JP2012515891A - Insert for flow-through heater - Google Patents

Abstract

  When feedback loop control is used to control the temperature of the liquid at the outlet 5 of the flow-through heater, the volume of the ineffective portion 4 at the outlet 5 constitutes a dead volume that causes a delay in the feedback process, It results in instability and inaccuracy. In order to minimize the delay, an insert 6 is utilized that functions to reduce the dead volume by occupying most of the volume. In practical cases, the insert 6 has a tube system 12 for transporting liquid from the liquid conduit 2 of the flow-through heater to the outlet 10 of the insert 6. Preferably, the volume of such a liquid conduit system 12 is relatively small so that the presence of the tubing 12 in the insert 6 does not impair the dead volume reduction effect due to the use of the insert 6.

Description

  The present invention is an apparatus for heating a liquid, comprising a liquid conduit for carrying the liquid, and a heating means for heating the liquid while the liquid flows through the liquid conduit. And means for detecting the temperature of the liquid at the outlet of the flow-through heater, the means being part of a device for controlling the temperature of the liquid at the outlet of the flow-through heater, It is related with the device which has.

  The invention further relates to a method for improving the accuracy of controlling the temperature of the liquid at the outlet of the flow-through heater.

  In many types of devices, there is a need for a means capable of heating a certain amount of liquid to be utilized during operation of the device. For example, in an apparatus suitable for making warm coffee, an amount of water is heated before being passed through an amount of ground coffee beans.

  For the purpose of heating liquids such as water, many devices use a boiler, a container for storing a quantity of liquid, and heating that is associated with the container and serves to heat the liquid present in the container. And a device having means. As soon as the temperature of the liquid reaches the desired level, the liquid is removed from the boiler and used for the intended purpose.

  However, the use of boilers has some significant drawbacks and therefore alternative methods for heating liquids have been developed. The method includes the use of a flow through heater, ie a device having a conduit for carrying the liquid and a means for heating the liquid while flowing through the conduit. In a practical embodiment of the flow-through heater, an electric heating element is arranged around the liquid conduit. Some important advantages of using a flow-through heater are that the liquid heating process is performed almost immediately, has little latency, requires less energy than using a boiler, and flow-through The heater is suitable not only for use as a boiler replacement, but also in high pressure systems such as espresso machines.

  For the purpose of controlling the temperature of the liquid at the outlet of the flow-through heater, a feedback control loop is likely to be used. In practice, however, it is considered difficult or even impossible to meet the high requirements regarding outlet temperature as described above. In other words, it would be difficult or even impossible to control the operation of the flow-through heater based on outlet temperature detection in a sufficiently accurate manner.

  An object of the present invention is to optimize a feedback control loop in an apparatus having a flow-through heater and a feedback control loop for controlling outlet temperature. The purpose is an insertion tool partially inserted into the liquid conduit of the flow-through heater on the outlet side of the flow-through heater, which is located in the liquid conduit of the flow-through heater This is accomplished by providing an insert that occupies at least a substantial portion of the space present in the portion of the liquid conduit that is not directly associated with the heating means of the flow-through heater.

  According to the insight behind the present invention, the difficulty of controlling the outlet temperature is caused by delays in the feedback process associated with the normal design of the flow-through heater. In particular, in this design, the liquid conduit and the heating element are arranged so that the conduit projects over a length with respect to the heating element at both the inlet and outlet sides of the flow-through heater. Is done. Therefore, when the temperature of the liquid is detected at the outlet of the flow-through heater, i.e. actually the outlet of the conduit, the length of the conduit that is not directly related to the heating element is reached before reaching the location where the detection takes place. There is a delay caused by the fact that the liquid passes first. Hereinafter, this phenomenon is referred to as the presence of dead volume in the flow-through heater, and the portion of the conduit that is not directly related to the heating element is referred to as the ineffective portion of the flow-through heater.

  Note that with respect to dead volume and associated delay time, the larger the dead volume, the more difficult it is to achieve the desired average outlet temperature in all environments. This is particularly evident when the dead volume is significant relative to the total volume of the flow-through heater, which is the case with flow-through heaters suitable for use in, for example, espresso devices. In general, the longer the delay time, the slower the response of the feedback control loop, and the instability appears earlier. Therefore, longer delay times result in constraints on the availability of flow-through heaters. For example, since use in an espresso device requires a fast response feedback control loop, such use is practically impossible.

