DRINKS PUMP, ESPECIALLY SWIMMING PISTON PUMP

Description

State of the art

[0001] The invention relates to a beverage pump, in particular an oscillating piston pump. A beverage pump, in particular an oscillating piston pump, for a household appliance, especially a beverage vending machine, for pumping a liquid, has already been proposed. It comprises a working piston, a pump chamber in which the working piston is axially movably guided and which, with a working piston installed, has a pre-chamber, a pressure chamber and an outlet chamber, a magnetic actuator designed to provide a magnetic field for driving the working piston, and an outlet valve arranged fluidically between the pressure chamber and the outlet chamber, which has at least one compression chamber unit and at least one valve element.

[0002] Furthermore, a beverage pump with an outlet valve is already known from EP 3 767 104 A1, which has at least one compression chamber unit and at least one valve element made of an acrylonitrile butadiene rubber with a coating of parylene.

[0003] Document JP 5 355624 discloses a beverage vending machine whose outlet valve body contains silicone.

[0004] The object of the invention is, in particular, to provide a generic device with improved properties with regard to food conformity and durability. This object is achieved according to the invention by the features of claim 1, while advantageous embodiments and further developments of the invention can be found in the dependent claims. Advantages of the invention

[0005] The invention relates to a beverage pump, in particular a oscillating piston pump, for a household appliance, in particular for a beverage vending machine, for pumping a liquid, with a working piston, with a pump chamber in which the working piston is guided axially movable and which, with a working piston installed, has a pre-chamber, a pressure chamber and an outlet chamber, with a magnetic actuator which is provided to supply a magnetic field for driving the working piston, and with an outlet valve which is arranged fluidically between the pressure chamber and the outlet chamber and which has at least one compression chamber unit and at least one valve element.

[0006] It is proposed that the valve element be made at least largely of silicone, in particular poly(organo)siloxane. Preferably, the valve element is made entirely of silicone, in particular poly(organo)siloxane. The valve element is formed, in particular, by a valve rubber made entirely of an elastomer. The outlet valve is, in particular, a check valve with a flow direction from the pressure chamber to the outlet chamber. Preferably, the outlet valve also includes a spring element which, in an assembled state, presses the valve element against a valve seat of the compression chamber unit. The spring element is, in particular, a helical spring. The inventive design of the beverage pump allows, in particular, the provision of an advantageously food-grade outlet valve.Furthermore, a particularly advantageous and cost-effective outlet valve, and thus an advantageously cost-effective beverage pump, can be provided.

[0007] In this context, a "beverage vending machine" is understood to mean, in particular, a machine designed for the portion-based dispensing and / or preparation of beverages, such as coffee, tea, cocoa, and / or other milk-based drinks and / or brewed beverages. Preferably, the beverage vending machine is a coffee vending machine, more preferably a fully automatic coffee machine. Preferably, the beverage pump is a oscillating piston pump. Preferably, the beverage pump has at least one floating working piston, which is designed to be driven, in particular, by a magnetic flux guided by a pole sleeve. In particular, the working piston is designed for free movement within the pump chamber. Preferably, the working piston is designed for movement at least substantially parallel to a central axis of the pole sleeve.Preferably, the beverage pump is designed as a high-pressure oscillating piston pump and is intended to provide a pressure of at least 10 bar, preferably at least 15 bar. It is also conceivable that the beverage pump is designed as a low-pressure oscillating piston pump and is intended to provide a pressure of at least 3 bar. In particular, the beverage pump is designed as a household appliance oscillating piston pump. Preferably, the beverage pump is designed as a vending machine pump. Preferably, the beverage pump has an iron circuit comprising two pole sleeves. Preferably, the pole sleeves are at least substantially tubular. Preferably, the pole sleeve has the form of a hollow cylinder and a central axis. The pole sleeve surrounds the pump chamber. Preferably, the pole sleeve is arranged outside the pump chamber. In particular, the beverage pump has a pump chamber in which the working piston is guided.Directional terms such as "axial," "radial," and "circumferential" are to be understood in relation to a central axis of the pump chamber and / or the central axis of the pole sleeve. "Axially" is to be understood as in the direction of the central axis of the pump chamber and / or the central axis of the pole sleeve. "Radial," in this context, is to be understood in particular as a direction perpendicular to the central axis of the pole sleeve and / or perpendicular to the central axis of the pump chamber, extending outward from the respective central axis. "Circular" is to be understood in this context in particular as a direction along a circular arc around the central axis of the pole sleeve and / or the central axis of the pump chamber in a plane perpendicular to the central axis of the pole sleeve and / or the central axis of the pump chamber.

