Patent Description:
In the technical filed of gas burner appliances there are in principle two different types of gas burner appliances, namely fully-premixed gas burner appliances and partially-premixed gas burner appliances. In both types of these gas burner appliances a mixture of gas and air becomes combusted within a combustion chamber of the respective gas burner appliance. The present invention relates to a partially-premixed gas burner appliance.

<CIT> and <CIT> disclose fully-premixed gas burner appliances. In fully-premixed gas burner appliances an air flow provided by a fan is fully premixed with a gas flow provided by a gas modulator before the resulting gas/air mixture is combusted. <CIT> discloses another fully-premixed gas burner appliance,.

<CIT> discloses a partially-premixed gas burner appliance comprising a combustion chamber in which gas is combusted. A fan provides an air flow to the combustion chamber. The fan is assigned to an exhaust gas outlet port of the combustion chamber. Air is sucked into the combustion chamber when the fan being assigned to the exhaust gas outlet port is running, wherein the air enters into the combustion chamber through an air inlet port. An air flow restriction element is assigned to the air inlet port of the combustion chamber. A gas modulator provides a gas flow to the combustion chamber, namely to a gas burner rod positioned within the combustion chamber. In partially-premixed gas burner appliances only a first portion of the air flow provided by a fan is premixed with the gas flow before combustion takes place. In partially-premixed gas burner appliances a second portion of the air flow provided by the fan is mixed with the gas while the combustion of the gas takes place. <CIT> discloses another partially-premixed gas burner appliance.

<CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose other prior art.

Against this background, a novel partially-premixed gas burner appliance according to claim <NUM> is provided.

The novel partially-premixed gas burner appliance comprises a combustion chamber.

The novel partially-premixed gas burner appliance further comprises a fan being configured to provide air or an air flow to the combustion chamber. The fan is assigned to an air inlet port of the combustion chamber or to an air duct providing the air to the air inlet port.

The novel partially-premixed gas burner appliance further comprises an air flow restriction element assigned to the air inlet port of the combustion chamber or to the air duct. The air flow restriction element is configured to cause a pressure drop so that the air pressure downstream of the air flow restriction element is lower than the air pressure of the air flow provided by the fan upstream of the air flow restriction element.

The novel partially-premixed gas burner appliance further comprises a gas modulator being configured to provide a gas flow to the combustion chamber.

A first portion of the air or air flow provided by the fan is premixed with the gas or gas flow before the gas is combusted. A second portion of the air or air flow provided by the fan is mixed with the gas while the gas is combusted.

The gas modulator of the novel partially-premixed gas burner appliance is a pneumatic gas control valve being configured to be used in a fully-premixed gas burner appliance. The pneumatic gas control valve has a main gas valve, a safety gas valve, a servo gas valve and a gas outlet pressure regulator. Such a pneumatic gas control valve is configured to be used in a fully-premixed gas burner appliance.

The gas outlet pressure regulator of the pneumatic gas control valve, namely a first chamber of the gas outlet pressure regulator in which a pressure is present that influences the nominal-value of the gas outlet pressure, is connected to the air inlet port of the combustion chamber or to the air duct upstream of the air flow restriction element such that the gas outlet pressure provided by the pneumatic gas control valve depends on the air pressure provided by the fan upstream of the air flow restriction element.

The present invention proposes to make use of a pneumatic gas control valve being configured to be used in a fully-premixed gas burner appliance within a partially-premixed gas burner appliance. The fan is assigned to the air inlet port of the combustion chamber or to an air duct providing the air to the air inlet port. The gas outlet pressure regulator of the pneumatic gas control valve, namely the first chamber of the same in which the pressure is present that influences the nominal-value of the gas outlet pressure, is connected to the air inlet port of the combustion chamber or to the air duct, namely upstream of the air flow restriction element. This makes it possible to provide a <NUM>:<NUM> ratio of the air pressure upstream of the air flow restriction element and the gas outlet pressure of the pneumatic gas control valve without the need of an electronic gas modulator. The present invention allows a very simple and reliable <NUM>:<NUM> gas-air control for a partially-premixed gas burner appliance.

