阅读说明：本技术 阀、此类阀的用途、包括此类阀的分离器以及清洁分离器主体的方法 (Valve, use of such a valve, separator comprising such a valve and method of cleaning a separator body ) 是由 安德列斯·福格尔贝里 于 2018-05-02 设计创作，主要内容包括：本公开提供了一种阀(123),包括：通道主体(1231),其限定弯曲通道空间；能弹性地挠曲的膜(1233),其将通道空间中的控制空间(Sc)与流动空间(Sf)分隔开；控制连接件(1232),其提供到控制空间(Sc)的流体连接。按照通道弯曲半径(Ro),控制空间(Sc)设置在通道空间的径向最外部分(Co)处,以使膜(1233)能够在打开位置和关闭位置之间挠曲,在打开位置,流动空间(Sf)的横截面基本上为通道的横截面,在关闭位置,按照通道弯曲半径(Ri),膜基本上密封在通道的径向最内部分(Ci)上。公开了该阀在分离器中的用途,以及包括此类阀的分离器和清洁分离器主体的方法。(The present disclosure provides a valve (123), comprising: a channel body (1231) defining a curved channel space; an elastically flexible membrane (1233) separating the control space (Sc) from the flow space (Sf) in the channel space; a control connection (1232) providing a fluid connection to the control space (Sc). The control space (Sc) is arranged at a radially outermost portion (Co) of the channel space according to a channel bending radius (Ro) to enable a flexing of the membrane (1233) between an open position, in which the cross-section of the flow space (Sf) is substantially the cross-section of the channel, and a closed position, in which the membrane is substantially sealed against a radially innermost portion (Ci) of the channel according to a channel bending radius (Ri). The use of the valve in a separator is disclosed, as well as separators comprising such a valve and methods of cleaning separator bodies.)

1. A valve (123), comprising:

a channel body (1231) defining a curved channel space,

an elastically flexible membrane (1233) separating the control space (Sc) from the flow space (Sf) in the channel space, and

a control connection (1232) providing a fluid connection to the control space (Sc),

it is characterized in that

Said control space (Sc) being arranged at a radially outermost portion (Co) of said channel space according to a channel bending radius (Ro),

so as to enable the membrane (1233) to be flexed between an open position, in which the cross-section of the flow space (Sf) is substantially the cross-section of the channel, and a closed position, in which the membrane is substantially sealed against the radially innermost portion (Ci) of the channel, according to the channel bending radius (Ri).

2. The valve of claim 1, wherein the membrane (12333) is formed of a material having rubber elastic properties.

3. The valve according to claim 1 or 2, wherein the membrane (1233) is substantially planar in a relaxed position, i.e. a position in which the pressure difference over the membrane is substantially zero.

4. A valve according to claim 3, wherein the membrane (1233) intersects the passage space in the relaxed position such that the volume of both the control space (Sc) and the flow space (Sf) is larger than zero.

5. A valve according to claim 1 or 2, wherein the membrane (1233) is moulded to provide a non-planar shape such that the membrane is non-planar in a relaxed position, i.e. a position in which the pressure differential across the membrane is substantially zero.

6. The valve according to claim 5, wherein the membrane (1233) is molded out of plane towards the control space (Sc).

7. The valve according to claim 5, wherein the membrane (1233) is molded out of plane towards the flow space (Sf).

8. The valve according to any of the preceding claims, further comprising a cross-sectional cut-out (12311) from the channel body (1231), whereby an edge of the membrane is attached between the channel body and the cut-out (12311).

9. The valve according to claim 8, wherein the edges of the passage body (1231) and the cut-away portion (12311) are provided with flanges (1234a, 1234 b).

10. The valve of claim 9, wherein the membrane (1233) is sandwiched between the flanges (1234a, 1234 b).

11. A valve according to claim 9 or 10, wherein the membrane (1233) is attached at the outer portion (12341) of the flange to enable movement of the inner portion of the membrane rim between the flanges (1234a, 1234 b).

