GB2168759A - Rotary blower in a pneumatic transporting apparatus - Google Patents

Abstract

In order to pneumatically transport a wide range of materials, an air aggregate (5, Figs. 1 and 2) on a tank lorry incorporates a blower 18 which is equipped with slit-shaped cooling air inlets 77 arranged in its housing on opposite sides of outlet 24. The provision of the cooling air inlets produces good cooling so that a close tolerance can be selected for the sealing gap between the blower impellers 19 and the housing, whereby a strong vacuum or a strong compression can be realised and materials such as gravel can be pneumatically transported. The apparatus may instead be a road sweeping machine with a dust aspirator and a roller brush. <IMAGE>

Description

GB 2 168 759 A 1

SPECIFICATION

Pneumatic Transporting Apparatus The invention concerns a pneumatic transporting apparatus according to the commencement of Claim 1.

A pneumatic transporting apparatus of this kind is known from JP 58-95033.

The vacuum which can be created by the blower is limited, on account of the considerable temperature 10 rise and the related expansion of the blower components. To solve this problem, blowers with figure-of-eight shaped impellers have already been proposed, for example in JP 58-91390, with air being supplied via cooling air inlets. The cooling air 15 passes through the flat side walls of the housing in an axial direction, into the hollow spaces of the impellers, thus cooling the impellers primarily internally, and leaves the hollow spaces of the impellers via cooling air outlets, which give access 20 to the air intake side of the blower. This supply of air 85 to the air intake side substantially reduces the capacity of the blower. Moreover, deposition of dirt in the impellers leads them to become unbalanced.

The aim of the invention is to strengthen the 25 suctional force of the pneumatic transporting apparatus, so that more different types of material, including gravel, can be transported thereby and/or the size of the filter apparatus can he reduced. To this end, the characteristic of Claim 1 is applicable.

30 Owing to the application of this characteristic, the surfaces of both the housing and the impellets which have been heated by air-compression are well cooled, whereby indefinite expansion is so effectively countered that the housing and the 35 impellers can be dimensioned with a narrow mutual 100 clearance, without any danger of the blower seizing.

Through this, a strong vacuum can be realized by the blower, so thatthe pneumatic transporting apparatus can be effectively used for heavy 40 materials which are difficultto suck up, such as 105 gravel.

It should be noted that a pneumatic transporting apparatus is known from 2314 Pumps, Pompes, Pumpen no. 136 (January 1978), in which air 45 emerging from a blower is cooled by a cooler, and is 110 then partially returned via cooling air inlets of the blower, which are arranged practically in the centre of the angle between the air intake and the air outlet in the housing of the blower. The capacity of this 50 known blower is limited, in particular on account of 116 the factthat the impellers no longer have the essentially figure-of-eight shape, with two principally cylindrical rotor ends and a narrowed middle section bounded by a single levelling curve, 55 but instead have very wide rotor ends which demand, on each side of the cooperating impeller, two constrictions instead of one, whereby the middle section of the impellers becomes large, and the compression space correspondingly small. The 60 point that the suction or compressive power of this blower is limited is confirmed in the literature reference cited here, by the placing of a number of these blowers in series in order to realize the req u i red vacu u m.

An important advantage of the pneumatic transporting apparatus according to the invention is that it can be constructed compactly and with a relatively small filter apparatus, so that it is particularly suitable for embodiment as a tank lorry, 70 with there being much space left over, on account of the small filter apparatus, for a large tank to be carried by the vehicle chassis.

The eff iciency of this strong blower is yet further improved if the filter apparatus is provided with filter bags which are connected to a pulsed air source. A filter apparatus of this kind is known in its own right from FR-A-2 341 505.

The above-mentioned and other characteristics of the invention, and its advantages, will be elaborated 80 in the following description with reference to the drawings.

The drawings represent, schematically, the following:

Figures 1 and 2 represent a partially cut-away side and top view, respectively, of a pneumatic transporting apparatus according to the invention, embodied as a tank lorry.

