EP2784406B1 - Volume flow regulator - Google Patents

Description

The invention relates to a mechanically automatic volume flow regulator with a flap leaf which is pivotably arranged in a flow channel and which is held on a pivot axis running transversely to the flow direction through the flow channel and which is divided by the pivot axis into a front flap leaf part and a rear flap leaf part as seen in the flow direction front flap leaf part has a greater length in the direction perpendicular to the pivot axis than the rear flap leaf part, and with a return mechanism which exerts a torque acting in the opening direction on the flap leaf.

Volume flow controllers are used in ventilation and air conditioning systems to regulate the volume flow of a medium, in particular a gaseous medium, to a predetermined, preferably adjustable setpoint, or to limit it to a predetermined, preferably adjustable maximum value. In the latter case, one speaks of a volume flow limiter, which is to be viewed here as a special case of a volume flow controller.

The resistance that the valve blade opposes to the flow of the medium depends on the angle of attack of the valve blade relative to the direction of flow. The angle of incidence of the flap blade thus also determines the volume flow that is established in the flow channel at a given differential pressure.

If the angle of attack is greater than 0 °, i.e. the valve blade is not oriented exactly parallel to the direction of flow, flow and pressure loads or forces that cause opposing torques act on the front and rear valve blade parts. If both flap parts have the same shape and the same area, the torques caused by an even pressure load would cancel each other out at an angle of attack of 90 °. However, due to the inclined position of the damper blade at smaller angles of attack, the medium is deflected to one side, so that as the cross-sectional narrowing increases, the flow against the rear flap leaf part is greater than that of the front flap leaf part. Due to Bernoulli's law, this leads to a pressure drop in the flow path over the valve blade, so that a lower resulting pressure acts on the rear valve leaf part than on the front valve leaf part, with the result that a torque acting in the closing direction, i.e. in the sense of an increase in the angle of attack is produced.

Because of this effect, the flap leaf or its pivot axis does not necessarily have to have an active actuator. Rather, mechanically automatic volume flow controllers and volume flow limiters can also be implemented in which there is no actuating or closing mechanism or an actuating mechanism, for example in the form of a return spring, at most serves to generate an opening torque that is dependent on the angle of attack of the damper blade and that is aerodynamically generated Counteracting closing torque. The spring characteristic of the reset mechanism then determines the equilibrium position in which the opening torque and the closing torque are balanced. With a suitable course of the characteristic, this equilibrium position is stable, so that the volume flow is regulated to a value which corresponds to this stable equilibrium position of the damper blade.

Out U.S. 4,301,833 and FR 1 313 310 as well as from DE 607 229 C Volume flow regulators of the type mentioned are known in which the pivot axis extends eccentrically through the flap leaf so that the front flap leaf part is larger than the rear flap leaf part (or vice versa). The consequence of this is that the pressure forces are also unbalanced and thus a higher closing torque acts on the damper blade even with a low volume flow. However, the damper blade is also subject to weight-related torque here
exposed because the two flap parts are not statically balanced. A volume flow regulator of this type cannot therefore be installed in any position. document GB2378233 shows a mechanically automatic volume flow regulator with the features of the preamble of claim 1.

GB 2,378,233 shows a fire damper in which the damper blade parts lying on both sides of the pivot axis differ in their width.

The object of the invention is to create a volume flow controller with which the set or limit volume flow can be set and regulated more easily and more precisely, particularly in the range of small volume flow rates.

This object is achieved according to the invention in that the front flap leaf part has a smaller width in the direction parallel to the pivot axis than the rear flap leaf part.

The valve leaf is thus approximately T-shaped in plan view, with the front valve leaf part as a vertical web and the rear valve leaf part as a transverse bar. Even in the case in which the two flap leaf parts have the same surface area - and thus the same weight with the same flap leaf thickness - a greater closing torque is achieved here because the resulting pressure force acts on the front flap part with a larger lever arm than the resulting one Pressure force on the rear flap part. The regulating or limiting behavior can therefore be adjusted in a very simple manner by suitable selection of the contour shape of the damper blade as required.

Advantageous configurations and developments of the invention are given in the subclaims.

In the case of a flow channel with, for example, a circular or rectangular cross-section, the different contours of the two flap leaf parts mean that the flap leaf cannot completely block the cross-section of the flow channel even at an angle of incidence of 90 °. Rather, an area that is open for a flow remains at the free end of the (shorter) rear one Damper blade part and one or two areas open for a flow to the side next to the (narrower) front damper blade part. In many applications, a complete shut-off of the flow channel is also not necessary. The geometry of the flap blade according to the invention then has the advantage that the controllability or adjustability of the volume flow in the area of high volume flow throughputs is improved by the areas open to flow.

