Instantaneous water heater and this comprehensive electronic decentralized water heater

Abstract

A continuous flow heater (10) comprising an inlet connection (12) for connecting the instantaneous water heater (10) to a cold water supply, an outlet connection (14) for connecting the instantaneous water heater (10) to a fitting, a fluid channel (16) which ensures a fluid connection from the inlet connection (12) to the outlet connection (14), a heating element arrangement (2) arranged on or in at least one segment of the fluid channel (16) for transferring heat to the fluid in the fluid channel (16), an electronic controller (6) for controlling the heating power provided by the heating element arrangement (2), wherein the instantaneous water heater (10) further comprises: a flow sensor (1) arranged on or in the fluid channel (16) behind the heating element arrangement (2), wherein the electronic controller (6) is configured to detect the presence of air bubbles in the fluid channel (16) based on a change in a flow signal provided by the flow sensor (1) and to adjust the heating power provided to the heating element arrangement (2) in response to the detection of air bubbles, wherein the electronic controller (6) is configured to delay the onset of the provision of heating power to the heating element arrangement (2) after the flow signal indicates the start of a dispensing operation.

Description

BackgroundPrior ArtThe present invention relates to a continuous flow heater and an electronic distributed water heater comprising the continuous flow heater.Description of Related ArtContinuous flow heaters are well known for residential and industrial applications. Air bubbles in the fluid channel in the continuous flow heaters can lead to overheating of heating elements, which leads to damage to the continuous flow heater or even to a fire due to overheating.Continuous flow heaters with an air detection system to avoid overheating are known, for example, from DE 197 25 977 C2 or DE 43 03 325 A1.DE 43 03 325 A1 describes a continuous flow heater having two separate flow meters, one flow meter being arranged in front of a heating element in the vicinity of the cold end and the other flow meter being arranged behind the heating element at the warm end. A simultaneous change in the flow signals determined by each flow sensor is detected as air bubbles in the water supply line of a continuous-flow heater.DE 197 25 977 C2 discloses that air bubbles in the water supply of the heater lead to a lower rotational speed of an impeller compared to a pure water supply without air bubbles. The characteristic frequency pattern of the instantaneous rate of change of the rotational speed of the impeller is used for detecting air bubbles with the aid of a detection and evaluation circuit.Document DE 10 2016 013 052 A1 shows a continuous flow heater which comprises a bare wire heating element which is connected to an electronic temperature control system.DE 10 2008 011 117 A1 describes a device for detecting air bubbles in a heating device through which fluid flows, having at least one heating element, having at least one flow meter which detects the flow rate of the fluid by means of pulse signals, and having at least one control circuit which evaluates the pulse signals of the flow meter.In the known applications, the flow sensor is arranged in the cold water supply, so that a reliable detection of air bubbles flowing into the continuous heater is possible. However, since a certain amount of air is dissolved in the water flowing into the continuous flow heater, for example, the drinking water supply, the air escapes from the water as soon as the water is heated in a heating chamber of a water heater system, for example, a continuous flow heater.If a plurality of heating elements are arranged in series in an arrangement of a plurality of heating elements, water contaminated with air is supplied at least to the last heating element at the rear in the heating element arrangement on account of the upstream heating process. As a result, the subject heating element is not properly cooled and is likely to overheat due to the air contamination.It was therefore an object of the present invention to provide a continuous flow heater and an electronic decentral water heater which enables reliable detection of air bubbles in the fluid channel, irrespective of their origin, i.e. irrespective of whether they originate from the cold water supply or occur on the warm side of the heating chamber due to the heating process.Summary of the InventionAccording to a first aspect, a continuous flow heater is provided. The continuous flow heater comprises an inflow connection for connecting the continuous flow heater to a cold water connection, an outflow connection for connecting the continuous flow heater to a fitting, a fluid channel which ensures a fluid connection from the inflow connection to the outflow connection, a heating element arrangement which is arranged on or in at least one segment of the fluid channel for transferring heat to the fluid located in the fluid channel, and an electronic regulator for regulating the heating power provided by the heating element arrangement. The continuous flow heater also includes a flow sensor disposed on or within the fluid channel behind the heater assembly, wherein the electronic controller is configured to detect the presence of air bubbles within the fluid channel based on a change in a flow signal provided by the flow sensor and adjust the heating power provided to the heater assembly in response to the detection of air bubbles.Since the flow sensor is arranged behind the heating element arrangement, the flow sensor detects both air bubbles which flow into the continuous heater through the cold water supply and air bubbles which arise due to the heating by the heating element arrangement. In comparison with previously known solutions, it is thus also possible to detect air bubbles which are generated by the heating element arrangement. Moreover, reliable detection can be achieved with a single flow sensor, so that the overall system complexity is reduced. For this purpose, a fine evaluation of a change in the flow signal provided by the single flow sensor by the electronic regulator enables an efficient detection of the presence of air bubbles.The heating element arrangement preferably comprises a plurality of heating elements arranged at least partially in series with respect to the fluid channel. Downstream heating elements thus receive a fluid stream with a higher temperature as compared to heating elements arranged further forward by the heating power transmitted from the upstream heating elements to the fluid stream. Downstream heating elements are more likely to be exposed to air bubbles in the fluid channel.Some of the plurality of heating elements are also preferably arranged in parallel to maximize heat transfer to the fluid by dividing the stream into parallel channels.In a preferred embodiment, the continuous flow heater further comprises a first temperature sensor configured to sense the temperature of a fluid in the fluid channel upstream of the heater assembly and a second temperature sensor configured to sense the temperature of a fluid in the fluid channel downstream of the heater assembly.The provision of two temperature sensors enables efficient regulation of the continuous flow heater by the electronic regulator in order to achieve a desired setpoint value at the outflow connection.In a preferred embodiment, the second temperature sensor is arranged between the flow sensor and the heating element arrangement with respect to the fluid channel.In a preferred embodiment, the electronic