GB2169192A

GB2169192A - Compressed air powered suction unit

Info

Publication number: GB2169192A
Application number: GB08519755A
Authority: GB
Inventors: James David Coleman; Anthony Gregory Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-27
Filing date: 1985-08-06
Publication date: 1986-07-09
Also published as: GB8516264D0; GB2169192B; GB8519755D0

Abstract

A unit uses compressed air to produce a suction force. This force can be applied in a portable manner either directly from the unit, or with the unit as part of a larger system, to remove materials and transport them to a preferred location. A Coanda surface 3 and divergent section 4 are used to enhance entrainment into a primary flow of compressed air from the peripheral nozzle 10. The flow of compressed air is controlled by a manually- operated valve 7. The overall flow results in suction at the unit inlet 2. The suction is applied to materials which are transported through the unit body and via the pipe 11 to a preferred location. The unit can easily be adapted for use as a portable blow gun which produces a high mass flow, low pressure jet. <IMAGE>

Description

SPECIFICATION Compressed air powered suction unit This invention relates to the use of a conventional compressed air supply to produce a suction force.

Many work places are equipped with a compressed air supply which may be employed in a variety of ways. Typical uses include small hand drills, rivet guns and blow guns. Blow guns are used in manufacturing processes to clear metal shavings or swarf from work pieces and machinery, but they do have a number of disadvantages. It has been found that guns of this kind can be dangerous, for if the outlet nozzle contacts the operatives skin when the gun is "on" then high pressure air may penetrate the skin. In addition, the swarf that is blown away has a haphazard trajectory and may prove dangerous to other operatives or machinery.

Furthermore this waste has to be removed at a later stage either by hand or by electrical vacuum cleaners. Removal by hand is both inefficient and hazardous. Work places often offer a hostile environment to electrical equipment; cables may be cut or tripped over, liquids may cause shorting and even electrocution. The need therefore arises for a device which may be operated from a compressed air line, to replace electrical vacuum cleaners, hand removal methods, and in many cases the dangerous direct use of a compressed air line to blow away material. An advantage of sucking away unwanted material is that it may then be transported to a preferred location ready for further treatment, thereby improving manufacturing efficiency.

Pumps using compressed air as the motive force are already widely used. Those based on the principle of entrainment into a Coanda jet are particularly efficient. In such pumps the high pressure air is caused to follow a wall thereby inducing a secondary mass flow. Uses for which Patents already exist include furnace air movers.

The present invention provides a unit incorporating a nozzle which outlets a primary flow of air from a compressed air supply. This flow entrains neighbouring air thus producing suction upstream of the nozzle exit plane. This suction can then be utilised for the purpose of pumping materials whether gaseous, liquid, solid or any combination thereof. A typical example is the removal of machining waste, such as swarf, and coolant. The unit is completely isolated from any electrical supply, therefore the pumping of liquids does not involve associated safety hazards. As the purpose of the unit is not only to remove materials but also to transport them in a controlled manner, it is inevitable that the unit will be incorporated into some type of removal and collection system. It is therefore necessary to describe the possible ways in which this may be achieved.

Primarily it is envisaged that the unit will be used directly on the end of a compressed air line in a manner similar to the blow guns referred to above.

In this configuration the suction can be applied in a particularly portable way. It is anticipated that suitable pipework will be fitted to the unit outlet for the transportation of the removed materials to a preferred location for collection and treatment. An advantage of this configuration is that the materials that have been removed are then blown, rather then sucked, to the preferred location: this prevents pipework collapse and reduces the possibility of blockage. Three examples of collected material treatment are the removal of swarf from the air flow, the separation of swarf from coolant and the complex handling of asbestos dust with filtering to appropriate safety standards.

In this simple configuration the unit may be fitted with adaptors enabling suction to be applied in difficult location. For example a tapered nozzle may be fitted to the unit, allowing access to restricted areas. This not only reduces the effective inlet area but also creates a potential for increased suction.

Further adaptors could take the form of brushes, extension pipes, scraping devices or any combination thereof.

In all of the above configurations it is intended that the unit be hand-held whilst in operation.

However, in some cases it may be more convenient to mount the unit away from the point of application of the suction force. For example the unit can be used when it is attached by some method to a machine tool body. In this case a flexible tube can be fixed to the unit inlet. The tube itself can then be used to apply the suction force in a portable manner. The outlet pipe can be fitted to a receptacle suited to the materials being collected. In a further example the unit can be mounted on, or within the receptacle. The mode of operation would then become comparable with that of a conventional electrical vacuum cleaner.

Should the desired destination be situated at some distance from the unit, causing an excessive outlet pipe length, one or more further units can then be fitted in series with the first. This will enable suction and transportation forces to be maintained throughout the system.

Although the important feature of the unit is the ability to remove materials by the application of a suction force, the unit can very easily be used as a blow gun if so desired. This can be achieved by decoupling the unit from the removal and collection system and turning the unit so that the outlet now faces the point of application. In this mode a high mass flow rate, low pressure jet is created. The blow gun thus formed has several advantages over more conventional types. For example if the outlet becomes blocked, then the airflow is reversed and can exit through the unit inlet. The blow gun is therefore safe even if the operator's hand blocks the outlet. High pressure air can not build up within the unit and penetrate the skin.

One presently preferred construction according to the invention is more particularly described with reference to the accompanying drawing wherein: Figure 1 is a sectional elevation of a suction unit.

Referring now to the drawing, Figure 1, a section is shown of an axisymmetric version of the unit which comprises four main parts; these being the inlet chamber body 1, the unit inlet 2, the Coanda surface 3, and the divergent section 4. The inlet chamber body 1 is attached to the divergent section 4 via an interference fit at 5 which provides sealing.

