The invention relates to a gas valve unit for setting a gas volume flow supplied to a gas burner of a gas appliance, in particular a gas cooker, the gas valve unit having a valve housing and an actuation pin, an operating segment of which projects from the valve housing and a shutoff valve being configured in the valve housing.
Gas valves of such design are frequently referred to as safe gas valves. The gas valve unit has a variable cross section, which can be set by way of the actuation pin. The opening cross section here can be set infinitely. The size of the gas volume flow flowing through the gas valve unit and therefore also the flame size at the gas burner are a direct function of the opening cross section. Generally with generic gas valve units the opening cross section can be set to zero, in other words the gas valve unit can be closed completely.
The gas valve unit also has a shutoff valve that can be actuated independently of the setting of the opening cross section. The shutoff valve generally has an open switching position and a closed switching position but no intermediate positions. When the shutoff valve is closed, the gas flow through the gas valve unit is stopped completely. In contrast the opened shutoff valve has no influence on the opening cross section of the gas valve unit. The shutoff valve serves on the one hand to ensure complete closure of the gas valve unit in a redundant manner. On the other hand it is possible to actuate the shutoff valve automatically for example as a function of the signal from a flame sensor.
Known gas valve units of the type mentioned in the introduction are generally embodied as plug valves. The opening cross section here is set as a function of the rotation position of a plug that can be rotated in a valve seat. The actuation pin is disposed coaxially to the plug and connected thereto. The opening cross section of the gas valve unit is set by rotating the actuation pin. The shutoff valve can be opened by pushing the same actuation pun.
Gas valve units of such design frequently have an unfavorable switching response. In particular the opening cross section can frequently only be set in an imprecise and non-reproducible manner.
The object of the present invention is to provide a generic gas valve unit having an improved switching response.
According to the invention this object is achieved in that at least two on-off valves are configured in the valve housing, it being possible to actuate the on-off valves by rotating the actuation pin and it being possible to actuate the shutoff valve by axially displacing the actuation pin. The on-off valves serve to set the opening cross section of the gas valve unit and thus the size of the gas volume flow flowing through the gas valve unit. This can be done for example by opening the on-off valves one after the other and closing them again. The on-off valves are actuated by rotating the actuation pin. The gas valve unit also has an additional shutoff valve, which when closed completely stops the gas flow through the valve unit. When open the shutoff valve has an opening cross section of such size that the size of the gas volume flow is set exclusively by opening and closing the on-off valves. The shutoff valve is actuated by axial movement of the actuation pin. Both the on-off valves and the shutoff valve can thus be actuated by way of the same actuation pin.
At least two throttle points, each having at least one throttle opening, are particularly advantageously configured in the valve housing. Gas can flow through said throttle points as a function of the switching position of the on-off valves. Just one throttle point is preferably assigned to each on-off valve. When an on-off valve is opened, gas can flow through said throttle point but when an on-off valve is closed, gas cannot flow directly from the gas inlet through the throttle point assigned to said on-off valve but by way of a diversion through other throttle points.
The shutoff valve is preferably disposed in the region of a gas inlet of the gas valve unit. When the shutoff valve is closed, there is therefore no gas present at any of the on-off valves or at any throttle point. If there are leak points in the region of the on-off valves or the throttle points, an outflow of gas from said leak points is reliably prevented when the shutoff valve is closed.
The shutoff valve preferably has a movable shutoff element. The shutoff element can be formed for example by an axially movable valve plate, which pushes onto an annular valve seat in the closed state.
The movable shutoff element of the shutoff valve is pretensioned in the closing direction, in particular by means of spring force. This means that the shutoff valve is always closed when the gas appliance is out of operation.
The movable shutoff element of the shutoff valve can be moved into an open position counter to the pretensioning by pushing the actuation pin. The pushing movement of the actuation pin is transferred directly or indirectly to the shutoff element. In the open position the shutoff element is raised from the valve seat of the shutoff valve, thereby releasing the gas path from the gas inlet of the valve housing in the direction of the on-off valves.