12. A valve according to claim 1 or 2, wherein the membrane is provided by a bladder (2233) attached to a channel wall at the radially outermost portion (Co) of the channel space, the bladder surrounding the control space (Sc).

13. A valve according to any of the preceding claims, wherein the membrane area within the channel space is at least twice the cross-sectional area of the channel, preferably 3 to 7 times the cross-sectional area of the channel.

14. Use of a valve according to any of the preceding claims as an inlet valve (123) arranged on the upstream side of a separator (12) for separating particles from a particle laden fluid stream.

15. Use according to claim 14, wherein fluid is sucked through the separator (12) and thus through the valve by means of a suction generator (14) arranged downstream of the separator (12).

16. Use according to claim 15, wherein the control connector (1232) is connected to the suction generator (14) at a position downstream of the separator (12) so that the pressure applied to the control connector is lower than the pressure applied to the interior of the separator (12).

17. Use according to claim 14 or 15, wherein the control connector is connected to a separate pump device arranged to supply vacuum and/or pressure to the control space (Sc).

18. Use according to any one of claims 14 to 17 for separating particles from particle laden air.

19. A separator (12) for separating particles from a particle laden fluid stream, comprising:

the space of the separator is provided with a separator,

a suction generator (14) connected to a downstream side of the separator space, an

A valve (123) according to any of claims 1-13, arranged on an upstream side of the separator space.

20. A decoupler according to claim 19, wherein the control connector (1232) is in fluid connection with the suction generator (14) at a location downstream of the decoupler (12) such that the pressure applied to the control connector (1232) is lower than the pressure applied to the decoupler space.

21. A separator as claimed in claim 19 or 20, further comprising separate pump means arranged to supply vacuum and/or pressure to the control space (Sc).

22. A separator according to any of claims 19 to 21, further comprising an accumulator (1251) arranged to accumulate vacuum and/or pressure and selectively connected to the control space to apply the vacuum and/or pressure to the control space.

23. A method of cleaning a separator body (126) contained in a separation space in a separator (12), comprising:

closing an inlet (121) to the separation space,

sucking a negative pressure at a downstream side of the separator main body (126), and

connecting a downstream side of the separator body (126) to a pressure higher than the negative pressure to cause fluid to flow rapidly upstream through the separator body (126),

it is characterized in that

The inlet (121) is closed by means of a valve (123) according to any one of claims 1 to 13, which is operated to assume its closed position.

24. A method according to claim 23, wherein the valve (123) is operated by increasing the pressure in the control space (Sc) with respect to the pressure in the separation space (Sf).

25. Method according to claim 24, wherein the pressure is increased by connecting the control space (Sc) with a pressure at least corresponding to the ambient pressure.

Technical Field

The present invention relates to a valve, to the use of such a valve as an inlet valve for a separator, to a separator comprising such a valve, and to a method of operating a separator.

Background

Separators are used to separate particles (including powders, pellets, chips, etc.) from a fluid stream (such as air, oil, or water).

Some separators utilize a permeable separator body that traps particles as a flow is directed through the separator body. The separator body may take the form of a grid, mesh or filter. The filter may comprise a woven or non-woven material.

As the particles become trapped in the separator body, the separator body will become progressively clogged, causing the pressure drop across the filter to increase, thereby affecting the efficiency of the overall system.

Therefore, it may be necessary to service the separator body, for example by replacing or cleaning it.

In many applications, cleaning the separator body is the method of choice, as the life of the separator body itself is much longer than the time required for it to clog.

There are a number of methods of cleaning separator bodies, some of which involve removing the separator body from its operating position, others involve cleaning the separator body in situ. The latter may involve various methods of scraping, rapping or shaking the separator body.