In addition, there is the possibility of closing these open areas completely or partially by means of appropriate blocking bodies in the flow channel.

A blocking body in the space between the inner surface of the flow channel and the free end of the rear valve blade part causes a certain venturi effect, i.e. an increase in the flow velocity in the narrowed gap which the blocking body forms with the edge of the valve blade. As a result, the pressure component acting on the rear flap part is further reduced and the closing torque is thus additionally increased. According to a further aspect of the invention, this effect can also be used when the two flap leaf parts differ only in length but not in width. The content of this application is thus also a volume flow regulator with a flap leaf pivotably arranged in a flow channel, which is held on a pivot axis running transversely to the flow direction through the flow channel and is divided by the pivot axis into a front flap leaf part and a rear flap leaf part, as seen in the flow direction, that the front flap leaf part has a greater length in the direction perpendicular to the pivot axis than the rear flap leaf part, in which a blocking body is arranged in the flow channel so that it lies opposite the free end of the rear flap leaf part when the flap leaf is closed.

The areas that are open for a throughflow and that remain on one side or both sides of the front flap leaf part are preferably provided by blocking bodies in the Form of closed housing-like, preferably aerodynamically shaped structures that adjoin the wall of the flow channel or are part of this wall. These structures can then be used to accommodate mechanical components of the volume flow regulator, for example an elastic return mechanism, vibration damper or the like, in a space-saving manner in the flow channel in such a way that they can act on the flap blade via the pivot axis, but are fluidically separated from the medium. This has the advantage of improved hygiene, since no impurities can adhere to the mechanical components which are encapsulated in relation to the medium.

The blocking bodies are preferably extended in the longitudinal direction of the flow channel in such a way that they are not only effective when the flap leaf is in the closed position, but their effect already begins gradually when the flap leaf approaches the closed position.

An exemplary embodiment is explained in more detail below with reference to the drawing.

Fig. 1

einen Schnitt durch einen Volumenstromregler längs der Linie I-I in Fig. 2, jedoch bei praktisch vollständig geschlossenem Klappenblatt;

Fig. 2

den Volumenstromregler nach Fig. 1 in einem Längsschnitt bei nicht ganz geschlossenem Klappenblatt;

Fig. 3

einen Längsschnitt des Volumenstromreglers bei weiter geöffnetem Klappenblatt; und

Fig. 4 und 5

Volumenstromregler gemäß weiteren Ausführungsbeispielen.

Show it:

Fig. 1

a section through a volume flow controller along line II in Fig. 2 , but with the valve leaf practically completely closed;

Fig. 2

the volume flow controller Fig. 1 in a longitudinal section with the valve blade not completely closed;

Fig. 3

a longitudinal section of the volume flow regulator with the damper blade open; and

Figures 4 and 5

Volume flow controller according to further exemplary embodiments.

The in Figs. 1 and 2 The volume flow regulator shown is designed in a tubular housing 10 which forms a flow channel 12 with a generally circular cross-section, but which is narrowed at the location of a flap leaf 14 by blocking bodies 16, 18, 20. The locking bodies 16, 18, 20 are formed in this example by indentations in the peripheral wall of the tubular housing 10.

The damper blade is in Fig. 1 shown in a completely closed position (opening angle of almost 90 °), in which it practically completely fills the inner cross-section of the flow channel 12 left free by the blocking bodies 16, 18, 20. To illustrate the T-shaped shape of the valve leaf 14, the valve leaf is shown in FIG Fig.1 shown with a fill pattern. The flap leaf sits rigidly on a pivot axis 22 that runs centrally through the housing 10 and is rotatably mounted in the circumferential wall of the flow channel 12, more precisely in two parallel wall sections that extend at right angles to the pivot axis and are part of the blocking bodies 18 and 20.

The direction of view in Fig. 1 corresponds to the direction in which the flow channel 12 is flowed through by a medium (air). When the damper blade 14 from the in Fig. 1 is pivoted into an open position in which it runs almost parallel to the flow, so moves the in Fig. 1 lower edge of the flap leaf towards the viewer and the upper edge away from the viewer. The pivot axis 22 divides the flap leaf 14 into a front flap leaf part 14a, seen in the flow direction, which essentially corresponds to the vertical web of the T-shaped outline, and a rear flap leaf part 14b, which forms the transverse bar of the "T".

The two flap leaf parts 14a and 14b have the same area. This has the advantage that the valve blade can be statically balanced more easily by the Thicknesses of both parts can be selected accordingly, so that the leverage of the weight forces of both valve leaf halves is compensated. This enables installation in any position. Alternatively, this can also be achieved by statically balancing the damper blade with the aid of counterweights.

