Valve for use in a hot drinks vending machine

Abstract

In a valve having at least two ports in the form of exits of a valve bore formed in a valve body and having a longitudinally displaceable valve piston which is sealingly accommodated within the valve bore and, depending on its position, either blocks the two exits of the valve bore or fluid-conductively connects them together, it is provided that a first of the exits is formed by a valve seat, which is formed on an end face of the valve bore, and the end of the valve piston bears an in particular conical valve needle which tapers to a point and interacts with the valve seat. By contrast, the second exit leads laterally into the valve bore, wherein the valve piston, in a first piston position in which said valve piston is moved in the direction of the valve seat, sealingly blocks off the second exit and, in a second piston position, with the valve needle raised, the valve piston opens up a fluid-conducting connection between the first and the second exit. The sealing function of the valve piston is separate here from a throttle function of the valve needle. The valve is a directional control valve which is particularly suitable both for switching and for controlling fluid flows in a hot drinks vending machine, in particular a coffee machine.

Description

[0001] Valve for use in a hot drinks machine

[0002] Description

[0003] The present invention relates to a valve for use in a hot beverage machine, in particular a coffee machine, with at least two connections in the form of outlets of a valve bore formed in a valve body and with a longitudinally displaceable valve piston which is sealingly received within the valve bore and which, depending on its position, either blocks the two outlets of the valve bore or connects them to one another in a fluid-conducting manner.

[0004] So-called piston valves, in which a valve piston selectively opens or closes outlets of the valve depending on its position, are known per se and can be used in hot drink machines to switch fluid flows.

[0005] Often, however, fluid flows also need to be precisely controlled. Needle valves are typically used for this purpose. The opening gap between a conical valve needle and a corresponding valve seat can be precisely adjusted via a valve spindle. While electromagnetically switched piston valves typically have two switching states (open / closed), needle valves can be freely adjusted between a fully closed and a fully open valve position.

[0006] The present invention has the object of providing a directional control valve with which fluid flows, particularly in a hot beverage dispenser, can be easily switched and regulated. This object is achieved by a valve having the features of claim 1. Advantageous

[0007] Details can be found in the dependent claims.

[0008] In a valve of the type mentioned above, the invention provides that a first of the outlets is formed by a valve seat formed on one end face of the valve bore, and the valve piston carries at its end a valve needle that tapers to a point, in particular a conical one, which interacts with the valve seat. The second outlet, in contrast, opens laterally into the valve bore, wherein the valve piston, in a first piston position in which it is adjusted towards the valve seat, sealingly blocks the second outlet, and in a second piston position, with the valve needle raised, the valve piston opens a fluid-conducting connection between the first and second outlets.

[0009] In the valve according to the invention, the sealing function of the valve piston is separate from the function of the valve needle, in particular its throttling function. The valve is a piston-directional valve with a continuously adjustable piston position. If the valve needle is raised, a connection to the lateral outlet can be opened in a controlled manner due to the tapered geometry of the needle.

[0010] In one embodiment, the valve can be designed as a 2 / 2-way valve, which has two ports and two switching positions. In this case, the valve needle serves as a throttle, which can be controlled via a drive.

[0011] In another embodiment, the valve can be designed as a 3 / 2-way valve which has three connections and two switching positions. In this case, the valve is provided with a third outlet which opens laterally into the valve bore, and the valve piston has at least two areas of different outer diameters which, depending on the switching position, either block the second and third outlets or connect them to one another in a fluid-conducting manner. In this case, it can be provided in particular that the second and third outlets are fluid-conductingly connected to one another in the first valve position, i.e. when the needle valve is closed, and that a connection between the second and third outlets is blocked in the second valve position. However, the needle and valve piston can also be designed such that the second and third connections can be metered simultaneously.The geometry of the needle and valve piston can thus be designed either so that only two of the three ports are open at any one time, or so that all three ports are open and the opening ratio can be controlled by the needle position. The valve thus represents a piston directional control valve with a continuously adjustable operating position that can be actuated by a suitable actuator.

[0012] The drive is any linear actuator. A threaded spindle connected to the valve piston can serve as the valve drive. This spindle runs in a spindle nut fixed relative to the valve body or in a mating thread for the threaded spindle formed in the valve body or the valve piston, thus adjusting the valve piston. In this case, the threaded spindle can be motor-driven, particularly by a stepper motor. Alternatively, manual adjustment would also be possible.