controller comprises a setpoint monitoring device configured to adjust the heating power provided to the heating element arrangement based on a difference between the temperature determined by the second temperature sensor and a predefined setpoint temperature.In a preferred embodiment, the continuous flow heater further comprises a throttle valve, wherein the set point monitoring device is configured to decrease the flow rate using the throttle valve when a predetermined set point temperature is not reached.In a preferred embodiment, the setpoint monitoring device is configured to adjust the flow rate in response to the temperature determined by the first temperature sensor using the throttle valve. The reduction in the flow rate is particularly advantageous if, for example, the first temperature sensor detects a low inflow temperature, so that the temperature increase that should be generated by the heating power of the heating element arrangement would exceed the maximum power of the heating element arrangement in the case of a higher, i.e. not reduced flow rate.In a preferred embodiment, at least the flow sensor, the fluid channel, the heating element arrangement and the electronic regulator are arranged in a housing.In a preferred embodiment, the flow sensor comprises an impeller, wherein the flow signal indicates a rotational speed of the impeller. A higher rotational speed of the impeller corresponds to a greater fluid flow, while air bubbles in the fluid channel reduce the rotational speed of the impeller and thus the flow signal provided.In a preferred embodiment, the electronic controller is configured to delay the onset of providing heating power to the heater assembly after the flow signal indicates the beginning of a draw operation. This makes it possible to prevent overheating at the beginning of a removal process owing to air bubbles already present at the location of the heating elements.In a preferred embodiment, the electronic controller is configured to stop providing heating power to the heater assembly when a change in the flow signal is indicative of the presence of air bubbles. Air bubbles in the fluid channel are hazardous to the continuous flow heater since they lead to overheating at some time. Thus, since the heating is stopped upon detection of air in the air passage, overheating can be reliably prevented.In a preferred embodiment, the electronic controller is configured to detect the presence of air bubbles in the fluid channel by analysis of the characteristic frequency pattern of the flow signal provided by the flow sensor. The change of the flow signal by the change between the flow of liquid, i.e. generally water, and air at the flow sensor leads to a change of the flow signal with a characteristic frequency pattern which can be evaluated for detecting whether or not air is present.According to a further aspect, an electronically controlled decentral water heater is provided. The electronically controlled distributed water heater includes the continuous flow heater according to the first aspect.Brief Description of the Various Views of the DrawingsThe invention will be described in more detail below with reference to exemplary embodiments with reference to the attached figures. FIG. 1 shows schematically and by way of example a continuous flow heater according to the invention.DETAILED DESCRIPTIONFIG. 1 shows schematically and by way of example a continuous flow heater 10 according to one embodiment of the present invention. The continuous flow heater 10 comprises in this example an optional housing 20, in which a fluid channel 16 runs from an inflow connection 12 to be connected to the cold water connection to an outflow connection 14 to be connected, for example, to a fitting or another point of consumption at which warm or hot water is desired.The fluid channel 16 is arranged on its path through the continuous heater 10 such that it comes into contact with a heating element arrangement 2 which comprises a plurality of heating elements for transferring thermal energy, in particular electrical thermal energy, to the water in the fluid channel 16.An individual flow sensor 1 is arranged on the warm side behind the heating element arrangement on or in the fluid channel 16. Several different flow sensors 1 for providing a flow signal indicative of a flow through fluid channel 16 are known, preferably flow sensor 1 comprises an impeller and provides a signal indicative of a rotational speed of the impeller.Flow sensor 1 is arranged downstream in order to detect air bubbles in fluid channel 16 due to air contamination of the incoming water, i.e. water which reaches continuous heater 10 through inflow connection 12, and air bubbles which are produced by the solvent evaporation.The temperature range of the water flowing out of the outflow port 14 is preferably between 40° C. and 100° C., more preferably between 60° C. and 95° C.A first temperature sensor 3 and a second temperature sensor 4 are connected upstream and downstream of the heating element arrangement 2. Temperature sensor 3 measures the water inflow side and temperature sensor 4 the water outflow side after heating the water by the heating element arrangement 2. additionally a throttle valve 5 is arranged on the cold or water inflow side and can be used for adjusting the flow through fluid channel 16. While throttle valve 5 is shown on the cold water side, it is of course contemplated to provide throttle valve 5 on the hot or hot water side since the flow through fluid passage 16 is the same throughout the continuous heater 10.In addition, an electronic controller 6 is provided which is configured to control the heating power of the heating element arrangement 2 such that the temperature measured by temperature sensor 4 is close to the setpoint temperature, which is preferably determined by a setpoint monitoring device 7, which can be integrated into the electronic controller 6. If the available heating power is not sufficient for satisfactory heating of the water to the desired desired setpoint temperature, the water flow can be reduced by means of throttle valve 5, so that the available heating power is then sufficient. This is the case, for example, when the temperature of the supplied water is low or the set target temperature is high.All sensor elements 1, 3 and 4 and the throttle valve 5 are shown to be connected to the electronic controller 6 via a wire 8. Of course, it is contemplated that one, more, or all of the sensing elements may communicate with the electronic controller 6 in another manner, such as wirelessly.Continuous flow heater 10 begins to heat up, more precisely electronic controller 6 supplies energy to heating element arrangement 2 when flow sensor 1 detects a removal process, with delay, in order to prevent heating element arrangement 2 from overheating. The delay serves to ensure that no residual air bubbles remain in a heating chamber, i.e. in the region of fluid channel 16 in which water from heating element arrangement 2 can be heated.In addition, when controller 6 detects air bubbles based on the sensor signals from flow sensor 1, the heating is stopped. Air bubbles can be detected from a momentary rate of change of the rotational speed of the impeller of flow sensor 1. Additionally or alternatively, an analysis of the characteristic frequency pattern of the flow sensor signal is used for evaluation by electronic controller 6.List of reference numbers:1 Flow sensor 2 Heating element arrangement 3 Temperature sensor 4 Temperature sensor 5 Throttle valve 6 Electronic controller 7 Setpoint monitoring device 8 Wire 10 Continuous heater 12 Inflow connection 14 Outflow connection 16 Fluid channel 20 Housing