[0008] The valve element is formed, in particular, by a movable, closing part of the exhaust valve. The valve element specifically forms a valve body. Various embodiments of the valve element are conceivable that would appear sensible to a person skilled in the art. The valve element is guided, in particular, within the compression chamber unit. Furthermore, the compression chamber unit specifically forms a valve seat for the valve element. "Provided" is understood to mean, in particular, specially programmed, designed, and / or equipped.

[0009] The fact that an object is intended for a specific function should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0010] Furthermore, it is proposed that, to prevent adhesion between the valve element and the compression chamber unit and to avoid material loss on the valve element, the compression chamber unit should consist at least largely of a food-grade commodity plastic, in particular a polyolefin. Preferably, the compression chamber unit should consist at least largely of polypropylene. This allows for a particularly advantageous material combination for the exhaust valve. Specifically, this enables both the compression chamber unit and the valve element to be manufactured from a material that is non-adherent yet food-grade. The difficulty here lies in the fact that the elastomer silicone has significantly lower mechanical strength and is known to be prone to cracking.Conventional exhaust valve designs are therefore particularly unsuitable or only conditionally usable, as a crack in the valve element quickly leads to total failure. It is therefore also important that the compression chamber unit is made of a material such as polypropylene, as this results in minimal material loss from the valve element.

[0011] Furthermore, it is proposed that at least a large portion of the valve element's surface be free of any coating. Preferably, the valve element is completely free of any coating. In particular, the silicone forms an outer surface of the valve element. This ensures a significantly high level of food contact compliance. Specifically, it prevents the coating from flaking off.

[0012] It is further proposed that the valve element be free of ethylene propylene diene monomer (EPDM) rubber, acrylonitrile butadiene rubber (ABM), and parylene. This ensures a significantly high level of food contact compliance. In particular, this allows for the creation of a valve element free of polycyclic aromatic hydrocarbons (PAHs). Furthermore, it eliminates the need for an expensive parylene coating.

[0013] It is further proposed that the compression chamber unit comprises at least a first chamber element, which at least partially delimits the pressure chamber, at least a second chamber element, which at least partially delimits the outlet chamber, and an orifice arranged between the first and second chamber elements with a through-opening that at least partially forms a sealing seat for the valve element. Preferably, a pressure piston element of the working piston with a delivery channel and a piston valve projects into the first chamber element during operation. Preferably, the valve element is guided in the second chamber element. In particular, the valve element is arranged entirely within the second chamber element. The orifice particularly has a circular through-opening, wherein the valve element, in a closed state of the outlet valve, is designed to close the through-opening.This allows, in particular, the provision of an advantageous compression chamber unit.

[0014] Furthermore, it is proposed that the first chamber element, the second chamber element, and the orifice are formed in one piece. The compression chamber unit is, in particular, sleeve-shaped. Preferably, the compression chamber unit is formed separately from a housing, especially a pump housing unit. "In one piece" is understood to mean, in particular, at least a materially bonded connection, for example, by a welding process, an adhesive bonding process, an injection molding process, and / or another process that would appear appropriate to a person skilled in the art, and / or advantageously formed in one piece, such as by manufacturing from a single casting and / or by manufacturing using a single- or multi-component injection molding process, and advantageously from a single blank. This allows, in particular, the number of components to be kept to a minimum. Furthermore, sharp-edged component transitions can be avoided.

[0015] Furthermore, it is proposed that the passage opening on the side facing the valve element has a radius of at least 0.2 mm. Preferably, the radius is at least 0.3 mm, more preferably at least 0.4 mm. However, the radius is preferably a maximum of 1 mm, more preferably a maximum of 0.8 mm, and more preferably a maximum of 0.6 mm. It is further proposed that the orifice in a transition to the second chamber element has a radius of at least 0.1 mm. Preferably, the radius is at least 0.2 mm. However, the radius is preferably a maximum of 0.8 mm, more preferably a maximum of 0.6 mm, and more preferably a maximum of 0.4 mm. This allows for the creation of particularly advantageous transitions. This, in particular, prevents damage to the valve element. At the same time, sufficient sealing can be ensured.

