CZ289638B6 - Apparatus and method for the control of heating energy supply to heating coils of an electric instantaneous water heater - Google Patents

Abstract

The proposed apparatus for regulating supply of power to heating coils (1a, 1b, 1c, 1d) of an electric instantaneous water heater comprises a flow transmitter (21), a measuring module (22) and adjusting element (23) of required value. Using switching contacts (11a, 11b, 11c) and disconnecting contacts (12a, 12b, 12c), the apparatus regulates power supply in dependence on water flow. The power supply line to heating coils (1a, 1b, 1c, 1d) there are arranged points (31, 32, 33) for sensing electric potential on these heating coils (1a, 1b, 1c, 1d) and the disconnecting contacts (12a, 12b, 12c) are connected together with the electric potential sensing points (31, 32, 33) with a safety switching circuit (26), which is in turn connected with the flow transmitter (21). Electric potential present on the heating coils (1a, 1b, 1c, 1d) is continuously scanned and safety disconnection of the heating power supply to said heating coils (1a, 1b, 1c, 1d) takes place when presence of electric potential is detected on the heating coils (1a, 1b, 1c, 1d) while the monitored liquid flow dropped below a preset limit value or liquid is in rest.

Description

(57)

The device for regulating the energy supply to the heating coils (1a, lb, lc, ld) of an electric instantaneous heater, comprises a flow sensor (21), a measuring module (22) and a setpoint adjuster (23) which, by switching contacts (11a, 1). 1b, 1c) and break contacts (12a, 12b, 12c) control the power supply depending on the water flow. In the power supply to the heating coils (1a, 1b, 1c, 1d), electrical voltage sensing points (31, 32, 33) are arranged on these heating coils (1a, 1b, 1c, 1d) and break contacts (12a, 12b, 12c). ) are coupled with the electrical voltage sensing points (31, 32, 33) to a safety switch circuit (26) which is further coupled to a flow sensor (21). The electrical voltage on the heating coils (la, lb, lc, ld) is continuously monitored and the safety disconnection of the heating energy supply to the heating coils (la, lb, lc, ld) is performed when the presence of electrical voltage on the heating coils is detected. , lb, lc, ld) while the monitored liquid flow has fallen below a predetermined limit value or the liquid is at rest.

(11) Document number:

289 638 (13) Document type: B6 (51) Int. Cl ⁷ :

H05B 1/02

F24H 9/20

L1 L2 L3

Apparatus and method for regulating the supply of heating energy to the heating coils of an electric instantaneous heater

Technical field

BACKGROUND OF THE INVENTION The invention relates to an apparatus for regulating the energy supply to the heating coils of an electric instantaneous heater comprising a flow sensor, a measuring module and a setpoint adjuster which, by means of normally open and normally closed contacts, regulate the energy supply.

The invention further relates to a method for controlling the supply of heating energy to the heating coils of an electric instantaneous heater, in which the flow of liquid through a flow heater is monitored and the supply of heating energy is regulated as a function of the liquid flow.

BACKGROUND OF THE INVENTION

Electric current is supplied to the heating coils of the electric instantaneous heaters via the NO contacts. The contact closes only when the preset flow rate is exceeded, that is to say at a certain preset water draw-off, by means of a control coil which mechanically closes these contacts. The heating capacity is selected so that the liquid temperature cannot exceed the preset limit value during normal operation. Coil operated switches are known to be prone to malfunctions. In particular, the anchors tightened by the control coils remain stuck in the retracted position after the control coil has been disconnected, so that the heating energy supply continues unchanged, although the flow sensor signals a reduced flow or even stopping the flow of heated liquid. Therefore, in new-generation electric instantaneous heaters, safety circuits are used which, in the event of an extreme pressure and / or temperature rise in the fluid circuit, are forced to interrupt the heating energy supply. The safety circuit or device will remain effective or locked until the operator manually turns it off or unblocks it after the fault has been rectified.