According to a preferred embodiment, a gas burner rod having at least two segments is positioned within the combustion chamber, wherein the combustion chamber comprises for each segment of the gas burner rod an individual gas inlet port. The pneumatic gas control valve provides a gas flow to each of the individual gas inlet ports of the combustion chamber. A shut off valve may be assigned to at least one of the individual gas inlet ports to selectively open or close the respective gas inlet port thereby selectively operating the respective segment of the gas burner rod. Such a multiple segment configuration of the burner rod enables a high turn down ratio with a turn down in power input to the burner. A very effective operation of a the partially-premixed gas burner appliance can be provided.

Alternatively, the gas burner rod may not be segmented. A gas burner rod not being segmented does not require a shut off valve assigned to the gas inlet port.

According to a preferred embodiment, the first chamber of the gas outlet pressure regulator of the pneumatic gas control valve is connected to the air inlet port of the combustion chamber through a pipe or duct. This provides a very simple and reliable way to balance the air pressure drop with the gas pressure drop.

According to a preferred embodiment, the gas outlet pressure regulator of the pneumatic gas control valve comprises a diaphragm. The first chamber of the gas outlet pressure regulator of the pneumatic gas control valve is positioned on a first side of said diaphragm such that the air pressure being present within the within first chamber acts on the first side of said diaphragm. A second chamber of the gas outlet pressure regulator of the pneumatic gas control valve is positioned on a second side of said diaphragm, wherein the second chamber of the gas outlet pressure regulator is connected to a gas outlet chamber of the pneumatic gas control valve such that the gas outlet pressure being present within the within second chamber acts on the second side of said diaphragm. The gas outlet pressure regulator further comprises a first spring and a second spring, wherein a spring force provided by the first spring acts on the first side of said diaphragm and a spring force provided by the second spring acts on the second side of said diaphragm. The gas outlet pressure regulator of the pneumatic gas control valve further comprises a presetting unit acting on the first spring to adapt the spring force acting on the first side of said diaphragm thereby adapting the nominal-value of the gas outlet pressure. It is possible to provide a very simple and reliable <NUM>:<NUM> gas-air control for a partially-premixed gas burner appliance without the need of an electronic gas modulator.

Preferred developments of the invention are provided by the dependent claims and the description of the drawings. Exemplary embodiments are explained in more detail on the basis of the drawing, in which:.

The present invention relates to a partially-premixed gas burner appliance <NUM>.

The partially-premixed gas burner appliance <NUM> comprises a combustion chamber <NUM> in which gas G is combusted. In the shown embodiment, a gas burner rod <NUM> having at least two segments 12a, 12b is positioned within the combustion chamber <NUM>. Gas G is provided to the gas burner rod <NUM> for combustion. The combustion of the gas G takes place under the presence of air A. The combustion of the gas G results into flames <NUM> and exhaust-gas E. Alternatively, the gas burner rod <NUM> may not be segmented in multiple segments.

In the shown embodiment, a heat exchanger <NUM> is positioned within the combustion chamber <NUM>. The heat exchanger <NUM> is used to heat e. sanitary water or central heating water W for a water consumer.

The water W to be heated within the heat exchanger <NUM> is provided by a supply pipe <NUM> to the heat exchanger <NUM>. Water W which has been heated within the heat exchanger <NUM> is flowing through a return pipe <NUM> to the respective water consumer.

The partially-premixed gas burner appliance <NUM> comprises a fan <NUM>.

The fan <NUM> provides a flow of air A to the combustion chamber <NUM>. The fan <NUM> is assigned to an air inlet port 11A of the combustion chamber <NUM> or to an air duct <NUM> providing the air A to the air inlet port 11A.

The novel partially-premixed gas burner appliance <NUM> further comprises an air flow restriction element <NUM> assigned to the air inlet port 11A of the combustion chamber <NUM> or to the air duct.