[0016] It is further proposed that the beverage pump comprises a pump housing unit, wherein the compression chamber unit is designed as an insert intended for placement within the pump housing unit. Preferably, the pump housing unit comprises a compression chamber housing and a valve chamber housing, which are assembled to form the pump housing unit. The compression chamber housing and the valve chamber housing, in particular, form two nested housing shells. However, another embodiment of the pump housing unit, which would appear advantageous to a person skilled in the art, would also be conceivable. Preferably, the compression chamber unit is designed as an insert intended for placement within the valve chamber housing.In this context, a "compression chamber housing" is understood to mean, in particular, a housing that includes at least the pump chamber in which a fluid is compressed by means of the working piston, especially in at least one operating state. In this context, a "fluid" is understood to mean, in particular, a liquid, preferably water, a gas, and / or a gas-liquid mixture. A "valve chamber housing" is understood to mean, in particular, a housing that includes at least one valve chamber in which the outlet valve is, in particular, fixedly arranged. The compression chamber unit can be, for example, pressed, bonded, and / or welded into the valve chamber housing. This allows for a particularly advantageous modular design.This makes it particularly advantageous to manufacture the compression chamber unit from a defined material without compromising the strength of the pump housing unit.

[0017] It is further proposed that the valve element comprises a valve body, in particular a cylindrical one, and a guide body directly connected to the valve body. The valve body forms a sealing surface on a side facing away from the guide body, which, in a sealed state of the exhaust valve, is designed to bear against an orifice of the compression chamber unit. The valve body is in particular circular-cylindrical in shape. It is further proposed that the valve body of the valve element has a radius of at least 0.05 mm at an outer edge of the sealing surface. Preferably, the radius is at least 0.1 mm. However, the radius is more preferably a maximum of 0.6 mm, more preferably a maximum of 0.4 mm, and most preferably a maximum of 0.2 mm. It is further proposed that the sealing surface of the valve element is free of a flow seam and that the mean roughness Ra is in particular less than 0.4.Preferably, the mean roughness Ra is less than 0.3, and particularly preferably at least approximately 0.25. The sealing surface must be completely tapered and without a flow seam. Preferably, the valve body has a Shore A hardness of at least 60, more preferably at least 70, more preferably a maximum of 90, and most preferably a maximum of 80. This allows for the provision of a particularly robust valve element.

[0018] A stop surface of the orifice corresponding to the sealing surface of the valve element is, in particular, at least partially frustoconical in shape. The stop surface of the orifice has an angle of between 91° and 95° with respect to the central axis of the exhaust valve. Preferably, the stop surface of the orifice has an angle of at least approximately 92° with respect to the central axis of the exhaust valve. A radially outer edge of the stop surface is, in particular, further away from the sealing element than a radially inner edge. In a closed state of the exhaust valve, the valve body rests, in particular, against the radially inner edge of the stop surface. This ensures, in particular, an advantageous seal.

[0019] Furthermore, it is proposed that the valve element has a service life of at least 20 million piston strokes at 12 bar. Preferably, the valve element has a service life of at least 35 million piston strokes at varying pressures. A piston stroke of the beverage pump at 12 bar results in a corresponding stroke of the valve element at 12 bar. This ensures a particularly long service life for the beverage pump. A corresponding service life for the valve element can be achieved, in particular, through the design of the outlet valve.