Overpressure or overheating sensors, which are still used to control safety circuits and devices, have some problems. On the one hand, for operational reasons, in order to prevent false disconnections and interruptions of operation, it is attempted to set the pressure or temperature thresholds as high as possible from a safety point of view. As a result, known safety circuits and devices react slowly, so that other damaging consequences on the electric instantaneous water heater cannot be reliably prevented in the event of operating failures and safety disconnections. On the other hand, there are also relatively high costs for safety circuits and equipment in known electric instantaneous heaters.

SUMMARY OF THE INVENTION It is therefore an object of the invention to achieve a safety disconnection of heating coils in the event of a failure with higher reliability and speed than hitherto.

SUMMARY OF THE INVENTION

The problem is solved and the drawbacks of known devices of this kind are largely eliminated by a device for regulating the energy supply to the heating coils of an electric instantaneous heater comprising a flow sensor, a measuring module and a setpoint adjuster which regulate by means of make contacts and break contacts Energy supply according to the invention, characterized in that in the energy supply to the heating coils are arranged voltage sensing points on these heating coils and break contacts

Together with the voltage sensing points are connected to a safety switch circuit, which is further connected to a flow sensor.

From the point of view of the method, the object of the invention is solved by continuously sensing the electrical voltage on the heating coils and safely disconnecting the heating energy supply to the heating coils if the presence of the electrical voltage on the heating coils is detected. or the liquid is at rest.

The device according to the invention makes it possible to achieve a hitherto unreachable rate of reaction when the heating energy supply is interrupted in case of a failure. While the known safety circuits and devices had to wait for a correspondingly high pressure and / or temperature rise before the safety cut-off, in the device according to the invention the direct sensing of the electrical voltage on the heating coils allows their immediate disconnection if heated liquid or water is standing. As a result, there is no pressure increase due to overheating. The control response of the switching contacts, which are controlled by the flow sensor, is continuously monitored. Another great advantage lies in the low installation and operating costs of the device according to the invention. Voltage sensing is done by simple electrical means; The processing of the sensed signals can be carried out without problems and with little extra cost in electronic control circuits, which are already part of modern electric instantaneous heaters. The operation of the NC contacts is independent of the operation of the NC contacts.

Advantageously, in the energy supply to the heating coils, the break contacts are connected upstream of the break contacts, which are connected to the flow switch circuit.

A further improvement of the safety function of the device according to the invention can be achieved by opening the normally open contacts via a safety circuit to the overheating sensor to interrupt the heating energy supply when the preset water temperature is exceeded.

It is furthermore advantageous if the break contacts are connected to a control logic consisting of a safety switching circuit and a measuring module, which comprises a logic product gate for the voltage sensing point signals and the flow sensor.

The break contacts are preferably connected to a latch to release at least one spring-loaded break contact, the control coil of which is connected to a safety switch circuit.

The break contacts and the break contacts are preferably multiphase, the individual break contacts being connected in series with the individual break contacts in the heating energy supply to the individual heating windings.

In order to synchronize the operation, it is advantageous if the make contacts and the make contacts are arranged on a movable guide bridge.

The guide bridges of all the connected phases of the heating coils are coupled to one another.

In this case, the make contacts and the make contacts are provided with an operating coil for actuating the latch and / or the rod.

Finally, it is preferable that the make contacts and the make contacts are provided with expansion springs with an adjustable spring force.

-2GB 289638 B6

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further illustrated by a non-limiting example of its embodiment, which is described on the basis of the accompanying drawings, which show:

FIG. 1 shows an electrical wiring diagram of the essential electrical components of an electric instantaneous water heater with an example of the device of the invention;

Fig. 2 is a plan view of a three-phase switch for switching the heating energy supply in the circuit of Fig. 1; and Fig. 3 is a side view of the three-phase switch of Fig. 2.

DETAILED DESCRIPTION OF THE INVENTION

The circuit diagram of FIG. 1 contains all the essential electrical components of the electronically controlled electric instantaneous water heater and incorporates the device of the invention.

The heating current is connected to the heating elements or the heating coils 1a, 1b, Ic. is supplied by three phase conductors L1. L2, L3 via a first switch 11 with three switching contacts 11a. 11b, 11c. a second switch 12 of the break contacts 12a, 12b, 12c. a terminal block 13 and a control device 2 comprising control electronics with triac circuits controlling the individual phases continuously. Another heating coil 1d is connected directly between the phase conductors L1 and L2.

