Valve device for priming a pump, particularly for coffee making machines

Abstract: The valve device for priming a pump, particularly for coffee making machines, includes a body having a first conduit (2) connected to a pump (3) for sucking water (4) from a tank (5), a second conduit (6) for connecting the body to a heater (7) provided with a calibrated delivery valve (9) for delivering superheated water, and a third conduit (10) for discharging air during the priming of said pump, valve means (11,12) for a free passage of water from the body to the heater and, when said pump is deactivated, for the flow back of said water into the body only when the pressure inside said heater has reached a selected value near, but lower than, the pressure setting of the calibrated delivery valve (9).

Description: The present invention relates to a valve device for priming a pump, particularly for coffee making machines. Conventional coffee machines have a pump for drawing water from a tank or reservoir and feeding the water to a heater where it is superheated and, when the required pressure is reached, sent to a coffee holder filter through a valve. It is apparent that this system has two inconveniences. The first inconvenience is that when the tank empties, the pump draws air and therefore, even when the tank is again filled with water, it is not possible to prime it before purging the air out of the pump. The second inconvenience is that when the pressure inside the heater goes over the pressure setting of the calibrated water delivery valve, the valve releases water thus emptying the heater. Valve devices have been introduced to overcome these inconveniences. These valve devices cause the automatic exit of air from the conduit connecting the pump to the heater, allowing the automatic priming of the pump, however these valve device do not prevent water from leaking out of the heater delivery valve, and/or from the air venting valve, and therefore do not prevent the heater from emptying. FR-A-2 364 640 discloses a valve device for priming a pump comprising a conduit for connection to a pump, a conduit for connection to heater, a conduit for discharging and valve means for free passage of water to the heater. The preamble of claim 1 is based on this document. The aim of the present invention is to overcome the above described inconveniences by providing a valve device which allows the automatic priming of the pump and prevents water from exiting from the water delivery valve of the heater. Within this aim, an important object of the invention is to provide a valve device which prevents water from exiting from the air venting valve, thus preventing the heater from emptying. A further object of the invention is to provide an extremely compact valve device having a single discharge conduit for the air, for priming the pump, and for the water, from the safety valve. Still a further object of the invention is to provide a valve device wherein the air discharge pipe and the heater connecting pipe can be disassembled from the main body for an easy cleaning and for an easy substitution of the seal members of the main body. A further object of the invention is to provide a valve device which can be easily applied to existing apparatus, regardless of the configuration, because, for example, the air discharge pipe is rotatable around its axis according to the requirements. The above aim and objects are achieved by a valve device for priming a pump, particularly for coffee making machines, as claimed in claim 1. Further characteristics and advantages of the invention will be more apparent by the description of a preferred but not exclusive embodiment of a device according to the invention, illustrated, by way of indicative but not exclusive example in the enclosed drawings wherein: Fig. 1 is a schematic view of the feeding system of a heater in a machine for producing coffee, according to the invention; Fig. 2 is a side elevated section view of the valve device for automatically priming the pump in a machine for preparing coffee, according to the invention. With reference to the above figures, the valve device for priming a pump, particularly for machines for preparing coffee, is indicated by the reference numeral 1 and comprises a first conduit 2 connected to a pump 3 for sucking water 4 from a tank 5. The body of the device also comprises a second conduit 6 for connecting the body to a heater 7 having a valve 9 for delivering superheated water inside it. The body of the device also comprises a third conduit 10 for discharging air inside the tank 5, during priming of the pump 3. The device 1 comprises valve means for allowing the water to flow from the body to the heater 7 and, when the pump 3 is inactive, for allowing the water to return inside the body only when the pressure inside the heater has reached a selected value close to , but lower than, the pressure setting of the calibrated delivery valve 9. More particularly, the valve means comprises a mobile seal member 11, biased by an elastic means, namely a calibrated spring 12. The seal member 11 moves inside a chamber 13 connecting the first, second and third conduits 2, 6 and 10. As illustrated in Fig. 2, the seal member 11 has an inner cavity 14 and, at one end directed towards the second conduit 6, the seal member 11 has two walls 15 which are normally closed but can be opened when the water flows from the body to the heater, when the pump is activated. The seal member 11 may, for example, be of silicon rubber and comprises an annular ledge 16. The calibrated spring 12 abuts one side of the ledge 16, while the opposite side of the ledge provides a seal for the water coming from the heater as long as inside the heater the pressure is lower than a selected value, for example 3 bar. Conveniently, third conduit 10 is connected to the chamber 13 through a passage 18 formed inside a closure member 19 of the chamber 13. Closure member 19 comprises a seat 20, accommodating the calibrated spring 12, and an annular slot 21, accommodating a ring 22 providing a seal between the walls of the closure member 19 and the walls of the chamber 13. In the region of the slot 21 in contact with the seal ring 22, the passage 18 has a reduced section 23 which is closed by the compression on the seal ring 22, when the pressure inside the chamber becomes higher than the above cited pressure setting. A safety valve 25 is conveniently provided inside the valve device for connecting