  In many applications, it is important to have the lowest possible manufacturing cost. Therefore, in many cases, changing the design of the flow-through heater to solve the problems outlined above is a viable option. Instead, other solutions based on the assumption that conventional flow-through heaters are utilized are also required. The present invention is an insertion tool partially inserted into the liquid conduit of the flow-through heater on the outlet side of the flow-through heater, and is located in the liquid conduit of the flow-through heater. Such a solution is provided by proposing the use of an inserter in which the portion of the inserter occupies at least a significant portion of the dead volume.

  When the insert according to the invention is utilized, it is achieved that the dead volume is significantly reduced. This is due to the fact that the portion of the insert located within the liquid conduit of the flow-through heater fills the dead volume. In many practical cases, the portion of the insert is longer than required to keep the insert in place in the liquid conduit, as viewed in the direction of liquid flow in the flow-through heater.

  Due to the reduction in dead volume achieved by using the insert described above, the delay time in detecting the liquid outlet temperature is significantly reduced, and as an advantageous result, the control of the outlet temperature is more effective. And can be performed accurately. According to the present invention, in order to achieve such advantageous results, no change in the design of the flow-through heater is required, no upgrade of the components utilized in the temperature control process is required, and a simple addition It only requires the use of a typical component, i.e. an insertion tool.

  In order to reduce the dead volume of the ineffective part of the flow-through heater as much as possible and to achieve a stable placement of the inserter in the conduit, the inner surface of the liquid conduit of the flow-through heater and the liquid conduit It is preferred that there is little play between the outer surface of the part of the inserter located at the position.

  In practical cases, the insert has a liquid conduit system for transporting liquid from the liquid conduit of the flow-through heater to the outlet of the insert. In this case, the tube of the liquid conduit system of the insert functions to carry liquid through the ineffective portion of the flow-through heater. Preferably, the diameter of the tube of the liquid conduit system is substantially smaller than the diameter of the liquid conduit of the flow-through heater at the outlet of the flow-through heater, so that the volume of the tube is flow-through heated. The volume of the ineffective portion of the vessel becomes considerably smaller, and the dead volume reduction effect by using the insertion tool can be optimized.

  The insert according to the present invention may have a tube extending from the outer surface of the insert to the liquid conduit system at a portion of the insert located outside the liquid conduit of the flow-through heater, A means for detecting the temperature of the liquid at the outlet of the flow-through heater is associated with the tube. Preferably, the tube is arranged as close as possible to the end of the liquid conduit of the flow-through heater so that the detection of the outlet temperature takes place as close as possible to the end of the liquid conduit. In other words, even with a relatively small dead volume, the length of the dead volume is kept to a minimum.

  Note that with respect to a liquid conduit system that may be part of the insert, the conduit system may have at least two conduits oriented at an angle relative to each other. In an advantageous design, the tube system has at least one inlet tube for introducing liquid into the conduit system, the at least one inlet tube being substantially perpendicular to the liquid flow direction in the flow-through heater. Having an orientation and extending from one side of the insertion tool to the other, the liquid conduit system further comprising an outlet tube for discharging liquid from the liquid conduit system, the outlet tube comprising: The at least one inlet pipe and the outlet pipe are connected to each other with a substantially horizontal orientation in the flow direction of the liquid in the flow-through heater.

  Utilizes the liquid conduit system design of the insert, wherein at least one inlet tube is oriented at an angle with respect to the outlet tube, and the inlet tube extends from one side of the insert to the other. The advantage is that a situation where liquid remains at the outlet of the insert is prevented. The inlet tube functions as a kind of shortcut, and liquid cannot reach the outlet of the insertion tool unless suction and / or pushing force is applied. Furthermore, if the concept of having an angle between the inlet tube and the outlet tube is utilized, it is possible to create different inlet passages so that the mixing of the liquid at the inlet tube connection Realized and results in more accurate temperature detection.