Claims

A continuous flow heater (10) comprising an inflow port (12) for connecting the continuous flow heater (10) to a cold water supply, an outflow port (14) for connecting the continuous flow heater (10) to an armature, a fluid channel (16) which ensures a fluid connection from the inflow port (12) to the outflow port (14), a heating element arrangement (2) which is arranged on or in at least one segment of the fluid channel (16), for transferring heat to the fluid located in the fluid channel (16), an electronic regulator (6) for regulating heating power provided by the heating element arrangement (2), wherein the continuous flow heater (10) further comprises: a flow sensor (1) which is arranged on or in the fluid channel (16) behind the heating element arrangement (2), wherein the electronic regulator (6) is configured such that, detecting the presence of air bubbles in the fluid channel (16) based on a change in a flow signal provided by the flow sensor (1) and adjusting the heating power provided to the heating element arrangement (2) in response to the detection of air bubbles, wherein the electronic controller (6) is configured to delay the onset of the provision of heating power to the heating element arrangement (2) after the flow signal indicates the beginning of a removal process.The continuous flow heater (10) of claim 1, further comprising: a first temperature sensor (3) configured to detect the temperature of a fluid in the fluid channel (16) upstream of the heater assembly (2); and a second temperature sensor (4) configured to detect the temperature of a fluid in the fluid channel (16) downstream of the heater assembly (2).The continuous flow heater (10) according to claim 2, wherein the second temperature sensor (4) is arranged between the flow sensor (1) and the heating element arrangement (2) with respect to the fluid channel (16).The continuous flow heater (10) according to claim 2 or 3, wherein the electronic controller (6) comprises a set point monitoring device (7) configured to adjust the heating power provided to the heating element arrangement (2) based on a difference between the temperature determined by the second temperature sensor 4) and a preset set point temperature.The continuous flow heater (10) according to claim 4, further comprising: a throttle valve (5), wherein the target monitoring device (7) is configured to decrease the flow rate using the throttle valve (5) when a predetermined target temperature is not reached.The continuous flow heater (10) according to claim 5, wherein the set point monitoring device (7) is configured to adjust the flow rate of the throttle valve (5) in response to the temperature detected by the first temperature sensor (3), for example, when the first temperature sensor (3) detects a very low inflow temperature.The continuous flow heater (10) according to any one of the preceding claims, wherein at least the flow sensor (1), the fluid channel (16), the heating element arrangement (2) and the electronic regulator (6) are arranged in a housing (20).The continuous flow heater (10) according to any of the preceding claims, wherein the flow sensor (1) comprises an impeller, wherein the flow signal is indicative of a rotational speed of the impeller.The continuous flow heater (10) according to any of the preceding claims, wherein the electronic controller (6) is configured to stop the provision of heating power to the heater assembly (2) when a change in the flow signal indicates the presence of air bubbles.The continuous flow heater (10) according to any one of the preceding claims, wherein the electronic controller (6) is configured to detect the presence of air bubbles in the fluid channel (16) by means of an analysis of the characteristic frequency pattern of the flow signal provided by the flow sensor (1).Electronically controlled decentral water heater, characterised in that it comprises the continuous flow heater (10) according to any one of the preceding claims.

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