[0020] The beverage pump and / or the outlet valve according to the invention are not intended to be limited to the application and embodiment described above. In particular, the beverage pump and / or the outlet valve according to the invention may, to achieve a functionality described herein, have a different number of individual elements, components, and units than the number specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also considered disclosed and freely usable. Drawings

[0021] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0022] They show: Fig. 1 a schematic view of a household appliance according to the invention, Fig. 2 a section along a longitudinal axis through a beverage pump of the household appliance, Fig. 3 a compression chamber unit of an outlet valve of the beverage pump in a schematic sectional view and Fig. 4 a valve element of the outlet valve of the beverage pump in a schematic side view. Description of the exemplary embodiment

[0023] Figure 1Figure 12 shows a household appliance 12 designed as a beverage dispenser. In the present embodiment, the household appliance 12 is designed to prepare and dispense portions of beverages. The household appliance 12 is designed as a fully automatic coffee machine. The household appliance 12 includes reservoirs for water and coffee (not shown in detail). The household appliance 12 has a control unit 48 for user input. The household appliance 12 includes a drip tray 50 and a container holder 52. The household appliance 12 includes a dispensing unit 54 for dispensing portions of beverages, in particular into a container arranged in the container holder 52. The household appliance 12 includes a beverage pump 10 (see Figure 1). Figure 2The beverage pump 10 is designed to pump a liquid, for example water, at a pressure of at least 12 bar. The beverage pump 10 is designed to pump liquid against a back pressure of 12 bar. It is conceivable that the beverage pump 10 is designed to pump a liquid at a lower pressure, such as at least 8 bar, 7 bar, or 4 bar. It is also conceivable that the beverage pump 10 is designed to pump a liquid at a higher pressure, for example, 15 bar. The beverage pump 10 is designed to pump the liquid in a main flow direction 56.

[0024] The beverage pump 10 comprises a magnetic actuator 20 with a magnetic coil 58. The beverage pump 10 includes a working piston 14. The magnetic actuator 20 is designed to provide a magnetic field for driving the working piston 14. The working piston 14 is floatingly mounted. The beverage pump 10 includes two spring elements 62, 64 acting on the working piston 14. The spring elements 62, 64 are designed to act on the working piston 14 in opposite directions. One of the spring elements 62 is designed as a pump spring. The spring element 62 designed as a pump spring is designed to drive the working piston 14 during a pressure stroke. The spring element 62 is designed as a helical compression spring. The working piston 14 has a defined rest position. The beverage pump 10 has a pump chamber 16 in which the working piston 14 is guided for axial movement.The pump chamber 16 has a pump chamber wall 66, which is designed as a piston guide. The working piston 14 is guided in the pump chamber 16 and, for this purpose, contacts the pump chamber 16 at least partially. The pump chamber 16 extends through the coil housing containing the magnetic coil 58. The magnetic coil 58 is designed to generate a magnetic field that partially extends through the pump chamber 16. In the present embodiment, the pump chamber 16 is at least substantially cylindrical. The pump chamber 16 has a central axis 68, which corresponds to a cylinder axis and is aligned at least substantially parallel to the main flow direction 56.

[0025] To control the magnetic field, the beverage pump 10 comprises an iron circuit that partially surrounds the magnetic coil 58. The iron circuit includes at least one pole sleeve 70, 72 for conducting a magnetic flux generated by the magnetic actuator 20. The iron circuit includes two separate pole sleeves 70, 72 for conducting a magnetic flux generated by the magnetic actuator 20. The first pole sleeve 70 is designed at least substantially in the form of a hollow cylinder. The first pole sleeve 70 has a central axis corresponding to a cylinder axis. In an assembled state, the central axis 68 of the pump chamber 16 and the central axis of the first pole sleeve 70 coincide at least substantially. In an assembled state, the first pole sleeve 70 is arranged coaxially with the pump chamber 16. In the present embodiment, the first pole sleeve 70 is rotationally symmetrical.

[0026] The beverage pump 10 has a second pole sleeve 72, which is spaced apart from the first pole sleeve 70. The iron circuit of the beverage pump 10 has the second pole sleeve 72, which is spaced apart from the first pole sleeve 70. The second pole sleeve 72 is designed at least substantially in the form of a hollow cylinder. The second pole sleeve 72 has a central axis that corresponds to a cylinder axis and a central axis of the first pole sleeve 70. In an assembled state, the central axis 68 of the pump chamber 16 and the central axis of the second pole sleeve 72 coincide at least substantially. In an assembled state, the second pole sleeve 72 is arranged coaxially with the first pole sleeve 70 and with the pump chamber 16. In the present embodiment, the second pole sleeve 72 is rotationally symmetrical. The second pole sleeve 72 is spaced apart from the first pole sleeve 70 by a gap.