All control and switching functions of the electric instantaneous heater are combined in the control device 2.

The continuously operating flow sensor 21 provides a flow rate dependent signal to the metering module 22 flowing through the electric flow heater. The setpoint adjuster 23 externally accessible serves to set the desired water temperature, i.e., to switch the power supply on and off to the heating coils 1a, 1b, Ic for operational switching on and off. Id. A temperature sensor 24 measuring the supply water temperature is connected to the measuring module 22. In addition, the metering module 22 is connected to a flow switch 25 operating in dependence on the water flow. This flow switch circuit 25 activates the first control coil 14 at a predetermined desired flow rate threshold, for example when the water draw exceeds 3.5 rpm, which closes the first switch 11. The heating coils 1a, 1b, 1c are then via the triac unit 20 supplied with heating current. If the flow rate drops below the second threshold, which in the practical example is 3.01 / min, the first control coil 14 is switched off by the flow switch circuit 25 and all the switch contacts 11a, 11b, 11c of the first switch 11 open.

The safety switch circuit 26 can actuate the second switch 12 by means of the second control coil 6. This second switch 12 consists, in the described embodiment, of three mechanically coupled break contacts 12a, 12b, 12c. When the second control coil 16 is energized, the break contacts 12a, 12b, 12c are opened so that the power supply for all heating coils 1a, 1b, 1c, 1d, which are then de-energized, is interrupted.

The safety switch circuit 26 comprises voltage sensors which are connected at the electrical voltage sensing points 31, 32, 33 to the leads to all the heating coils 1a, 1b, 1c and thus also to the heating coil 1d. Thus, the voltage sensors in the safety switch circuit 26 continuously monitor the voltages at the leads to the heating coils 1a, 1b, 1c, 1d. The safety circuit 26 is also connected via line 27 to the measuring module 22 and through it to the flow sensor 21. Pojistná

The function of the safety circuit 26 is to cooperate with the second control coil 16 and the break contacts 12a, 12b. 12c of the second switch 12 interrupts the heating current supply if the water consumption is interrupted or falls below a certain minimum value, and at least one sensing point 31, 32, 33 is nevertheless detected an electrical voltage. Indeed, this electrical voltage would be an unmistakable indication that at least one of the switching contacts 11a, 11b, 11c of the first switch 11 is closed and at least one heating coil 1a, 1b. As a result, lc is energized. Obviously, this safety switch circuit 26 must react extremely quickly and reliably even when a defect is present, consisting of heating the water at too low a flow rate or interrupting the flow of water in the electric flow heater. In the embodiment shown in FIG. 1, an overheating sensor 28 is additionally used which monitors the temperature of the water behind the heating coils 1a, 1b, 1c, 1d. When the water overheats, the overheating sensor 28 sends a fault signal which, like the malfunction of the first switch 11 and the first control coil 14, performs a safety disconnection by means of the second switch 12 and the second control coil 16. This disconnection function is independent of the other conditions throughout the electronic system, since under all circumstances the user must be prevented from taking overheated water.

The measuring module 22 generates, as has already been said, a signal for the switching circuits 25, 26 depending on exceeding or not reaching the water withdrawal thresholds. If this signal is applied via a line 27 to the input of the safety circuit 26, voltage or voltage differences in the sensing points 31, 32, 33 are required for operation. The second control coil 16 can only be energized if, at the same time as the voltage is present at at least one of the sensing points 31, 32. 33 there is no signal on the line 27. This condition can be realized by an inverter integrated in the safety circuit 26 or upstream by means of this safety circuit 26, in conjunction with a logic product gate, wherein at least one other logic product gate input receives digitalized measurement results from the sensing points 31, 32, 33 of the electrical voltage. The logic product gate output is coupled to one logic sum gate input, the other input of which receives a digitized output signal from the superheat sensor 28. It will be apparent to those skilled in the art that a variety of other analog and digital circuits may also be used to realize the switching functions described above.