[0013] Two or more sealing elements, particularly sealing rings, spaced apart in the direction of displacement can expediently be provided to seal the valve piston within the valve bore. The sealing elements ensure that the valve piston is sealed within the valve bore in a displacement-tight manner.

[0014] In a particularly preferred embodiment, the valve has a modular design, wherein, in particular, a 2 / 2-way valve or a 3 / 2-way valve can be produced as desired, particularly using at least partially identical valve components. For this purpose, the valve body is designed in several parts, with a lower valve part forming the first and second outlets, an upper valve part closing the valve bore and providing a mechanical interface for a valve drive, and preferably a middle valve part connecting the lower and upper valve sections and optionally forming the third outlet. The valve according to the invention is for use in a hot drinks machine, in particular a coffee machine. Therefore, the present invention also includes a corresponding hot drinks machine, in particular a coffee machine, having a valve of the type described above.

[0015] In a first embodiment, the valve according to the invention serves as a brewing valve. The brewing valve in a coffee machine, in particular a fully automatic coffee machine, controls the flow of hot water through the ground coffee in the brewing group. The hot drinks machine comprises a hot water heater and a brewing device. The valve is designed as a 3 / 2-way valve and arranged in a fluid line between the hot water heater and the brewing device, such that the first outlet is connected to the hot water heater, the second outlet to the brewing device, and the third outlet to a drainage line, which serves to drain residual liquid from the brewing device after the end of brewing. The valve controls the amount of water that flows through the ground coffee in the brewing device and thus influences the strength of the coffee. After a portioned amount of water has flowed through the ground coffee, the valve closes and stops the water flow.

[0016] The brewing device can, in particular, be a brewing group with a brewing piston, through which the ground coffee is pressed and ejected. It is particularly advantageous if the moist ground coffee is pressed out after the brewing process to remove any residual moisture. This can be drained into the drainage line through the third outlet of the valve.

[0017] The integrated needle valve regulates the flow of hot water. This additional throttling function of the brewing valve allows for dynamic, controlled wetting of the ground coffee, ensuring optimal wetting of the coffee powder. Furthermore, profiling the flow rate over the preparation time can improve the coffee quality. Furthermore, splashing at the outlet and noise during beverage preparation can be minimized. Using a stepper motor as the drive, not only can the needle position be precisely adjusted and, if necessary, regulated, but the valve holding pressures can also be increased.

[0018] In a preferred development of the hot beverage vending machine, additional control parameters can be implemented, for example, by regulating the integrated needle valve depending on a measured input pressure on the inlet side of the valve. In another development, a second needle valve can also be arranged downstream of the brewing unit, with which the flow through the brewing device is adjusted and regulated. In particular, a flow meter can be arranged upstream of the brewing unit, and the needle throttle integrated in the brewing valve and the second needle valve downstream of the brewing unit can be regulated to achieve a desired flow rate.

[0019] In a second embodiment, the hot beverage machine comprises a hot water heater and a brewing device, which can be connected to the hot water heater on the inlet side. The valve is again designed as a 3 / 2-way valve and, in this case, is arranged on the outlet side of the brewing device in a fluid line leading to a beverage outlet. The valve is connected such that the first outlet is connected to the beverage outlet, the second outlet to the brewing device, and the third outlet to a drainage line for draining liquid from the brewing device.

[0020] The valve needle integrated into the valve acts as an adjustable needle throttle. This can be used to regulate the flow rate of the freshly brewed hot beverage, for example to a predetermined brewing time. This ensures consistent beverage quality. If the hot beverage machine is not in use for an extended period, the brewing device cools down, meaning that the temperature of the next brewed hot beverage will be significantly lower than expected. To avoid this, the brewing device can be warmed up with hot water. To prevent this water from ending up in the user's drinking vessel, the 3 / 2-way valve behind the brewing device connects the outlet side to the drainage system so that the water can be drained away during the warming process. In a third embodiment, the hot beverage machine has a steam generator and a milk system with a pump for cold milk.A steam line coming from the steam generator flows into a milk line coming from the milk pump, with the valve according to the invention being arranged in the steam line. A temperature sensor can preferably be arranged downstream of the steam introduction point, depending on which the valve for metering the steam quantity is controlled.

[0021] The valve can be designed as a 2 / 2-way piston valve. The valve allows for throttling the steam admixture. The throttling steam admixture allows for compensation of influences on the resulting milk or milk foam temperature, such as pressure fluctuations in the steam generator (steam boiler), pressure fluctuations in the milk flow, or temperature fluctuations in the cold milk. This allows for a more stable admixture of steam into the flowing milk or milk foam. The valve, which can be adjusted using the valve needle, allows the degree of opening of the valve to be regulated depending on the milk flow, the measured temperature after steam admixture, or the measured pressure at the steam generator, in order to achieve optimal heating with minimal pressure surges.