  In a practical embodiment, in particular in an embodiment where the insert has a liquid conduit system, the device according to the invention comprises an outer surface of the part of the insert located in the liquid conduit of the flow-through heater and There may be further provided means for sealing a space between the inner surface of the liquid conduit. By utilizing suitable sealing means, liquid leakage from the liquid conduit through the (narrow) space between the outer surface of the insert and the outer surface of the conduit is prevented. Of course, the sealing means, which may have an O-ring or the like, is located behind the inlet of the liquid conduit of the insert as viewed in the direction of liquid flow in the flow-through heater.

  Many of the above-described aspects of the invention are from an insert when considered separately. In this case, these aspects are described as follows.

The insert is generally an insert intended for use in an apparatus for heating a liquid as described above,
An end suitable for insertion into a conduit for carrying a liquid, in particular a liquid conduit which is part of a flow-through heater further comprising means for heating the liquid flowing through the conduit;
A conduit system for transporting liquid through the insert, wherein the diameter of the tube of the liquid conduit system is significantly smaller than the outer diameter of the end;
Is described as an inserter.

  In the insert according to the invention, it is advantageous if the liquid conduit system has at least two tubes oriented at an angle to each other. Preferably, in this case, the liquid conduit system has at least one tube for introducing liquid into the tube system, the at least one inlet tube being in the axial direction of the inserter, ie the long axis of the inserter Extending from one side of the inserter to the other, the system further comprising a tube for draining liquid from the tube system, the outlet tube comprising the The at least one inlet pipe and the outlet pipe are connected to each other and oriented substantially horizontally in the axial direction of the insertion tool.

  For the purpose of enabling temperature detection of the liquid in the insert, the insert is further separated from the end suitable for being inserted into a conduit for carrying liquid. It is advantageous if it has a tube extending from the outer surface of the insert to the liquid conduit system.

  Sealing means suitably utilized to prevent liquid leakage from the liquid conduit of the flow-through heater may be provided as a component of the insert. In such a case, the insert further comprises means such as an O-ring suitable for being used to seal the space between the two surfaces, which sealing means Located at the end suitable for insertion into a conduit for carrying.

  In addition to the apparatus for heating a liquid described above, the present invention also includes a liquid conduit for carrying the liquid, and heating means for heating the liquid while the liquid flows through the liquid conduit. A method for improving the accuracy of controlling the temperature of the liquid at the outlet of the flow-through heater, the liquid conduit of the flow-through heater not directly related to the heating means of the flow-through heater At least a substantial portion of the space present in the portion of the flow path is provided with an insert and is filled by introducing at least a portion of the insert into the liquid conduit of the flow-through heater on the outlet side of the flow-through heater. Provide a method.

  Preferably, when the method according to the invention is carried out, there is little play between the inner surface of the liquid conduit of the flow-through heater and the outer surface of the part of the insert inserted into the liquid conduit. Not allowed.

  The insert used when the method according to the invention is carried out is an insert as defined above, if the reduction of dead volume is achieved by occupying the volume and the flow of liquid is not interrupted. It may be any other suitable insertion tool.

  The above-described aspects and other aspects of the invention will be apparent from and will be elucidated with reference to the following detailed description of embodiments of inserts according to the invention.

  The present invention will now be described in more detail with reference to the drawings, wherein like or similar parts are indicated by the same reference symbols.

A flow through heater is shown typically. 1 schematically shows a part of a flow-through heater and an insert according to the present invention. Figure 3 shows a longitudinal cross section of the end of the liquid conduit of the flow-through heater and the insert. Figure 3 shows a longitudinal cross section of the end of the liquid conduit of the flow-through heater and the insert.

  FIG. 1 schematically shows a flow-through heater 1 known in the art. In general, the flow-through heater 1 has a conduit 2 for transporting liquid and a heating element 3 arranged to surround the liquid conduit 2 in close proximity. In most cases, the cross section of the liquid conduit has a circular shape, but this does not overturn the fact that other shapes can be used.

  In FIG. 1 it can clearly be seen that the entire length of the liquid conduit 2 is not covered by the heating element 3. On either the inlet side or the outlet side of the flow-through heater 1, the location 4 of the liquid conduit 2 is not directly related to the heating element 3. These locations 4 are referred to as ineffective portions 4 of the flow-through heater 1.

