WO2005005925A1

WO2005005925A1 - Spirit level

Info

Publication number: WO2005005925A1
Application number: PCT/GB2004/002952
Authority: WO
Inventors: Michael Keith Ching
Original assignee: Michael Keith Ching
Priority date: 2003-07-08
Filing date: 2004-07-08
Publication date: 2005-01-20

Abstract

A magnetic spirit level includes a housing (3) within which is mounted at least one level indicating means (5,7). Mounted within the housing is at least one magnet (27,29), all the surfaces of the or each magnet being surrounded by the housing or other securing means. Also provided is a magnetic spirit level having at least one magnet (27,29) mounted in or on the housing (3). Indication means (47) are operatively connected to the at least one magnet of the level and switching means (41) are connected in turn to the illumination means.

Description

SPIRIT LEVEL

Field of the invention

This invention relates to spirit levels in particular spirit levels incorporating magnets which are extensively used within, for instance, the scaffolding and steel industries.

Background to the invention

So called magnetic spirit levels enable the level to be attached magnetically to an appropriate surface. A particular use of such magnetic levels is in the scaffolding and steel industries. Scaffolders, for instance, need to check that their scaffolding poles are accurately aligned either horizontally or vertically.

In practice, a scaffolder carries his spirit level in a pouch on his belt. When checking the alignment of a scaffolding pole he will take the level from the belt and apply it to the metal tube. He will normally automatically let go of the level expecting it to remain in place due to the magnetic attraction between the level and the tube.

Known magnetic spirit levels have magnets glued into the base of the level with one surface of the magnet exposed to the exterior. Not infrequently, the magnets can be incorrectly fitted so that they stand proud of the exterior surface of the housing of the level and render the instrument inaccurate. Furthermore, one or more of the magnets of a known spirit level may fall out thereby reducing the magnetic effect of the level. If the scaffolder then follows his normal procedure of applying the magnet to a pole and automatically letting go, the level will fall from the pole and drop to the ground below. This is potentially dangerous. If the falling level should hit an unprotected person below, serious head injuries or even death could result. Furthermore, there is often a problem with the use of spirit levels in poor lighting conditions in that they cannot easily be "read" and/or it is easy to leave a spirit level in position, particularly in poor light conditions.

Statements of the invention

According to the present invention there is provided a magnetic spirit level comprising a housing within which is mounted at least one level indicating means and at least one magnet, all the surfaces of the or each magnet being surrounded by the housing or other securing means.

The magnets located within the housing may be any suitable magnets including traditional ferrite magnets. However, preferably they are rare earth magnets, in particular relatively powerful rare earth magnets. The magnets are positioned within the housing of the spirit level such that the "magnetic pull" is exerted through the wall of the housing.

The housing may be in the form of a metal casting or plastic moulding or may be made by any suitable process out of any suitable material.

Preferably the or each level indicating means is in the form of a phial containing liquid and providing a bubble which gives a visual indication of the alignment of the level. Normally the phial includes markings between which the bubble is position when the alignment is correct. Preferably the level is provided which two such phials, one for indicating horizontal alignment and the other for indicating vertical alignment.

Preferably the or each magnet is located within a recess which extends from an upper surface of the level to a position within the housing adjacent that surface of the level which, in use, contacts the surface whose alignment is to be determined. More preferably the recess extends to a position below a level indicating means, typically, in the form of a phial and positioned to take horizontal level readings.

Preferably the or each magnet is secured within the recess by means of an appropriate adhesive compound applied at least above the magnet to prevent movement of the magnet out of the recess.

In another aspect, the present invention also provides a magnetic spirit level in which the level includes illumination means and, operatively connected to at least one magnet of the level, switching means connected in turn to the illumination means.

In an alternative embodiment in accordance with this aspect of the invention, the illumination means is replaced by noise generating means. The level may, of course, include both illumination means and noise generating means.

Preferably, the level has one or more magnets located entirely within the housing of the level. The level may be such that at least one magnet, which attracts the level to a metallic surface such as that provided by a scaffolding pole also includes a switch which, when operated by the magnet, switches on illumination to one or more phials in the level. The resultant illumination makes it relatively easy to read the level in dim or even dark conditions.

The same switching mechanism may also be used in connection with additional or alternative features of the device, for instance:

(1 ) an electronic levelling feature making use of neon lights or an audible sound generator signifying if the instrument is level or out of level.

(2) an electronic device that signifies whether the level is in use, that is to say, it has magnetic contact, or has been in use, that is to say, using a time delay switch to release an audible signal (for instance a bleep or a tune) to warn the user that he has left the instrument in place. It is a common problem of a magnetic level that it gets forgotten i.e. left attached to a scaffold tube, necessitating a long climb by the user to retrieve it.

A spirit level in accordance with the second aspect of the present invention may provide one or more of the following features:

(a) automatic illumination in dim conditions;

(b) An audible warning device which sounds after an adjustable or predetermined length of time to remind the user that it is still attached to a metal surface;

(c) concealed batteries which are recharged via a solar cell (photovoltaic cell) mounted directly below the phial or at some other appropriate position within the instrument.

(d) coloured (red/green) neon lights displayed when the level is in contact with a metal surface. For instance a green light may show that the instrument is level and a red light warning that it is out of level. This feature could be switched off or switched to an audible signal arrangement that indicates level or otherwise.

Description of the drawings

The accompanying drawings are as follows:

Figure 1 is a side view of a spirit level in accordance to the present invention; Figure 2 shows underneath views of three spirit levels, A and B being prior art levels and C being in accordance with the present invention;

Figure 3 is a diagrammatic side view of the level of figure 1 showing that part of the interior where the magnets are accommodated;

Figure 4 is a top view of the level of figure 1 as depicted in figure 3; and Figure 5 illustrates a spirit level in accordance with the second aspect of the present invention.