Due to the T-shape, however, the rear flap leaf part 14b has a greater maximum width in the direction parallel to the pivot axis 22 than the front flap leaf part 14a. Conversely, the front flap leaf part 14a has a greater maximum length in the direction perpendicular to the pivot axis 22 than the rear flap leaf part 14b. The latter has the consequence that, despite the same surface area, the center point P1 of the front flap leaf part 14a is further away from the pivot axis 22 than the center point P2 of the rear flap leaf part 14b. When the medium flows against the flap leaf, the pressure or the resulting pressure force acting on the front flap leaf part 14a consequently acts on the flap leaf via a larger lever arm than the pressure or the resulting pressure force which acts on the rear flap leaf part 14b . The corresponding torques that act on the damper blade therefore do not cancel each other out, but an increased resulting torque in the closing direction. This does not only apply to the in Fig. 1 Shown closed position of the valve leaf, but for every angular position of the valve leaf with the exception of the extreme case that the valve leaf is aligned exactly parallel to the longitudinal axis of the flow channel.

The opening position of the valve leaf is limited by stops in such a way that the valve leaf is also positioned slightly obliquely to the flow direction in the maximum open position, so that the above-mentioned torque imbalance is also effective in the open position. There is an imbalance in the pressure caused by the deflection of the flow to the rear valve blade part 14b. This effect contributes to a relatively high torque in even with a low volume flow and correspondingly low flow speed Closing direction acts on the damper leaf. If the damper blade is pivoted as a result of this torque, the torque imbalances increase further, so that a self-amplification of the closing torque occurs. Overall, the result is that the volume flow controller responds very sensitively even at low volume flow and low pressure losses and thus the volume flow can be better regulated.

A restoring mechanism 24, which exerts a counter-torque acting in the opening direction on the valve blade, is shown in FIG Fig. 1 shown only schematically and is arranged in the blocking body 20 within the circular cross section of the housing 10, but outside the channel through which the medium flows. The return mechanism can be of any known construction and can be formed, for example, by a leaf spring connected to the pivot axis 22, which rests against an adjustable stop and is more or less bent when the valve leaf is pivoted. An example of such a reset mechanism is shown in EP 1 134 507 B1 described.

With increasing deflection of the valve leaf in the closing direction, the counter-torque generated by the leaf spring increases until a torque equilibrium is finally reached. The angle of attack of the valve blade in this equilibrium position then determines the volume flow through the flow channel 12. If the volume flow increases due to a disturbance, the aerodynamically induced torque increases and the valve blade continues to pivot in the closing direction until a new equilibrium is reached at a larger angle of attack, see above that the volume flow is throttled accordingly. Conversely, as the volume flow decreases, the aerodynamically induced torque decreases, so that the restoring torque of the restoring mechanism 24 predominates and a new equilibrium position is reached when the valve blade is opened further. In this way, the volume flow is mechanically and automatically regulated to a target value, which can be adjusted by adjusting the Stop for the leaf spring in the reset mechanism 24 can be selected within a wide range. The sensitive response of the valve blade according to the invention, even at low flow velocities, allows setting and precise maintenance of a very small volume flow.

In the blocking body 18 at the opposite end of the pivot axis 22, a damping element 26 is accommodated in the example shown, which can have a known design and is therefore also only shown schematically. For example, it can be a pneumatic damper in the form of a bellows, the volume of which can only change gradually in accordance with the rotation of the pivot axis 22.

Optionally, the front flap leaf part can also be designed asymmetrically, so that a free space remains on only one side, which is filled by a single blocking body. This locking body can then accommodate both the reset mechanism 24 and the damping element 26.

Fig. 2 shows a longitudinal section of the tubular housing 10, which has receptacles 28 at both ends for lip seals for insertion into ventilation ducts, not shown. The flap leaf 14 is shown here in a not fully closed position. A stop 30 is formed on the blocking body 16, against which the free end of the rear flap leaf part 14b strikes when the maximum closed position is reached.

It can be seen that the locking bodies 16 and 18 (the locking body 20 is in Fig. 2 not visible, but is designed symmetrically to the blocking body 18) each extend over a greater length of the flow channel 12 and are rounded at the ends so that the medium can flow around them with little resistance. In the example shown, the length of the blocking bodies 16, 18, 20 in the axial direction of the flow channel 12 is greater than half the diameter of the flow channel cross section. Even if the flapper blade 14 is not in the fully closed position, lies hence the front flap leaf part 14a still between the two locking bodies 18 and 20, and these deflect the medium onto the flap leaf part 14a, whereby the closing torque is further increased. This effect occurs to a lesser extent even when the valve blade is in the almost completely open position.

