IL45196A - Work cabin for unhealthy environments - Google Patents

Description

The present invention relates to a safety enclosure or work cabin for use in unhealthy or otherwise harmful environments, which is primarily intended to provide protection against polluted air, e.g. air containing stone dust, but which is also intended to provide protection against vibration and high noise levels, as well as unfavourable climatic conditions. . The work cabin according to the present invention obviously is eminently suitable as a working or operating position, e.g. at a crushing plant for stone or other materials 0 Work cabins in the form of cubicles for these and similar purposes are already known, the walls, ceiling and floos' of the cubicle being made from sound-absorbing materials and the work cabin incorporating an air filter in combination with a fan for ensuring a fresh air supply to the cabin. The purified air supplied is discharged from the cabin through a vent to the surrounding air outside. This known type of work cabin suffers from significant disadvantages, however. For exam lee a relatively large flow of air through the air filter is necessary which results in rapid contamination and stoppage of the air filter, as well as high air circulation with consequent draughts in the cabin. Temperature regulation of the air supply is . : difficult to achieve in a satisfactory way and entails great energy consumption. Furthermore, the degree to which the air supply is purified is often insufficient. An additional disadvantage is that the sound-absorbing effect is often- limited Another desirable feature, namely a vibration-reducing effect, has also not been met, which means that the operator located in the cabin is subjected to harmful vibrations from machines,, crushers or other vibration-producing units located nearby.

V7ith a work cabin according to the present invention^ all of the above-mentioned disadvantages of previously known types of cabins are overcome. Furthermore/ additional advantages are gained, as outlined in the following description of an embodiment of a cabin according to the present invention.

According to the present invention, a work cabin comprises inner and outer enclosures separated from one another by means of an air space substantially surrounding the inner enclosure and connected to it by means of one or more inlets, a fan unit with at least two separate air filter elements serving to supply purified air to the inner enclosure via the air space and the inlets, the air being returned through an outlet unit to a point between the two filter elements.

Preferably, the inner enclosure is separated from and supported by the outer enclosure by means of vibration-reducing elements made of an elastic material. ~ .... r,„ ... . :.. ,·. ..... , ·...

In accordance with a preferred embodiment of the. invention, the work cabin according to the present invention is provided with a unit for regulating the circulation area at the inlets and/or outlets of the inner enclosure. It is also especially preferable for the inside of the outer enclosure to be covered with a sound and heat insulating material. In addition to this, a further desirable feature is for the inner enclosure to be connected to the atmosphere surrounding the outer enclosure by means of a ventilation unit, which is arranged to open when the pressure inside the inner enclosure exceeds the normal working pressure.

In order that the work cabin or safety cubicle according to the present invention may be fully appreciated, a preferred embodiment thereof is more fully described below with reference to the accompanying drawings , wherein; Fig. 1 shows a diagrammatic cross-section of one form of work cabin according to the present invention? Fig. 2 shows a perspective view of a work cabin according to the present invention; Fig. 3 shows in cross-section a part of the lower portion of the work cabin „ fastened to a foundation! Fig. 4 shows a part-sectional perspective view of the work cabin according to the present invention, including an operating or control panel.

In the drawings, the work cabin comprises an outer cubicle-like section or enclosure 1 which encloses a second, inner cubicle-like section or enclosure 2. These enclosures 1 and 2 are separated from one another substantially completely on all sides by a surrounding air space 3. The enclosures 1 and 2 are desirably of parallelipiped shape and the air space 3 not only separates them at the four sides, but also on top and underneath the inner enclosure 2. As a separating unit between these outer and inner enclosures 1 and 2, a number of elements 4 4° of vibration-absorbing material are utilized- These elements support the inner cubicle-like enclosure 2 as shown in the drawings, but elements with equivalent properties are also desirably located between the vertical walls of the enclosures 1 and 2, e.g. at the outer and inner openings' provided for a door 5, where the vibration-absorbing elements are also utilized as sealing elements.

