GB2025034A

GB2025034A - Apparatus for Use in Throttling Devices

Info

Publication number: GB2025034A
Application number: GB7920507A
Authority: GB
Original assignee: Carl Munters AB
Current assignee: Carl Munters AB
Priority date: 1978-06-21
Filing date: 1979-06-13
Publication date: 1980-01-16
Also published as: JPS5510193A; FR2429389B1; GB2025034B; DE2924872C2; FR2429389A1; SE412110B; DE2924872A1; SE7807129L

Abstract

An air-jet cleaning device (15), for cleaning the fine parallel passages (11) of a throttling member (14) of a ventilation system, has a hollow, divided central shaft (20) and two box-shaped shields (30 and 32) arranged against the inlet and the outlet surfaces of the throttling member (14). The air-jet cleaning device is rotated by a motor or by air impinging on vane 48 to sweep across the surfaces of the throttling member and diverts part of the air flowing through the throttling member in the reverse direction to that of the main flow so that the passages are cleaned by a reverse jet of air. The two air streams (54) flow through the two passages in shaft (20), and dust removed from the throttling member is carried into the main air stream at (56). <IMAGE>

Description

SPECIFICATION Apparatus for Use in Throttling Devices The following invention is concerned with an apparatus for use in throttling devices of the type intended for mounting in ventilation ducts for admitted or supply air, such devices comprising an element, hereafter designated the throttling member, having a number of through, parallel passages and commonly mounted so as to cover almost the entire cross-sectional are of the ventilation duct with the passages running in a longitudinal direction along the duct.

Throttling devices of the type described above are designed for mounting in the air ducts of ventilation systems in order to ensure that the distribution of air within the system is as desired and, while avoiding irritating noise, to bring about a fall in pressure such that the spreading of flue gases, etc., from one room to another will be made more difficult in case of fire.

The chief purpose of the invention is the realization of a device preventing the throttling member from becoming clogged or choked by deposits of dust and other solid particles.

More particularly, the invention aims at defining a means of cleaning the member at its inlet, which is the site at which such deposits are likely to occur.

A further purpose of the invention is to define such means both simple and inexpensive in manufacture and operation, and which functions reliably and efficiently.

These and other objectives are achieved in that the device provided for by the invention is given the characteristic features described in the claims to follow.

The invention and a number of additional advantages it offers will be described in the following paragraphs by reference to a preferred embodiment shown by way of example in the appended drawings.

Figure 1 shows a perspective view of a throttling device provided with an air-jet cleaning device as specified by the invention.

Figure 2 shows a cross-section of the device illustrated in Figure 1.

In the drawings the numeral 10 is used to denote the wall of a duct for supply air incorporated in a ventilation system, into which air is introduced by means of a pressure fan (not shown here) and flows in the direction indicated by the arrow 12. The air conveyed through the duct 10 is blown into a room by means of e.g. a discharger as described in greater detail in the British Patent No. 1312674.

In this duct 10 is mounted a throttling member 14 having a number of through parallel passages 11 running in a longitudinal direction along the duct 10. A ring-type seal or gasket 1 6 is used to form a seal between the throttling member 14 and the wall of the duct 10.

There is a tendency for dust and other solid particles to be deposited at the inlet 1 8 of the throttling member 14, this tendency being more or less depending on the design of the throttling member itself. For the purpose of continuously removing these particles as they are deposited, -the invention provides for an air-jet cleaning device 1 5 to be mounted in conjuction with the throttle, such device comprising a tubular shaft 20 mounted centrally in the throttling member 14 and divided by a partition 22 into two semicircular halves which also serve as ducts 24, 26 (see also Fig. 2), The shaft 20 should preferably be mounted on ball bearings 28 or by some other means allowing the shaft to rotate freely in the throttling member 14.At each end of the shaft 20, the two halves, 24 and 26, project beyond the surface of the throttling member and support a closed, box-shaped shield or arm, 30 and 32, against the inlet and outlet of the throttling member. On each side of these arms, facing the throttling member 14, these arms, 30 and 32, being essentially identical and located opposite each other on the upper 18 and lower 34 surfaces of the throttling member 14, is a sector-shaped opening, 36, 38, extending across the radius of the circular throttling member. Each arm 30, 32 is also provided with an opening, 40 and 42, corresponding in shape to the outline of the semicircular halves 24, 26 of the shaft, on the side of the arm 30, 32 facing the throttling member, and a similar opening, 44 and 46, on that side facing away from the throttling device.

The circumferential edges of each opening 40, 42, 44 and 46 are sealed snugly against their equivalent half of the shaft 24, 26; the arms are thus supported by the shaft 20 and each duct 24, 26 of the shaft leads both into the interior of one arm 30, 32 and to the exterior surface of the other arm 32, 30.

At least one of the arms 30, 32-in the example discussed here, the lower 32-is provided with a vane 48 so mounted as to be struck by the air streaming through the duct 10 and the throttling member. The vane 48 therefore serves to keep the air-jet cleaning device in rotation, thus causing the arms 30, 32 to sweep continuously over the surfaces of the throttling member 14 as indicated by the arrow 50 at the top of Figure 1.

