EP2952810B1 - Valve assembly for filtering liquid fuel - Google Patents

Description

The invention relates to a connection fitting for filtering liquid fuel, in particular fuel oil, with a fitting housing having a first nozzle for connecting a supply line of a fuel tank, a second nozzle for connecting a flow line to a fuel consuming or further processing burner, a third nozzle for Connecting a return line from the burner, and having a filter chamber with a filter cartridge for the fuel, wherein the valve body has a first flow channel connecting the first port to the second port via the filter chamber and the filter cartridge.

Such connection fittings are known in the art. They are installed between a fuel tank and a burner. It is achieved by the appropriate design, a return of the unconsumed fuel to the burner. Typical are such connection fittings with an additional venting device or with an automatic breather arrangement.

The fuel oil not consumed by the burner, for example, is fed back via the return line and a spring-loaded overflow valve of the supply line to the burner pump, namely in the flow direction behind the filter insert.

Here, the overpressure generated by the burner pump in the return has the function to flush out air via a manually operable valve, so that the line, filter and burner pump are vented and filled only with fuel.

Embodiments are also known in which, for small burner powers, the return fuel is fed in front of the filter insert, so that the fuel is filtered several times.

From the DE 42 38 044 C1 a fuel filter / Entlüfterkombination is known in which no venting takes place to the environment. The corresponding fitting is closed to the environment. The air components in the fuel and the Fuel itself, which is supplied from the burner via the return line, flows through a capillary tube and a nozzle behind the filter insert to the burner feed, so that the air is discharged through the burner nozzle during the firing process. In this case, however, optimum combustion of the fuel is not achievable.

The flow channel formed by the capillary tube is associated with a spring-loaded overflow valve in parallel, which also supplies larger return quantities to the burner inlet behind the filter insert.

Multiple filtering does not take place here. A safety function achieved by such a construction concerns the possibility of hose breakage of the return line. Due to the permanently open flow channel in the capillary tube and nozzle, air is drawn into the system during the demolition of the return hose during the fuel supply in the suction mode and the system shuts off due to fuel shortage. Brenner goes on error. This prevents further leakage of fuel from the demolished return line.

In the prior art, a corresponding valve is also known, in which a non-pressurized return is provided. In normal operation, the spring of a relief valve is relaxed. All of the fuel coming back from the burner is returned directly to the supply line and the burner pump. An assembly consisting of overflow and Vent valve, tensioned only when they are actuated, the spring of the overflow valve, wherein a valve stem cooperates with a valve seat in the filter housing. The pressure thus generated in the return line allows both air / fuel can escape from the released vent hole of the assembly, as well as fuel through the spill valve is still supplied to the flow line to the burner. Multiple filtering does not take place here.

There is also known an embodiment in which an automatic venting takes place by a float system, wherein the overflow also opens by the pressure generated by the burner pump, or on the level and the return fuel is supplied to the burner inlet in the flow direction behind the filter again. Again, no multiple filtering takes place.

Even with a solution that, for example, in the DE 10 2005 006 878 B4 is described, the safety function, which is described above, is known, which comes at a destruction of the return line from the burner to the fuel filter (hose breakage) to wear and causes an interruption of the burner operation. This function is made possible by the design-related permanent opening of the return channel within the fuel filter via which air is sucked in with a hose break.

Another known solution is in the EP 2 446 951 B1 described. Here, a switching device according to the preamble of the first claim is provided. This can be switched from a first mode in which returns fuel through the vent and the spill valve directly to the burner feed, in a second mode, in which a multiple filtering takes place, the return fuel passes through breather and overflow before the filter insert to the burner. According to the manufacturer, the function "multiple filtering" should be set up to a burner consumption of 20 liters per hour (corresponding to a burner output of up to approx. 200 kW), but this is only possible manually. For larger flows, it is necessary to switch manually to the first operating mode, that is, the one-time filtering. The flow resistance of the filter insert would be too large for multiple filtration because of the large flow.

For burners with small outputs or throughputs of, for example, 20 kW and an oil consumption of about 2 liters per hour, often accumulates an air cushion before a filter insert, regardless of whether it is a fitting with automatic ventilation or manual ventilation, in particular when the filter cartridge is still clean. Multiple filtering achieves higher throughput. Air bubbles then collect According to experience, because of the larger flow rate not before the filter cartridges.

At high burner outputs, that is, with larger fuel flow, the air cushion problem does not occur. However, a multiple filtering is then no longer feasible, because the thereby caused even higher volume flow when flowing through the filter generates too large pressure differences, which would have to overcome the burner pump.

In the prior art, there is a manual switchover to solve this problem, but only one of the two operating states possible.

