EP1686329A2 - Apparatus for heating water - Google Patents

Abstract

The apparatus has a heater (5) having an inlet and outlet (2, 3) and a heating stage (4) with water provided by the inlet warmed to a first and second temperature T1, T2. The temperature of water per unit time flowing through the heater is measured (8). The measuring instrument produces an electrical signal representing the information about flow of water. An electronic control unit (9) controls the supplied amount of heat by a discrete switching status, so that for a first flow interval a first switching status is provided and for further flow intervals further switching status is provided.

Description

The present invention relates to a device for preparing hot water. In particular, the present invention relates to a domestic water heater in which the control of the amount of heat supplied to the water to be heated by an electronic control device based on the amount of water flowing through the water heater.

In known instantaneous water heaters according to the prior art, the amount of heat supplied to the water flowing through the instantaneous water heater is regulated as a function of the temperature of the water flowing out of the instantaneous water heater and the drawn hot water quantity, that is to say on the hot water side. These are so-called electronic instantaneous water heaters.

In this case, when falling below a predetermined target temperature by an electronic control device, the energy supplied to the heater - and thus the amount of heat released to the water - continuously up-regulated until the temperature of the water leaving the water heater reaches the set temperature. Likewise, when the setpoint temperature is exceeded by the electronic control device, the energy supplied to the heating device is regulated down until the temperature of the water leaving the instantaneous water heater has dropped to the setpoint temperature.

It is essential here that it is a Temperarurregelkreis, which must be able to continuously regulate relatively high energy densities. Such water heaters with electrical control devices prove to be relatively expensive to manufacture and therefore are used only relatively rarely.

In a further known type of instantaneous water heater according to the prior art, a control of the amount of heat supplied to the water to be heated takes place on the basis of the amount of water flowing through the water heater per unit of time (River). In this case, usually via a arranged in the flow channel or parallel Venturi nozzle and an associated pressure cell with diaphragm plunger, depending on the flow rate, a mechanical switching element so that when a high hot water demand switching to a high power level occurs and so the water supplied heat and to increase the energy supplied to the heater. With a low hot water requirement, switching to a low power level occurs, so that the energy supplied to the heater and thus also the amount of heat supplied to the water is reduced.

The flow measurement is usually carried out in such flow heaters in the flow area, ie cold water side. Furthermore, the control of the energy supplied to the heating device or the amount of heat supplied to the water takes place at discrete switching levels, ie is not continuously increased or reduced with the flow rate, but only for different flow intervals, d. H. Areas between a first flow rate and a second flow rate, switched.

In such flow heaters, it is considered disadvantageous that the mechanical switching elements due to the fact that relatively high energy densities must be switched and due to the associated pressure box are relatively large and cumbersome, which among other things greatly affects the size of the entire water heater. In addition, in the case of mechanical switching elements for switching electrical currents due to the high currents to be switched, it frequently occurs during the switching process that the switch contacts weld together or corrode, and thus a reliable switching process is no longer guaranteed.

Object of the present invention is therefore to provide a device for preparing hot water and in particular a water heater available, which overcomes the disadvantages of the prior art and in particular has a compact and inexpensive to manufacture type.

This object is achieved by a device for preparing hot water with the features of claim 1. Further preferred embodiments of the present invention are the subject of the dependent claims.

Accordingly, a device according to the invention for the preparation of hot water at least one heating device, which has at least one inlet and a drain and at least one heating stage is heated by the water, which flows through the inlet at a first temperature T ₁ in the heater, so that it flows out of the heater at a second temperature T ₂ .

The device according to the invention furthermore has at least one measuring device for determining a quantity of water (flow) flowing through the heating device per unit time, wherein the measuring device outputs an electrical signal representing the information about the flow. Furthermore, an electronic control device is provided which registers the electric signal representing the flow from the measuring device and on the basis of this signal controls the amount of heat supplied to the water by the heating device, whereby this control takes place by means of discrete switching states, so that for a first flow interval, In other words, a first switching state is activated for a region between a first flow F ₁ and a second flow F ₂ and, if appropriate, further switching states are activated for further flow intervals.

The device according to the invention makes it possible, in a surprising manner, to provide devices for the preparation of hot water, which are distinguished, in particular, by a compact construction and the possibility of a favorable production and, in particular, by reliable and long-lasting operation. Furthermore, the control of high powers is avoided by electromechanical switching sets by the present invention, whereby the known disadvantages of such sets are bypassed.