  During operation of the flow-through heater 1, a liquid such as water is flowed through the liquid conduit 2 and the heating element 3 is operated to supply heat to the liquid to achieve an increase in the temperature of the liquid. . Three important factors for achieving the desired temperature of the liquid at the outlet 5 of the flow-through heater 1 are the initial temperature of the liquid, the flow rate, and the supply of heat. Check whether the actual outlet temperature of the liquid is within the desired range and whether parameters of the flow-through heating process such as power supply to the heating element 3 of the flow-through heater 1 should be adjusted It is common practice to provide a feedback control loop to determine the outlet temperature, where the outlet temperature is detected and utilized as a basis for possible adjustments. However, due to the presence of the ineffective portion 4 at the outlet of the liquid conduit 2 of the flow-through heater 1, there is a delay in the feedback control loop, which adversely affects the accuracy of the temperature accuracy process.

The delay in the feedback control loop is directly related to the volume of the ineffective portion 4 at the outlet of the flow-through heater 1, which volume is called the dead volume. For example, if the ineffective portion 4 has a length of 2 cm, the inner diameter of the liquid conduit 2 is 1 cm, the flow rate is 5 ml / s, and the outlet temperature is detected at the outlet 5 of the flow-through heater 1, the delay time Is considered to be 0.314 s. This value is obtained by determining the dead volume and dividing the dead volume by the flow rate. The dead volume is π * r ² * l = π * 0.5 ² * 2 = 1.57 ml, where r represents the inner radius of the liquid conduit 2 and l is the ineffective portion 4 of the flow-through heater 1. Represents the length of. Therefore, the delay time is 1.57 / 5 = 0.314 s. For example, for applications related to making espresso, the dead volume of 1.57 ml is large compared to the total volume. Therefore, in such a case, the dead volume has a considerable influence on the final temperature of the beverage.

  In order to minimize the delay in the feedback control loop, the present invention proposes means to make the dead volume as small as possible. These means include the use of an insert 6 that is partially inserted into the liquid conduit 2 of the flow-through heater 1, as shown in FIG. 2, in which the insert 6 is shown in broken lines. Furthermore, FIG. 2 shows a suitable position of the temperature sensor 7, which is the part of the insert 6 just outside the flow-through heater 1. The insert 6 is preferably designed to remove as much dead volume as possible and at the same time allow the required liquid flow rate. The design of the insert 6 will be further described with reference to FIGS. 3 and 4, in which the longitudinal portion of the insert 6 and the liquid conduit 2 of the flow-through heater 1 in which the insert 6 has been partially inserted. Some are shown.

  The example of the insert 6 shown in FIGS. 3 and 4 has three parts. The first part 8 is an end suitable for being placed in the ineffective part 4 of the flow-through heater 1. Therefore, the outer diameter of the end 8 is smaller than the inner diameter of the liquid conduit 2 of the flow-through heater 1. The second part 9 is the other end for enabling connection to an insertion tool 6 such as a hose and has an outlet 10 for liquid as a free end. The third part 11 is an intermediate part intended to be configured to abut the end of the liquid conduit 2 of the flow-through heater 1. Therefore, the outer diameter of the intermediate portion 11 is larger than the inner diameter of the liquid conduit 2 of the flow-through heater 1.

  In the insertion tool 6, a tube system 12 is arranged for carrying liquid through the insertion tool 6. On the inlet side, i.e., the side closest to the flow-through heater 1, the tube system 12 has two tubes extending in the radial direction of the insert 6, i.e. in the direction perpendicular to the liquid flow direction of the flow-through heater 1. 13a and 13b. These tubes 13a, 13b serve to put liquid into the insert 6 and carry the liquid to a central position in the insert 6 where the tubes 13a, 13b intersect. An outlet tube 14 is present in the insertion tool 6 extending from that position to the outlet of the insertion tool 6. Note that for the sake of completeness, the liquid flow direction in the flow-through heater 1 is indicated by arrows in the figure.