[0022] In a fourth embodiment, the beverage vending machine has a steam generator and a steam dispensing device, preferably designed as a steam lance, for manually frothing milk. The valve according to the invention, which is designed as a 3 / 2-way valve, is arranged between the steam generator and the steam dispensing device. The first outlet of the valve is connected to the steam generator, the second outlet to the steam dispensing device, and the third outlet to a drainage line for removing residual steam and / or condensate after the frothing process has ended. The needle throttle integrated into the valve, in turn, serves to regulate the flow of steam. Depending on the type of milk used, it can be frothed better in different temperature ranges and more difficult in others.In a temperature range in which the milk used can be easily frothed, for example between 35°C and 55°C or below 20°C, the heating process can be slowed down by throttling the steam supply in order to froth the milk for as long as possible. In temperature ranges in which air supply is not advisable because the milk froths poorly in this range, the steam supply can be increased in order to heat the milk as quickly as possible. The degree of opening of the valve can depend on the addition of air (air pump or air valve), the milk temperature and the type of milk. These parameters are adjustable and programmable for each product via a control device that controls an electric drive for the valve. In addition, different volume flow profiles of the steam can be programmed in order to minimize the noise generated by the escaping steam, for example during cleaning.By using a stepper motor as a drive, not only can the needle position be precisely adjusted, but the holding pressure of the valve can also be massively increased, thus allowing larger cross-sections of the valve seat to be used.

[0023] In a fifth embodiment, the hot beverage vending machine has a hot water heater. A hot water line coming from the hot water heater and a cold water line are combined via the valve according to the invention to mix hot and cold water in an adjustable ratio to provide tempered water. The valve thus serves as a mixing valve. This allows the temperature of the prepared hot beverage to be adjusted. A 3 / 2-way mixing valve is used, whose two inlets can be throttled independently of one another. The throttleable cold-hot water mixture allows a more stable beverage temperature to be achieved at the outlet.

[0024] The aforementioned embodiments can be combined in any desired combination in a single hot beverage vending machine. For example, a brewing valve on the inlet side of the brewing device can be combined with a second, adjustable throttle valve on the outlet side, primarily for preparing coffee beverages. Additionally, a mixing valve can optionally be used to adjust the beverage temperature. If, for example, milk-based beverages are also to be offered in a fully automatic coffee machine, a steam mixing valve can also be used. However, the option for manually frothing milk using a steam valve described above on a steam dispensing device can also be provided.

[0025] In a further development of hot beverage vending machines according to the invention, it can be provided that an automatic calibration of the flow rate is carried out once or several times, at regular intervals, as part of device maintenance or the like, depending on the position of the valve piston. For this purpose, the hot beverage vending machine is equipped with a flow measuring device arranged in a fluid path and a control device which is programmed to control a valve drive of the valve to carry out an automatic calibration of the flow rate, in order to set different positions of the valve needle (17) and to determine the resulting flow rate with the aid of the flow measuring device. In this way, reproducible flow rates can be achieved.

[0026] Further advantages and embodiments of the invention will become apparent from the following description of embodiments with reference to the figures.

[0027] It shows:

[0028] Figure 1 is a sectional view of a 3 / 2-way valve according to the invention with integrated needle throttle in a first embodiment,

[0029] Figure 2 shows a longitudinal section through a valve according to the invention designed as a 2 / 2-way valve in a second embodiment,

[0030] Figure 3 shows the use of a 3 / 2-way valve according to the invention as a brewing valve in a coffee machine,

[0031] Figure 4 shows the use of a 3 / 2-way valve according to the invention as a throttle valve in the outlet line of a coffee machine, Figure 5 shows the use of a 2 / 2-way valve according to the invention as a steam addition valve in a hot drinks machine,

[0032] Figure 6 shows the use of a 3 / 2-way valve according to the invention as a steam valve for manual frothing of milk and

[0033] Figure 7 shows the use of a 3 / 2-way valve according to the invention as a mixing valve for adjusting the hot water temperature in a hot drinks machine.