In a preferred embodiment of the present invention, the discrete switching states of the electronic control device consist of switching on or off further heating stages of the heating device. In the case of only a small flow of water through the heating device, for example, only a first heating stage is actuated or switched on by the electronic control device, whereas with an increased water flow through the device according to the invention for the first heating stage, second and optionally further heating stages arranged in series are activated or switched on.

In contrast thereto, however, it is also possible to control a single heating stage, depending on the size of the flow passing through the device according to the invention, with different discrete switching margins such that the heating stage only supplies a small amount of heat to the water in a first switching state and Of these discretely separated switching states the water further, increased amounts of heat supplies.

Particularly preferably, the flow measurement is carried out by continuous or discontinuous probe, such. B. flow turbines with corresponding sensors for measuring the number of revolutions such. As Hall sensors, optical sensors or the like or paddle switch, which have a defined flow in the water surface, which are moved depending on the flow size from its rest position and thereby a switching state on or off.

In addition to such flow sensors, there is also the possibility of non-contact flow measurement such as optical or electromagnetic flow meter.

Preferably, the electrical signal generated by the sensor for determining the amount of water flowing through the heating device per unit of time is represented in the form of pulses, preferably counting pulses or else a sequence of counting pulses integrated over a predetermined time unit.

Particularly preferably, the electronic control device for controlling the heating stage or the heating stages to a power output stage, which is preferably controlled by a likewise contained in the electronic control device control stage. In this case, the control stage processes the electrical signal representing the flow and optionally further information relevant to the control of the device according to the invention, such as, for example, As security information, power preset information and the like, and determines therefrom the switching state to be controlled. Depending on the switching state then the control of the power output stage takes place in such a way that it controls the energy supplied to the heating stage or stages.

Particularly preferably, the power output stage comprises electronic power switching elements which are selected from a group which includes thyristors, power transistors and in particular IGPT and MOSFETs, triacs and the like, similar power semiconductors for switching large currents.

The use of such power semiconductors makes it possible to make the power output stage low and in particular also very reliable, since in this case at least partially standard components can be used.

In a further preferred embodiment of the device according to the invention, the power output stage and in particular the power semiconductors on a cooling device, which dissipates heat loss and preferably heat transfer between the power output stage or the power switching elements and the water flowing through the device according to the invention allowed. Particularly preferably, the cooling device for cooling the power output stage or the power switching elements in the flow of the heater is arranged so that the heat transfer between the power output stage or the power switching elements and the water, which has the temperature T ₁ occurs.

In this way, a particularly effective cooling of the power output stage or the power switching elements is made possible because on the one hand by the high heat capacity of water to air a particularly effective heat dissipation is possible and on the other eliminates the need for a sufficient Belüfrung the cooling device. Furthermore, the water cooling of the power output stage or the power switching elements allows a further, significant reduction of the space requirements of the power output stage, since a small compared to the air cooling heat transfer surface is needed.

Particularly preferably, the device according to the invention has a power selection switch, which is connected to the electronic Steuerungseinrichiung and causes a selection and optionally an exclusion of the controllable by the electronic control device switching states. By the power selection switch thus the Berriebseinstellung the device of the invention and thus the electronic control device can be influenced insofar as the amount of water supplied to the water does not exceed a certain value even with a large flow through the device according to the invention. In this case, a selection would thus be made of switching levels, which have only a low energy input into the heating stages and thus in the device flowing through the water result, ie lower switching levels, which is essentially synonymous with an exclusion of high switching levels, ie large energy inputs in the Heat levels or the water to be heated is.

Furthermore, the device according to the invention in a particularly preferred embodiment, safety devices which are connected to the electronic control device and causes an exclusion of substantially all controllable by the electronic control device switching states when a safety-relevant state is detected. This is to be understood that when capturing a security-relevant State, the device according to the invention, for example, completely switched off, so no switching levels, which would have an energy supply to the heating stages or a heat input into the water flowing through the device would result in more or can be.

In a further embodiment, furthermore, it would be possible to continue to operate the device according to the invention, depending on the type of safety-relevant condition, in a kind of emergency operation only at a very low level until the safety-relevant condition has been remedied by maintenance or repair.

The safety devices mentioned are particularly preferably temperature sensors which measure the temperature of the water flowing through the heating device or else also individual heating stages and output a measured value to the electronic control device. When a predetermined maximum temperature is exceeded then takes place by the electronic control device, if necessary, the shutdown, d. H. the connection, single or all switching states.

