank connector is more effective than in known coffee machines as the water leaking from the self-priming valve is transported back to the water tank instead of the discharged in the waste water container. in an embodiment, the first channel and the second channel are separated from each other inside the water tank connector. In this way the water and air coming back from the self-priming valve is not mixed with the water going out to pump. It is an advantage that the two flows are separated as the air otherwise may disturb the functioning of the pump. Further, the flow direction of water in the first channel is opposite the flow direction of the water and air in the second channel.

!n another embodiment, the water tank connector comprises a filter member being located upstream (or above) the first channel. The inlet to the first channel is located close under the filter member, i.e. downstream the filter member.

In an embodiment, the second channel is arranged through the filter member. This means the outlet of the second channel is located above the filter member. In this way, the water and air mixture coming from the self-priming valve may let out the air into the water tank and it is avoided that the air is stuck around the filter which is located below the water level in the water tank connector.

Furthermore, a ceiling of the outlet of the second channel is located directly under the valve opening of the water tank. This means that the outlet from self-priming valve is always immersed in water and the air from water and air mixture may easily rise and disappear through the water tank.

Furthermore, the water tank connector comprises a sealing member adapted to provide a sealed connection with the water tank.

In an aspect of the invention, a coffee machine is provided comprising a water tank connector according to embodiments. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention, as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which: Fig. 1 is a schematic view of a coffee machine and its different parts according to the present invention,

Fig. 2a-2c show side, front and top view of a water tank connector adapted to be arranged in a coffee machine of Fig.1 ,

Fig. 3 shows a cross sectional detailed view of the water tank connector of Fig. 2a-2c arranged at the outlet of a water tank. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described more fully with reference to the

accompanying drawings, in which example embodiments are shown. However, this invention should not be construed as limited to the embodiments set forth herein.

Disclosed features of example embodiments may be combined as readily understood by one of ordinary skill in the art to which this invention belongs. Throughout the following description similar reference numerals have been used to denote similar elements, parts, items or features, when applicable.

In Fig. 1 a schematic view of a coffee machine and its different parts is shown. The coffee machine may comprise of a water tank 1 for housing the water to be used in brewing the coffee. The coffee machine further comprises a water tank connector 2 connecting the water tank with a tube system for transporting water to the brewing unit 7. The brewing unit comprises a single way valve 8 releasing the hot water through the filter with the coffee grounds at a certain pressure. The brewed coffee leaves the machine through an outlet opening 11 in the brewing unit. A pump 4 transports the water to the brewing unit via a boiler 6 (or thermo biock) heating the up the water to an optimal brewing

temperature. Water from the water tank flows out of the tank through a valve opening 12 located in the bottom of the tank. The water tank connector 2 is connected to the water tank at the valve opening.

In Fig. 1 it is further illustrated with arrows the flow of water and the flow of air/water mixture respectively. The thin arrow represents the flow of air/water mixture. The self- priming valve 5 primes the pump 4 to optimize the working conditions for the pump.

During the self-priming some water and air will leak out. The amounts are relatively small, somewhere between 1-5 ml in each brewing. The water and air mixture is lead back in the tube 10 to the water tank connector 2. The air is then allowed to disappear up through the water tank. The water tank 1 stands in connection with the atmosphere. The thick arrow represents the flow of water from the water tank through the water tank connector 2 to the brewing unit outlet opening, via the pump 4 and boiier 6.

In Fig. 2a-2b a side and front view of the water tank connector 2 is illustrated respectively. The water tank connector has a first end 2a, which is a top end during normal use of the connector, and a second end 2b, which is the bottom end during normal use of the connector. The second end 2b has two separate openings. A tube 3 may lead water from the water tank to the pump 4. A tube 10 may lead water and air from the self-priming valve 5 back to the water tank.

Fig. 2c shows a top view of the water tank connector. The valve opening 12 in the bottom of the water tank is connected to the coffee machine via the first end 2a of the water tank connector 2, It is also illustrated in this top view a sealing member 15 located around the inner circumference of the water tank connector. The sealing member seals against the outer surface of the valve opening on the water tank. Below the sealing member 15 a filter member 17 or screen is located. The filter member 17 functions as a trap to any small particle or debris that might have been present in the water tank and followed the water into the water tank connector. The filter member 17 may consist of a mesh, a fine net or screen of any suitable material such as polymeric material, metal, metal alloy or composite material.

In the centre of the first end 2b in Fig. 2c a ceiling 14 is visible. The ceiling 14 covers the outlet of the second channel 19. Further, the ceiling 14 acts on the valve opening 12 when the water tank is installed in its location by acting on the valve spring 13 (see Fig. 3).

Fig. 3 show a schematic enlarged cross section of the water tank connector 2 in relation to the water tank 1 and the valve opening 12 in the water tank in particular. The first channel 18 provides water to the pump 4 for further transportation to the boiler 6. All water passing through the first channel 18 has to pass the filter member 17 on its way from the water tank. The filter member 17 is arranged upstream the first channel 18 and below the water level 16. The second channel 19 is arranged in the central part of the water tank connector 2 and passes through the filter member 7. Accordingly, the water and air mixture coming from the self-priming valve 5 does not pass through the filter member. The second channel 19 has a ceiling 4. The ceiling 14 is also the portion of the water tank connector that acts on the valve opening 12 in the bottom of the water tank 1. The outlet opening of the second channel 19 is located directly under the ceiling 14. Accordingly, the outlet opening of the second channel 19 will always be immersed when the water tank is placed into its position in the coffee machine. The first channel 18 and the second channel 19 are separated from each other. Water flowing from the tank out to the pump 4, boiler 6 and brewing unit 7 is thus separated from the flow of water and air from the self-priming valve 5. This means that any air present in the water and air mixture coming from the self- priming valve 5 never comes into the flow of water on its way out to the pump 4. Thereby, a proper functioning of the pump is provided at all times.

During operation of the pump 4, water flows though the pump to the brewing chamber via the boiler. At the same time water and air is re-circulated from the self-priming valve 5 back to the water tank 1 in the tube 10. The flow direction of water in the first channel 18 is opposite the flow direction of the water and air in the second channel 19. The water leaking from the self-priming valve may thus be re-used as it is returned to the water tank instead of being discharged, while the air disappears up through the atmosphere via the water tank. List of reference numerals

1 Water tank

2 Water tank connector

2a First end of water tank connector

2b Second end of water tank connector

3 Tube from water connector to pump

4 Pump

5 Self-priming valve

6 Boiler (or thermo block)

7 Brewing unit

8 Single way valve

9 Waste water container

10 Tube from self-priming valve to water tank

11 Outlet opening

12 Valve opening in water tank

13 Valve spring Ceiling (of second channel) Sealing member

Water level

Filter member

First channel (A)

Second channel (B) ► Air flow

Water flow