[0034] The valve 10 shown in Figure 1 has a valve body 11 with an axially extending valve bore 12 in which a valve piston 13 is arranged for longitudinal movement. A total of three outlets 14, 15, 16, each provided with connections for fluid lines, open into the valve bore 12. The outlet 14 is formed by a valve seat 14a formed on the front side of the valve bore 12. The valve piston 13 carries, at its end facing the valve seat 14a, a conical valve needle 17 which interacts with the valve seat 14a and, when closed, enters the valve seat 14a and closes it. As an alternative to a conical geometry, the tip of the valve needle 17 could also taper in a different way, e.g., parabolically.

[0035] The outlets 15, 16 open laterally in radial direction into the valve bore 12 and are closed or opened by the valve piston 13 depending on the position of the latter.

[0036] The valve piston 13 is sealed within the valve bore 12 by several seals 18a, 18b, 18c, which can be longitudinally displaced. The seals can be designed as O-rings, for example. An O-ring seal 18a is located between the first end outlet 14 and the second lateral outlet 15. A second O-ring seal 18b is located between the radial outlet 15 and the radial outlet 16. The third seal 18c, which in this case has an x-profile, seals the valve piston 13 at its actuation-side end. In the area where the valve piston 13 merges into the valve needle 17, it has a shoulder 13a, which covers the valve seat 14a in the closed valve position shown in Figure 1 (the valve piston 13 is in its end position). The end of the valve piston 13 is sealed by the seal 18a so that the outlet 14 is closed.If the valve piston 13 is raised, the shoulder 13a moves into a position above the seal 18a, so that the valve piston releases the outlet 14. In this state, the valve needle 17 is located in the region of the valve opening formed by the valve seat 14a and thus acts as an adjustable throttle for a fluid flow between the outlets 14 and 15. The outlet 16 is blocked in this valve position because the region 13b of the valve piston above the shoulder 13a rests against the seal 18b and thus blocks a fluid flow between the outlet 15 and the outlet 16. If, however, the valve piston 13 is in the end position, as shown in Figure 1, in which the outlet 14 is blocked, there is a region 13c of the valve piston 13 with a reduced outer diameter at the level of the seal 18b, so that fluid can flow past the seal 18b. In this piston position, a valve flow is possible between the side outlets 15 and 16.

[0037] The valve 10 shown in Figure 1 thus functions as a 3 / 2-way valve in that, in the position shown in Figure 1, in which the valve piston 13 is in the end position at the valve seat 14, a connection is switched between the outlets 15 and 16. In the raised position of the valve piston 13, the connection to the outlet 16 is blocked and a connection is opened between the outlets 14 and 15. This can be finely adjusted by a gradual adjustment of the valve piston 13 and thus the position of the valve needle 17 within the valve seat 14a.

[0038] In the exemplary embodiment, the drive for the valve piston 13 is a stepper motor 19, which rotates a threaded spindle 20 that is connected to the valve piston 13 and moves it in the direction of displacement. The stepper motor and threaded spindle are usually designed as an integrated unit. Suitable integrated linear drive units with a stepper motor and spindle drive are commercially available and can be used within the scope of the invention. The valve body 11 has a modular design and consists of a lower valve part 11a, which forms the front outlet 14 and the first lateral outlet 15, a middle valve part 11b, which forms the third outlet 16, and an upper valve part 11c, which closes the valve bore 12 and provides a mechanical interface for the valve drive, in this case the stepper motor 19.

[0039] A second embodiment of a valve 10' according to the invention, which in this case is designed as a 2 / 2-way valve, is shown in Figure 2. In this case, the valve body 11 has two outlets 14, 15 from the central valve bore 12, wherein the outlet 14 is in turn arranged on the end face of the valve bore 12 and is provided with a valve seat 14a. The valve needle 17 carried by the valve piston 13' engages in this and enables finely metered opening of the valve. In the first embodiment, the second outlet 15 is arranged laterally and closed by the valve piston 13'. For this purpose, two seals 18a, 18b are arranged above and below the lateral outlet 15, which seal the outer diameter of the valve piston 13' against the valve bore 12.

[0040] Figure 2 shows the closed state of the valve. The valve needle 17 is fully inserted into the valve seat 14a, and a shoulder formed on the valve piston 13' rests against the valve seat 14a. The valve needle 17 acts separately from the seal 18a. If the valve piston is raised until the shoulder 13a is above the seal 18a, a connection is released between the outlet 14 and the outlet 15, which can be opened in a controlled manner due to the conical geometry of the valve needle 17.

[0041] A stepper motor 19 is provided as the drive, which adjusts a threaded spindle 20 connected to the valve piston 13' so that the valve piston 13' is moved in the axial direction.