As a further safety device is particularly preferred a pressure gauge is used, which is upstream or downstream of the device or individual heating stages, and by which the hydrostatic pressure in the system, ie the device according to the invention determined and a corresponding measured value is output to the electronic control device. If the undershooting of a predetermined minimum pressure is detected, it can be assumed that the system is pressureless or leaking and the electronic control device shuts down or excludes individual or substantially all switching states. In the case of an overpressure in the system can be assumed, for example, from a system overheating, which could also have an immediate shutdown of individual or all switching states by the electronic control device would result or would have.

Likewise, the said safety devices also include electrical or electronic sensors which monitor the correct or error-free operation of the heating stage or heating stages and in the event of malfunction, a shutdown or exclusion of individual or substantially all switching states by the electronic control device.

Further features of the present invention will become apparent from the following detailed description taken in conjunction with the claims and the drawings.

Fig. 1

eine erfindungsgemäße Vorrichtung zum Bereiten von Warmwasser;

Fig. 2

eine bevorzugte Messeinrichtung zur Flussmessung;

Fig. 3

eine weitere bevorzugte Messeinrichtung zur Flussmessung.

It shows:

Fig. 1

a device according to the invention for the preparation of hot water;

Fig. 2

a preferred measuring device for flow measurement;

Fig. 3

Another preferred measuring device for flow measurement.

1 shows an apparatus according to the invention for preparing hot water 1, which has three heating stages 4a, 4b and 4c connected in series in terms of flow technology. The arrows 13 indicate the flow direction of the water flowing through the device 1 according to the invention.

In further, not shown embodiments of the present invention, moreover, there is the possibility of srrömungstechnischen parallel connection of individual heating stages and the combination of parallel and series connection of several heating stages. The heating stages 4 are particularly preferably electrical heating elements which transmit heat generated by the flow of electronic current to the water flowing through the heating stage.

The device according to the invention according to FIG. 1 has shut-off valves 6, 7 both at the inlet and at the outlet, which make it possible to carry out water installation work on the device according to the invention without the device having to be emptied of water.

The device for preparing hot water 1 according to FIG. 1 furthermore has a measuring device 8 installed on the cold water side, which determines the quantity of water flowing through the device 1 or its heating device 5 per unit of time (flow) and communicates this information to the measuring device 8 electronic control device 9 transmitted in the form of an electrical signal.

In the case illustrated in FIG. 1, the electronic control device 9 has a control stage 10, which determines the system information regarding the system pressure, water temperature, which is determined by the measuring device 8 and by a power selection switch 15 and by a pressure sensor 16 and the temperature sensors 17 and 18 and evaluates the operating state and determines and controls the switching state to be triggered therefrom.

The control stage of the electronic control device controls the power switching elements 12a, 12b and / or 12c of the power output stage 11 of the electronic control device 9, so that they cause an activation or deactivation of the heating stages 4a, 4b and / or 4c.

The power output stage 11 of the electronic control device 9 of the device according to the invention for preparing hot water 1 according to FIG. 1 further comprises a cooling device 20, which serves to cool the power switching elements 12a, 12b and 12c, and which heat transfer between the power switching elements and the device permeable water allows. For this purpose, flow channels of the cooling device 20 are connected in parallel to the main water flow through the device, so that a portion of the device flowing through the water flows through the cooling device and thus serves to dissipate heat loss of the power switching elements.

Preferably, the electronic control device 9 with the power output stage 11 and the liquid cooling device 20 for cooling the power switching elements 12a to 12c cold water side connected to the heater, so that between the temperature of the power switching elements and the cooling water, the largest possible difference and thus allows the most effective cooling of the power switching elements becomes.

The power selection switch 15 allows the operating state of the device to be adjusted, i. H. the control of the heating stages 4a, 4b and / or 4c to influence such that depending on the hot water demand, the maximum amount of heat flowing to the device 1 water is limited by a selection or limitation of the electronic control device 9 only certain, preferably low switching levels.

The pressure sensor 16 is connected to the electronic control device 9 and transmits to this information about the hydrostatic system pressure. If an exceeding of a predetermined maximum pressure p _max or an undershooting of a predetermined minimum pressure p _{min is} registered, then the control device switches off all power switching elements 12a, 12b and 12c, so that none of the heating stages 4a, 4b or 4c is energized and thus no heat energy to the water is delivered. equally shutdown of some or all of the power switching elements 12a to 12c of the power output stage 11 of the electronic control device 9, if by one of the temperature sensor 17, 18, the exceeding of the water temperature over a predetermined temperature value T _{max is} registered.

