EP1510756A1 - Ratio Controller with Dynamic Ratio Evaluation - Google Patents

Abstract

Fuel ratio regulator (6) has: a housing in which there is a valve seat and at least a variably positioned valve closing element, that divides the valve housing into delivery and outlet cambers; a membrane drive connected to the valve closing element in order to adjust it according to a pressure difference and; an impulse channel for influencing the membrane drive, whereby the channel pressure tap can be made at an adjustable measurement tap and or simultaneously at two different taps on the outlet chamber of a connected gas line (5).

Description

The invention relates to a ratio controller in particular for Brenngaszumessung at gas burners, for example Blower burners can be applied.

For gas burners must be at the burners a given gas-air Ratio can be adjusted to the correct operation of the burner. The gas-air ratio must be set independently of the load condition. Especially at burners, not only at rated load, but operate at partial load, this requires one Adjustment of the gas supply according to the air supply. It This is strived for with simple, robust and versatile to enable useable devices.

In the construction of gas heating systems, gas boilers and gas burners, System vendors usually rely on vendor parts back, as problem-free as possible in the overall system should be inserted. It is particularly desirable that the assemblies, such as corresponding Ratio regulator, no special control signals from others Assemblies require the desired gas-to-air ratio adjust correctly. Additional pressure taps or pressure lines, for example, from the burner to the ratio controller, turn off View of the system provider unwanted restrictions dar.

From DE 197 40 666 C1 a ratio controller is known, which regulates the gas supply to a burner. To the desired Setting a given gas-air ratio serves a ratio controller, which is a first pressure tap at the gas line and a second pressure tap on the Firebox is assigned. Both pressure taps are each provided with a throttle. About the between the two taps existing connection line gas flows into the furnace. Between the throttles is a control pressure for the ratio controller tapped.

An additional pressure tap on the firebox is common not available, thus limiting the use of this ratio pressure regulator is restricted.

From EP 06 44 377 B1 is another ratio controller known by a pilot-controlled, with a membrane drive provided control valve is formed. For pilot control serve a pressure tap on one to the burner leading gas line, as well as two further pressure taps, on the air duct leading from a fan to the burner. The two pressure taps of the air line detect the pressure difference over a throttle point.

In this arrangement arises through the throttle point behind the fan burner an undesirable obstruction of the Air flow. The pressure loss caused by the throttle must be overcome by the blower. This should be especially with regard to possible adjustments to different ones Burner operating conditions, such as loads and the like, as well as with regard to different gas compositions or The same thing happens.

On this basis, it was an object of the invention a simple and rugged ratio regulator without external pressure taps to accomplish.

This object is achieved with the ratio controller according to claim 1 solved:

The ratio regulator according to the invention has a main valve with membrane drive, wherein for controlling the membrane drive a pulse channel is used. This allows the pressure tap optionally at the outflow chamber of the ratio regulator, or at least two different ones at the same time Measuring points. By selecting the measuring point, the at the Output of the ratio controller as a function of the gas velocity Pending gas pressure a given gas-air Ratio be regulated accordingly. It is about it out possible, this gas-air ratio over different Load cases from extreme low load to full load to maintain. There are no external pressure taps required.

The formation of the correct pressure ratio at the gas nozzle depends on the pressure difference at the air supply (Air nozzle) made. Sit the air nozzle and the gas nozzle for example, at the suction connection of a blower, decreases with increasing fan speed and thus with increasing Air flow both the air pressure, and the gas pressure evenly in front of the gas nozzle. The readjustment of the ratio controller is thus based on the gas pressure in front of the gas nozzle performed. This is done pneumatically by a special Throttle arrangement. The pressure regulator is adjusted so that he regulates about the static pressure (atmospheric pressure) at the gas nozzle. An opening of the regulator then takes place in air and Gas take-off pneumatically by the applied pressures.