Fig. 3 shows the valve leaf 14 in a more open position. Flow lines illustrate here how the flow of the medium is deflected through the valve leaf so that it flows at a higher speed through a gap between the free end of the rear valve leaf part 14b and the blocking body 16. The rear flap leaf part 14b is therefore approached with an increased flow velocity, so that the pressure here is lower than on the front side of the front flap leaf part 14a. This pressure imbalance intensifies the torque-increasing effect which is achieved by the unequal shape of the flap leaf parts 14a and 14b.

In the example shown, the top of the blocking bodies 18 and 20 is approximately level with the pivot axis 22. Behind this pivot axis in the direction of flow, the upper side of the blocking bodies rises slightly. Since the rear flap leaf part 14b is widthwise (perpendicular to the plane of the drawing in Fig. 3 ) overlaps with the blocking bodies 18, 20, the rising upper sides of the blocking bodies here form a stop 32 which thus defines the open position of the flap leaf.

The exemplary embodiment described here can be modified in many ways. For example, it is not imperative that the flap leaf 14 is flat and has a uniform thickness. It can optionally also be profiled or curved like a wing.

Fig. 4 is a schematic representation of a volume flow regulator, in which in one of the lateral blocking bodies, in this example in the blocking body 18, a pneumatic Damper 34 is housed (as a specification of the damping element 26 according to Fig.1 ). This damper 34 has two flexible, in the view according to Fig. 4 approximately circular sector-shaped bellows 36, 38, which are arranged on both sides of a displacement arm 40 extending radially from the pivot axis 22. The bellows 36, 38 and the displacement arm 40 are roughly fitted into a sector-shaped chamber which is delimited in the interior of the blocking body 18 by a partition 42 (which is not hermetically sealed and thus allows pressure equalization).

On the upstream side of the blocking body 18, on the left in Fig. 4 , an inlet opening 44 is formed into the interior of the tubular housing 10, which opens against the direction of flow of the medium. This inlet opening 44 communicates via a throttle opening 46 with the bellows 36 and via a connecting hose 48 laid inside the blocking body 18 and a further throttle opening 50 with the bellows 38 , 38 connected to each other.

The space inside the blocking body 18 outside the bellows 36, 38 is connected to the interior of the housing 10 on the outflow side of the flap 14 via ventilation openings 45. The same pressure prevails in this space as on the outflow side of the flap 14 (or it is optionally under ambient pressure). Consequently, the dynamic pressure of the medium flowing into the inlet opening 44 has the tendency to inflate the two bellows 36, 38 somewhat so that they press against the displacement arm 40 from opposite sides. If the flap blade 14 is pivoted during operation of the volume flow regulator, the displacement arm 40, which is rigidly seated on the pivot axis 22, is also pivoted, with the result that one of the two bellows 36, 38 is compressed and the other bellows is expanded accordingly. The pressure equalization is effected in that the medium from the compressed bellows via the throttle openings 46, 50 and the connecting hose 48 into the expanded bellows or through the inlet opening 44 back into the interior of the tubular Housing flows. The flow resistance of the two throttle openings 46, 50 has a damping effect, so that any vibrations of the flap 14 are effectively damped. The space inside the blocking body can be covered further to the outside, that is to say to the ventilation pipe, by a cover (not shown) and the two bellows can thus be protected.

The advantage of this arrangement is that control deflections of the flap 14 in opposite directions can be dampened with approximately the same effectiveness with the aid of the two bellows 36, 38. This principle can generally be used with advantage in volume flow controllers for damping vibrations of the flap. The content of this application is therefore, independently of the features claimed here in the claims, also a volume flow regulator with a flap blade pivotably arranged in a flow channel, which is held on a pivot axis running transversely to the flow direction through the flow channel, and with a damper for damping vibrations of the flap blade , the damper being formed by two bellows which are arranged on both sides of a displacement arm extending radially from the pivot axis and which communicate with one another via throttle openings.

The embodiment is particularly advantageous in which the complete damper is accommodated in a space-saving manner and protected against contamination in a blocking body which narrows the cross section of the flow channel in the area of the flap leaf. The ventilation openings 45, which are located behind the valve leaf in the direction of flow, ensure that the pressure in the locking body is always slightly lower than in front of the valve leaf and thus in the damping bellows; this means that they always fill up safely and their dampening effect is guaranteed.

Since the damper 34 is accommodated in the blocking body 18 and thus lies completely within the (here circular) cross section of the flow channel 12, it is possible to also the in Fig. 4 After the damper and the reset mechanism have been suitably set, slide the volume flow controller shown into a ventilation pipe when installing the ventilation system so that it is no longer accessible after installation.