Detailed description of the invention

The invention will now be described, by way of example only, and with reference to the accompanying drawings.

Referring to figure 1 of the accompanying drawings, a spirit level 1 includes a cast metal housing 3 within which is accommodated level indicating means 5, 7 each in the form of a phial of a liquid such as an oil and including a bubble whose position indicates the extend of alignment of the level. Each phial 5, 7 is provided with a pair of indicating lines and it is the location of the bubble between the pair of lines which indicates the appropriate alignment.

Phial 5 is used when vertical alignment is being determined and phial 7 is used when horizontal alignment is being determined.

In another embodiment, a different level indicator might be employed, for instance, an electronic device.

The level has a flat base 9 which is precision ground to provide an appropriate working edge which is laid against the surface whose alignment is being determined. The phials 5, 7 are located within a central region of the level 1, the length of the level being extended by wing portions 11, 13. One of the wing portions 13 is provided with a hole which enables the level to be attached to a lanyard.

The overall length of the level is about 250 mm although in other embodiments the level may be either shorter or longer. Referring to figure 2 of the accompanying drawings, the basis of 3 levels, A, B and C are illustrated.

Levels A and B are prior art levels which are fitted with disc-like magnets set into recesses in the base of the level. Accordingly one end surface the magnets is exposed on the exterior surface of the base of the level.

Level A is fitted with two relatively powerful rare earth magnets 21 whereas level B is fitted with four more traditional ferrite magnets 23. The exposed surfaces of the magnets 21 and 23 are intended to be flush with the base of the levels A and B respectively. In practice this does not always happen and any protrusion of the base of the magnets causes an unevenness of the base of the level thereby rendering inaccuracy in the level readings. Furthermore one or more magnets can become loosened within its recess and then drop out of the level.

This may not be appreciated by the user of the level who then assumes that the level will magnetically adhere to, for instance, a scaffolding pole as it is intended to do.

The loss of a magnet may be sufficient to render the level incapable of adhering to the scaffolding pole and it may therefore drop to the ground, inflicting injury on any person standing below.

As can be seen in 2, level C does not have any exposed magnets. Level C, which is the level depicted in figure 1, is also shown, diagrammatically, in figures 3 and 4. These figures show the level 1 in outline but also show the interior of the level at least as far as the accommodation of the magnets is concerned.

A recess or aperture 25 is formed in the body 3 of the level before the phial 7 is located in the level. Recess 25 extends from the upper surface of the level to a position just above the base 9 so that in this case the body thickness between the bottom of the recess and the base 9 is about 1.5 mm. In other cases the thickness is determined according to the strength of the magnets as well as the extents of magnetic pull that the level is to posses.

Once the recess 25 has been formed two disc-like rare earth magnets 27, 29 are located at the bottom of the recess. As illustrated, they are separated within the recess and are held in position by means of adhesive compound 31 which extends between the magnets and above them.

Once the magnets have been position as described above, the phial 7 is located in place as illustrated in figure 1.

As a result of the positioning of the magnets within the body of the spirit level, there is no danger that they will interfere with the correct level indicating of the device. Furthermore, there is also no danger that one or both of the magnets will fall out of the level since they are held firmly in place by the body of the level which extends around the bottom and sides of the magnets and also the adhesive compound 31 which securely holds the magnets in position. Even if the adhesive compound 31 were to deteriorate sufficiently that the magnets were no longer held in place thereby, they would not be able to fall out of the level due to the location of the phial 7 hindering any such movement of the magnet.

Referring to Figure 5 of the accompanying drawings, a spirit level is provided with internal magnets as described above and as illustrated in, for instance, Figure 3. However, in this case a compressible switch 41 is located below at least one magnet 43 within an internal aperture 45 which houses the magnets and switches. Aperture 45 is, in effect, a void within the body of the instrument in which batteries and other electronics are housed and which provide the illumination feature described above or indeed other additional or alternative features such as a sound generating arrangement. The switch is arranged so that electrical contact is only made when it is compressed by the magnet moving under a magnetic attraction force towards the metal surface on which the instrument has been placed. Electronic circuitry interconnects the switch 41 with a low voltage bulb, or series of bulbs 47 which illuminate the phial 49. Located against a second phial 51 is a solar (photovoltaic) cell 53 which provides electric current to the bulb or bulbs.

Claims

1. A magnetic spirit level comprising a housing within which is mounted at least one level indicating means and at least one magnet, all the surfaces of the or each magnet being surrounded by the housing or other securing means.

2. A spirit level according to Claim 1, wherein the or each magnet is a rare earth magnet.

3. A spirit level according to Claim 1 or Claim 2, wherein the or each magnet is located within a recess which extends from an upper surface of a level to a position within the housing adjacent that surface of the level which, in use, contacts the surface whose alignment is to be determined.

4. A spirit level according to Claim 3, wherein the recess extends to a position below a level indicating means. „

5. A spirit level according to any of the preceding claims, wherein the at least one level indicating means is in the form of a file containing liquid and providing a bubble which gives a visual indication of the alignment of the level.

6. A spirit level according to any of the preceding claims, wherein the or each magnet is secured within a respective recess by means of an appropriate adhesive compound applied at least above the magnet to prevent movement of the magnet out of the recess.

7. A spirit level according to any of the preceding claims and including indication means operatively connected to at least one magnet of the level, and switching means comiected in turn to the illumination means. ,,

8. A magnetic spirit level comprising a housing within which is mounted at least one level indicating means, at least one magnet mounted in or on said housing, indication means operatively connected to at least one magnet of the level, and switching means connected in turn to the illumination means.

9. A spirit level according to Claim 8, wherein the indication means is illumination means or noise generating means.