The downstream of the valve directly in the outflow chamber or at the gas nozzle removed pressure and a tapped elsewhere pressure form together in an example adjustable ratio, a control pressure for controlling a pilot valve for the ratio controller. By setting the ratio in which the tapped pressures are included in the control pressure, an adjustment of the ratio controller to different types of gas or calorific values or excess air numbers is possible. The set by the ratio controller output pressure can be set constant over a wide power range. It is both possible to set the ratio controller, the ratio with which the two pressure taps are used to form a control pressure to set by means of a 3/2-way valve, as well as by throttling only a branch of the branching pulse channel, in which then each another branch a fixed or an adjustable throttle is arranged. The adjustment can be done both manually and via a remote-controlled actuator such as a solenoid valve, a servomotor or the like. The latter opens the possibility to assume the gas quantity regulation of a control device. The control device may for example be connected to corresponding sensors which detect the calorific value of the gas or the CO content, the O ² content or the NO x content of the exhaust gas. A correction of the gas-air ratio can then take place on the basis of these measured values, the correction once again being valid for a wide power range.

Further details of advantageous embodiments of Invention are the subject of the drawing, the description or claims.

Fig. 1

einen Gebläsebrenner mit vorgeschaltetem Verhältnisregler, sowie weiteren Gasventilen, zur Steuerung des Betriebs,

Fig. 2

den Verhältnisregler nach Fig. 1 in einer längs geschnittenen und schematisierten Darstellung,

Fig. 3

eine abgewandelte Ausführungsform eines Verhältnisreglers in längs geschnittener schematisierter Darstellung,

Fig. 4

eine weiter abgewandelte Ausführungsform eines Verhältnisreglers in längs geschnittener, schematisierter Darstellung,

Fig. 5

einen Verhältnisregler mit fernbetätigter Verstellung des Gas-Luft Verhältnisses in längs geschnittener schematisierter Darstellung,

Fig. 6

eine weitere abgewandelte Ausführungsform eines Verhältnisreglers in längs geschnittener, schematisierter Darstellung und

Fig. 7

eine vereinfachte Ausführungsform eines Verhältnisreglers in längs geschnittener und schematisierter Darstellung.

In the drawing, embodiments of the invention are illustrated, showing:

Fig. 1

a blower burner with upstream ratio regulator, as well as other gas valves, to control the operation,

Fig. 2

the ratio controller of Figure 1 in a longitudinal and schematic representation,

Fig. 3

a modified embodiment of a ratio controller in longitudinal sectional schematic representation,

Fig. 4

a further modified embodiment of a ratio controller in longitudinally sectioned, schematic representation,

Fig. 5

a ratio controller with remote-controlled adjustment of the gas-air ratio in a longitudinal sectional diagram,

Fig. 6

a further modified embodiment of a ratio controller in longitudinal section, schematic representation and

Fig. 7

a simplified embodiment of a ratio controller in longitudinal sectional and schematic representation.

In Fig. 1 is a schematic form a fan burner 1 with upstream blower 2 illustrates that a gas-air mixture sucks. For this purpose, the fan 2 on the input side an air nozzle 3, in which a gas nozzle 4 is arranged. This is fed by a gas line 5, which is a ratio controller 6 and control valves 7, 8 are connected upstream. The latter are used to release and block gas. The ratio controller 6 is used with open control valves 7, 8, regardless of the delivery rate of the blower 2, i. from its speed set a predetermined gas-air ratio. The ratio controller 6 accomplishes this alone Taps from its own valve body or gas line 5 without measuring or tapping the amount of air. These are on the Paths between the ratio controller 6 and the gas nozzle 4 in the Gas line 5 or in the housing of the ratio controller 6 at least formed two different flow cross sections, of which branches branch off branches 9f of an impulse line 12. This serves to control an actuator 14, the Regulator 6 regulates. To understand the structure and the function of the ratio controller 6 is referred to Fig. 2. The ratio regulator 6 illustrated here has one Housing 15, in which a through-channel is formed. To this include an inflow chamber 16 and a discharge chamber 17. Between both a valve seat 18 is formed, which is associated with a valve closure member 19. The latter is via a valve stem 21 with the membrane 22 of a membrane drive 23 connected. The membrane 22 shares in his Housing two working chambers 24, 25 from. A spring 26 tensions the valve closure member 19 via the valve stem 21 against the valve seat 18 before. Between the outflow chamber 17 and the Working chamber 24, the negative pressure opening the valve closure member 19 causes a connection channel 27 is arranged, for a pressure equalization between the outflow chamber 17 and the working chamber 24 provides.