[0027] Furthermore, a section of the working piston 14 guided in the pump chamber 16 has two opposing stop surfaces. The first stop surface is formed by the end face of the working piston 14 facing the flow. The second stop surface is formed by the end face of the working piston 14 facing away from the flow, from which a pressure piston element 92 of the working piston 14 with a delivery channel and a piston valve 78 projects.

[0028] The working piston 14 of the beverage pump 10 comprises an armature element 74, which consists entirely of a magnetizable material. An actuating force acts on the armature element 74, deflecting it from its rest position against a force exerted by the spring element 62, which is designed as a pump spring. In the present embodiment, the armature element 74 is bonded to a base body of the working piston 14. The armature element 74 is formed by a section that can penetrate the wall.

[0029] The beverage pump 10 comprises a flux guide element 76, which is designed to guide and / or focus the magnetic flux generated by the magnetic actuator 20. The flux guide element 76 is designed to amplify a magnetic force acting on the armature element 74. The flux guide element 76 is designed as a sleeve. The flux guide element 76 is arranged within the pump chamber 16. In its assembled state, the flux guide element 76 rests against the pump chamber wall 66. The flux guide element 76 is arranged radially between the spring element 62, which is designed as a pump spring, and the pump chamber wall 66.

[0030] To achieve a pumping effect, the magnetic coil 58 is energized with a pulsed voltage, thereby generating a constantly changing magnetic field in the pump chamber 16. This pulsed magnetic field, guided by the pole sleeves 70 and 72, causes the working piston 14 to be deflected from its rest position against the force of the spring element 62, which acts as a pump spring, as the magnetic field strength increases. The magnetic force acting on the working piston 14 depends on the field density at the location of the armature element 74, which in turn is determined primarily by the shape of the pole sleeves 70 and 72. As soon as the current through the magnetic coil 58 is reduced and the strength of the magnetic field decreases again, the working piston 14 is moved back towards its rest position by the force of the spring element 62.The magnetic coil 58 is preferably connected in series with a diode unit (not shown in detail), whereby the magnetic coil 58 is only energized with one half-wave of an alternating voltage. In the illustrated embodiment, the magnetic coil 58 is designed for an alternating voltage of 230 V at 50 Hz.

[0031] With a working piston 14 installed, the pump chamber 16 comprises a pre-chamber 22, a pressure chamber 24, and an outlet chamber 26. The working piston 14 includes the piston valve 78, which is fluidically arranged between the pre-chamber 22 and the pressure chamber 24. The piston valve 78 is located centrally within the beverage pump 10 and centrally within the working piston 14 with respect to a longitudinal axis of the beverage pump 10. The piston valve 78 is located at the end of the working piston 14 adjacent to the armature element 74. The piston valve 78 is designed as a check valve, allowing flow from the pre-chamber 22 into the pressure chamber 24. The piston valve 78 comprises a valve seat, a closing element, and a closing spring. The closing spring is designed to pull the closing element onto the valve seat.In a filling stroke, where the working piston 14 is moved by the magnetic field against the force of the spring element 62 (designed as a pump spring), fluid flows from the pre-chamber 22 through the piston valve 78 into the pressure chamber 24. In a subsequent pressure stroke, where the working piston 14 is moved by the force of the spring element 62, the fluid is forced out of the pressure chamber 24. The maximum pressure acting on the fluid depends in particular on the force of the spring element 62. The distance traveled by the working piston 14 depends on the design of the beverage pump 10, in particular on the shape of the pole sleeves 70, 72.

[0032] The beverage pump 10 has a pump housing unit 40. The pump housing unit 40 comprises a compression chamber housing 88 and a valve chamber housing 90, which are assembled to form the pump housing unit 40. The compression chamber housing 88 and the valve chamber housing 90 form two nested housing shells of the pump housing unit 40. The compression chamber housing 88 accommodates the pump chamber 16. The compression chamber housing 88 forms the pump chamber 16.