Figures 3 and 4 show a diagram of the tank lorry of figure 1 during, respectively sucking up and 90 expulsion of material.

FIgure 5 shows a partially cut-away perspective view of detail V of figure 3.

Figures 6 and 7 show, on an enlarged scale, cross-sections through line VI-VI in figure 1, and 95 line VII-VII in figure 5, respectively.

The tank lorry 1 according to the invention comprises a chassis 2 which carries a cylindrical tank 3. Tank 3 is fastened to chassis 2 at its rear end 7 tiltably around a horizontal axis 6, and at its front end 8 raisably by a hydraulic jack 9, so that the tank 3 can be tilted as far as the raised position indicated by dashed lines in figure 1. The front end 8 of the tank encloses a filter space 10 of a filter apparatus 4, which isseparated by a partition 11 from a space 12 for storage of material. The rear end 7 of tank 4 is closed off by means of a cover 14, which is fastened to tank 3 pivotably around a horizontal axis 13, is sealed by means of a gasket (not shown) and is locked in the closed position by means of latches (not shown). Material can be discharged where necessary by letting it run from tank 3, with tank 3 in the raised position, and cover 14 open.

Tank 3 has on its top two airtight removable covers 15. When tank 3 is filled from a silo, the material can be discharged into tank 3 with the covers 15 removed.

For sucking up material, a hose 16 is connected via a shut-off valve 17 to tank 3, and furthermore, to create a vacuum in tank 3, there is a suction 120 aggregate 5 present, comprising a blower 18 with figure-of-eight shaped impellers 19. This is a socalled Roots compressor, which, according to the power of the motor 54, can displace 1000-7000 m3 per hour. The intake side of the blower 18 is 125 connected to the storage space 12 via a conduit 21, a silencer 22 and the filter apparatus 4, while its outlet side 24 is connected to the atmosphere via a conduit 25 with a silencer 26, and via a shut-off valve 23.

Conduit 25 branches by means of a distribution GB 2 168 759 A 2 control valve 45 into a fluidization air conduit 29 provided with a control valve 27, and a blow air conduit 31. Before control valve 27, the fluidization air conduit is connected to a secondary air conduit 5 28, provided with a control valve 30. The fluidization air conduit 29 is closed off when gravel is being discharged, but is opened for use with fine material. At the bottom of cover 14 there is a discharge funnel 32 present, a bottom funnel part 70 being 10 connected, as shown in figure 6, to a discharge bin 33, such that an edge 40 extends further inwards than the wall 35 of fluidization bin 34, so that turbulence in the material arises at edge 40. The opening 96 of the funnel 32 has a diameter g of 70 15 cm., that is to say large enough to prevent obstructive arching in the material. In the fluidization bin 34, there is welded a funnel 36, under which funnel 37 is located, leaving free a fissure 38. The fluidization conduit 29 is connected 20 to the fluidization bin 34 beneath funnel 37 which is provided with apertures 39, so that fluidization air from conduit 29 can reach the downwards flowing material via apertures 39 and fissure 38.

The funnel 37 projects at an edge 41 further 25 inwards than wall 43 of the mixing bin 42 connected thereto. The conduit 28 for secondary air projects with its discharge orifice 81 from wall 43 into the mixing bin 42 for some way inwards up to a certain distance from, and in line with, the entrance 71 of a 30 discharge tube 44, so that the fluidized material which, owing to the edge 41, has extra turbulence, mixed with secondary air 57, is directed into discharge tube 44 in the direction of arrow 46. The entrance 71 projects, relative to wall 43 of mixing 35 bin 42, some way inwards. The discharge tube 44 is connected via a shut-off valve (48) and mixer 47 to a delivery hose 49. In the mixer 47, blow air from the thereto connected blow air conduit 31 is added to the material/air stream, insofar as that is necessary 40 in order to transport the material for a large distance and/or to a considerable height. The air delivered by suction aggregate 18 may be supplied, distributed according to requirements by means of a distribution control valve 45 between fluidization air 45 and secondary air via conduits 29 and 28 respectively to discharge bin 33. With the discharge bin 33 110 of figure 6, even gravel with a grain diameter of 10-60 mm. can be blown onto roofs of a height, for example, of 40 metres. Similarly, garden earth and 50 other material can be blown to distant, high and inaccessible places.