In the embodiment shown, a fan unit 6 is placed between two air filters 7, 7' in an air inlet unit located on top of the outer cubicle-like enclosure 1. An outlet member 8 of flexible or bellows-like type connects the top of the inner enclosure 2 with a point in the air inlet unit situated between the two air filters 7,7'. The outlet member 8 has associated with it a unit 9 for effecting variation of the circulation area of the outlet member 8. Two inlets 10,10" (Fig. 1) are arranged-adjacent the floor in the side walls of the inner enclosure 2.

These inlets 10,10" connect the inner enclosure 2 with the surrounding air space 3. In order to allow adjustment 2 with the surrounding air space 3. In order to allow adjustment of the air flow through the inner enclosure 2, a unit 11 is provided for adjusting the circulation area of the outlet member 8, in the embodiment shown. This unit 11, in its simplest form, can consist of a disc valve of known type, which can move axially in relation to the outlet member 8. Naturally, control of the air circulation can also be achieved at the inlets 10,10" <, In order to allow control of the air pressure in the inner enclosure 2, an air pressure indicator 12 is arranged in the inner enclosure 2. A ventilation unit 13 serves to connect the: inner enclosure 2 with the surrounding atmosphere and is arranged to open when the pressure exceeds normal working pressure,? e0g0 when the door of the work cabin is closed,, At this pointy a significant rise in pressure takes place, which is adjusted by the aforesaid ventilation unit 13 ■> In order to allow for temperature regulation of the work cabin and the inside air, both cooling and heating units are arranged An encased cooling unit 14 is located adjacent the work cabin and is connected with the surrounding atmosphere by means of an air filter 15. A cooling coil 16 is connected to the cooling unit 14 and also with a fan 17 located within the upper part of the inner enclosure 2» Heating of the circulating air can be carried out either by applying electrically-heatable material to all or part of the inside wall surfaces of the outer enclosure 1 or by placing electric radiators against the inner walls of the inner enclosure 2. In order to further insulate the inner enclosure 2 frorphoise as well as from the ambient temperature, a sound and heat insulating material 18 of known type is applied to the inner surfaces of the outer enclosure 1. The embodiment shown also includes a window area 19 , which is arranged to incline upwards and outwards.

The work cabin according to the present invention shown in the drawings has significant advantages over earlier known types of work cabins .

By constituting the cabin from two inter-nested enclosures 1 and 2, separated from each other by means of the air column or space 3, significantly improved thermal insulation is achieved, in addition to improved sound insulation. As an example, a noise level of 82 dB outside the cabin results in a reduction to 46 - 48 dB with the fan unit 6 not in operation. This noise level naturally increases if the fan unit 6 is in operation, in which case the noise level reaches up to 60 dB, which means that a reduction of 22 dB is achieved.

One advantage of the recirculation system according to the present invention is that the circulating air speed can be kept low, without neglecting the degree of purity. As a typical example, with the measuring point in the centre of the inner enclosure 2, the following values were obtained.

Without cooling fan: 0.15 m/s With cooling fan; 0.35 m/s These values of the circulating air speed entail no undesirable consequences in the form of draughts as in earlier known types of work cabins.

In the work cabin, the air pressure indicato 12 serves two purposes. Firstly, it allows adjustment to a suitable working pressure and also indicates when a change of filter should take place. For this, 1.5 mm water column can be taken as a suitable limit.

The most important advantage of the air recirculation system described is the higher degree of purity which is achieved in combination with a significantly increased useful life for the air filters 7,7° „ In order to further illustrate the high purifying effect which is achieved with a ventilation system arranged for a work cabin according to the present invention, the values shown below have been measured.

The measurement interval was 1.3 minutes.