The air flow restriction element <NUM> causes a pressure drop so that the pressure downstream of the air flow restriction element <NUM> within the combustion chamber <NUM> is lower than the pressure of the air flow provided by the fan <NUM> upstream of the air flow restriction element <NUM>. The air flow restriction element <NUM> can be provided by an orifice plate or by a venturi nozzle.

The novel partially-premixed gas burner appliance <NUM> further comprises a gas modulator <NUM> providing a flow of gas G to the combustion chamber <NUM>, namely through at least one gas inlet port <NUM> of the combustion chamber <NUM>. For each segment 12a, 12b of the gas burner rod <NUM> the combustion chamber <NUM> may have an individual gas inlet port <NUM>. For a gas burner rod <NUM> not be segmented or for each segment 12a, 12b of the gas burner rod <NUM> the combustion chamber <NUM> may have multiple gas inlet ports <NUM>.

A gas flow restriction element <NUM> is assigned to each of the gas inlet ports <NUM>. Such a gas flow restriction element <NUM> causes a pressure drop such that the gas pressure upstream of the gas flow restriction element <NUM> is greater than the pressure downstream of the gas flow restriction element <NUM> within the combustion chamber <NUM>. The gas flow restriction element <NUM> can be provided by an orifice plate or by a venturi nozzle.

In the embodiment of <FIG>, a shut off valve <NUM> is assigned to the gas inlet port <NUM> providing gas G to the segment 12b of the gas burner rod <NUM>. This makes it possible to selectively open or close the gas inlet port <NUM> thereby selectively operating the segment 12b of the gas burner rod <NUM>.

It would also be possible to assign such a shut off valve <NUM> the gas inlet port <NUM> providing gas G to the segment 12a of the gas burner rod <NUM>.

The exhaust-gas E flows out of the combustion chamber <NUM> through an exhaust-gas outlet port 11E of the combustion chamber <NUM>.

A first portion A1 of the air flow or air A provided by the fan <NUM>, which enters the combustion chamber <NUM> through the air inlet port 11A, is premixed with the gas G provided by gas modulator <NUM> before the gas G is combusted.

A second portion A2 of the air A provided by the fan <NUM>, which enters the combustion chamber <NUM> through the air inlet port 11A, is mixed with the gas G while the gas G is combusted.

The gas modulator <NUM> is provided by a pneumatic gas control valve. Said pneumatic gas control valve <NUM> is configured to be used in fully-premixed gas burner appliance.

The pneumatic gas control valve <NUM> comprises a housing <NUM> providing an inlet gas chamber 21a, an outlet gas chamber 21b and an intermediate gas chamber 21c coupled between the inlet gas chamber 21a, an outlet gas chamber 21b.

The pneumatic gas control valve <NUM> comprises further a main gas valve <NUM>, a safety gas valve <NUM>, a servo gas valve <NUM> and gas outlet pressure regulator <NUM>.

When the safety gas valve <NUM> is closed, the inlet gas chamber 21a and the intermediate gas chamber 21c are fluidically separated from each other. When the safety gas valve <NUM> is opened, the intel gas chamber 21a and the intermediate gas chamber 21c are fluidically connected to each other.

The safety gas valve <NUM> is opened by an actuator <NUM> against a closing force provide by a spring <NUM>. When the safety gas valve <NUM> is opened, also the servo gas valve <NUM> becomes opened. Safety gas valve <NUM> and servo gas valve <NUM> are both opened by the actuator <NUM>.

When the main gas valve <NUM> is closed, the intermediate gas chamber 21c and the outlet gas chamber 21b are fluidically separated from each other.

When the main gas valve <NUM> is opened, the intermediate gas chamber 21c and the outlet gas chamber 21c are fluidically connected to each other.

The main gas valve <NUM> comprises a diaphragm <NUM> and a spring <NUM>. The diaphragm <NUM> separates the outlet gas chamber 21b from a servo pressure chamber <NUM>. The servo pressure chamber <NUM> is fluidically connected to the servo gas valve <NUM>.