In addition, at the outflow chamber 17 or at the at its output 28 subsequent gas line 5 two pressure taps in the form of openings 31, 32 are provided, at which different Flow conditions prevail. For example is the outflow chamber 17 to in a first area with a relatively large flow cross-section and in a second Area with a relatively small flow cross-section Mistake. The measuring points (openings 31, 32) are in these arranged in different areas. Accordingly prevail in front of these openings 31, 32 different speeds Gas flows before, so that at the openings 31, 32 different Pressures are detected. From the measuring points or Openings 31, 32 extend the branches 9; 11 gone, that too the impulse line 12 belong. The branches 9, 11 lead, for example. to a throttle block 33, which brings the two branches 9, 11 together and with a likewise belonging to the impulse line 12 Pressure measuring line 34 connects. The throttle block 33 leads the two branches 9, 11, for example as a T or Y branch together. In the branch 9, a fixed throttle 35 can be arranged be. Preferably, in the branch 11 is an adjustable Throttle 36 is arranged. This can be done by a control screw 37 may be formed, which sealed to the outside is screwed into the throttle block 33 and their pointed End the branch 11 depending on the setting more or less free. If necessary, the function can also be reversed be in which the throttle 35 adjustable and the Throttle 36 is rigid. If necessary, too be configured adjustable both throttles.

The pressure measuring line 34 leads to a pilot valve 38. This has a housed in a housing 39 membrane 41, in the immediate vicinity of a gas outlet 42 is arranged. The membrane 41 splits in the housing 39, an air chamber 43 and a control chamber 44 from. The Control chamber 44 is connected to the pressure measuring line 34. The ruling between the air chamber 43 and the control chamber 44 Pressure difference determines the position of the diaphragm 41. This is arranged with respect to the gas outlet opening 42, that the gas outlet opening 42 is closed when the air pressure outweighs, while it has the tendency to open, if the gas pressure prevails. A spring 45, which has a suitable Adjusting screw 46 can be adjusted, provides the zero point the membrane 41, i. the pressure ratio at the membrane 41 just at the opening 42 abuts a. It is here by a zero point adjustment, by changing the spring preload a performance-dependent change of the mixing ratio can be achieved. Being affected but the lower power range prevails.

The gas outlet 42 is part of a conduit 47, with possibly via a throttle 48 gas pressure from the inflow chamber 16 is tapped. From line 47 branches a line 49, which leads to the working chamber 25.

In the simplest case, the air chamber 43 is in the ambient air in connection. Optional, i. if desired, However, a connection 51 may be provided, with which the Air chamber 43 are connected to a pressure measuring point may be the air pressure in front of the mixture formation device detected. This is particularly useful if this clearly deviates from the ambient air pressure.

The ratio regulator 6 described so far works in the Related to the system illustrated in FIG. 1, such as follows:

Open the illustrated in Fig. 1 control valves 7,8 and by the blower 2 is formed at the air nozzle 3, a negative pressure. This continues first through the gas line 6 and is thus detected at the measuring points 31, 32. The negative pressure enters the specified by the throttle block 33 Ratio via the pressure measuring line 34 to the pilot valve 38th and thus also produces a certain amount in the control chamber 44 Vacuum. This leads to the closing of the gas outlet opening 42, whereby the on-line 47 pending gas pressure less reduced and thus via the line 49 to the working chamber 25 can get. At the same time, he works on the Gas line in the outflow chamber 17 penetrating negative pressure via the connecting channel 27 on the opposite side of the membrane 22 on. It creates a pressure difference, which is the membrane 22 upwards and thus the valve closure member 19 in Opening direction moves. This process lasts so long until the provided at the gas nozzle 4 and in the outflow chamber 17 Target pressure is restored.