Number of particles per 3 1 air (particle size in μ) 0.3 - 0.5 0.5 - 1 1 - 10 10 6693 3210 2280 14 2548 1452 1054 0 1047 642 449 0 552 376 254 0 254 146 103 0 154 103 59 0 73 47 40 0 47 27 24 0 25 21 8 0 15 13 8 0 8 7 2 0 Class 100 3 3 1 0 tt 4 2 2 0 1 1 2 0 From the table above, it is clear that the work cabin cording to the present invention in a period of 10 - 15 minutes reaches a degree of purity equivalent to or exceeding purity class 100, which corresponds to the purity requirements needed for bacteriological work. Comparable results are entirely out of the realms of possibility for earlier known types of work cabins As shown in Fig. 4, the work cabin according to the present invention can be equipped with a control panel 21 from which an operator can operate machines, etc., located outside the cabin. For the purpose of improving the operator's visual contact with such machines, the cabin according to the present invention is provided with a glass window 19 inclined upwards and outwards. Visual control is significantly improved and reflections in the glass surface 19 are avoided.

Because the inner enclosure 2 is connected to the outer enclosure 1 by means of the vibration-reducing elements 4,4s, the transmission of unhealthy vibrations to the operator is avoided. This effect is further increased by arranging for the outer enclosure 1 to be supported by vibration-reducing elements 20,20'.

The work cabin according to the present invention is well suited in every way to use in environments in which there is not now any satisfactory protection. Because it is designed as a mobile unit, great advantages are also gained. The cooling section 14 of the work cabin is protected in a particularly satisfactory way by the encasement and the only contact with the surrounding atmosphere takes place through the air filter 15.

It should also be emphasized that the construction according to the present invention results in a thermal insulation from the surrounding atmosphere by means of the insulating materia 18 in combination with the air column 3„ The air inside the inner enclosure 2 can be ke t at any desired temperature with a minimum of extra' energ , regardless of the air temperature in the atmosphere surrounding the cabin. This is enhanced by the fact that a large portion of the air is recirculated in the system and thus temperature compensation is^ to a greater extent, not required.

Claims (1)

1. Appln.No. 45196/2 C L A&,I M S ¾i. 1 · A work cabin £o use in unhealthy environments comprising: tvo cabin-shaped containers comprising an inner container positioned within an outer container and spaced therefrom to form an air space surrounding said inner container, at least one inlet connecting said air space with the space contained by the inner container; fan means with at least tvo air filter means spaced from each other; outside air inlet means positioned on the upstream side of a first filter means; outlet means on the downstream side of a to second filter connecting said air space; a second outlet means for exhausting the air from said space in the inner container to a plenum between the downstream side of the first filter means and the upstream side of the second filter means; and \ a number of vibration-absorbing elements made of elastic material separating said inner and outer containers, 2, The work cabin according to claim 1 comprising further means for regulation of the circulation positioned at the second outlet means* 3· The work cabin according to claim 1 wherein the inside surface of the outer container is covered with a sound and heat insulating matefclal* 4· The work cabin according to claim 1 wherein the inner container is connected to the atmosphere surrounding the outer container by means of ventilation means arranged to open when the pressure in the space contained by the inner container exeeeds normal working pressure. Appln.No. 45196/2 5* The work cabin according to claim 1 means for indication of the inside air pressure is positioned in the inner container* 6, The work cabin according to claim 1 wherein said at least one inlet is arranged adjacent to the floor level* 7. The work cabin according to claim t vherein the outer container is supported by further vibration-absorbing elements made of elastic material* 8* The work cabin according to claim 1 vherein the air pressure inside said spaee contained by the inner container exceeds the surrounding atmospheric pressure* 9. The work cabin according to claim 1 vherein at least one window area with the surface inclined upwards and outwards is arranged in one of the walls* 10* The work cabin according to claim f wherein there is a third outlet means connecting said spaee contained by the inner container to the surrounding atmosphere, which outlet means functions when the pressure in Slid spaee reaches a predetermined level above atmospheric pressure·,