Liquid pumping device comprising a gear pump for beverage dispenser

Abstract

A liquid pumping device (1) for beverage dispenser comprising: -a housing (2) with a liquid inlet (3) and a liquid outlet (4); -a gear pump (5) positioned in the housing with the liquid inlet communicating with the gear pump; wherein a flowmeter (6) is fluidly positioned in the housing (2) preferably between the gear pump (5) and the liquid outlet (4).

Claims

1. A liquid pumping device for a beverage dispenser, the liquid pumping device comprising: a housing with a liquid inlet and a liquid outlet; a gear pump positioned in the housing with the liquid inlet communicating with the gear pump, wherein the gear pump comprises a driving shaft arranged to protrude from a first side of the housing; and a flowmeter fluidly positioned in the housing, the flowmeter comprises a measuring member rotatable by the a liquid flow passing through the flowmeter, the flowmeter further comprises a sensor for sensing a rotation-related parameter of the measuring member, and the sensor is positioned on a second side of the housing opposed to the first side.

2. The liquid pumping device according to claim 1, comprising an electrical rotary motor connected to the driving shaft.

3. The liquid pumping device according to claim 1, wherein the gear pump is configured to communicate with the flowmeter in the housing by a non-deformable intermediate conduit.

4. The liquid pumping device according to claim 3, wherein the non-deformable intermediate conduit extends in an axial direction perpendicular to a plane of extension the gear pump extends in.

5. The liquid pumping device according to claim 1, wherein the measuring member has a rotation bearing arranged in the same axial direction as an axial direction of a driving shaft of the gear pump.

6. The liquid pumping device according to claim 1, wherein the measuring device comprises at least one magnet, and the sensor is a Hall sensor.

7. The liquid pumping device according to claim 1, wherein the sensor senses a rotation-related parameter by a characteristic selected from the group consisting of induction, capacitive effect, ultrasounds, and infra-red.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described with reference to the drawings attached.

(2) FIG. 1 shows a perspective view of the device of the invention;

(3) FIG. 2 shows a view of profile of the device of the invention

(4) FIG. 3 is an exploded view of the device of the invention (inlet and outlet connectors missing);

(5) FIG. 4 is a view of the device in sectional plane A-A;

(6) FIG. 5 is a view of the device in sectional plane B-B.

DESCRIPTION OF A PREFERRED EMBODIMENT

(7) The liquid pumping device of the invention is illustrated in the attached FIGS. 1 to 5. The device 1 comprises a housing 2 comprising a liquid inlet 3 and a liquid outlet 4. The inlet and outlet can take the form of liquid connectors protruding from the housing. The connectors are designed to be connected to liquid hoses of a beverage dispenser. In particular, the liquid inlet 3 can be connected to a hose which links with a water tank of the dispenser for supplying the device with fresh water. The liquid outlet 4 can be connected to a hose which links with a heater such as a thermoblock or tube heater for heating the pressurized water coming out of the device.

(8) According to an aspect of the invention, the housing comprises both a gear pump 5 and a flowmeter 6 arranged in a manner to save space and provide the minimal length of internal conduit. In relation with FIG. 3, the housing is built from several blocks which are assembled together, e.g., for forming solid, unified assembly of blocks, by connection means such as by screws 7. A first housing block 8 is provided which comprises the gear pump 5. A second housing block 9 is provided adjacent the first housing block which comprises the flowmeter and a third housing block 10 is provided adjacent the second housing block 9 which comprises the sensor 11 for the flowmeter.

(9) In the first housing block 8 (FIG. 4), a pump cavity 12 is provided to receive the driving gear 13 and following gear 14 of the gear pump. The driving gear 13 has a drive shaft 15 which is connected to an electrical motor 16. If necessary, the drive shaft may be connected directly or via a gear reduction.

(10) The drive shaft 15 preferably protrudes on a first side 17 of the housing whereas the sensor 11 is positioned on a second side 18 of the housing which is opposed to the first side. This arrangement is preferred to prevent electromagnetic disturbance but could be different, e.g., with the sensor being on another side of the housing.

(11) The liquid inlet 3 communicates to the pump cavity 12 via an inlet conduit 19 to the entry of the gear pump. The pump cavity 12 communicates with an outlet conduit 20 which extends in the transversal plane FT of the first housing block. The length of the conduit can be minimal, e.g., 0.5-2 cm. It must be noted that the outlet conduit 20 could also just be an extension of the cavity.

(12) The gear pump's cavity 12 further comprises a sealing gasket 21 encompassing the two gears and outlet conduit 20.

(13) The second housing block 9 comprises a flow cavity 22 for lodging the measuring member or impeller 23. The impeller is rotatably mounted in the cavity 22 by a rotation bearing 24. Preferably, the rotation bearing 24 extends in the same transversal plane FT as the drive shaft 15 of the gear pump. A parallel arrangement of the gear pump and flow meter is therefore obtained. As a result, the thickness of the first and second blocks in the axial direction D can be reduced making the device very compact and limiting the length of the flow path between the two blocks.