One particular way of cleaning the separator body is to subject it to a reverse impact of the fluid. That is, the fluid is caused to flow rapidly backwards through the separator body, whereby particles caught on the separator body side upstream in normal operation are released from the separator body and preferably collected.

In heavy duty separators (essentially heavy duty "vacuum cleaners") for separating particles from air, for example in connection with the grinding of stone or concrete, a suction generator is usually arranged downstream of the separator, so that the suction generator sucks in air through the separator and thus through the separator body.

Such heavy separators may include a pre-separator, which may be in the form of a settling chamber, a coarse filter, a cyclone separator, or a centrifugal separator, and a post-separator, such as a HEPA filter for separating out the finest particles not captured by the main separator. The suction generator will then typically be located downstream of the rear separator.

To clean the separator body, the separator inlet is typically closed while the suction generator is allowed to operate so that a negative pressure (vacuum) is established inside the separator. Once the negative pressure has been established, the valve on the downstream side of the separator body will open quickly, connecting the downstream side of the separator body to higher pressure air (such as ambient air), whereby the air will flush back through the separator body, causing agitation of the separator body and releasing particles trapped on the upstream side of the separator body. If the separator body is sufficiently vertical, the particles will fall to the bottom of the separator where they can be collected and removed.

As an alternative, it is possible to provide an accumulated pressurized air volume, which can be applied in the reverse direction of the separator body.

Thus, the cleaning procedure utilizes two valves: an inlet valve on the upstream side of the separator body and a cleaning valve on the downstream side of the separator body.

The inlet valve should provide a sufficient shut-off for the incoming flow to the separator.

It is desirable to provide an inlet valve that is robust and can be manufactured at low cost. Preferably, the inlet valve should also be easy to maintain and allow automation. That is, it should be possible to operate the valve by digital control so that the cleaning operation can be fully automated and initiated by the controller when needed or commanded by the operator.

Although inlet valves are discussed in, for example, WO2009041890a2, there is still room for improvement.

Disclosure of Invention

It is an object of the present invention to provide an improved inlet valve, in particular an inlet valve which at least partially meets the criteria set forth via introduction.

The invention is defined by the appended independent claims, embodiments being set forth in the dependent claims, the drawings and the following description.

According to a first aspect, there is provided a valve comprising a channel body defining a tortuous channel space; an elastically flexible membrane separating a control space in the channel space from the flow space; and a control connection providing a fluid connection to the control space. The control space is arranged at a radially outermost portion of the channel space according to a channel bending radius to enable the membrane to be deflected between an open position, in which the cross-section of the flow space is substantially the cross-section of the channel, and a closed position, in which the membrane is substantially sealed against a radially innermost portion of the channel according to the channel bending radius.

The term "bend (bent)" is to be understood as a channel section providing a change in flow direction. The channels may thus be curved or angled. The term does not limit the manner in which the tortuous path portion is formed. That is, it may be initially formed as a curve, or it may be formed by bending a straight or pre-curved blank.

The cross-sectional area of the channel may be about 7cm²To 300cm²Preferably 7cm²To 200cm²、20cm²To 170cm²Or 40cm²To 120cm²。

The channel cross-section may be substantially constant. A circular channel cross-section may be preferred, but the flexibility of the membrane also allows other cross-sections to be used as well as varying cross-sections.

Digital control is possible by a simple on/off valve controlling the pressure at the control connection, i.e. in the control space.

The membrane, which can be formed as a low cost replaceable component, will act as a wear protection for the channel body.

The membrane may be formed of a material having rubber elastic properties.

The membrane may be impermeable to the medium in which it operates. However, it is sufficient if the membrane is sufficiently impermeable to allow a negative pressure to be maintained in the control space

The thickness of the film may be about 0.1mm to 10mm, preferably about 1mm to 5mm or about 1mm to 3 mm.

The membrane may be substantially planar in the relaxed position (i.e., the position where the pressure differential across the membrane is substantially zero).