This process takes into account the gas velocity and the more the further the control screw 37 is opened. It can therefore at the control screw 37 of caused by a certain negative pressure at the gas nozzle Gas flow are fine-tuned. This is the gas-air ratio over a wide power range of the fan burner 1 kept constant according to a desired value. Takes the fan speed and thus the air delivery at the same time, the back pressure at the gas nozzle 4, which is a correspondingly increased gas flow result. To what extent the gas flow increases with increasing pressure drop leaves to adjust to the control screw 37. They are neither Taps on a burner room still other air taps the blower or burner required.

Fig. 3 illustrates a modified embodiment of the ratio controller 6. As far as conformity with the above Embodiment is based on the same reference numerals to the above description directed. The difference between the ratio controller 6 According to Fig. 2 and therefore Fig. 3, is located in the throttle block 33rd This is formed as shown in FIG. 3 as a 3/2-way valve. The Branches 9, 11 open into a common channel 52, in which a spindle-shaped regulating body 53 is seated. This one is with the Control screw 37 connected. In the area of the equator of the Regulierkörpers 53 branches off the pressure measuring line 34. With the Regulierkörper 53, the ratio of the measuring points 31, 32 tapped pressures are adjusted, with which they contribute to the formation of a control pressure for the pilot valve 38.

The two embodiments described above assume stationary measuring points 31, 32. However, it is possible to manage only with a single measuring point, if this is designed to be mobile. This illustrates Fig. 4 based on an embodiment with an on a roller slide 54 provided measuring point 55. The roller slide 54 forms a bottleneck, in the outflow chamber 17. Depending on the rotational position of the roller slide 54 is the measuring point 55 rather at a bottleneck or (if in Fig. 4 turned to the left), rather to find a wide spot. The roller slide 54 is connected to the impulse line 12. With the rotation of the roller slide 54 changes not only the position of the measuring point 55 with respect to detected flow velocity, but also their orientation to the flow direction. Even then it can be the size of the tapped pressure and the influence of the gas velocity to regulate it. As a result, can by the rotational position of the roller slide 54 turn the Gas-air ratio regulated for a wide load range become. On the throttle block 33 can be omitted here. The pulse line is then directly to the pilot valve 38th connected. Otherwise, the function of the ratio controller is correct 6 of this embodiment with the function of the above ratio controller described match.

FIG. 6 shows a further modified embodiment the ratio controller 6 illustrated. This is largely based on the embodiment of Figure 4, to the description thereof referring to the same reference numerals becomes. However, in place of the roller slide 54 with only a single measuring point 55 a combined Slider 57 is provided, on its front side or, as represented, on its rear side, the opening 32 carries. Of the Slider can be cylindrical or cuboid be. At the opening 32, the branch 11 connects, in the slider body merges with the other branch 9 is. The branch 9 is in communication with the opening 31. Of the Slide 57 can be moved axially to the out of the outflow chamber 17 out leading channel more or less narrow. Accordingly, the detected at the opening 32 changes Pressure value. In addition, the adjustment of the slider be used to throttle the branch 9. It will however, preferably, the cross section constituting the branch 9 Channels so big that in every usable one Position of the slide 57 full passage from the opening 31st in the branch 9 and in the pressure measuring line 34 is given.

FIG. 7 illustrates another embodiment of the invention Ratio regulator 6, which on the embodiment of Figure 4 based. The given to this description is based on the same reference numerals. However, that is in place of the roller slide 54, of a measuring channel is traversed transversely, a passive slide 58 is provided, the the measuring point 55 is arranged opposite to the before the measuring point 55 prevailing free flow cross-section depending on the slide position more or less narrow. The slide can be a flat slide or a round slide be. He can with a threading device or be provided other adjusting means. He narrows the flow channel in front of the measuring point 55, a greater flow velocity prevails here and it gets a lower static Gas pressure tapped. If the flow cross section is widened a relatively higher gas pressure is tapped. These Embodiment may also be in a to the ratio controller. 6 be applied to Figure 6 based embodiment, in which the line 12 divides into two branches 9, 11, wherein the branch 9 to a measuring point 31, as shown in FIG. 6 then, during branch 11, leads to the measuring point 55 leads. Even with such an arrangement can by Adjustment of the slide 58 a fuel gas / air ratio adjustment respectively.