The device according to the invention according to FIG. 1 thus makes it possible to increase or reduce the quantity of heat supplied to the water by the heating stages 4a, 4b and 4c in a stepwise manner and in dependence on the flow through which the device flows. By the power switching elements 12a, 12b and / or 12c of the power output stage 11 takes place an individual energization of the heating stages 4a, 4b and 4c, which corresponds to a switching on or off of the heating stages.

Fig. 2 shows the structure of a particularly preferred measuring device 8 of a device for preparing hot water 1 according to the present invention. The measuring device 8 in this case has a first paddle switch 22 and a second paddle switch 23, which each change their switching state upon reaching a first flow F ₁ and a second flow F ₂ . The signal generated by the first paddle switch 22 is superimposed on the signal generated by the second paddle switch 23 in the over-bearing device 24 and transmitted to the electronic control device 9.

In a measuring device 8 according to FIG. 3, the water flow flowing through the flow pipe 25 is determined by a turbine arranged in the flow such that the rotational speed of the turbine is determined by, for example, a Hall sensor or an optical sensor, and from this the size of the flow through the flow pipe 25 flowing water flow is determined. The signal generated by the flow sensor 26 is transmitted to the electronic control device 9 and made by this to the basis of the determination of the switching states to be controlled.

In the description of the present invention, the possibility of using the invention in the field of domestic appliances or for water water heaters has been used merely by way of example. An application of the present invention in other areas such. B. in the field of heating or air conditioning or for heating other fluid media than water, however, is just as conceivable.

Claims (11)

Device for preparing hot water (1), in particular instantaneous water heater with: - At least one heating device (5) having at least one inlet (2) and a drain (3) and at least one heating stage (4), which water entering through the inlet (2) with a first temperature T ₁ in the heater , heated so that it flows out of the heater (5) at a second temperature T ₂ ; at least one measuring device (8) for determining a quantity of water (flow) flowing through the heating device (5) per unit time, the measuring device outputting an electrical signal representing the information about the flow, characterized in that
at least one electronic control device (9) is provided, which controls the amount of heat supplied to the water by the heating device (5) on the basis of the electrical signal representing the flow;
the control of the amount of heat supplied by means of discrete switching states takes place, so that for a first flow interval, a first switching state and possibly further switching states are controlled for further flow intervals. Apparatus for preparing hot water according to claim 1,
characterized in that
the discrete switching states in an on or off additional heating stages (4a, 4b, 4c) exist. Apparatus for preparing hot water according to claim 1 or 2,
characterized in that
the electronic control device (9) comprises a power output stage (11) which controls the heating stage (4). Apparatus for preparing hot water according to claim 3,
characterized in that
the power output stage (11) for driving the heating stage (4) has at least one electronic power switching element (12) which is selected from a group comprising thyristors, power transistors, in particular IGPT and MOSFET, triacs and the like, similar power semiconductors. Apparatus for preparing hot water according to claim 3 or 4,
characterized in that
the power output stage (11) has a cooling device (20) which dissipates heat loss and preferably heat transfer between the power output stage (11) and / or the power switching element (12) and the water, preferably the water with the temperature T ₁ , allows. Device for preparing hot water according to one of the preceding claims,
characterized in that
a power selection switch (15) is provided, which is connected to the electronic control device (9) and causes a selection and optionally an exclusion of the controllable by the electronic control device (9) switching states. Device for preparing hot water according to one of the preceding claims,
characterized in that
at least one safety device (16, 17, 18) is provided, which is connected to the electronic control device (9) and causes a selection and in particular an exclusion of individual or substantially all by the electronic control device (9) controllable switching states, if a safety-relevant state is detected. Apparatus for preparing hot water according to claim 7,
characterized in that
the safety device is a temperature sensor (17, 18) and / or pressure gauge (16), which causes a shutdown of all heating stages (4a, 4b, 4c) in particular as a result of reaching or exceeding a maximum temperature or a minimum pressure or exceeding a maximum pressure , Device for preparing hot water according to one of the preceding claims,
characterized in that
the heating stage (4) has at least one electric heating element for generating heat. Device for preparing hot water according to one of the preceding claims,
characterized in that
the measuring device (8) has at least one discrete flow sensor and preferably a paddle switch (22, 23) which changes its switching state when a predetermined flow is reached. Device for the preparation of hot water according to one of the preceding claims,
characterized in that
the measuring device (8) has at least one continuous flow sensor and preferably a turbine, screw or the like whose speed changes with the size of the flow passing through it and which is determined by a Hall sensor, an optical sensor or the like non-contact speed sensors.

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