Referring to Figures 2 and 3, a particularly preferred embodiment in which the two switches 11 and 12 are grouped together will be described below.

A first switch 11 and a second switch 12, their control coils 14, 16, the connection terminals 41a, 41b are arranged on the support plate 4. 41c. 4 ld for phase conductors L1. L2, L3 and the protective conductor and the connection terminals 13a, 13b, 13c for heating coils 1a, 1b, 1c made as sockets. Id. The support plate 4 is detachably fastened to suitable support plate 42 or electric flow heater cover by means of suitable fasteners 42.

Both the first control coil 14 and the second control coil 16 control all contacts of their associated switches 11, 12. It is therefore sufficient to describe the construction and operation of the first switch 11 and the first control coil 14 and the second switch 12 and the second control coil 16 based on FIG. , which shows only one switch contact 11b at a time. optionally, a break contact 12b and other components involved in the operation of the contacts 11b, 12b.

In Fig. 3, the entire mating switch is shown in normal operating condition, i.e. when there is no fault or malfunction. The water withdrawal exceeds a preset threshold - see setpoint adjuster 23 in FIG. 1 - triggering the actuation of the first control coil 14 and thus the closing of the first switch 11. The electric current flows through the closed switch contact 11b to the connected heating coil. The switching contact 11b by the first control coil 14 is actuated by its first armature 15 and the first rod 17 of insulating material which supports the pressure spring 18. This pressure spring 18 presses the guide bridge 50 to the arm 19 of the first rod 17. A relatively strong first the expansion spring 43 tries to displace the first rod 17 from the closed

3 to the open position of the switch contact 11b, in which the first armature 15 is spaced from the core of the first control coil M. The force of the first expansion spring 43 can be adjusted by the first set screw 44.

The second switch 12 and its second control coil 16, with the exception of the fault condition, are in the rest position shown in FIG. 3 in which the break contacts 12a, 12b, 12c are closed. The second link 45 serves as an adjusting member for the second switch 12, which is latched in the position shown in FIG. 3 by the latch 46 locked against the force of the second expansion spring 47. The bias and stroke of this second expansion spring 47 can be adjusted again by the second adjusting screw 48. 3 is retained by the spring 49 in the locked position shown in FIG. 3. Upon actuation of the second actuating coil 16, the respective second armature 16a is pulled by the core of the second actuating coil 6, deflects and slides latch 46 in the arrow direction A, i.e. After a certain stroke of the pawl 46 has been traveled in the direction of the arrow A, the recess 60 formed in the pawl 46 aligns with the latching projection 61 of the second rod 45. As a result, the second rod 45 is released from the locking position shown in FIG. the strong second expansion springs 47 can move in the direction of arrow B. Stroke type Rod 45 in the direction of arrow B, sufficient to reliably opening the normally closed contact 12b. As a result, the conductive path is interrupted from the connection terminal 41b via a substantially stationary contact tab 51, a movable switch contact 11b, a guide bridge 50 and a fixed contact 52, together with the guide bridge 50, forming a break contact 12b to which the respective heating coil is connected. .

It can be seen from FIG. 3 that the guide bridge 50 is a movable connecting bridge which connects the make contact 11b to the break contact 12b with one another and at the same time forms the movable contact elements for both contacts 11b, 12b. The two switches 11, 12 can be switched on and off independently of each other. In the longitudinal direction, the guide web 50 is held by the second rod 45. In the first rod 17, the guide web 50, on the other hand, is guided only in the lateral direction and in the direction of switching the contacts 11b. 12b. This embodiment provides a particularly precisely adjustable and virtually independent function of the two contacts 11b in a particularly advantageous manner. 12b. The described simple construction also ensures high reliability and compactness because only one movable element is used for each phase. Since the two rods 17, 45 are made of electrically insulating material, the guide bridges 50 belonging to the phase conductors L1, L2, L3 or their connection terminals 41a, 41b, 41c can be coupled in motion by these rods.