The movable shutoff element of the shutoff valve can also be held in the open position counter to the spring force by the force of a magnetic coil. The shutoff valve has a magnetic coil, with which a force acting in the opening direction can also be applied to the shutoff element. Voltage can be applied to the magnetic coil here for example by a thermocouple or an electronic controller. The magnetic coil is designed so that when it is already in the open position the shutoff element can be held in this position by means of the force of the magnetic coil. In contrast it is not possible to move the shutoff element from a closed position into the open position by means of the force of the magnetic coil. The magnetic coil is coupled to a flame sensor in the region of a gas burner in such a manner that the shutoff valve is held open when a gas flame burns at the gas burner. When the gas flame has been extinguished, the power supply to the magnetic coil is interrupted and the shutoff valve closes automatically by means of spring force.
According to one expedient embodiment of the invention a deflection apparatus is provided, which converts an axial movement of the actuation pin to an axial movement of the shutoff element of the shutoff valve essentially at right angles thereto. The movement direction of the shutoff element here is perpendicular to the axial actuation direction of the actuation pin. Such a gas valve unit structure is chosen to minimize the dimensions of the housing of the gas valve unit in the axial direction of the actuation pin.
The deflection apparatus has a first slide element, which is disposed on the actuation pin in the region of the end of the actuation pin opposite the operating segment. The first slide element is moved with the actuation pin when the actuation pin is moved axially. The first slide element and the actuation pin can be embodied for example as a single piece.
The first slide element is preferably embodied as a first conical element so that a tip of the first conical element points away from the operating segment of the actuation pin. When the actuation pin is pushed, the first conical element moves in the direction of its tip. When the actuation pin is rotated, the spatial location of the first conical element does not change however, as it is rotated about its axis of symmetry.
The deflection apparatus preferably has a second slide element, which is in contact with the first slide element at least when the actuation pin is pushed. In this process the second slide element slides down along the first slide element.
The second slide element is preferably configured as a second conical element, the center axis of which is disposed essentially perpendicular to the actuation pin and the tip of which points in the direction of the first slide element. The configuration of the second slide element as a second conical element has the advantage that the rotation position of the second conical element in relation to its axis of symmetry has no impact on the mode of operation of the deflection apparatus.
The first slide element and the second slide element are configured and disposed so that an axial displacement of the actuation pin as a result of pushing on the operating segment is converted to an axial displacement of the second slide element in the direction away from the actuation pin.
The second slide element is also actively connected to the shutoff element of the shutoff valve so that an axial movement of the second slide element in the direction away from the actuation pin is transferred to the shutoff element. When the actuation pin is pushed, the shutoff element of the shutoff valve is therefore raised from its valve seat, thereby opening the shutoff valve.
Also provided in the gas valve unit is an actuation apparatus for the on-off valves, which is coupled to the actuation pin by means of a coupling apparatus at an end of the actuation pin within the valve housing. The actuation apparatus for example comprises a permanent magnet, which can be moved relative to the on-off valves. A rotation movement of the actuation pin is transferred to the actuation apparatus for the on-off valves by means of the coupling apparatus.
The coupling apparatus here is embodied so that the actuation apparatus is coupled to the actuation pin with torsional rigidity.
The coupling apparatus is also embodied so that an axial displacement of the actuation pin is not transferred to the actuation apparatus.
To this end the coupling apparatus has a slot-type recess on an end face of the end of the actuation pin opposite the operating segment.
The coupling apparatus further comprises a flat carrier, which engages in the slot-type recess. The flat carrier engaging in the slot-type recess allows transmission of a torque from the actuation pin to the actuation apparatus of the on-off valves. Axial movement of the actuation pin is compensated for in that the flat carrier is inserted to a greater or lesser degree into the slot-type recess.
The recess is particularly advantageously disposed in a base of a third conical element, which is configured on the actuation pin in the region of the end of the actuation pin opposite the operating segment, so that a tip of the third conical element points in the direction of the operating segment of the actuation pin and is connected to a tip of the first conical element. The configuration of the end of the actuation pin as a conical element has the advantage that the spatial extension of a conical element does not change when the actuation pin is rotated. There is therefore no risk of unintended movement of the second slide element because it accidentally comes into contact with the third conical element.