The membrane may intersect the channel space in the relaxed position such that the volume of both the control space and the flow space is greater than zero.

The ratio of the volume of the control space to the volume of the flow space may be about 1/2 to 1/10, preferably 1/2 to 1/5.

The membrane may be moulded to provide a non-planar form such that the membrane is non-planar in the relaxed position (i.e. a position in which the pressure differential across the membrane is substantially zero).

The membrane may be moulded out of plane towards the control space.

Alternatively, the membrane may be moulded out of plane towards the flow space.

The valve may further comprise a cross-sectional cut-out portion from the channel body, whereby the edge of the membrane is attached between the channel body and the cut-out portion.

The "cut-off portion" may be formed by actually cutting off a part of the channel body, or may be formed by a portion separately formed to be fitted with the channel body as if the "cut-off portion" was cut off from the channel body. Furthermore, the cut-away portion may be formed as a wall portion that follows and slightly overlaps the channel wall.

The edges of the channel body and the edges of the cut-out may be provided with flanges.

These flanges may extend substantially parallel to the plane of the membrane.

The membrane may be sandwiched between the flanges

The membrane may be attached at an outer portion of the flanges such that an inner portion of the membrane rim is movable between the flanges.

Alternatively, the membrane may be provided by a bladder attached to the channel wall at the radially outermost portion of the channel space, the bladder surrounding the control space.

The membrane area in the channel space may be at least 2 times the cross-sectional area of the channel, preferably 3 to 7 times the cross-sectional area of the channel.

According to a second aspect, there is provided the use of a valve as described above as an inlet valve arranged on an upstream side of a separator for separating particles from a particle laden fluid stream.

In such applications, fluid may be drawn through the separator, and thus through the valve, by a suction generator disposed downstream of the separator.

In such applications, the control connector may be fluidly connected to the suction generator at a location downstream of the separator such that the pressure applied to the control connector is lower than the pressure applied to the passage. That is, a pressure differential is applied across the membrane.

In this use, the control connector may be connected to a separate pump device arranged to supply vacuum and/or pressure to the control space.

The use may be for separating particles from particle laden air.

According to a third aspect, there is provided a separator for separating particles from a particle laden fluid stream, comprising: a separator space;

a suction generator connected to a downstream side of the separator space; and a valve as described above, which is arranged on the upstream side of the separator space.

The control connector may be fluidly connected to the suction generator at a location downstream of the separator such that a pressure applied to the control connector is lower than a pressure applied to the passage.

The separator may also comprise a separate pump device arranged to supply vacuum and/or pressure to the control space.

The separator may further comprise an accumulator arranged to accumulate vacuum and/or pressure and selectively connected to the control space for applying said vacuum and/or pressure to the control space. Such an accumulator may be filled by the suction generator and/or by a separate pump.

According to a fourth aspect, there is provided a method of cleaning a separator body accommodated in a separation space of a separator, the method comprising:

the inlet to the separation space is closed, a negative pressure is sucked on the downstream side of the separator body, and the downstream side of the separator body is connected to a pressure higher than the negative pressure to cause a rapid flow of fluid in the reverse direction of the separator body. The inlet may be closed by means of a valve as described above, which is operated to assume its closed position.

The valve may be operated by increasing the pressure in the control space relative to the pressure in the separation space.

The pressure may be increased by connecting the control space with a pressure at least corresponding to the ambient pressure.

Drawings

Fig. 1 is a schematic view of a system comprising a floor grinding machine 2 and a heavy duty vacuum cleaner 1.

Figure 2 is a schematic perspective view of a separator 12 which may form part of the vacuum cleaner 1.

Fig. 3 is a schematic cross-sectional view of a valve 123 according to a first embodiment.

Fig. 4a to 4b are schematic cross-sectional views of a valve 123 according to a second embodiment.

Fig. 5 schematically shows an embodiment of the membrane connection.