All above-described ratio controller 6 can manually be set. It is also possible to use these called ratio controllers with a remote-controlled actuator, such as a servomotor 56, in terms of gas flow and thus to adjust the gas-air ratio. Fig. 5 illustrates this on the basis of the ratio controller according to Fig. 2. However, corresponding actuators can also on the Actuators of the disclosed in the following ratio controller. 6 be attached. The servomotor 56 may be connected to a control device be connected in Fig. 1 is not further illustrated is and to adjust the gas-air ratio serves. This can, for example, with suitable probes or sensors or input means connected to an adjustment signal from measured operating conditions or control commands derive.

To set a desired gas-air ratio on a burner over the widest possible load range without additional pressure taps from the burner, a combustion chamber or air lines, a ratio controller 6 is provided, the a setting of the backpressure dependent to be passed Gas flow allowed. For adjustment, the ratio controller 6 at least one positionally variable measuring point 55 or at least two measuring points 31, 32, which via a Valve block or throttle block 33 directly or indirectly via a pilot valve connected to a diaphragm actuator 23 are. Depending on whether the control pressure more of the one or more can be tapped from the other measuring point, the Gas flow and thus the gas-air ratio smaller or larger be set.

Claims (15)

Ratio regulator (6) for fuel gas metering for a gas burner,
with a housing (15), in which at least one valve seat (18) and at least one adjustably mounted valve closure member (19) associated therewith is arranged, which subdivides the interior of the valve housing (15) into an inflow chamber (16) and an outflow chamber (17) .
with a diaphragm drive (23), with the valve closure member (19) is connected to adjust this according to a pressure difference, and
with a pulse channel (12), for influencing the membrane drive (23), wherein the pressure tap by the pulse channel (12) at an adjustable measuring point (55) and / or at least two different measuring points (31, 32) of the outflow chamber (17) or a connected gas line (5) with different flow conditions. Ratio regulator according to claim 1, characterized in that on the ratio controller (6) an actuator (54) is arranged for adjusting the position of the pressure tap. Ratio regulator according to claim 2, characterized in that the different positions of the actuator (54) differ by a different direction of flow of the pressure tap. Ratio regulator according to claim 2, characterized in that differ the different positions of the actuator (54) by different flow cross sections at the pressure tap. Ratio regulator according to claim 1, characterized in that the pulse channel (12) is connected to a pilot control valve (38). Ratio regulator according to claim 1, characterized in that the pulse channel (12) branches (9, 11) belonging to different measuring points (31, 32) of the outflow chamber (17) or the gas line (5) to a pneumatic ratio adjustment valve ( 53) connected to a pilot control valve (38). Ratio regulator according to claim 6, characterized in that in at least one of the branches (9, 11) an adjustable throttle (36) is arranged. Ratio regulator according to claim 6, characterized in that between the branches (9, 11), a 3/2-way valve (53) is arranged. Ratio regulator according to claim 7, characterized in that the throttle (36) is infinitely adjustable. Ratio regulator according to claim 8, characterized in that the 3/2-way valve (53) is infinitely adjustable. Ratio regulator according to claim 9 or 10, characterized in that the throttle (36) or the 3/2-way valve (53) by means of an actuator (56) is adjustable by a control device. Ratio regulator according to Claim 1, characterized in that the pilot valve (38) has a control diaphragm (41) which is acted upon by the pressure of the pulse line (12) and controls a pressure channel (47) which flows from the inflow chamber (16) to the diaphragm drive (16). 23) leads. Ratio regulator according to claim 12, characterized in that the other side of the control diaphragm (41) is acted upon by the ambient air pressure. Ratio regulator according to claim 12, characterized in that the other side of the control diaphragm (41) is acted upon by the prevailing pressure in front of a gas / air mixture forming means. Ratio regulator according to claim 1, characterized in that between the outflow chamber (17) and the membrane drive (23) a connecting channel (27) is provided.

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