[0042] As in the first embodiment, the valve body is also modular in design, with a lower valve part 11a, in which the two outlets 14 and 15 are formed, an upper valve part 11c, which provides a mechanical interface for coupling the stepper motor 19 and closes the valve bore 12, and a middle valve part 11b, which sealingly connects the upper and lower valve parts 11a, 11c. The upper and lower valve parts 11a, 11b can essentially be designed identically to the first embodiment, so that these two valve parts can be used to construct a 3 / 2-way valve or a 2 / 2-way valve, and only a separate middle valve part 11b and a different valve piston 13, 13' need to be installed.

[0043] The valve shown in Figure 2 is therefore a piston directional control valve with a continuously adjustable working position, which is electrically operated by a stepper motor.

[0044] Both the 3 / 2-way valve shown in Figure 1 and the 2 / 2-way valve shown in Figure 2 were developed for use in a hot beverage dispenser, in particular a coffee machine or a fully automatic coffee machine. Various exemplary embodiments in which one of the aforementioned valves is used are explained below. The individual exemplary embodiments can be combined as desired.

[0045] In the first embodiment, the hot beverage maker is a fully automatic coffee machine with a hot water maker 21, in this case a hot water boiler, and a brewing group 22 of a conventional design. A pressure relief valve 23 and a temperature sensor 24 are located on the hot water boiler. A cold water supply line 25 opens into the hot water boiler, and a hot water line 26 leads toward the brewing group 22 via a valve 10 of the invention. This serves as a brewing valve.

[0046] The brewing valve in a fully automatic coffee machine controls the flow of hot water through the ground coffee filled into the brewing group. Freshly brewed coffee flows from the brewing group via an outlet line 27 to a beverage outlet (not shown). A water tank or water connection is connected to the cold water supply line 25 via a water pump and, if necessary, another shut-off valve.

[0047] When the water flow is activated and the brewing valve 10 is opened, brewing water flows from the hot water boiler 21 to the brewing group 22 via the hot water line 26, initially moistening the ground coffee contained therein. The brewing valve 10 controls the amount of water flowing through the ground coffee, thus influencing the strength of the brewed coffee. After the water has flowed through the ground coffee, the brewing valve 10 closes and stops the water flow. To remove the residual moisture from the ground coffee, the moist ground coffee is pressed out after brewing and drained through the third connection of the brewing valve 10 via a drainage line 28 into a drainage system.

[0048] Referring to Figure 1, the throttleable connection 14, provided with the valve needle 17, is connected to the hot water heater 21, connection 15 to the brewing group 22, and the third connection 16 to the drainage line 28. The hot water supply to the brewing group 22 can be finely regulated via the integrated needle throttle via the electrically controllable drive, implemented as a stepper motor. This additional throttle function of the brewing valve 10 allows the coffee grounds to be moistened in a controlled manner, thereby achieving optimal wetting of the coffee cake. Furthermore, the integrated needle valve allows the flow rate to be profiled over time, thereby improving the coffee quality and minimizing splashing and noise during coffee dispensing. The use of a stepper motor not only allows the needle position to be precisely adjusted or regulated, but also significantly increases the holding pressure of the valve 10.If the valve 10 is closed after the end of the brewing process, the fluid connection between the brewing group 22 and the drainage line 28 is automatically released so that residual water from the brewing group 22 can flow into the drainage.

[0049] In a further development of the exemplary embodiment, a pressure sensor could additionally be arranged between the water pump and the brewing valve 10, and the needle throttle integrated into the brewing valve 10 could be regulated depending on the measured pressure. It would also be possible to measure the flow rate using a flow meter upstream of the brewing unit 22 and regulate the integrated needle throttle depending on the flow rate.

[0050] As a second embodiment, Figure 4 shows a further development of the first embodiment, in which, in addition to a brewing valve 10a upstream of the brewing group 22, as in the first embodiment, a further 3 / 2-way valve 10b according to the invention is arranged on the outlet side in the outlet line 27 leading to the beverage outlet 27a. Starting from Figure 1, the first connection 14 is connected to the beverage outlet 27a, the second outlet 15 is connected via the outlet line 27 to the outlet of the brewing group 22, while the third connection 16 is connected to a drainage line 29 leading to a drain. Using the adjustable needle throttle integrated in the valve 10b, the brewing time can be regulated, thus ensuring consistent coffee quality.