Fig. 6a to 6b schematically show another embodiment of the valve 223.

Detailed Description

In the following description, the valve will be described with reference to its use in a separator forming part of a heavy duty vacuum cleaner useful in a floor grinding environment.

Referring to fig. 1, the system comprises a floor grinding machine 1, which floor grinding machine 1 can be any type of floor grinding machine, with a connection for emptying grinding residues. The system further comprises a heavy duty vacuum cleaner unit 1 comprising a pre-separator 11, illustrated as a cyclonic separator; the main separator 12, which includes an inlet 121, an outlet 122, an inlet valve 123, a cleaning valve 124, and a separator body 126, such as a filter. The system also includes a rear decoupler 13, such as a HEPA filter and a suction generator 14, which may include a motor that drives a fan to generate an airflow.

FIG. 2 schematically illustrates the separator 12 having a separator inlet 121, an outlet 122, an inlet valve 123, and a housing 127. The cleaning valve 124 is also visible at the top of the housing 127.

In the following, the valve 123 will be described with reference to being used as an inlet valve in a heavy duty vacuum cleaner. It should be understood that the same principles may be applied to other types of separators and applications.

Referring to fig. 3, the valve 123 includes: a curved channel 1231 defining a channel space, a membrane 1233 dividing the channel space into a flow space Sf and a control space Sc, and a control connection 1232.

In the illustrated embodiment, the channel is curved in the sense that it exhibits a curve having an inner radius of curvature Ri and an outer radius of curvature Ro. As can be seen from these bending radii, the passage 1231 has a cross section which extends in the radial direction Ro of the bend from the radially innermost wall Ci portion to the radially outermost wall portion Co.

As shown in fig. 3, the cross-section may be substantially circular. However, other cross-sections may be provided, including oval, square, or rectangular cross-sections.

The curvature of the channel may be formed by bending a straight channel blank. Alternatively, the channels may be initially formed in a curved configuration, for example, based on pre-cut sheet metal and/or using a mandrel that provides such a curved configuration.

Alternatively, the passage 1231 may be curved in the sense that it includes a change in flow direction. As shown in fig. 4 a-4 b, this may be the case where the channel is made up of two or more channel portions that join between the opening to provide two or more channel angles.

The membrane 1233 is arranged such that it forms a control space Sc such that the control space is arranged at the radially outermost part Co of the channel, seen from the channel bending radius Ro, and is sealed from the flow space Sf.

For example, the membrane 1233 may assume a substantially planar form in the relaxed state (i.e. a state in which the pressure in the control space Sc is equal to the pressure in the flow space Sf), thereby forming a planar base of the control space Sc defined by the membrane and the channel wall Co.

In case the channel 1231 is formed as a curved tube with a circular cross-section, the control space Sc will be delimited by the planar membrane 1233, and in case the channel is curved and has a circular cross-section, a double curved surface Co is formed by the channel walls. In this case, the control space will have a shape defined by a curve provided by the curvature of the channel and a curve provided by the curvature of the cross-sectional profile of the channel according to the channel bending radius. These curves may be orthogonal to each other.

The shape of the control space Sc will vary depending on the shape of the channel.

A control connection 1232 is provided to the control volume Sc to allow evacuation, or optionally application of pressure. The control connection may be connected to the suction generator 14 as a fluid connection 125. Alternatively, the control connection may be connected to a separate pump for evacuating and/or applying pressure to the control space Sc.

The connection 125 between the connector 1232 and the suction generator 14 may be controlled by a valve 1253, which may be arranged to selectively connect the control volume Sc to the suction generator 14 or to ambient pressure.

The membrane 1231 is formed of a flexible material that is preferably elastic in the sense that the material is capable of stretching and then returning to its original shape.

Thus, the membrane 1231 is flexible, preferably elastically flexible, between a valve closed state, in which a portion of the membrane contacts the radially innermost channel wall portion of the bend to close the flow space, and an open state, in which the membrane contacts the outermost channel wall portion of the bend and preferably follows the outermost channel wall portion of the bend.