The air-jet cleaning device functions in the following manner: Although the greater part of the supply air 12 passes through the ducts of the throttling member 14 in the normal fashion, part of it will flow through the opening 44 in the upper arm 30 as indicated by the arrow 52. The flow of air so diverted then flows through the duct 24 in the shaft to the opening 42 of the lower box-shaped arm or shield 32, passes to the interior of this, changes direction and flows upwards through the sector-shaped opening 38. The cleansing air jet passes back through the throttling member 14 and into the equivalent sector-shaped opening 36 in the upper arm or shield 30.By this means, any dust or similar deposit is removed from the upper surface 1 8 of the throttling member at the place covered by the sector-shaped opening 36 in the arm 30, which is at a position equivalent to the corresponding opening 38 of the lower arm 32.

The air jet and the particles it has removed are then diverted to the other semicircular half 26 of the tubular shaft, this half being connected to the interior of the upper arm 30. Finally, the cleansing air jet and the particles it has removed are led via this half 26 of the shaft to the exterior of the lower arm 32 and are ejected through the opening 46 into the main duct 10 on the outlet side of the throttling member 14 as indicated by the arrow 56. The path taken by the air jet between the inlet 44 and the outlet 46 is shown in the figure by the broken line 54.

A characteristic feature of throttling members of the type described above having numerous parallel channels or ducts, and one that is essential to their function, is that they are able to create large drops in pressure without giving rise to irritating noise. It should also be observed that this feature, essential as far as noise is concerned, is also retained by the air jet, which also passes through the fine channel of the throttling device, albeit in the opposite direction.

Clearly, the embodiment illustrated and described here is merely one way of realizing the invention, which may be varied or modified while still remaining within the framework of the basic idea. Thus, although it is here described as being driven by the flow of air, the air-jet cleaning device may in certain -applications of the invention be driven by a motor provided for the purpose.

Similarly, the throttling member 14 may also be of a type other than that described here (which is the equivalent of that described and illustrated in the Patent application as published for opposition no. 359 367 mentioned above).

The cleansing sectors and air-jet cleaning device may also be of forms and extent differing from the examples illustrated here.

In the example discussed above mention was made that the air passing through the throttling device consists of supply air. In well-designed systems the supply air is filtered so efficiently before it reaches the throttling device that air-jet cleaning of deposits on the surface of the device is.

hardly necessary in itself. However, it often happens that fibres and particles break away from the ducts themselves-from insulating or sound absorbing material, for example-and this occurs in the duct system itself, that is, after the filter.

Here the danger of clogging is evident unless airjet cleaning is provided for.

The need for throttling devices to control and maintain the desired volume of air is also apparent in exhaust air ducts. Here the type of throttling member featuring fine channels or ducts as exemplified above has previously been unusable, since filters cannot be used for exhaust air. Dust suspended in indoor air rapidly deposits itself on the throttling member to such thicknesses that the latter is soon put out of function. However, if an air-jet cleaning device as provided for by the invention is used, throttling members of the type under discussion may also be incorporated in exhaust air systems.

In the embodiment exemplified in the present, the central part of the throttling member is used to unite the high and low pressure sides of the airjet cleaning device with the main air flow before and after its passage through the throttling member, that is to say the fall in pressure over the throttling device is used to create the air jet flowing in the opposite direction. Naturally, it would also be feasible for one or both of the ducts via which the air is forced into or sucked out of the air-jet cleaning device to be so designed as to take the form of by-pass ducts passing outside the throttling member. It is, however, essential that the fall in pressure occurring over the throttling device be used to create the cleansing air jet flowing in a direction opposite to that of the main air flow.

Claims

1. Apparatus for use in throttling devices of the type intended for mounting in ventilation ducts for admitted or supply air, such devices comprising an element having a number of fine, through parallel passages for this air flow, characterized by an air-jet cleaning device caused to sweep across the surface of the inlet of the throttling member and having a shield which diverts part of the air flowing through the throttling device in a direction opposite to that of the main air flow through the throttling element for the purpose of cleaning its passages and inlet by a jet of air.

2. Device of claim 1, characterized in that the air-jet cleaning device comprises a tubular shaft located centrally in the throttling member through which the cleansing air jet is conveyed to and/or from the shield incorporated in the device.

3. Device of claim 2, characterized in that the shield of the air-jet cleaning device is rigidly united with the tubular shaft in such manner that both are caused to rotate above the inlet and outlet surfaces of the throttling element.

4. Device of claim 3, characterized in that a vane or similar device is rigidly united with the airjet cleaning device in the passage of the main air flow so as to bring about the rotation of the shield.

5. An air-jet cleaning device for use in throttling devices of the type intended for mounting in ventilation ducts and including a piurality of fine channels for air flow, the cleaning device comprising a movable shield arranged in use to sweep across the surface of the inlet of the throttling member and to divert part of the air flowing through the throttling device in a direction opposite to that of the main air flow through the throttling device for the purpose of cleaning the fine channels and-the inlet by a jet of air.

6. An air-jet cleaning device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

7. A throttling device including an air-jet cleaning device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.