In the above described from the DE 42 38 044 C1 Although known solution takes place an adaptation to small or large power by the integrated overflow automatically, but a multiple filtering does not take place. In addition, an optimal combustion of the fuel during the burner process is not achieved because it is virtually mitentlüftet only via the burner nozzle.

Based on this prior art, the present invention seeks to provide a corresponding connection fitting available in which a multiple filtering, especially at low fuel flow without manual switching to small and large burner power can be realized.

To achieve this object, the invention proposes that the third nozzle communicates with a flow distributor via which the fuel returned via the third nozzle is supplied to the inlet of the filter insert in a first partial volume flow, and in a second partial volume flow to the outlet of the filter insert to the second nozzle is supplied.

This results in a division of the recirculated from the burner in normal operation, unused fuel into a first partial flow, which is fed together with newly aspirated fuel from a fuel tank for further filtering the filter insert, and in a second partial flow, the size determined by a flow resistance is and is fed to the burner feed along with the filtered portion behind the filter insert.

In particular, it is provided that the flow distributor has or forms a flow resistance in the flow path of the second partial volume flow, by means of which the size of the volume flow is determined.

Furthermore, it is provided in particular that the flow distributor in the flow path of the first partial volume flow has a fixed set or variably adjustable cross-sectional constriction.

The first partial volume flow is guided through a first flow channel, which has a fixed or variable cross-sectional constriction, so that in the burner supply lower pressure prevails than in the return, wherein the first flow channel is formed quasi as a bypass to the second flow channel. The second partial flow is guided through a second flow channel, which has a flow resistance, whereby it is achieved that, when a sufficiently high pressure is created by an increased fuel volume flow in the return channel or by a larger burner output opens.

In particular, it is provided in these embodiments that the flow paths of the flow distributor are formed by flow channels.

Particularly preferably, it is provided that the cross-sectional constriction is formed by at least one nozzle, an annular gap or a diaphragm.

Most preferably, it is provided that a spring-loaded overflow valve is arranged as a flow resistance in the flow path of the second partial volume flow.

By the spring-loaded overflow valve ensures that, if a sufficiently high pressure by an increased fuel flow in the return channel or due to a larger burner output, the valve opens. Otherwise it is closed by spring force.

In particular, in this embodiment, it is achieved that the flow volume guided via the first flow channel is repeatedly filtered several times in normal burner operation. A manual switch is not required here.

In this case, it is provided, in particular, that the flow resistance or an overflow valve serving as a flow resistance opens in the flow path of the second partial volume flow or releases the flow path as soon as a sufficiently high pressure is produced by an increased fuel volume flow in the burner return connected to the third connection.

A further embodiment is that branches off from the flow path of the first partial volume flow a vent pipe into which a manually or by means of actuatable valve is used, which blocks the output of the vent in a first end position and opens in a second end position and the first partial flow, the consists of air or air / fuel mixture through the vent to the outside eg dissipates into the atmosphere.

In this case, a manual or by means of tool actuable ventilation option is available provided, wherein in the first end position of the normal operation is made possible and in the second end position of the first partial volume flow, which consists of air or an air / fuel mixture is discharged through the vent unit into the environment.

Preferably, it is provided that the valve is adjustable in an intermediate position between the first and second end position, wherein in the intermediate position of the first partial volume flow is shut off and the entire volume flow forms the second part volume flow.

In the intermediate layer, in which the first flow channel is closed, the entire return fuel is passed through the second flow channel and filtered only the newly sucked from a fuel oil tank fuel.

An alternative preferred embodiment is seen in that in the flow path between the third nozzle and the flow distributor, an automatic ventilation device is installed.

In this case, it is preferably provided that the third connection communicates openly with the inlet of the ventilation device via a flow path and the ventilation device is connected via a channel to the flow distributor, in which channel a spring-loaded overflow valve is inserted. In this case, an automatic venting is achieved, as is known per se in the prior art.

In particular, in the embodiment in which a manual venting is provided, a deliberate burner failure is still achieved in the case of a demolished return line, is sucked in the air over the first flow channel, so that the burner shuts off due to fuel shortage. This is a safety function in case of hose breakage.

• Es erfolgt eine Aufteilung des vom Brenner im Normalbetrieb zurückgeführten, nicht verbrauchten Brennstoffes in einen ersten Teilvolumenstrom, der zusammen mit neu angesaugtem Brennstoff aus einem Brennstofftank für eine weitere Filterung dem Filtereinsatz zugeführt wird und in einen zweiten Teilvolumenstrom, dessen Größe durch einen Strömungswiderstand bestimmt ist und der hinter dem Filter zusammen mit dem gefilterten Anteil dem Brennervorlauf zugeführt wird.