In embodiments where the membrane 1231 is planar in its relaxed state, the membrane may be said to extend tangentially to a point of the channel bend.

The membrane 1231 may be formed from a sheet that is sufficiently impermeable to such gases to be transported in the channel.

Thus, the membrane 1231 is sufficiently impermeable to maintain the open or closed state of the valve, respectively.

Examples of materials include resiliently flexible materials, such as rubber and rubber-like materials,

the film thickness may be about 0.1mm to 10mm, preferably 1mm to 5mm or 1mm to 3 mm.

The attachment of the membrane in the channel may be performed by a cut-out 12311 of the radially outermost channel wall portion.

For example, a portion 12311 of the channel wall may be cut away by a cut, which may be planar. Along the cut edge of the remaining channel 12312, as well as along the cut edge of the cut-away portion, flanges 1234a, 1234b may be provided, which may be continuous along the edges or may form separate attachment tongues.

The film 1233 can thus be arranged along the plane of the cut, and the cut-out portions 12311 repositioned and attached.

As mentioned above, flanges or attachment tongues may be used for such attachment.

The edges of the flange 1234a, flange 1234b and cut-out 12311 of the channel cutting edge may be connected to one another by, for example, clamps, snap connections, screws, or nut/bolt connections 1235.

Optionally, the membrane 1233 may be sandwiched between edges or flanges.

Referring to fig. 5, for example, a membrane 1233 may be attached (e.g., clamped) to the outermost portions 12341 of the flanges 1234a, 1234b, spaced from the channel walls, such that the membrane is movable relative to the innermost portions 12342 of the flanges 1234a, 1234b that are closest to the walls 12311, 12312. To this end, the distance between the flanges may taper outwardly from the channel walls. Thus, the surface of the film available for elastic deformation increases.

In an alternative set of embodiments, the film may be molded to an out-of-plane (out-of-plane) type. That is, instead of the film generally having a two-dimensional shape when relaxed, the film may have a three-dimensional shape when relaxed.

For example, in the relaxed position the membrane may be formed towards a valve open position (fig. 4a), whereby when the pressure in the control space Sc is sufficiently higher than the pressure in the flow space Sf, the membrane will close towards the radially innermost channel wall portion and optionally be bendingly deformed towards the radially innermost channel wall portion.

In another embodiment, in the relaxed position the membrane may be formed towards the valve closed position (fig. 4b), whereby when the pressure in the flow space Sf is sufficiently higher than the pressure in the control space Sc, the membrane will open towards the radially outermost channel wall portion and optionally bendingly deform towards the radially outermost channel wall portion.

The control connection 1232 provides a fluid connection to the control space Sc such that the pressure in the control space Sc can be adjusted. The connection may be provided by means of a through hole in the wall of the channel, optionally provided with a coupling member or other means by which a fluid connection may be established.

As a further alternative, the connection may be provided in a joint between the resected channel wall portion and the remaining channel wall.

Typically, this connection 1232 will be connected to a suction generator, such as the same suction generator that generates the primary suction in the decoupler 12. Thus, the connection may be provided by a hose connected to a point in the air path downstream of the separator 12 and upstream of the suction generator 14.

Of course, it is possible to apply pressurized fluid to the connection if needed and available.

The valve 123 will typically be disposed at or near the inlet for dust laden air to the separator housing 127.

The operation of the valve 123 will now be described.

In normal operation of the valve 123, suction is provided on the downstream side of the separator, and preferably even on the downstream side of the post-separator 13, such as a HEPA filter.

This suction will therefore draw air through the system 1 so that dust laden air is drawn in via the system inlet, optionally pre-separated, and then introduced through the valve 123 into the separator 12 where at least some of the dust is captured by the filter body 126. The so-cleaned (but not necessarily completely cleaned) air leaves the separator 12, optionally enters the post-separator 13, and is then drawn into the suction generator 14, after which it can be discharged into the surroundings.