[0033] The beverage pump 10 has two connection elements 80 and 82. The first connection element 80 is designed as an inlet element and is intended for connection to a water supply, for example, a water reservoir. The first connection element 80 has a connection nozzle 84 for connection to a hose. It is conceivable that the first connection element 80 has a coupling. The first connection element 80 is arranged on the compression chamber housing 88. The first connection element 80 is formed integrally with the compression chamber housing 88. The second connection element 82 is designed as an outlet element and has a coupling 86. It is conceivable that the second connection element 82 has a connection nozzle. The second connection element 82 is arranged on the valve chamber housing 90. The second connection element 82 is formed integrally with the valve chamber housing 90.The outlet chamber 26 is formed by the further connecting element 82.

[0034] The other of the spring elements 64 is designed as a damping element. In the present embodiment, the other of the spring elements 64 is designed as a helical spring. The working piston 14 is floatingly mounted between the two spring elements 62, 64. The working piston 14 is in at least substantially continuous contact with both spring elements 62, 64. It is conceivable that the other of the spring elements 64 is designed as a different elastic element, for example as a bellows element and / or as a porous element.

[0035] The beverage pump 10 further comprises an outlet valve 18, which is fluidically arranged between the pressure chamber 24 and the outlet chamber 26. The outlet valve 18 forms a check valve, which allows flow from the pressure chamber 24 to the outlet chamber 26. The outlet valve 18 is located centrally within the beverage pump 10 and centrally within the outlet chamber 26 with respect to the longitudinal axis of the beverage pump 10. The outlet chamber 26 is fluidically arranged between the pressure chamber 24 and an outlet opening.

[0036] The outlet valve 18 comprises a compression chamber unit 28 and a valve element 30. The valve element 30 is axially movably mounted in the compression chamber unit 28. The compression chamber unit 28 has a first chamber element 32, which partially delimits the pressure chamber 24, a second chamber element 34, which partially delimits the outlet chamber 26, and an orifice 36 arranged between the first chamber element 32 and the second chamber element 34, with a passage opening 38 that forms a sealing seat for the valve element 30. The pressure piston element 92 of the working piston 14 projects into the first chamber element 32 with a delivery channel and the piston valve 78 during operation. Preferably, the valve element 30 is guided in the second chamber element 34. The valve element 30 is arranged completely within the second chamber element 34.The orifice 36 has the circular passage opening 38, and the valve element 30, when the outlet valve 18 is closed, is designed to close the passage opening 38. The first chamber element 32 is hollow cylindrical and has an outwardly directed collar 94 at one end facing away from the second chamber element 34, which forms a circumferential groove on its inside. The groove serves, in particular, to receive a sealing element 96. The sealing element 96 is designed to seal the pre-chamber 22 against the pressure chamber 24. The sealing element 96, together with the working piston 14, forms a sliding seal. The second chamber element 34 is hollow cylindrical and has an externally circumferential step 98 at one end facing away from the first chamber element 34. The step 98 serves to support the compression chamber unit 28 in the pump housing unit 40.The first chamber element 32 and the second chamber element 34 are coaxial. The first chamber element 32, the second chamber element 34 and the aperture 36 are formed as a single piece.

[0037] The compression chamber unit 28 is designed as an insert intended for placement in the pump housing unit 40. The compression chamber unit 28 is intended for placement in the valve chamber housing 90. The compression chamber unit 28 forms an inner surface of the valve chamber housing 90. The compression chamber unit 28 rests with its step 98 and collar 94 in a recess in the valve chamber housing 90.

[0038] The passage opening 38 has a radius r1 on a side facing the valve element 30, which is at least 0.2 mm, preferably at least 0.3 mm, and particularly preferably at least 0.4 mm. Preferably, however, the radius r1 is a maximum of 1 mm, more preferably a maximum of 0.8 mm, and particularly preferably a maximum of 0.6 mm. For example, the radius r1 is exactly 0.4 mm. Furthermore, the orifice 36 has a radius r2 in a transition to the second chamber element 34, which is at least 0.1 mm. Preferably, however, the radius r2 is a maximum of 0.8 mm, more preferably a maximum of 0.6 mm, and particularly preferably a maximum of 0.4 mm. For example, the radius r2 is exactly 0.2 mm. Furthermore, the orifice 36 has a surface roughness Ra of 0.15 on a side facing the valve element 30. The side of the aperture 36 facing the valve element 30 forms the valve seat.