In summary, the peculiarities of the invention are the following:

• There is a division of the recirculated from the burner in normal operation, unused fuel in a first partial volume flow, which is supplied together with newly aspirated fuel from a fuel tank for further filtering the filter insert and in a second partial volume flow whose size is determined by a flow resistance and which is fed behind the filter together with the filtered portion of the burner feed.

The first partial volume flow is guided through a first flow channel, which has a fixed or variable cross-sectional constriction, for example a nozzle or an annular gap, so that a lower pressure prevails in the burner inlet than in Return, wherein the first flow channel is formed as a bypass to the second flow channel.

The second partial volume flow is passed through a second flow channel, which has as a flow resistance, for example, a spring-loaded overflow valve, which, as soon as a sufficiently high pressure arises through an increased fuel volume flow in the return channel opens.

There is provided a manually operated vent unit, the normal operation in the valve housing in one end position and in the other end position, the first partial volume flow, which consists of air or an air / fuel mixture, dissipates through the vent unit into the environment.

In a middle position of the breather valve of the manually operated vent unit, the first flow channel is closed and the entire return fuel is passed through the second flow channel. Only the fuel sucked from the fuel tank is filtered.

• Es zeigt:

  Figur 1-3

  eine erste Ausführungsform einer erfindungsgemäßen Anschlussarmatur im Mittelschnitt gesehen;

  Figur 4

  eine zweite Ausführungsform in gleicher Ansicht.

Embodiments of the invention are illustrated in the drawings and described in more detail below:

• It shows:

  Figure 1-3

  a first embodiment of a connection fitting according to the invention seen in the central section;

  FIG. 4

  a second embodiment in the same view.

In the drawings, the fuel paths are symbolized by arrows.

In the exemplary embodiments, a connection fitting for filtering liquid fuel is shown. It consists essentially of a fitting housing 1, which has a first connecting piece 2 for connecting a flow line of a fuel tank, a second nozzle 3 for connecting a flow line to a burner and a third nozzle 4 for connecting a return line from the burner. Furthermore, a filter chamber 5 is provided with a filter insert 6 for the fuel.

The valve body has a first flow channel which connects the first nozzle 2 with the second nozzle 3. This connection is indicated by corresponding arrows in the drawing. The connection takes place via the filter chamber 5 and the filter insert 6. The inflowing fuel is thus filtered and then fed via the second port 3 to the burner.

The third port 4 communicates with a flow distributor 7, via which the recirculated via the third port 4 fuel in a first Partial volume flow 8 is supplied to the input of the filter cartridge 6, so that this component of the recirculated fuel is filtered again, and is supplied via the in a second partial volume flow 9 of the recirculated fuel to the output of the filter cartridge 6 to the second port 3.

The flow distributor 7 has in the flow path of the second partial volume flow 9 to a flow resistance explained later or forms such, by means of which the size of the volume flow is determined. Furthermore, the flow distributor 7 in the flow path of the first partial volume flow 8 to a fixed or variably adjustable cross-sectional constriction 10.

All flow paths of the flow distributor 7 are formed by corresponding flow channels. The cross-sectional constriction 10 is formed by a nozzle, an annular gap or a diaphragm.

As a flow resistance in the flow path of the second partial volume flow 9, a spring-loaded overflow valve 11 is arranged. The flow resistance or serving as a flow resistance overflow valve 11 in the flow path of the second partial volume flow 9 opens or releases this flow path, as soon as a sufficiently high pressure through a increased fuel flow in connected to the third port 4 burner return arises.

In the embodiment according to Figure 1 to 3 is branched off from the flow path of the first partial volume flow 8, a vent pipe 12, in which a manually or by means of a tool operable valve 13 is inserted. This valve 13 locks in a first end position, which in FIG. 1 is shown, the output of the vent neck 12. In a second end position, the in FIG. 3 is shown, the valve 13 opens the way to the vent pipe 12, so that the first partial volume flow, which consists of air or air / fuel mixture, is discharged through the vent pipe 12 to the outside to the atmosphere.

The valve 13 is also adjustable in an intermediate position, which in FIG. 2 is shown, with this intermediate layer is between the first and second end position. In this intermediate position, the first partial volume flow 8 is shut off, so that the entire volume flow forms the second partial volume flow 9. The opening to the atmosphere is still closed.

In the embodiment according to FIG. 4 An automatic air vent is provided. In this case, an automatic ventilation device 14 is installed in the flow path between the third port 4 and the flow distributor 7. In this case, the third port 4 is open via a flow path 15 with the inlet of the ventilation device 14 connected. The venting device 14 is in turn connected via a channel 16 to the flow distributor 7. In the channel 16 is an overflow valve 17, which may be spring loaded, for example, arranged. In the automatic ventilation device 14, floats 18, 19 are arranged, as well as chamber walls with ventilation openings 20, 21.