As described above, during such normal operation, suction is applied to control link 1232. By connecting the control connection 1232 to the suction generator 14 downstream of the separator, the pressure drop difference will ensure that the pressure in the control space Sc is always lower than the pressure in the flow space Sf, whereby the membrane 1233 will assume the open position.

Preferably, the membrane 1233 may be pulled all the way to the outermost wall part Co of the channel, so that it provides a minimum obstruction to the flow in the channel.

For example, when a decrease in overall suction efficiency is found, the user may determine whether cleaning of the filter is required. Alternatively, it may be determined automatically, for example by measuring a pressure differential across the separator 12, or by measuring a motor parameter indicating that the system resistance is increasing. As another alternative, cleaning may be performed at predetermined time intervals.

As a first action, the valve 123 will be actuated by simply closing the suction at the control space Sc, by connecting the control space to ambient pressure, or by connecting the control space to a source of compressed air.

When the pressure in the control space Sc is sufficiently larger than the pressure in the flow space, the membrane 1233 will move towards the radially innermost wall part Ci of the channel to close the flow.

The suction generator 14 continues to draw a vacuum in the separator housing 127.

Once a sufficiently low pressure is reached, the cleaning valve 124 on the downstream side of the filter is actuated to connect to higher pressure air, such as ambient air, to provide a reverse air jet through the separator body 126 to clean the separator. Agitation of the separator body 126 may be achieved with sufficient flexibility of the separator body. The purge valve 124 may then be closed and the process repeated as many times as necessary.

Once cleaning is determined to be complete, the suction generator 14 is reapplied to the control volume Sc, thereby pulling the membrane 1233 to the open position and normal operation can resume.

Referring to fig. 6a to 6b, an alternative embodiment of a valve 223 is shown, wherein the membrane is formed by a bladder 2233, which surrounds the control space Sc and which is attachable to the radially outer wall so that it substantially follows the wall when in a contracted state, as shown in fig. 6 a. When the pressure difference over the membrane moves such that the pressure in the flow space is lower than the pressure in the control space Sc, the bladder will expand and contact the radially inner wall, as shown in fig. 6 b.

The bladder may be mechanically attached (by rivets, bolts, etc.) to the outer wall by adhesive and/or by means of, for example, flanges provided along the edges of the bladder.

The bladder may be attached to the inner wall of the channel, or to a removable portion of the wall, such as the cut-out portion described previously. It will be appreciated that the edge of the bladder may be sandwiched between such cut-away arrangement of flanges.

Furthermore, the radially outer portion of the bladder may be formed of a rigid material which may be adapted to follow the shape of and seal against the channel wall, while the portion facing the flow space has the form of a flexible membrane, as described above.

Optionally, an accumulator 1251 may be disposed between the suction generator 14 and the control connection 1232. By allowing the suction generator 14 to operate via the accumulator 1251 and check valve 1252, it is possible to accumulate vacuum, which can provide a faster response time for the valve 123 when it is desired to open the valve.

The connection 125 between the connector 1232 and the suction generator 14 may be controlled by a valve 1253, which may be arranged to selectively connect the control volume Sc to the accumulator 1251 or to ambient pressure.

Similarly, it is possible to build up pressure, for example in a separate accumulator, and to apply this pressure to the control space Sc in order to achieve a rapid closing of the valve. The accumulator may be driven by a separate pump or through the outlet of the suction generator 14. A valve (not shown) may be arranged to control the connection between such a pressure accumulator and the control space Sc.

The accumulator may be formed by a hollow chassis of the machine. That is, the vacuum or pressure may be stored inside a hollow beam forming, for example, a machine chassis.

In one embodiment, the cut-away portion may be formed of a transparent material so that the film can be inspected at the time of operation.