[0051] If the coffee machine is left idle for an extended period, the brewing group 22 cools down, and the coffee temperature of the next brew would be significantly lower than intended. The 3 / 2-way valve 10 according to the invention, located behind the brewing group 22, allows the brewing group 22 to be heated with hot water. However, to prevent the hot water from ending up in the cup, the valve 10b is switched to the position shown in Figure 4 (needle throttle closed, fluid paths between port 15 and port 16 open), so that the hot water is drained into the drainage system via the drainage line 29.

[0052] This additional warm-up function ensures that a high-quality coffee product can be produced even after the coffee machine has been idle for a long time.

[0053] The third embodiment shown in Figure 5 concerns the heating or reheating of a beverage or beverage component using steam. A 2 / 2-way valve 10' according to the invention is used for this purpose. Reheating using steam can be used, for example, in a milk system of a fully automatic coffee machine, such as the one described in EP2583596A1, which is incorporated herein by reference to avoid unnecessary repetition.

[0054] Figure 5 shows a milk line 30, which originates, for example, from a milk pump and leads toward a beverage outlet. A steam line 32 flows into this line via a T-connector or a mixing chamber 31. The inventive valve 10' from Figure 2 is connected in the steam line 32, which originates from a steam generator, such as a thermoblock or high-pressure boiler. This allows the steam admixture to be throttled. The throttleable steam admixture makes it possible to compensate for influences on the resulting milk or milk foam temperature, such as pressure fluctuations in the steam generator, pressure fluctuations in the milk flow, or temperature fluctuations in the cold milk. Using a temperature sensor 33, the temperature of the heated medium can be measured, and the steam quantity can be regulated accordingly.A check valve 34 prevents milk from being drawn in via the steam line 32 when the steam admixture is turned off and any remaining steam condenses in the line 32. The adjustable 2 / 2-way piston valve 10' with integrated needle throttle allows the degree of opening of the valve 10' to be regulated depending on the milk flow, the measured temperature after the steam admixture, and, if applicable, the pressure measured at the steam generator, in order to achieve optimal heating with minimal pressure surges.

[0055] Another exemplary embodiment for the use of a valve according to the invention is shown in Figure 6. This is a so-called steam lance 40, i.e., a steam dispensing device for manually frothing milk, which is connected via an adjustable 3 / 2-way valve 10 to a steam line 41 leading to a steam generator 42. The steam generator 42 is designed as a high-pressure boiler in which water is heated under pressure, thus generating and storing steam. Heating is achieved via an electric heater 43. Temperature sensors 44, 45 can measure the temperature of the steam, and the heater 43 can be regulated accordingly. A pressure relief valve 46 ensures that the steam pressure cannot rise above a permissible maximum pressure. A pressure gauge 47, with which the pressure in the steam line can be measured, is also connected to the steam line 41.The steam line 41 leads via the adjustable 3 / 2-way valve to a Venturi nozzle 48, through which air can be drawn in via an adjustable air valve 49. The steam, possibly mixed with air, is then directed to the steam dispensing device 40 and dispensed into a frothing vessel via a steam nozzle 40a.

[0056] When manually heating and frothing milk, the user first wants to heat the milk to a higher temperature as quickly as possible. The amount of steam per unit time is crucial. In the second step, the milk is frothed. The speed at which the steam is released is crucial to ensure that sufficient air can be mixed into the milk as it enters the milk.

[0057] Referring to Figure 1, connection 14 of the valve 10 is connected to the steam line 41 coming from the steam generator 42, connection 15 to the steam lance 40 and the third connection 16 to a drainage line 50. This serves to ensure that when the steam lance 40 is switched off and cooled down, no milk can be sucked out of the frothing vessel due to a susceptible negative pressure when residual steam remaining in the steam line 41 condenses.

[0058] The 3 / 2-way piston valve with integrated needle throttle, which serves as a steam valve, can be used to regulate the flow of steam. In a first phase for heating the milk, the valve can be opened with a larger cross-section, and in a second phase for frothing, the flow cross-section of the needle throttle can be reduced as needed. The valve 10 is controlled by a programmable control unit in which various frothing programs can be specified and stored. For example, the frothing behavior differs for different types of milk. For example, UHT milk is difficult or impossible to froth between 20 and 35°C. Frothing can therefore be carried out in a phase before 20°C and in a later phase between 35°C and approximately 55°C.The adjustable valve 10 can be used to throttle the heating process within this temperature range, and in the intermediate phase, in which no air supply is appropriate (air valve 49 closed), a rapid temperature rise can be achieved by selectively opening the valve 10. The degree of opening of the valve 10 depends on the amount of air added and the temperature of the milk. This can be measured via a temperature sensor 51 on the steam lance 40. These parameters are variable and can be programmed for different products in the programmable controller. In addition, different steam volume flow profiles can be programmed, for example to minimize the noise generated by escaping steam, e.g., during cleaning.By using a stepper motor, not only can the needle position be precisely adjusted, but the valve holding pressures can also be massively increased, thus allowing larger cross-sections of the valve seat to be used.