  It will be apparent that designs other than those described above for the liquid conduit system 12 of the insert 6 are possible within the scope of the present invention. For example, there may be a single central tube that extends through the insert 6. However, the configuration provided with the inlet pipes 13a and 13b oriented in the radial direction can avoid a situation in which the liquid remains unrefreshed on the outlet side of the insertion tool 6 when the configuration is implemented. Is preferable. This is important in view of the fact that the remaining liquid can be a source of bacterial growth. Furthermore, by mixing liquid from various sides of the insertion tool 6, mixing of the liquid is realized, contributing to smooth temperature detection.

  In addition to the tubes 13a, 13b, 14 for transporting the liquid, the insert 6 is also provided with one or more components or component parts (see FIGS. 3 and 4) to be utilized in the process of detecting the liquid outlet temperature. (Not shown) has a tube 15 for receiving. Hereinafter, the tube 15 is referred to as a detection tube 15. The detection tube 15 is arranged in the intermediate part 11 of the insertion tool 6 and allows free access to the liquid flowing through the detection component outlet tube 14 from the outer surface of the insertion tool 6 to the outlet tube 14. Extend to. In the illustrated example, the detection tube 15 has a radial direction in the insertion tool 6 like the inlet tubes 13a and 13b.

  For the purpose of preventing leakage of liquid from the liquid conduit 2 of the flow-through heater 1, the inner surface of the conduit 2 and the inner surface of the insertion tool 6 are located behind the position where the inlet tubes 13a, 13b of the insertion tool 6 are disposed. Sealing means is disposed between the outer surface. Any suitable type of sealing means may be utilized within the scope of the present invention. In the illustrated example, the sealing means has an O-ring 16 that is received in a groove disposed on the outer surface of the insertion tool 6.

  3 and 4 show that the size of the end 8 of the insert 6 suitable for being placed in the ineffective part 4 of the flow-through heater 1 is such that the insert 6 is in the proper position. It is shown that a minimum space is selected between the outer surface of the part 8 of the tool 6 and the inner surface of the liquid conduit 2 of the flow-through heater 1. Overall, when the insert 6 is placed on the outlet side of the flow-through heater 1, most of the volume of the ineffective portion of the flow-through heater 1 is filled, causing the delay in detecting the liquid outlet temperature. Is the space existing between the outer surface of the inserted part 8 and the inner surface of the liquid conduit 2 of the flow-through heater 1, the volume of the inlet tubes 13a, 13b of the insert 6 and the inlet tubes 13a, 13b. This is only the volume which is the sum of the volumes of the outlet pipe 14 between the connection portion of this and the position of the detection pipe 15.

  The diameter of the tubes 13a, 13b, 14 of the liquid conduit system 12 of the insert 6 is considerably smaller than the diameter of the liquid conduit 2 of the flow-through heater 1 on the outlet side of the flow-through heater 1, so that the dead volume is actually It is most advantageous if it is as small as possible. By reducing the dead volume of the ineffective portion 4 of the flow-through heater 1, the present invention enables an improved method of controlling the outlet temperature, resulting in the superior performance of the apparatus to which the present invention is applied. Examples of such devices that are worth mentioning here are various types of coffee and espresso devices, including drip filter types and pad processing types, and beverage making devices such as infant milk devices.

  During the manufacturing process of the device to which the present invention is applied, a conventional flow-through heater 1 is provided, and the dead volume at the outlet side of the flow-through heater 1 is provided with the insert 6 according to the present invention, and the flow-through heating. This is reduced by introducing the end 8 of the insert 6 into the liquid conduit 2 of the vessel 1.

  The scope of the invention is not limited to the examples discussed above, and several variations and modifications of the invention are possible without departing from the scope of the invention as defined in the appended claims. It will be apparent to those skilled in the art. While the invention has been illustrated and described in the drawings and foregoing description, such description and description are to be considered illustrative or exemplary and not restrictive; The invention is not limited to the disclosed embodiments.

  Variations to the disclosed embodiments can be understood and implemented by those skilled in the art implementing the claimed invention upon reading the drawings, the description and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the claim.