It should be remarked that in each of the conduits 21 and 25, there is a rotatable coupling 50 built in coaxially with the axis 6, and that a detachable tube 55 coupling 51 is built into the conduit 25 in the closure 120 plane of cover 14.

The blower 18 is driven by a motor 54via a belt-drive 52, a propellor shaft 53 and a clutch 55, the motor also being used for propulsion of the tank 60 lorry 1. When material is being blown out of tank 3, the blower 18 is connected to the atmosphere via a conduit 21 and a shut-off valve 56.

For sucking material into tank 3, a strong vacuum is created in the tank 3, preferably up to 98% if 65 necessary, that is, up to 200 mm. water-column equivalent.

The lower space 72 of filter space 10 is connected via a conduit 58 with a shut-off valve (59) to an evacuation chamber 60, which, via an entrance 61 70 provided with a check valve 62, connects at a high level to the storage space 12. The bottom of the evacuation chamber 60 consists of baff le plates 63. The evacuation chamber 60 is arranged in the top of storage space 12, in order that as little material as 75 possible should be sucked into filter space 10. In the filter space 10 there is arranged a multiplicity of adjacent flat suction grids 64, which have external filter bags 65. The cages 64 are largely closed at their tops by injection tubes 66, each of which is 80 connected via a separate valve to an air pressure vessel 68, which forms a pulsed air source. The suction conduit 21 is connected to the upper space 69 of the filter space 10, and thus stands in connection, via fissures 70 on each side of injection 85 tubes 66, with the interiors of cages 64, so that air is sucked out of the lower space 72 of filter space 10, through the filter bags 65, so that any material present in the air is held back. In order to maintain the suction efficiency of blower 18, the filter bags 65 90 are periodically beaten out by means of a control organ 73, through valves 67 each being briefly opened in turn for the injection of a compressed air pulse. The filter bags 65 are then suddenly inflated, and there results a beating effect which causes the 95 filter bags 65to be cleaned.

Owing to the vacuum in the cylindrical tank 3 being very strong, for example stronger than 1 m. water-column equivalent and preferably of the order of magnitude of 200 mm. water-column equivalent, 100 the air which passes through filter bags 65 is very thin, so that this air is easy to filter. Consequently the filter apparatus 4 can be given small dimensions, so that a large cargo space can be built onto tank lorry 1. The compressed air vessel 68, 105 which can also function as a brake-system air tank, is filled with compressed airfrom a compressor 74, driven by a motor 54.

The impeller space 75 of the blower 18 is provided in its circumferential wall on each side of blow air outlet 76 with a slit-shaped, extending principally in the axial direction 89 of the rotor shafts 90, cooling air inlet 77, which is connected to the atmosphere via a branch 88 of a manifold 80, a common cooling air supply 87, a shut-off valve 78 and a silencer 79.

As figure 7 shows, each cooling air inlet 77 is positioned at an angular separation j of approximately 1800 from the air intake 20, whereby it is brought about that the compression space 94 enclosed by the circumferential wall 92 and the two principally cylindrical head of a given impeller 19 remains closed off from the cooling air inlet 77 by the lower head 93, as long as compression space 94 stands in connection with the air intake. In the situation shown in figure 7, the compression space 125 94 is separated from air inlet 20 as well as from cooling air inlet 77 by a narrow gap 97, between each head 93 on the one hand, and the circumferential wall 92 on the other. The heads 93 of the impellers 19 are flattened at the position of gap GB 2 168 759 A 3 97toa radius r, which is greater than the main radius q of the principally cylindrical impeller heads 93. In the situation of figure 3, owing to the vacuum 50 predominating in the impulsion space 75, 5 atmospheric air is drawn in, and thus cools the blower 18 in a simple and effective way, such that this can be made with precision. Excessive expansion of the impellers 19, which would lead to their seizing, is avoided by cooling them. The.. 55 10 blower 18 can consequently work efficiently at various and high rotation speeds.