[0059] In the illustrated embodiment, air is added via the Venturi nozzle 48 and an adjustable air valve 49, which can, for example, be a solenoid valve operated in a timed manner to regulate the air flow. Alternatively, an air pump or compressor could be used instead of a Venturi nozzle 48, with the aid of which air can be injected under pressure into the steam line 41.

[0060] The fifth embodiment shown in Figure 7 concerns the temperature adjustment of the hot water used to prepare hot beverages. This can also be advantageously combined with the embodiments shown in Figures 3 and 4. This allows the temperature of the dispensed beverage to be adjusted. The hot water boiler 21, which is equipped with a pressure relief valve 23 and a temperature sensor 24, is again used to heat and store water. A water pump 60 is connected to the cold water supply line 25 of the hot water boiler 21 via a check valve 61. This pump pump delivers cold water from a water connection or a water tank to the hot water heater 21. On the outlet side, the hot water boiler 21 and the hot water line 26 are connected to a valve 10 serving as a mixing valve. A bypass line 63 branches off from the cold water supply line 25 to the mixing valve 10.A temperature sensor 62 measures the temperature of the mixed water at the outlet of the mixing valve 10.

[0061] Referring to Figure 1, the first port 14 is connected to the bypass line 63, the second port 15 to the hot water line 26, and the third port 16 to the mixed water line 64, which leads, for example, to a brewing unit 22 as shown in Figures 3 and 4. The valve sets the mixing ratio of cold and hot water and can be regulated depending on the temperature measured by the temperature sensor 62. The geometry of the valve piston is adapted so that all three ports of the 3 / 2-way valve are open, and the opening ratio can be controlled by the needle position.This is achieved by the reduced-diameter portion 13c of the valve piston 13 being shaped in such a way that it connects the lateral outlets 15, 16 even when the valve needle 17 is open, i.e., raised from the valve seat 14a. Depending on the position of the valve piston 13, the overflow path formed by the reduced-diameter portion 13c becomes wider or narrower. This allows both inlets, i.e., cold water and hot water, to be throttled independently of one another. The throttleable cold-hot water mixture allows a more stable beverage temperature to be achieved at the outlet. Furthermore, the temperature range can be extended downwards to the range from cold water to the maximum boiler temperature.

[0062] In a further development of hot beverage vending machines according to the invention, it can be provided that an automatic calibration of the flow rate is carried out once or several times, at regular intervals, as part of device maintenance or the like, depending on the position of the valve piston 13, in order to achieve reproducible flow rates. The mechanical position of the valve needle 17 is coordinated with the resulting flow. For this purpose, a flow measuring device is provided in the fluid path. To carry out a calibration, a control device controls the stepper motor 19 in order to set different positions of the valve needle 17 and, with the aid of the flow measuring device, determines the resulting flow in each case. Thus, the resulting flow can be determined in step units of the stepper motor, and a corresponding concordance table can be created.During normal operation, this can be used to determine which step position must be reached to set a desired flow rate.

Claims

Claims 1. A valve (10, 10') for use in a hot beverage machine, in particular a coffee machine, having at least two connections in the form of outlets (14, 15) of a valve bore (12) formed in a valve body (11) and having a longitudinally displaceable valve piston (13) sealingly received within the valve bore (12), which, depending on its position, either blocks the two outlets (14, 15) of the valve bore (12) or connects them to one another in a fluid-conducting manner, wherein a first of the outlets (14) is formed by a valve seat (14a) formed on an end face of the valve bore (12), and the valve piston (13) carries at its end a valve needle (17) tapering to a tip, in particular a conical, which cooperates with the valve seat (14a),and wherein the second outlet (15) opens laterally into the valve bore (12) and, in a first piston position with the valve piston (13) adjusted in the direction of the valve seat (14a), the valve piston (13) sealingly closes the second outlet (15) and, in a second piston position with the valve needle (17) raised, the valve piston (13) releases a fluid-conducting connection between the first (14) and the second (15) outlet.

