FLOW CONTROL FOR A CONTINUOUS-FLOW WATER HEATER

A flow control for a continuous-flow water heater is used to control the flow of gas to a burner (24) of a heat exchanger (29) as a function of the passage of water, in which only one operating element has to be actuated. The reduction in apertures through the housing wall of the flow control, reduces the risk of leaks. Furthermore, manufacturing expenditure is minimized. To this end, in addition to the operating element (8), a switching element (9) is rotatably mounted on a spindle (7) projecting from the water-carrying housing (5), wherein a rotary movement of the operating element (8) can be transmitted via drivers (10; 11) to the switching element (9), which also has a switching contour (13) by means of which a fixedly arranged microswitch (14) can be actuated, by means of which an electronic ignition and monitoring device (3) can be electrically actuated, by means of which gas flow to the burner can be shut off.

DESCRIPTION

Flow control for a continuous-flow water heater.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a flow control for a continuous-flow water heater according to the preamble of the first claim.

PRIOR ART

Flow controls of this type for continuous-flow water heaters are available in a very wide range of designs. They serve to control the gas flow rate to a burner of a heat exchanger as a function of the passage of water.

For example, a gas valve for a burner-heated water heater with a main gas valve on the inlet side connected to a flow meter is described in DE 198 25 046 A1, a German patent application open to public inspection. A water deficiency valve, which is connected to the flow meter, is located downstream of the main gas valve. A thermostatically controlled valve connected to an evaluation circuit is in turn located downstream of the water deficiency valve. When the water heater is in operation, both the water flow rate and the temperature of the hot water flowing off can be set by means of two operating elements.

A gas-heated continuous-flow water heater with a heat exchanger heated by a burner is known from EP 1 170 549 A2. A water valve in a water switch is located upstream of the heat exchanger and gas valves, one of which is controlled by a water switch and another by a gas pressure-controlled servo valve, are located upstream of the heat exchanger on the gas side. Whereas an adjusting valve downstream of the gas valve on the gas side is actuated by a first handle and the gas valve is controlled by the servo valve, the water valve can be actuated by a second handle.

A gas-heated continuous-flow water heater, which is described in DE 100 30 118 A1, a patent application open to public inspection, has a similar structure. This device also has two handles for operating the continuous-flow water heater.

A water heater, which has two operating elements, in this embodiment a control button and an ignition button, is also described in the Austrian patent specification, AT 406 611 B.

A disadvantage common to these flow controls is that in order to switch the continuous-flow water heater on and off or to set the required operating parameters, such as water temperature and water quantity, two separate operating elements are required for which corresponding apertures in the outer wall of the flow control must be made and therefore sealed as well of course. Furthermore, this makes the structure of the device and its operation by the user more complicated.

SUMMARY OF THE INVENTION

The invention addresses the problem of ensuring that a flow control for a continuous-flow water heater according to the preamble of the first claim can be operated easily and in a user-friendly manner by reducing to just one the number of operating elements that need be actuated. At the same time, the risk of leaks occurring is reduced because of the reduction in the number of apertures through the housing wall of the flow control. Furthermore, manufacturing costs are to be minimised.

The problem is solved according to the invention in that, in addition to the operating element, a switching element is rotatably mounted on the spindle projecting from the water-carrying housing, wherein a rotary movement of the operating element can be transmitted to the switching element by means of a driver. This switching element has in addition a switching contour by means of which a fixedly arranged microswitch can be actuated. An electronic ignition and monitoring device by means of which the gas flow to the burner can be shut off by means of an electrically actuated valve can be electrically actuated by means of this microswitch.

A solution was therefore found which eliminated the disadvantages in the prior art referred to above. The manual activation of only a single operating element makes it possible to manually shut down the continuous-flow water heater as well as to adjust the water flow rate to a preset value corresponding to the supply conditions, or to manually compensate for fluctuations in the cold water temperature.

Advantageous embodiments of the invention are set out in the dependent claims.

An advantageous embodiment of the flow control for reducing manufacturing costs even further has proved to be a flow control in which the valve serving to shut off15the gas flow by means of the operating element is formed by the servo valve forming part of the electronic ignition and monitoring device.

The rotary movement of the operating element can be transmitted simply and safely to the switching element by forming the driver by one or a plurality of ribs20located on the operating element and projecting into slots located on the switching element.

