Patent Description:
The invention refers to a pressure relief valve, which is commonly used in heating devices with a closed circuit of a heating medium, for example in hanging hot water boilers, to release pressure exceeding the predetermined nominal value of the valve, which may occur for various reasons in the heating system during operation.

The valves of this type use a diaphragm that keeps the valve in a closed position by means of a suitably calibrated spring depending on the operating pressure of the boiler or heating device.

The pressure relief valve is an automatic valve and ensures that the pressure of the medium in the system does not exceed the set value, which plays an important role in the safety and operation of the device.

It prevents exceeding the set value in the pipeline or in the equipment by discharging the medium from the system when the pressure of the medium in the equipment or pipeline rises above the set value.

Parts and fittings of water supply systems, such as valves, were historically made of metal, usually brass, and were able to withstand water pressures significantly higher than that of a standard water supply system which a heating device is connected to.

Currently, plastics, especially composites, have fully replaced metal in many applications, as they are sufficiently durable in devices working with normal water pressure in heating systems. By shaping the body from plastic material, it is possible to give the valve body or its part any functional shape, and therefore it is possible to produce a valve of a very simple design.

The pressure relief valve is fully assembled and calibrated during production and has the properties required by the applicable hydraulic standards, in particular.

Pressure relief valves made of plastic materials intended for use in heating devices are known in the state of the art.

<CIT> describes an indestructible cartridge safety relief valve and cartridge holder assembly for a safety relief valve for liquid or gas circuits. Since the pressures to be set can take on different values, depending on the applications considered and due to possible modifications of the system, the above safety relief valve is removably connected to a holder as a cartridge. The valve has a calibration assembly, the spring of which is placed between the piston element and the calibration threaded ring nut. Any attempts to control the pressure adjusting ring nut designed to adjust the calibration pressure of the calibration assembly would cause the cover to break and the valve to get damaged.

<CIT> describes a pressure relief valve for hanging boilers, where the valve body, seat and connections are made of plastic material
Calibration of the value of the opening pressure of the valve is possible, in the example shown, the threaded sleeve is guided along a rod, which is an integral part of the cap. The rod is threaded, and when it rotates, it is possible to move the threaded sleeve which the spring rests against.

Such a design of a safety relief valve is complicated.

Another pressure relief valve made of brass, known in the state of the art (of the RBM manufacturer) is also calibrated in production and does not allow to adjust opening pressure. The cross-section of the valve is shown in <FIG>.

The valve consists of a metal valve body, a valve chamber connected to the valve inlet and the valve outlet, a diaphragm resting on the valve seat and pressed by a calibrated spring, and a closing cap equipped with an external thread. The safety relief valve contains a relief mechanism for manual control of the valve using a rotating wheel.

When assembling the valve, the valve body is equipped with a diaphragm, the piston is fitted with a calibrated spring, and by turning and engaging the thread the closing cap firmly presses the diaphragm to the valve body with the calibrated spring.

A ring-shaped anti-friction pad prevents damage to the diaphragm when tightening the cap to the required torque.

When the relief mechanism with the cover is mounted, the pressure relief valve becomes unbreakable (it cannot be disassembled without damaging the cover), which complies with the applicable standards.

The disadvantage of the described valve is that the set pressure cannot be adjusted, changing the set pressure is possible only by using a different spring.

The impossibility of setting the pressure or finer adjustment of the valve turns out to be problematic, as the springs used in safety relief valves have their own tolerances, and therefore it is not possible to set the opening pressure to the nominal value accurately.

<CIT> discloses a module for a membrane safety valve to be mounted in a valve housing. The intention is to enable a module for a membrane safety valve for insertion in a valve housing to be manufactured in a simple and economical manner and to be used with different types of safety-valve housing. For this purpose, the module comprises a housing top part, a housing bottom part, a diaphragm clamped between the housing top part and the housing bottom part, a valve-closing member connected to the diaphragm, a loading spring which is arranged in the housing top part. This solution does not solve the opening pressure setting, it describes a possibility of universal assembly of internal components, which enables quick replacement in various pressure relief valve bodies.

<CIT> relates to a safety valve device for pressurized water tanks, for example for accumulating water heaters or for other applications, which can form part of a safety valve group applicable to a cold-water inlet of a water heater. The focus is at reducing wear of the swivel cap when manually opening the safety valve, it does not deal with pressure adjustment.

<CIT> discloses a valve and an actuator for a valve. In particular, the invention relates to a valve actuator responsive to rotational input for moving a first valve part axially between open and closed positions relative to a second valve part. The cam mechanism does not transmit spring force to the movable valve member when the valve member is in the closed position. The aim of the solution is to prevent incorrect pressing of the membrane against the valve seat.

<CIT> describes a pressure relief valve for protecting boiler against high pressure. It has a valve seat, valve body and spring element forming valve insert, which is mountable as unit in valve housing and demountable as unit from housing.

None of the cited documents take into account the inaccuracy and tolerances of the calibrated spring used and do not deal with the precise setting of the spring pressure.

The presented invention eliminates this disadvantage and enables fine adjustment of the nominal pressure of the valve with no need to replace the calibrated spring, while the adjustment refers only to the cap closing the valve in its upper part.

Claim <NUM> discloses an adjustable pressure relief valve according to the invention. The dependent claims disclose preferred embodiments.