2. Valve (10) according to claim 1, with a third outlet (16) opening laterally into the valve bore (12), wherein the valve piston (13) has at least two regions of different outer diameter (13, 13b) which, depending on the switching position, either block the second and third outlets (15, 16) or connect them to one another in a fluid-conducting manner.

3. Valve (10) according to claim 2, wherein the second and the third outlet (15, 16) are fluidly connected in the first valve position and a connection between the second and the third outlet (15, 16) is blocked in the second valve position.

4. Valve (10) according to claim 2, wherein the valve piston is designed such that only two of the three outlets (14, 15, 16) are always open.

5. Valve (10) according to claim 2, wherein the valve piston (13) is designed such that all three outlets (14, 15, 16) can be opened simultaneously and the opening ratio can be controlled by the position of the valve piston (13).

6. Valve (10, 10') according to one of the preceding claims, which has a threaded spindle (20) connected to the valve piston (13), which runs in a spindle nut fixed relative to the valve body (11) or a counter thread for the threaded spindle (20) formed in the valve body (11) or the valve piston (13) and serves as a drive for the valve piston (13).

7. Valve (10, 10') according to claim 6, wherein the threaded spindle (20) is driven by a motor, in particular by a stepper motor (19).

8. Valve (10, 10') according to one of the preceding claims, in which the valve piston (13) is sealed within the valve bore (12) by at least two sealing elements (18a, 18b, 18c) spaced apart in the direction of displacement.

9. Valve (10, 10') according to one of the preceding claims, in which the valve body (11) is designed in several parts with a lower valve part (11a), which forms the first and the second outlet (14, 15), an upper valve part (11c), which closes the valve bore (12) and provides a mechanical interface for a valve drive (19, 20) and preferably a middle valve part (11b), which connects the lower and the upper valve part (11a, 11c) and optionally forms the third outlet (16).

10. Hot drinks machine, in particular a coffee machine, with a valve (10, 10') according to one of the preceding claims.

11. Hot drinks machine according to claim 10 with a hot water heater (21) and a brewing device (22), wherein the valve (10) is designed as a 3 / 2-way valve according to claim 2 and is arranged in a fluid line (26) between the hot water heater (21) and the brewing device (22), in particular such that the first outlet (14) is connected to the hot water heater (21), the second outlet (15) is connected to the brewing device (22) and the third outlet (16) is connected to a drainage line (28) for draining residual liquid from the brewing device (22) after the end of the brewing process.

12. Hot beverage machine according to claim 10 with a hot water heater (21) and a brewing device (22) which can be connected to the hot water heater (21) on the inlet side, wherein the valve (10) is designed as a 3 / 2-way valve according to claim 2 and is arranged on the outlet side of the brewing device (22) in a fluid line (27) leading to a beverage outlet (27a), in particular such that the first outlet (14) is connected to the beverage outlet (27a), the second outlet (15) is connected to the brewing device (22) and the third outlet (16) is connected to a drainage line (29) for draining liquid from the brewing device (22).

13. Hot drinks machine according to claim 10 with a steam generator and a milk system with a conveying device for cold milk, in which a steam line (32) opens into a milk line (30) coming from the milk pump, wherein the valve (10') is arranged in the steam line (32), wherein downstream of the steam introduction point (31) there is preferably a temperature sensor (33) arranged, depending on which the valve (10') can be controlled to meter the amount of steam.

14. Hot drinks machine according to claim 10 with a steam generator (42) and a steam dispensing device (40) preferably designed as a steam lance for manually frothing milk, wherein between the steam generator (42) and the steam dispensing device (40) the valve (10) is arranged, which is designed as a 3 / 2-way valve according to claim 2, wherein in particular the first outlet (14) of the valve (10) is connected to the steam generator (42), the second outlet (15) is connected to the steam dispensing device (40) and the third outlet (16) is connected to a drainage line (50) for discharging residual steam and / or condensate after completion of a foaming process.

15. Hot drinks machine according to claim 10 with a hot water heater (21), wherein a hot water line (26) coming from the hot water heater (21) and a cold water line (25) are brought together via the valve (10) in order to mix hot and cold water in an adjustable mixing ratio to provide tempered water.

16. Hot drinks machine according to one of claims 10 to 15, with a flow measuring device arranged in a fluid path and a control device which is programmed to control a valve drive (19) of the valve (10) for carrying out an automatic calibration of a flow rate as a function of the position of the valve piston (13) in order to set different positions of the valve needle (17) and to determine the flow rate resulting therefrom with the aid of the flow measuring device.

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