In the operation according to FIG. 1 the return from the burner pump via the third port 4 and the flow distributor 7 flows partly across the cross-sectional constriction 10 and is combined with the fuel, which is supplied from the flow through the first port 2, and then flows through the filter cartridge 6 again to the second Nozzle 3 to the burner. Another part (depending on the amount of fuel supplied) flows through the third port 4 and the spill valve 11 directly to the second port 3 and thus to the burner.

In the operation according to FIG. 2 is the manual vent initiated. In this case, the path of the first partial volume flow 8 via the cross-sectional constriction 10 is blocked. The entire fuel supplied via the return (port 4) flows via the overflow valve 11 directly in turn to the flow of the burner via the second port 3 from.

In the bleeding position according to FIG. 3 flows a partial flow of the third port 4 recirculated fuel via the overflow valve 11 directly to the flow of the burner via the nozzle 3, while a partial flow is discharged via the vent pipe 12 to the outside.

In the embodiment according to FIG. 4 the venting takes place automatically. For the sake of completeness, it should also be mentioned that a backflow preventer 22 is installed in the first connecting piece 1, for example in the form of a valve body.

The invention is not limited to the embodiments, but often variable within the scope of the claims.

LIST OF REFERENCE NUMBERS

1.

fitting housing

Second

first nozzle

Third

second nozzle

4th

third neck

5th

filter chamber

6th

filter cartridge

7th

flow distributor

8th.

first volume flow

9th

second volume flow

10th

Cross-sectional narrowing

11th

overflow

12th

vent connection

13th

Valve

14th

automatic ventilation device

15th

flow

16th

channel

17th

overflow

18th

swimmer

19th

swimmer

20th

vent

21st

vent

22nd

Backflow preventer

Claims (11)

1. A connection fitting for filtering liquid fuel, in particular fuel oil, comprising a fitting housing (1) having a first nipple (2) for connecting a feed line from a fuel tank, a second nipple (3) for connecting a feed line to a fuel consuming or processing burner, a third nipple (4) for connecting a return line from the burner, and a filter chamber (5) with a filter cartridge (6) for the fuel, the fitting housing (1) including a first flow channel that connects the first nipple (2) to the second nipple (3) through the filter chamber (5) and the filter cartridge (6), characterized by that the third nipple (4) communicates with a flow distributor (7), by means of which the fuel returned through the third nipple (4) is fed, in a first partial volume flow (8), to the entrance of the filter cartridge (6), and is fed, in a second partial volume flow (9), to the exit of the filter cartridge (6) to the second nipple (3).
2. The connection fitting according to claim 1, characterized by that the flow distributor (7) includes or forms, in the flow path of the second partial volume flow (9), a flow resistance, by means of which the value of the volume flow is determined.
3. The connection fitting according to one of claims 1 or 2, characterized by that the flow distributor (7) in the flow path of the first partial volume flow (8) includes a fixed or variably adjustable constriction of the cross section (10).
4. The connection fitting according to one of claims 1 to 3, characterized by that the flow paths of the flow distributor (7) are formed by flow channels.
5. The connection fitting according to one of claims 3 or 4, characterized by that the constriction of the cross section (10) is formed by at least one nozzle, annular gap, or orifice plate.
6. The connection fitting according to one of claims 2 to 5, characterized by that as a flow resistance, a spring-loaded pressure-relief valve (11) is disposed in the flow path of the second partial volume flow (9).
7. The connection fitting according to one of claims 2 to 6, characterized by that the flow resistance or a pressure-relief valve (11) serving as the flow resistance in the flow path of the second partial volume flow (9) opens or releases the flow path, as soon as a sufficiently high pressure exists by an increased fuel volume flow in the burner return line connected to the third nipple (4).
8. The connection fitting according to one of claims 1 to 7, characterized by that from the flow path of the first partial volume flow (8) branches off a ventilation nipple (12), in which a valve (13) to be operated manually or by means of a tool is included, which in a first end position blocks the exit of the ventilation nipple (12) and in a second end position opens and discharges the first partial volume flow (8) composed of air or an air/fuel mixture, outwardly through the ventilation nipple (12), e.g., into the atmosphere.
9. The connection fitting according to claim 8, characterized by that the valve (13) is adjustable to an intermediate position between the first and second end positions, in the intermediate position the first partial volume flow (8) being blocked and the total volume flow forming the second partial volume flow (9).
10. The connection fitting according to one of claims 1 to 7, characterized by that in the flow path between the third nipple (4) and the flow distributor (7), an automatic ventilation device (14) is installed.
11. The connection fitting according to claim 10, characterized by that via a flow path (15), the third nipple (4) openly communicates with the entrance of the ventilation device (14), and the ventilation device (14) is connected through a channel (16) with the flow distributor (7), in which channel (16) a pressure-relief valve (17) being provided.

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