The Coanda surface 3 is also attached to the divergent section 4 by an interference fit. The advantage of producing the Coanda surface and divergent section in separate pieces is that different Coanda surface shapes can be used without reproducing the divergent section. The interference fits may be secured positively although to date this has not proved necessary. The unit inlet is secured via the screw thread on its inner surface which mates with a corresponding thread on the inlet chamber body. This method of attachment also enables the size of the nozzle exit to be altered as required. The inlet chamber 6 of the unit is supplied with compressed air from a manually-operated control valve 7. This air then passes via the passages 8 into the nozzle supply chamber 9, and exits through the annular nozzle 10 which is formed by the unit inlet 2 and the top of the Coanda surface 3.The nozzle exit surfaces are angled at slightly less than 90 degrees to the unit axis. The compressed air, which may also be referred to as the primary flow, forms a jet which attaches to the Coanda surface 3. In following this surface the jet entrains a secondary flow. The primary and secondary flows continue to mix in the divergent section 4 before entering a pipe 11. This resultant flow produces suction atthe unitinlet2which enables the unitto remove material in its vicinity. This material is then carried by the flow of airthrough the unit body into the pipe 11 and thence to a preferred location. The facility of controlling the nozzle size as detailed above allows the efficiency of the unit to be precisely controlled and optimised. This allows the suction force to be infinitely controllable within a given range.

Various modifications may be made within the scope of this invention. For example the unit may be of a rectangular section; the number of parts used may be reduced, perhaps by casting; the unit may have different primary flow inlet control devices; the nozzle angular position relative to the body axis may be varied; the unit inlet and Coanda surface shapes may be varied in order to optimise performance.

Claims

1. A unit which uses compressed air to produce a suction force, said unit having means by which said suction can be applied in a portable manner at any location for the purpose of removing materials whether gaseous, liquid, solid or any combination thereof, from said location and transporting them to a preferred location.

2. A unit according to claim 1 comprising a means of coupling said unit to a compressed air supply, a valve for controlling said supply to a nozzle which provides an exit for said air and in so doing creates a primary jet, said jet entraining and mixing with a secondary flow during its subsequent motion, an inlet upstream of said nozzle to admit said secondary flow and to expose it to said primary jet, said flow resulting in suction at said unit inlet for the purpose described in claim 1, and an outlet to allow the mixed flows and any collected materials to leave the unit.

3. A unit according to claim 1 or claim 2 which can accept at its inlet attachments taking the form of plain extension pipes, flexible pipes, tapered nozzles, brushes, scraping devices, or any combination thereof, to aid its effectiveness for removing materials and to enable suction to be applied remotely from the main unit body.

4. A unit according to claims 1, 2, or 3 which is always portable whether or not it is in operation.

5. A unit according to claims 1, 2 or 3 which makes use of inlet attachments so that it does not need to be portable when in operation and may, if so desired, be secured at a particular location.

6. A unit according to claims 1,2,3,4 or 5 wherein the unit outlet is connected to ducting, a recepticle or recepticles, or any combination thereof.

7. A unit according to any of the preceding claims, which has more than one exit for the compressed air supply and which therefore forms more than one primary jet.

8. A unit according to any of the preceding claims, wherein the body is an annulus.

(c) Claims 12-17 and 1921 above have been renumbered as 9--14 and 1517 respectively and their appendancies corrected.

8. A unit according to any of the preceding claims, wherein the body is an annulus such that the nozzle is formed on the inner surface of said body, said nozzle producing an internally peripheral primary jet which entrains and mixes with a secondary flow through said annulus.

9. A unit according to any of the preceding claims, wherein a Coanda surface or surfaces are used in orderto enhance the entrainment.

10. A unit according to any of the preceding claims, which has a Venturi downstream of the primary flow outlet.

11. A unit according to any of the preceding claims, which has a divergence downstream of the primary flow outlet.

12. A unit according to any of the preceding claims, wherein the body is again hollow but which may be of any cross section.

13. A unit according to any of the preceding claims, wherein the nozzle size and shape may be altered and optimised.

14. A unit according to any of the preceding claims, wherein the nozzle area to unit inlet area ratio may be varied and optimised.

15. A unit according to any of the preceding claims, wherein there exists means for producing a uniform peripheral jet from any supply geometry.

16. A unit according to any of the preceding claims, wherein the control valve may be built into the unit body.

17. A unit according to any of the preceding claims, wherein the control valve may be remote from the unit body.

18. A hand-held unit of similar operation to a compressed air blow gun, whereby materials are not blown away haphazardly but are removed by a suction force created by said unit and transported to a specific location.

19. A unit according to any of the preceding claims which forms an integral part of a material removal and collection system.

20. A unit according to any of the preceding claims which can be decoupled from any material collection system, of which it is a part, and used for the same purposes as a conventional blow gun but being one that produces a high mass flow, low pressure jet.

21. A compressed air powered suction unit substantially as hereinbefore described with reference to and as shown by the accompanying drawing.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1,2, S11 and 18 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows:

1. A compressed air powered suction unit comprising a hollow body, a nozzle on the inner surface of said body in order to produce an internally peripheral primary jet from a supply of compressed air, a Coanda surface immediately leading to a divergence, such that said primary jet flows through said body over both said surfaces according to the Coanda effect to produce a secondary flow and a suction, said unit possessing means by which said suction can be applied in a portable manner at any location for the purpose of removing materials whether solid, liquid, gas or any combination thereof, from said location and transporting them to a preferred location.

2. A unit according to claim 1 comprising a means of coupling said unit to a compressed air supply, a value for controlling said supply to said nozzle, an inlet upstream of said nozzle to admit said secondary flow and to expose it to the primary jet, said flow resulting in suction at the unit inlet for the purpose described in claim 1.