the third conduit 10 to the second conduit 6 in case the pressure reaches a dangerous high value. It is noted that the second and third conduits 6 and 10 are arranged in first and second pipe members 30 and 31 which are removably associated with the body of the device. In particular, the first pipe member is sealingly screwed on the device body by means of a threading 33 and a seal ring 34, while the second pipe member 31 is sealingly associated with the device body, in snap-together manner, by means of the elastic deformation of its edge 35 and of the respective slots 36 engaging a ridge 37. In this manner the second pipe member 31 is rotatable about its own axis and therefore can be directed in any desired direction according to the requirements of the structure wherein the device is applied. The operation of the device according to the invention is apparent from what has been described and illustrated. In particular, the automatic priming of the pump, when it is activated, occurs when the air contained in the first conduit 2 is expelled through the passage 18 and sent inside the tank 5 through the third conduit 10. As soon as there is no longer air in the conduit comprised between the pump 3 and the seal member 11, the water is pumped by the pump 3 and flows into the cavity 14 of the seal member 11 and, without difficulty, the water separates the walls 15 of the seal member 11 and flows into the heater 7. As the water is superheated inside the heater 7, the pressure will cause the water to flow back into the body of the valve device 1. In this case, the two walls 15 will tend to close, preventing the water from flowing inside the cavity 14 of the seal member 11. Should the pressure inside the heater increase further over the preset value of the calibrated spring 12, the seal member would move from left hand side to the right hand side (with reference to Fig. 2) and therefore the water would flow inside the chamber 13. In this situation, the water will flow from the chamber 13, through the passage 18, into the third conduit 10 and then back inside the tank 5. Because of this solution, there is no leaking of water through the calibrated delivery valve 9 arranged at the heater and the heater does not empty as long as the pressure inside the heater is lower than the pressure setting of the calibrated spring 12. It is also to be noted that when the pump 3 pumps water inside the heater 7, the pumping pressure will make the seal ring 22 compress the reduced section 23 of passage 18, thereby preventing water from leaking out of the passage. It has been seen in practice that the device according to the invention is particularly effective in preventing the water from leaking from the delivery valve of the heater 7 and in preventing the water from leaking out of the air discharge passage 18 when the pump 3 is primed. The materials employed, as well as the dimensions, may be any according to the specific needs and the state of the art. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Valve device for priming a pump, particularly for coffee making machines, comprising a body having a first conduit (2) for connection to a pump (3) for sucking water (4) from a tank (5), a second conduit (6) for connecting said body to a heater (7) provided with a calibrated delivery valve (9) for delivering superheated water, and a third conduit (10) for discharging air during the priming of said pump, and valve means (11,12) which, when the valve device is connected and in use, allow a free passage of said water from said body to said heater, whereby said valve means comprise a mobile seal member (11), biased by an elastic means (12), said seal member being movable in a chamber (13) connecting said first, second and third conduits, characterised in that said valve means comprise means (15) which prevent the flow back of said water into said body only when the pressure inside said heater is lower that a selected value near, but lower than, the pressure setting of said calibrated delivery valve (9), and in that said elastic means (12) allow said flow back into said body only when the pressure inside said heater has reached said selected value. Device, according to claim 1, characterized in that said seal member is internally hollow, said means (15) at its end directed towards said second conduit being two walls (15), said walls being normally closed but being able to open when said water flows from said body to said heater, an annular ledge (16) being provided on said seal member for providing a seal to said water coming from said heater up to said pressure setting. Device, according to one or more of the preceding claims, characterized in that said third conduit is connected to said chamber through a passage (18) formed inside a closure member (19) of said chamber, said closure member having a seat (20) accommodating said elastic means, and an annular slot (21) accommodating a seal ring (22) providing a seal between the walls of said closure member and the walls of said chamber. Device, according to one or more of the preceding claims, characterized in that in the region of said slot in contact with said seal ring, said passage has a reduced section (23). Device, according to one or more of the preceding claims, characterized in that when the pressure inside said chamber becomes higher than said pressure setting, said ring compresses and closes said reduced section. Device, according to one or more of the preceding claims, characterized in that a safety valve (25) is arranged in said body and is connected to said third conduit and said second conduit. Device, according to one or more of the preceding claims, characterized in that said second and third conduits are arranged in first and second pipe members (30,31) removably associated with said body. Device, according to one or more of the preceding claims, characterized in that said first pipe member is sealingly screwed to said body and in that said second pipe member is associated with said body in a snap-together manner. Device, according to one or more of the preceding claims, characterized in that said second pipe member can be oriented about its axis. Device, according to one or more of the preceding claims, characterized in that said elastic means comprises a calibrated spring (12).

Inventors: DE LONGHI GIUSEPPE, DE'LONGHI, GIUSEPPE
Applicants: LONGHI SPA DE, DE' LONGHI S.P.A.
Application year: 1995
Main classification: F16K17
IPC codes: F04D9, A47J31, F16K17