[0039] A stop surface 102 of the orifice 36, corresponding to a sealing surface 46 of the valve element 30, is frustoconical in shape. The stop surface 102 forms a shallow frustocone. The stop surface 102 of the orifice 36 has an angle α between 91° and 95° with respect to a central axis 104 of the outlet valve 18. The central axis 104 of the outlet valve 18 runs coaxially with the central axis 68 of the pump chamber 16. The stop surface 102 of the orifice 36 has an angle α of approximately 92° with respect to the central axis 104 of the outlet valve 18. It would also be conceivable that the angle α is 90° and the stop surface 102 is planar, or that the angle α is between 85° and 89°. A radially outer edge of the stop surface 102 is further away from the valve element 30 than a radially inner edge. In the closed state of the exhaust valve 18, the valve body 42 rests against the radially inner edge of the stop surface 102.

[0040] The valve element 30 comprises a cylindrical valve body 42 and a guide body 44 directly connected to the valve body 42. On a side facing away from the guide body 44, the valve body 42 forms a sealing surface 46, which, in a sealed state of the exhaust valve 18, is designed to bear against the orifice 36 of the compression chamber unit 28. The valve body 42 is essentially circularly cylindrical, with the sealing surface 46 being, in particular, slightly convex. The sealing surface 46 has a radius of curvature r4, in particular a spherical radius, between 10 mm and 40 mm, preferably between 20 mm and 30 mm. Preferably, the radius of curvature r4 is 27 mm. The valve body 42 has, by way of example, a diameter of 4.5 mm. Furthermore, the valve body 42 has, by way of example, a length of 1.6 mm.The valve body 42 of the valve element 30 further has a radius r 3 at an outer edge of the sealing surface 46, which is at least 0.05 mm. Preferably, however, the radius r 3 is a maximum of 0.6 mm, more preferably a maximum of 0.4 mm, and particularly preferably a maximum of 0.2 mm. For example, the radius r 3 is exactly 0.1 mm ±0.1. The sealing surface 46 of the valve element 30 is free of a flow seam. Furthermore, the mean roughness Ra of the sealing surface 46 is less than 0.4. The mean roughness Ra of the sealing surface 46 is less than 0.3, preferably at least approximately 0.25. The sealing surface 46 is completely tapered and without a flow seam. The guide body 44 is formed integrally with the valve body 42. The guide body 44 has a reduced diameter compared to the valve body 42. The guide body 44 has a circular cylindrical shape. The guide body 44 has, for example, a diameter of 3.2 mm.Furthermore, the guide body 44 has a frustoconical section at one end facing away from the valve body 42. The guide body 44 serves to guide the valve element 30 relative to a spring element 100 of the exhaust valve 18.

[0041] The valve element 30 has a Shore A hardness of at least 60, preferably at least 70, preferably a maximum of 90, and particularly preferably a maximum of 80. By way of example, the valve element 30 has a Shore A hardness of exactly 78 ± 3.

[0042] Valve element 30 has a service life of at least 20 million piston strokes at 12 bar. Valve element 30 has a service life of at least 35 million piston strokes at varying pressures.

[0043] Furthermore, the exhaust valve 18 also includes the spring element 100, which, in an assembled state, presses the valve element 30 against a valve seat of the compression chamber unit 28. The spring element 100 is formed by a coil spring. The spring element 100 forms a closing spring. The spring element 100 is supported on the valve chamber housing 90 on one side of the exhaust chamber 26 facing away from the orifice 36.

[0044] Valve element 30 consists at least largely of silicone. Valve element 30 consists entirely of silicone. Valve element 30 is also free of any coating. Furthermore, valve element 30 is free of ethylene propylene diene monomer rubber, acrylonitrile butadiene rubber, and parylene.