Figure 5 shows a manifold 80 for connection of the silencer 79 to the two inlets 77 on either side of the blow air outlet 76. Through the strong vacuum, 60 15 many different kinds of material, dry as well as wet substances and even gravel, sludge or stones can be sucked up. Discharging of the materials sucked up and transported by tank lorry 1 can take place, as well as by tipping, also, with cover 14 opened, by 20 blowing out, for which tank 3 is usually also tilted around axis 6. The top of the collecting space 12 of tank 3 does not have to be provided an air supply.

During discharging, the air and material stream is as indicated by arrows in figure 4. The material which 70 25 is retained by filter bags 65 during sucking up arrives in storage space 84 of the filter apparatus 4, and when tank 3 is tilted it falls through a check valve 85 into the storage space 12.

The pneumatic transporting apparatus according 30 to the invention is also applicable, for example, as a street sweeping machine, this being embodied as a dust aspirator with a roller brush.

Furthermore, the pneumatic transporting apparatus can be built, besides into a tank lorry, into 80 35 a transshipment plant, material being sucked up, for example, from a ship's hold and transported into a fixed or a mobile tank, in the case of a fixed tank the material subsequently being discharged by transportation of the material into another ship's 85 40 hold, or into a vehicle.

It should be noted that for a tank lorry, a hose of to 15 cm. diameter is usable, considerable lengths of stich a hose being easily conveyed with a tank lorry,12,Xhis narrow hose diameter is a 90 45 consequ6 of the powerful vacuum orthe high degree of compression which is realized with blower 18, whereby clumsy and heavy hoses with large diameters are avoided. After all, an adequate transportation velocity can be realized in the narrow hose.

Claims (7)

1. Pneumatic transporting apparatus comprising a chassis, at least one tank and suction aggregate means connected to the tank via filter apparatus, the suction means taking the form of at least one blower with figure-of-eight shaped impellers which are rotatablyjournalled in a blower housing the blower being equipped with at least one air inlet, wherein the compression space of the blower is equipped on each side of an air outlet with a cooling air inlet extending predominantly in the axial direction in the circumferential wall of the blower housing, and that each slit-shaped cooling air inlet is arranged at an angular separation of approximately 180'from the 65 airinlet.

2. Pneumatic transporting apparatus according to claim 1, wherein the filter apparatus is equipped with filter bags, each of which is connected to a pulsed air supply.

3. Pneumatic transporting apparatus according to claim 1 or 2, wherein the apparatus is embodied as a tank lorry comprising a vehicle chassis which carried the tank and also the suction aggregate.

4. Pneumatic transporting appara..js according to 75 claim 3, wherein the tank is tiltable in relation to the rear end of the chassis and is equippe-A with a discharging cover at its rear end.

5. Pneumatic transporting apparatus according to any one of the preceding claims, wherein the compression side of the blower is connected to at least one discharge funnel of the tank and the discharge funnel is connected to a material outflow conduit.

6. Pneumatic transporting apparatus according to any one of the preceding claims, wherein the cooling air inlets are connected via a manifold to a common cooling air supply, the branches of the manifold having a volume which is at least of the order of magnitude of one and a half times the volume of the compression chamber of the blower.

7. Apparatus substantially as described with reference to, and as illustrated in, any one or more of the Figures of the accompanying drawings.

Printed for Her Majesty's Stationery Office by Courier Press, Leamington Spa. 6/1986. Demand No. 8817356.

Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.