The gas outlet pressure being present in the outlet gas chamber 21b and a spring force provided by the spring <NUM> of the main gas valve <NUM> act on a first side of the diaphragm <NUM> of the main gas valve <NUM> tending to close the main gas valve <NUM>.

A servo gas pressure being present within the servo gas chamber <NUM> acts on the second side of the diaphragm <NUM> of the main gas valve <NUM> tending to open the main gas valve <NUM>.

The servo gas chamber <NUM> is further fluidically connected to the the gas outlet pressure regulator <NUM> of the pneumatic gas control valve <NUM> through a pressure relief valve <NUM>.

The gas outlet pressure regulator <NUM> of the pneumatic gas control valve <NUM> comprises a diaphragm <NUM> and two springs <NUM>, <NUM>. The diaphragm <NUM> of the gas outlet pressure regulator <NUM> separates a first chamber <NUM> of the gas outlet pressure regulator <NUM> from a second chamber <NUM> of the same.

The pressure being present within the first chamber <NUM> of the gas outlet pressure regulator <NUM> influences the nominal-value of the gas outlet pressure within the outlet gas chamber 21b of the pneumatic gas control valve <NUM>. The pressure being present within the first chamber <NUM> of the gas outlet pressure regulator <NUM> acts on a first side of the diaphragm <NUM> of the gas outlet pressure regulator <NUM>. Further on, a spring force provided by the spring <NUM> acts on a first side of the diaphragm <NUM>.

The second chamber <NUM> of the gas outlet pressure regulator <NUM> is positioned on a second side of said diaphragm <NUM>, wherein the second chamber <NUM> of the gas outlet pressure regulator <NUM> is fluidically connected to the gas outlet chamber 11b of the pneumatic gas control valve <NUM> such that the gas outlet pressure being present within the gas outlet chamber 21b and within the second chamber <NUM> of the gas outlet pressure regulator <NUM> acts on the second side of the diaphragm <NUM> of the gas outlet pressure regulator <NUM>. Further on, a spring force provided by the spring <NUM> acts on a second side of the diaphragm <NUM>.

The gas outlet pressure regulator <NUM> of the pneumatic gas control valve <NUM> further comprises presetting unit <NUM> acting on the first spring <NUM> to adapt the spring force acting on the first side of said diaphragm <NUM>. With the presetting unit <NUM> the nominal-value of the gas outlet pressure of the pneumatic gas control valve <NUM> can be adapted. The presetting unit <NUM> can be used to provide an offset or a delta between the pressure on either side of the diaphragm <NUM> of the gas outlet pressure regulator <NUM> and as a result an offset or a delta between the generated air pressure and the gas outlet pressure.

The pressure relief valve <NUM> through which the servo gas chamber <NUM> is fluidically connected to the gas outlet pressure regulator <NUM> of the pneumatic gas control valve <NUM> is integrated into the diaphragm <NUM> of the gas outlet pressure regulator <NUM>.

According to the present invention, the gas outlet pressure regulator <NUM> of the pneumatic gas control valve <NUM>, namely the first chamber <NUM> of the gas outlet pressure regulator <NUM> in which the pressure is present that influences the nominal-value of the gas outlet pressure, is permanently fluidically connected to the air inlet port 11A of the combustion chamber <NUM> or to the air duct providing the air A to the air inlet port 11A upstream of the air flow restriction element <NUM> such that the gas outlet pressure provided by pneumatic gas control valve <NUM> depends on to the air pressure provided by the fan <NUM> upstream of the air flow restriction element <NUM>.

As shown in the Figures, the first chamber <NUM> of the gas outlet pressure regulator <NUM> of the pneumatic gas control valve is connected to the air inlet port 11A of the combustion chamber <NUM> or to the air duct <NUM> through a pipe or duct <NUM>.

The pneumatic gas control valve <NUM> features a positive servo system. The main gas valve <NUM> is closed by the spring <NUM> in the normal shut down position and can only be opened when pressure within the servo gas chamber <NUM> is sufficient to overcome the spring force of the spring <NUM>. This ensures the main gas valve <NUM> will automatically close in the event of power or gas supply failure.