(14) The second housing block 9 fluidly connects to the first housing block by an intermediate conduit 25 which is also arranged in the axial direction D of the device. This axial conduit 25 links the flow cavity 22 to the transversal outlet conduit 20 of the pump cavity 12 of the gear pump. The length of the axial conduit 25 is preferably small, e.g., 0.5-1 cm. Since the conduit 25 is directly formed in the housing block 9 and the housing blocks 8, 9 are adjacent and connected to each other, the position and form of the conduit 25 is well defined in the device and remains so when the device is implemented and operated in the beverage dispenser.

(15) The flow cavity 22 further communicates with a liquid outlet conduit 31 which is preferably arranged tangential to the cavity. The position of the conduit 31 also in transversal plane FT is also preferably positioned fluidly away from the intermediate conduit 25 at an angle of less than 180 degrees. More preferably, the angle is between 90 and 120 degrees.

(16) The flow cavity 22 further comprises a sealing gasket 26.

(17) In the preferred arrangement, the external surface of the second housing block 9 closes the cavity 12 of the gear pump in liquid tight manner against the seal gasket 21. This arrangement saves an additional piece of the device. However, in an alternative arrangement, an intermediate housing lid can be placed between the two housing blocks to close the cavity 12 and compresses in sealing engagement with the sealing gasket 21.

(18) The third housing block 10 is arranged in a manner adjacent to the second housing block so that its internal surface closes the flow cavity 22 in a liquid tight manner against the sealing gasket 26 of the flowmeter.

(19) The flow sensor 11 is housed in the third housing block 10 such as in a dedicated sensor cavity 27. The sensor is preferably a Hall sensor which interacts with one magnet, more preferably two diametrically opposed magnets 28, 29 inserted in the impeller. The Hall sensor is positioned in axial alignment in direction D with the rotational path of the magnet(s) such that the magnetic field of the magnet is properly detected during rotation of the impeller by the sensor.

(20) During use of the flowmeter, liquid is circulated from the inlet to the outlet by the gear pump via the voids provided between the impeller and the flow cavity. The flow of liquid is intercepted by the blades of the impeller thus driving it in rotation about its bearing 24. The speed of rotation of the impeller is proportional to the flow of liquid circulating through the flowmeter. By rotating the impeller, the magnets are rotated adjacent to the Hall sensor. The Hall sensor detects the rotating magnetic field generated by the magnets and converts into a corresponding electrical signal having a frequency corresponding to the speed of rotation of the impeller. The sensor preferably comprises a Hall effect sensing element and a resistance (e.g. 5 KΩ). The sensor also comprises an electrical pin 30 to facilitate electrical mounting of the sensor to the input circuit of the control unit of the beverage dispenser.

(21) In the pressure working range of the device (i.e. 0.4-3 bar), the frequency or number of pulses generated by the Hall sensor may deviate from the actual flow rate depending on the pressure at the exit of the gear pump. This deviation is found to be linear and the higher the pressure the higher the deviation. This deviation can so be corrected automatically by a suitable algorithm of the control unit of the beverage dispenser. As a result, a very precise flow rate is obtained in the full pressure range of the gear pump.

(22) The accuracy of the measurement of the flow rate can be improved by reducing the diameter of the intermediate conduit 25 at the entry of the flowmeter. For example, for a device capable of delivering water at flow rates of from 50 to 400 ml/min, a diameter as low as 1-2 mm appears to provide a correct accuracy at an acceptable pressure loss.

(23) As an example, the device of the invention may be sized with a housing of only about 17 cm.sup.2 but capable of delivering a controllable water flow rate between 50 to 400 ml/min within a pressure range of 0 to 3 bar. The number of pulses at 400 ml/min can be as high as 7000 pulses. The diameter of the impeller can be as low as 8 mm and the distance between gears can be only about 6 mm. The diameter of the intermediate conduit can be as low as 2 mm and its length as low as 2.6 mm.

REFERENCES

(24) 1. Device

(25) 2. Housing

(26) 3. Liquid inlet

(27) 4. Liquid outlet

(28) 5. Gear pump

(29) 6. Flowmeter

(30) 7. Screws

(31) 8. First housing block

(32) 9. Second housing block

(33) 10. Third housing block

(34) 11. Flowmeter sensor

(35) 12. Gear pump cavity

(36) 13. Driving gear

(37) 14. Following gear

(38) 15. Drive shaft

(39) 16. Electrical motor

(40) 17. First side (housing)

(41) 18. Second side (housing)

(42) 19. Inlet conduit

(43) 20. Outlet conduit

(44) 21. Sealing gasket

(45) 22. Flow cavity

(46) 23. Impeller

(47) 24. Bearing

(48) 25. Intermediate conduit

(49) 26. Sealing gasket

(50) 27. Sensor cavity

(51) 28. Magnet

(52) 29. Magnet

(53) 30. Electrical pin

(54) 31. Liquid outlet conduit