In order to ensure operating element and switching element are securely fixed in a longitudinal direction it is advantageous if the switching element is connected to25the operating element by locking hooks.

The exemplary flow control according to the invention for a continuous-flow water heater shown in the diagrams serves to control the gas flow rate to a burner of a heat exchanger29as a function of the passage of water. In this execution example the burner comprises a pilot burner25and a main burner24.

The flow control comprises:a water part1controlling the passage of water to the heat exchanger29,a gas part2controlling the gas flow to the burner24as a function of the passage of water,an electronic ignition and monitoring device3,3aand3b.

A regulating valve19and a main valve18are housed in the gas part2in addition to other components which are known to a person skilled in the art and are therefore not explained in more detail here. The main valve18of servo valve22is actuated by an electronic ignition and monitoring device3, also known as a so-called automatic firing device, which is connected to the gas part2and is also known to a person skilled in the art.

The regulating valve19is actuated by a transmission4, known by U.S. Pat. No. 5,875,807A, incorporated by reference herein, which transmits the movement as a function of the passage of water of a water membrane20located in the water part1from the interior of the water-carrying housing5to the exterior and then from there into the gas-carrying housing6of the gas part2to the regulating valve19.

In addition, a Venturi nozzle21and a pre-setting element26, which enables the water flow rate to be set to a preset value corresponding to the supply conditions, are also located in the water-carrying housing6, in addition to other components which are known to a person skilled in the art and are therefore not explained in more detail either. This pre-setting element26serves at the same time as a temperature corrector, i.e. it enables fluctuations in the cold water temperature to be manually compensated.

To enable manual actuation a spindle7, which is connected to the pre-setting element26and to which an operating element8is attached, projects from the water-carrying housing5. In addition to the operating element8a switching element9is rotatably mounted on the spindle7projecting from the water-carrying housing5, wherein a rotary movement of the operating element8can be transmitted by a driver to the switching element9.

In this execution example the driver is advantageously formed by a plurality of axial ribs10which are located on the operating element8and extend into axial slots11assigned to them and located on the switching element9. In order to additionally ensure the switching element9is fixed in the longitudinal direction of the spindle7, operating element8and switching element9have locking hooks12and12afacing each other which ensure a reliable connection.

The switching element9has in addition a switching contour13by means of which a microswitch14fixedly arranged on the gas-carrying housing6in this execution example can be actuated. The microswitch14is electrically connected to the electronic ignition and monitoring device3and its voltage source23.

The flow control for a continuous-flow water heater illustrated in the diagrams has the following mode of operation:

FIGS. 1, 2A, 2B and 5show an embodiment of a flow control according to the invention for a continuous-flow water heater in the switched off state. The operating element8is in the off-position. In this position the switching element9has been turned until the switching contour13has exposed the button15of the microswitch14. The gas supply to the burner is thereby shut off by means of the electronic ignition and monitoring device3and the continuous-flow water heater remains switched off whether or not water is drawn off from a water tap downstream of the continuous-flow water heater.

In order to switch on the flow control the operating element8must be turned until it is in the possible setting range for adjusting the water flow rate or for manually compensating for fluctuations in the cold water temperature, as shown for example inFIGS. 3A, 3B, 4A, 4B, 7, 8, and 9.

As soon as water is then drawn from a downstream water tap, the gas inlet to the burner24of the heat exchanger29is opened by means of the electronic ignition and monitoring device3and the gas is ignited. The burner24remains in operation until no more water is drawn off. However, the continuous-flow water heater remains ready for operation and can be re-started when water is drawn off again.

In order to switch off the continuous-flow water heater manually the operating element8is moved into the off-position through the possible setting range for setting the water flow rate, as shown inFIGS. 1, 2A, 2B and 5. As already explained in more detail above, the gas supply to the burner24is thereby shut off whether or not water is drawn off.

The flow control according to the invention for a continuous-flow water heater is not of course restricted to the execution example depicted. On the contrary, modifications, variations and combinations can be made without departing from the so scope of the invention.

In order to prevent the off-position being inadvertently set when the required water flow rate is to be set or when fluctuations in the cold water temperature are to be manually compensated, it has, for example, proved to be advantageous if the off-position cannot be reached until a snap lug16and pin17is overcome which indicates the end of the setting range but beyond which the operating element8can be turned.

LIST OF REFERENCE NUMERALS