As mentioned earlier, the second control coil 16 can be energized and the safety break contacts 12a, 12b, 12c actuated by the second control coil 16 can be opened only if voltage is detected at the voltage sensing points 31, 32, 33. although the water in the electric instantaneous heater is not in motion, or a flow below the lower threshold is detected. This is a fault condition in which all heating coils 1a, 1b, 1c, 1d must be disconnected. As can be easily seen from Fig. 3, the safety elements cannot be unlocked automatically after a safety disconnection. The electric instantaneous water heater can then only be put back into operation if the fault that caused the safety disconnection has been eliminated and the second rod 45 is moved back to the position shown in Fig. 3 by manually moving the pushbutton head 45a in the direction of arrow B.

Claims (5)

An apparatus for regulating the supply of heating energy to the heating coils (1a, lb, lc, ld) of an electric flow heater comprising a flow sensor (21), a measuring module (22) and a setpoint adjuster (23) which, by means of switching contacts ( 11a, 11b, 11c) and break contacts (12a, 12b, 12c), depending on the water flow, regulate the energy supply, characterized in that sensing points (1a, 1b, 1c, 1d) are arranged in the energy supply to the heating coils (1a, 1b, 1c, 1d). 31, 32, 33) of the electrical voltage on these heating coils (1a, 1b, 1c, 1d) and the break contacts (12a, 12b, 12c), together with the sensing points (31, 32, 33), are connected to the safety circuit (26). ), which is further connected to a flow sensor (21). Device according to claim 1, characterized in that in the power supply to the heating coils (1a, 1b, 1c, 1d), the switching contacts (11a, 11b, 11c) are arranged before the break contacts (12a, 12b, 12c). ), which are connected to the flow switch circuit (25). Device according to claim 1 or 2, characterized in that the break contacts (12a, 12b, 12c) are connected via a safety switch circuit (26) to an overheating sensor (28) to interrupt the heating energy supply when the preset water temperature is exceeded. Device according to one of claims 1 to 3, characterized in that the break contacts (12a, 12b, 12c) are connected to a control logic consisting of a safety switching circuit (26) and a measuring module (22) comprising a logic gate. the product for the electrical voltage sensing point signals (31, 32, 33) and the flow sensor (21). Device according to claim 4, characterized in that the control logic comprises a logic sum gate, the inputs of which are connected to a logic product gate output and an overheat sensor (28). Device according to one of Claims 1 to 5, characterized in that the break contacts (12a, 12b, 12c) are connected to a latch (46) for releasing at least one spring-loaded break contact (12b), the control coil (16) of which is connected to a safety switch circuit (26). Device according to one of Claims 1 to 6, characterized in that the break contacts (12a, 12b, 12c) and the make contacts (11a, 11b, 11c) are multi-phase, the individual break contacts (12a, 12b, 12c) being in the heating energy supply to the individual heating windings (1a, 1b, 1c, 1d) are connected in series with the individual switching contacts (1a, 1b, 1c). Device according to one of Claims 1 to 7, characterized in that the make contacts (11a, 11b, 11c) and the make contacts (12a, 12b, 12c) are arranged on a movable guide bridge (50). Device according to claim 8, characterized in that the guide bridges (50) of all the connected phases of the heating coils (1a, 1b, 1c, 1d) are coupled to one another. Device according to one of Claims 1 to 9, characterized in that the make contacts (11a, 11b, 11c) and the make contacts (12a, 12b, 12c) are provided with an actuation coil (14, 16) for actuating the latch (46). and / or rods (17). -6GB 289638 B6 Device according to one of Claims 1 to 10, characterized in that the make contacts (11a, 11b, 11c) and the make contacts (12a, 12b, 12c) are provided with expansion springs (43, 47) with adjustable spring force. 12. A method for controlling the supply of heating energy to the heating coils (1a, lb, lc, ld) of an electric instantaneous heater, in which the flow of liquid through an electric instantaneous heater is monitored and the supply of heating energy is controlled according to the liquid flow, the electrical voltage on the heating coils is continuously monitored (la, lb, lc, ld) and the safety disconnection of the heating energy supply to the heating coils (1a, lb, lc, ld) is carried out 10 if the presence of electrical voltage on these heating coils is detected (la, lb, lc, ld) while the monitored liquid flow has fallen below a predetermined threshold or the liquid is at rest.