An adjustable pressure relief valve, intended for heating devices with a closed circuit of a heating medium, with a valve body equipped with a valve inlet and a valve outlet connected to a valve chamber, with a piston movably arranged in the valve chamber, on which there is a calibrated spring and a flexible closing diaphragm arranged. In the normal state, when the calibrated spring is pressing on the flexible closing diaphragm, the valve is closed, and wherein the valve is equipped with a two-part closing assembly, including an upper cap and a lower cap, for accurate setting of the nominal opening pressure by compressing the calibrated spring.

The upper cap is equipped with a thread to compress the spring and the lower cap is equipped with a stop to prevent the upper cap from being completely unscrewed. The calibrated spring is located between the upper cap and the piston. Spring compression can be finely adjusted by turning the upper cap and engaging the spring compression thread.

The lower cap is equipped with a thread to press the diaphragm to the valve body. There is an anti-friction pad arranged between the lower cap and the diaphragm to protect the diaphragm from damage. By turning and engaging the thread, the diaphragm is firmly pressed against the valve body by means of the calibrated spring. The safety relief valve is equipped with a relief mechanism to open the valve manually and to fix the two-piece closing assembly in the set position. The relief mechanism is advantageously equipped with a joint and a lever, after its installation both caps are fixed in the set positions and the valve cannot be disassembled without damage.

The valve is advantageously made of plastic, only the calibrated spring is metal.

The invention is further explained using the figures below, without limitation thereto. The figures show:.

<FIG> shows a brass valve from the RBM manufacturer - only for illustration and for better understanding of the advantages of the presented invention compared to the state of the art. The valve, known in the state of the art, is equipped with a closing cap <NUM>, which is used to press the diaphragm <NUM> against the body <NUM> of the valve. The closing cap <NUM> does not allow the spring <NUM> to be pressed. The relief mechanism <NUM> is designed here as a relief mechanism for manual control of the valve using a rotating wheel.

<FIG> shows a model of a pressure relief valve according to the presented invention.

An adjustable pressure relief valve, intended for heating devices with a closed circuit of a heating medium, with a valve body <NUM> equipped with a valve inlet <NUM> and a valve outlet <NUM> connected to a valve chamber.

There is a piston <NUM> movably arranged in the valve chamber and there is a calibrated spring <NUM> arranged on the piston <NUM>. There is a flexible closing diaphragm <NUM> in the valve chamber between the inlet <NUM> and the outlet <NUM>, which is pressed by a spring <NUM> so that the valve is closed in the normal state.

The safety relief valve is equipped with a two-part closing assembly, including an upper cap <NUM> and a lower cap <NUM> for pressing the diaphragm <NUM> to the valve body <NUM>.

The calibrated spring <NUM> is inserted between the upper cap <NUM> and the piston <NUM> during assembly. To compress the spring <NUM>, the upper cap <NUM> is equipped with a thread <NUM>.

The lower cap <NUM> is equipped with a stop <NUM> preventing the upper cap <NUM> from being completely unscrewed.

The lower cap <NUM> is also equipped with a thread <NUM> to press the diaphragm <NUM> to the body <NUM> of the valve by means of a calibrated spring <NUM>.

There is an anti-friction pad <NUM> arranged between the lower cap <NUM> and the diaphragm <NUM> to protect the diaphragm <NUM> from damage.

The pressure relief valve can be finely adjusted by turning the upper cap <NUM>, while the spring <NUM> is compressed.

The relief mechanism (not shown) is advantageously equipped with a joint and a lever and is used for manual opening of the valve (service).

When the relief mechanism is mounted, the two-piece closing assembly, including the upper cap <NUM> and the lower cap <NUM>, is fixed in a set position and the valve cannot be disassembled without damage.

The nominal pressure which the safety relief valve is calibrated to is, for example, <NUM> bars.

The adjustable pressure relief valve is designed to prevent exceeding the value set in a heating device with a closed circuit of a heating medium by discharging the medium from the system when the pressure of the medium in the device rises above the nominal value set.

Claim 1:
An adjustable pressure relief valve, intended for heating devices with a closed circuit of a heating medium, with a valve body (<NUM>) equipped with a valve inlet (<NUM>) and a valve outlet (<NUM>) connected to a valve chamber, with a piston (<NUM>) movably arranged in the valve chamber, on which there is a calibrated spring (<NUM>) and a flexible closing diaphragm (<NUM>) arranged, wherein the valve is closed in the normal state under the pressure of the calibrated spring (<NUM>) on the flexible closing diaphragm (<NUM>),
wherein the valve is equipped with a two-part closing assembly, including an upper cap (<NUM>) and a lower cap (<NUM>) for accurate setting of the nominal opening pressure,
the calibrated spring (<NUM>) is located between the upper cap (<NUM>) and the piston (<NUM>) and
the upper cap (<NUM>) is equipped with a thread (<NUM>) to compress the calibrated spring (<NUM>),
the lower cap (<NUM>) is equipped with a thread (<NUM>) to press the diaphragm (<NUM>) to the valve body (<NUM>)
and the valve is designed such that it is finely adjustable by turning the upper cap (<NUM>), while the spring (<NUM>) is compressed,
characterized in that
the lower cap (<NUM>) is equipped with a stop (<NUM>) to prevent the upper cap (<NUM>) from being completely unscrewed.