[0045] To prevent adhesion between the valve element 30 and the compression chamber unit 28, and to prevent material loss from the valve element 30, the compression chamber unit 28 consists at least predominantly of a food-grade, commodity plastic, in particular a polyolefin. The compression chamber unit 28 consists at least predominantly of polypropylene. The compression chamber unit 28 consists entirely of polypropylene. Reference sign

[0046] 10 Beverage pump 12 Household appliance 14 Working piston 16 Pump chamber 18 Outlet valve 20 Magnetic actuator 22 Pre-chamber 24 Pressure chamber 26 Outlet chamber 28 Compression chamber unit 30 Valve element 32 Chamber element 34 Chamber element 36 Orifice plate 38 Passage opening 40 Pump housing unit 42 Valve body 44 Guide body 46 Sealing surface 48 Operating unit 50 Stop grate 52 Vessel holder 54 Dispensing unit 56 Main flow direction 58 Solenoid coil 62 Spring element 64 Spring element 66 Pump chamber wall 68 Center shaft 70 Pole sleeve 72 Pole sleeve 74 Anchor element 76 Flow guide element 78 Piston valve 80 Connection element 82 Connection element 84 Connection nozzle 86 Connection coupling 88 Compression chamber housing 90 Valve chamber housing 92 Pressure piston element 94 Collar 96 Sealing element 98 Step 100 Spring element 102 Stop surface 104 Center axis r 1 radius r 2 radius r 3 radius r 4 curvature radius αAngle

Claims

1. A beverage pump, in particular oscillating piston pump, for a domestic appliance (12), in particular for a beverage vending machine, for conveying a liquid, having a working piston (14), having a pump chamber (16) in which the working piston (14) is guided in an axially movable manner and which, when the working piston (14) is mounted, has an antechamber (22), a pressure chamber (24) and an outlet chamber (26), having a magnetic actuator (20) which is configured to provide a magnetic field for driving the working piston (14), and having an outlet valve (18) which is arranged in terms of flow between the pressure chamber (24) and the outlet chamber (26) and which has at least one compression chamber unit (28) and at least one valve element (30), characterized in that the valve element (30) consists completely of silicone.

2. The beverage pump according to claim 1, characterized in that the compression chamber unit (28) consists at least for the most part of a mass plastic conforming to foodstuffs, in particular of a polyolefin, in order to avoid an adhesive bond between the valve element (30) and the compression chamber unit (28) and a material removal at the valve element (30).

3. The beverage pump according to claim 2, characterized in that the compression chamber unit (28) consists at least for the most part of polypropylene.

4. The beverage pump according to any one of the preceding claims, characterized in that at least a major part of a surface of the valve element (30) is free of a coating.

5. The beverage pump according to any one of the preceding claims, characterized in that the valve element (30) is free of ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber and parylene.

6. The beverage pump according to any one of the preceding claims, characterized in that the compression chamber unit (28) has at least one first chamber element (32) which at least partially delimits the pressure chamber (24), at least one second chamber element (34) which at least partially delimits the outlet chamber (26), and a diaphragm (36) which is arranged between the first chamber element (32) and the second chamber element (34) and has a passage opening (38) which at least partially forms a sealing seat for the valve element (30).

7. The beverage pump according to claim 6, characterized in that the first chamber element (32), the second chamber element (34) and the diaphragm (36) are formed in one piece.

8. The beverage pump at least according to claim 6, characterized in that the passage opening (38) has a radius (r1) on a side facing the valve element (30) which is at least 0.2 mm.

9. The beverage pump at least according to claim 6, characterized in that the diaphragm (36) has a radius (r2) in a transition to the second chamber element (34) which is at least 0.1 mm.

10. The beverage pump according to any one of the preceding claims, characterized by a pump housing unit (40), wherein the compression chamber unit (28) is formed as an insert which is configured to be inserted into the pump housing unit (40).

11. The beverage pump according to any one of the preceding claims, characterized in that the valve element (30) has a, in particular cylindrical, valve body (42) and a guide body (44) connected directly to the valve body (42), and the valve body (42) forms a sealing surface (46) on a side facing away from the guide body (44), which sealing surface, in a sealed state of the outlet valve (18), is configured to bear against a diaphragm (36) of the compression chamber unit (28).

12. The beverage pump according to claim 11, characterized in that the valve body (42) of the valve element (30) has a radius (r3) on an outer edge of the sealing surface (46) which is at least 0.05 mm.

13. The beverage pump at least according to claim 11, characterized in that the sealing surface (46) of the valve element (30) is free of a flow seam and a mean roughness Ra is in particular less than 0.4.

14. The beverage pump according to any one of the preceding claims, characterized in that the valve element (30) has a service life of at least 20 million piston strokes at 12 bar.

15. An outlet valve (18) of a beverage pump (10) according to any one of the preceding claims.