Optionally, however, the same component can also be used to implement a manually or possibly even motor-adjustable volume flow controller, which can be inserted as an intermediate piece between two sections of a ventilation pipe and whose setting or control mechanism is therefore accessible at all times.

An example is in Fig. 5 shown. The volume flow controller off Fig. 4 , the housing 10 of which can consist of plastic, for example (in Fig. 5 only shown in dashed lines) is received here in a tubular sleeve 52 made of sheet steel, which has connecting nipples 54 at both ends and can thus be inserted as an intermediate piece into a pipeline, for example a ventilation line. The tubular sleeve 52 in turn consists of two parts 56, 58. Before these two parts 56, 58 are joined together, the housing 10 can be pushed into the part 58. This part 58 is then inserted into an enlarged end 60 of the other part 56. The plug connection can be designed as a crimped connection or permanently fixed in some other way, for example by gluing, soldering or the like.

The housing 10 has elastic sealing lips 62 on the circumference, which are already used in connection with Fig. 2 mentioned receptacles 28 are held and the housing 10 frictionally hold in the part 58 of the tubular sleeve 52 in position.

This part 58 of the tubular sleeve has at least one inspection flap 64 in its circumferential wall at the point where the locking body 18 and / or 20 accommodating the reset, regulating or damping mechanism is located, via which access to the relevant mechanism can be obtained .

Claims (13)

1. Mechanically self-controlled volume flow regulator having a flap (14) that is pivotably mounted in a flow channel (12) and is held on a pivotal axis (22) that extends transverse to the flow direction through the flow channel, the pivotal axis dividing the flap, as seen in the flow direction, into a front flap portion (14a) and a rear flap portion (14b), wherein the front flap portion has, in the direction perpendicular to the pivotal axis (22), a greater length than the rear flap portion and the front flap portion (14a) has, in the direction in parallel with the pivotal axis (22), a smaller width than the rear flap portion (14b), characterized in that a return mechanism (24) is provided for exerting onto the flap a torque that acts in opening direction of the flap.
2. Volume flow regulator according to claim 1, wherein the front flap portion (14a) and the rear flap portion (14b) have equal surface areas.
3. Volume flow regulator according to any of the preceding claims, wherein the flow channel (12) has a circular or rectangular cross-section which, however, is restricted by at least one obstruction body (16, 18, 20) at the position of the flap (14).
4. Flow control regulator according to claim 3, wherein an obstruction body (16) is arranged such that it is opposed to the distal end of the rear flap portion (14d) when the flap (14) is closed.
5. Volume flow regulator according to claim 3 or 4, wherein at least one obstruction body (18, 20) is provided laterally of the front flap portion (14a).
6. Volume flow regulator according to any of the claims 3 to 5, wherein the obstruction body or bodies (16, 18, 20) are configured such that, when the flap (14) is in the maximally closed position, they close off the flow channel (12) together with the flap.
7. Volume flow regulator according to any of the claims 3 to 6, wherein at least one of the obstruction bodies (16, 18, 20) extends in axial direction of the flow channel (12) over a distance that amounts to at least one half of the diameter of the flow channel.
8. Volume flow regulator according to any of the claims 3 to 7, wherein at least one of the obstruction bodies (16, 18) is rounded-off in streamline fashion at its ends.
9. Volume flow regulator according to any of the claims 3 to 8, wherein at least one of the obstruction bodies (16, 18, 20) is formed by a depression in the peripheral wall of the flow channel (12).
10. Volume flow regulator according to any of the claims 3 to 9, wherein the pivotal axis (22) is supported in a wall of at least one of the obstruction bodies (20), and an adjusting mechanism (24) is accommodated in this obstruction body (20) so as to be separated from the flow channel (12).
11. Volume flow regulator according to any of the claims 1 to 10, wherein the pivotal axis (22) is supported in a wall of at least one of the obstruction bodies (18), and a damper element (26) for attenuating oscillations of the flap (14) is accommodated in this obstruction body (18) so as to be separated from the flow channel (12).
12. Volume flow regulator according to any of the preceding claims, comprising a pneumatic damper (34) for attenuating oscillations of the flap (14), wherein the damper (34) has two bellows (36, 38) arranged on both sides of a displacement arm (40) that extends radially from the pivotal axis (20), the bellows communicating with one another via throttle openings (46, 50).
13. Volume flow regulator according to claim 12, wherein the throttle openings (46, 50) are also in communication with an inlet opening (44) on the upstream side of the flap (14).

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