Further advantages and details of the invention are described in more detail with reference to the exemplary embodiment illustrated in the schematic figures, in which
A gas inlet 1 is shown, by way of which the gas valve unit is connected for example to a main gas line of a gas cooker. The gas provided for combustion is present at the gas inlet 1 with a constant pressure of for example 20 millibars or 50 millibars. Connected to a gas outlet 2 of the gas valve unit is a gas line, which leads for example to a gas burner of the gas cooker. The gas inlet 1 is connected by way of a gas inlet chamber 9 of the gas valve unit to the inlet side of the, in the present exemplary embodiment, five on-off valves 3 (3.1 to 3.5). Opening the on-off valves 3 connects the gas inlet 1 in each instance to a specified segment of a throttle section 5, into which the gas flows by way of the opened on-off valve 3. The throttle section 5 comprises an inlet segment 7, into which the first on-off valve 3.1 opens. The further on-off valves 3.2 to 3.5 open respectively into a connecting segment 6 (6.1 to 6.4) of the throttle section 5. The transition between the inlet segment 7 and the first connecting segment 6.1 and the transitions between two adjacent connecting segments 6.1 to 6.4 are formed respectively by a throttle point 4 (4.1 to 4.5). The last throttle point 4.5 connects the last connecting segment 6.4 to the gas outlet 2. The throttle points 4.1 to 4.5 have an opening cross section that increases along the row. The throughflow cross section of the last throttle point 4.5 can be selected to be of such size that the last throttle point 4.5 has practically no throttle function.
The on-off valves 3 are actuated by means of a permanent magnet 8, which can be displaced along the row of on-off valves 3. The force for opening the respective on-off valve 3 is formed here directly by the magnetic force of the permanent magnet 8. This magnetic force opens the respective on-off valve 3 counter to a spring force.
In the switching position according to
The gas flows through the opened second on-off valve 3.2 from the gas inlet chamber 9 directly into the first connecting segment 6.1 and from there by way of the throttle points 4.2 to 4.5 to the gas outlet 2. The gas flowing to the gas outlet 2 bypasses the first throttle point 4.1 due to the opened on-off valve 3.2. The gas volume flow in the switching position according to
Moving the permanent magnet 8 to the right in the drawing causes the on-off valves 3.3 to 3.5 to be successively opened, thereby increasing the gas volume flow through the gas valve unit in steps.
In the switching position according to
A cover 30 is configured on the upper face of the valve body, in which, from bottom to top, the valve sealing plate 12, the pressure plate 13, the first gas distribution plate 14, the throttle plate 15 and the second gas distribution plate 16 are disposed. The plates 12 to 16 can be accessed by removing the cover 30. Access to the plates 12 to 16 is from above, in other words from the same side from which the actuation pin 31 projects from the valve housing 20.
The throttle plate 15 in particular can be replaced to adapt the gas valve unit for a different type of gas. Present in the throttle plate 15 are the throttle openings 18, which largely determine the size of the gas volume flow. When the cover is removed upward, all the plates 12 to 16 are present in the cover 30.
Also shown is the arrangement for actuating the shutoff valve 40 (not shown in this figure). It comprises a first slide element 41, which is fastened to the actuation pin 31. The first slide element 41 is in contact with a second slide element 42, which is coupled by way of a connecting element 45 to a valve body of the shutoff valve. Both slide elements 41, 42 are formed by conical bodies. A third conical body 43 serves as part of a coupling apparatus 26, which transfers a rotational movement of the actuation pin 31 to the actuation apparatus 25. The coupling apparatus 26 consists essentially of a carrier 27, which engages in a slot-type recess 28.
In the position illustrated in
In the switching position according to
If the switching pin 31 is now pressed in downward in an axial direction, the shutoff valve 40 opens and the valve housing 20 fills with gas.
This state of the gas valve unit is illustrated in
In contrast
The nature of the actuation of the shutoff valve 40 is described in more detail again with reference to
In the illustration according to
In the switching position according to
In the illustration according to
The connecting element 45 configured as a spring is suitable for transferring a pressure force of the second slide element 42 to the shutoff body 10. In this process the second slide element 42 slides down along the first slide element 41, which is configured from the actuation pin 31.
Present below the first slide element 41 is the third conical element 43 with the coupling apparatus 26, which transfers a rotational movement of the actuation pin 31 to the permanent magnet 8. The magnetic force of the permanent magnet 8 opens the on-off valve 3 directly above it in each instance.
Number | Date | Country | Kind |
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10290660.9 | Dec 2010 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP11/72056 | 12/7/2011 | WO | 00 | 5/28/2013 |