An element of the pneumatic gas control valve <NUM> is the gas outlet pressure regulator <NUM> which comprises the pressure relief valve <NUM> integrated in the diaphragm <NUM> which controls the main gas valve <NUM>.

When the safety gas valve <NUM> and the servo gas valve <NUM> are both opened by the actuator <NUM>, then gas flows through the servo gas valve <NUM> into the servo pressure chamber <NUM> and to the pressure relief valve <NUM>. This gas pressure within the servo pressure chamber <NUM> moves the main valve diaphragm <NUM> upwards enough to open the main gas valve <NUM>. As soon as the main gas valve <NUM> has opened, the outlet gas pressure will be sensed by the regulator diaphragm <NUM> via a feedback channel <NUM> connecting the second chamber <NUM> of the gas outlet pressure regulator <NUM> to the gas outlet chamber 21b pneumatic gas control valve <NUM>.

When the force provided by the pressure within the second chamber <NUM> of the gas outlet pressure regulator <NUM> is greater than the force provided by the pressure within the first chamber <NUM> and by the presetting unit <NUM>, the pressure relief valve <NUM> opens relieving some of the working pressure within the servo pressure chamber <NUM>. This reduces the force against the main valve spring <NUM> allowing the main gas valve <NUM> to close proportionally. Thus, the main gas valve <NUM> limits the gas outlet pressure. As a result, the gas outlet pressure is continuously maintained by comparing the gas outlet pressure being present in the second chamber <NUM> of the gas outlet pressure regulator <NUM> with the pressure being present in the first chamber <NUM> of the gas outlet pressure regulator <NUM> and adjusting the position of the main gas valve <NUM> accordingly.

The fan <NUM> is located at the air inlet of the combustion chamber <NUM>. The air pressure which is generated by the fan <NUM> is transferred to first chamber <NUM> of the gas outlet pressure regulator <NUM> to generate the outlet gas pressure. This allows to provide a very simple and reliable <NUM>:<NUM> gas-air control for a partially-premixed gas burner appliance.

Claim 1:
Partially-premixed gas burner appliance (<NUM>), comprising:
a combustion chamber (<NUM>),
a fan (<NUM>) being configured to provide an air flow to the combustion chamber (<NUM>),
wherein the fan (<NUM>) is assigned to an air inlet port (11A) of the combustion chamber (<NUM>) or to an air duct (<NUM>) being configured to provide the air to the air inlet port (11A),
an air flow restriction element (<NUM>) being assigned to the air inlet port (11A) of the combustion chamber (<NUM>) or to the air duct (<NUM>) and being configured to provide a pressure drop so that the pressure downstream of the air flow restriction element (<NUM>) is lower than the pressure upstream of the air flow restriction element (<NUM>),
a gas modulator (<NUM>) being configured to provide a gas flow to the combustion chamber (<NUM>),
wherein a first portion of the air provided by the fan (<NUM>) is premixed with the gas flow before the gas is combusted,
wherein a second portion of the air provided by the fan (<NUM>) is mixed with the gas while the gas is combusted,
wherein the gas modulator (<NUM>) is a pneumatic gas control valve configured to be used in a fully-premixed gas burner appliance, the pneumatic gas control valve having a main gas valve (<NUM>), a safety gas valve (<NUM>), a servo gas valve (<NUM>) and gas outlet pressure regulator (<NUM>),
wherein the gas outlet pressure regulator (<NUM>), namely a first chamber (<NUM>) of the gas outlet pressure regulator (<NUM>) in which a pressure is present that influences the nominal-value of the gas outlet pressure of the pneumatic gas control valve, is connected to the air inlet port (11A) or to the air duct (<NUM>) upstream of the air flow restriction element (<NUM>) such that the gas outlet pressure provided by the pneumatic gas control valve depends on the air pressure provided by the fan (<NUM>) upstream of the air flow restriction element (<NUM>).