  The present invention is summarized as follows. In a general design flow-through heater, an effective part and two ineffective parts located at the end of the flow-through heater 1 are recognized, the ineffective part 4 being the liquid conduit 2 of the flow-through heater 1. However, this is a portion not directly related to the heating means 3 of the flow-through heater 1. When feedback loop control is used to control the temperature of the liquid at the outlet 5 of the flow-through heater 1, the volume of the ineffective portion 4 at the outlet 5 constitutes a dead volume that causes a delay in the feedback process, and temperature control Results in instability and inaccuracy. In order to prevent this, the delay should be minimized. It is therefore desirable to detect the outlet temperature as soon as possible after the effective part of the flow-through heater 1 in the direction of liquid flow in the flow-through heater 1. This is achieved by utilizing an insert that reduces the dead volume by occupying most of the volume. In practical cases, the insert 6 has a tube system 12 for transporting liquid from the liquid conduit 2 of the flow-through heater 1 to the outlet 10 of the insert 6. Preferably, in such a case, the diameter of the tubes 13a, 13b, 14 of the liquid conduit system 12 is considerably smaller than the diameter of the liquid conduit 2 of the flow-through heater 1 at the outlet 5 of the flow-through heater 1, As a result, the volume of the liquid conduit system 12 becomes relatively small, and the presence of the tube system 12 in the insertion tool 6 does not impair the effect of reducing the dead volume by using the insertion tool 6.

Claims (9)

An apparatus for heating a liquid,
A flow-through heater having a liquid conduit for carrying liquid and heating means for heating the liquid while the liquid flows through the liquid conduit;
Means for detecting the temperature of the liquid at the outlet of the flow-through heater, the means being part of an apparatus for controlling the temperature of the liquid at the outlet of the flow-through heater;
An insertion tool partially inserted into the liquid conduit of the flow-through heater on the outlet side of the flow-through heater, wherein the insertion tool is located in the liquid conduit of the flow-through heater. An insert that occupies at least a substantial portion of the space present in the portion of the liquid conduit that is not directly associated with the heating means of the flow-through heater;
Having a device.   The apparatus of claim 1, wherein there is little play between the inner surface of the liquid conduit of the flow-through heater and the outer surface of the portion of the insert located within the liquid conduit.   The insert has a liquid conduit system for transporting liquid from the liquid conduit of the flow-through heater to the outlet of the insert, and the diameter of the tube of the liquid conduit system is that of the flow-through heater The apparatus of claim 1, wherein the apparatus is substantially smaller than the diameter of the liquid conduit of the flow-through heater at the outlet.   4. The apparatus of claim 3, wherein the liquid conduit system of the insert has at least two tubes that are oriented at an angle with respect to each other.   The liquid conduit system of the insert has at least one inlet tube for introducing liquid into the liquid conduit system, the at least one inlet tube being substantially perpendicular to the liquid flow direction in the flow-through heater. Extending from one side of the insertion tool to the other, the liquid conduit system further comprising an outlet tube for discharging liquid from the liquid conduit system, the outlet tube comprising: The apparatus according to claim 4, wherein the apparatus has a substantially horizontal orientation in a flow direction of liquid in the flow-through heater, and the at least one inlet pipe and the outlet pipe are connected to each other.   The insert further comprises a tube extending from an outer surface of the insert to the liquid conduit system at a portion of the insert located outside the liquid conduit of the flow-through heater, the flow-through heating 4. The apparatus of claim 3, wherein the means for detecting the temperature of the liquid at the outlet of the vessel is associated with the tube.   4. The apparatus of claim 3, further comprising means for sealing a space between an outer surface of the portion of the insert located in the liquid conduit of the flow-through heater and an inner surface of the liquid conduit. .   Improve the accuracy of controlling the temperature of the liquid at the outlet of the flow-through heater having a liquid conduit for carrying the liquid and heating means for heating the liquid while the liquid flows through the liquid conduit For at least a substantial portion of the space present in the portion of the liquid conduit of the flow-through heater not directly associated with the heating means of the flow-through heater comprises an insert, and the flow A method of filling by introducing at least a portion of the insert into the liquid conduit of the flow-through heater on the outlet side of the through-heater.   9. The method of claim 8, wherein only a slight play is allowed between the inner surface of the liquid conduit of the flow-through heater and the outer surface of the portion of the insert inserted into the liquid conduit.

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