Link mechanism for a visor
The present invention relates to a link mechanism for a visor, comprising a lin arm which, at a first end, is connected in an articulated manner to the visor and, at a second end, is connected in an articulated manner to an item of headgear.
During working in an aggressive environment, such as welding and grinding, use is made of a visor worn in front of the face of the welder or grinder. The visor can be raised and lowered in front of the face by virtue of the fact that the visor is connected via an articulation to an item of headgear, such as a helmet or a head frame made from bands. The operator, that is to say the welder or the grinder, can then raise the visor between welding and grinding operations. It is desirable that the operator be able to wear ear protectors when the visor is in the raised and the lowered position.
From the final report of the STU [National Board for Technical Development] 72-1041/U849 , 73-5820 a + b, 75- 5325, it is previously known to arrange a welding visor on a protective helmet. The visor is connected to the helmet by means of a link mechanism comprising a link arm which, at a first end, is connected in an articulated manner to the visor at a fastening point arranged below a window and, at a second end, is connected in an articulated manner to the front edge of the helmet .
The link arm has a spring which, by means of the spring force, fixes the visor in, on the one hand, the lowered position and, on the other hand, the raised position. The helmet is provided with ear protectors which are arranged pivotably about a fastening point located in the rear region of the helmet .
As the fastening point of the first end of the link arm
is located below the window and thus below the field of vision of the operator, the link arm falls within the field of vision of the operator in the lowered position of the visor, which is an irritating experience for the operator.
When the visor is to be raised, the visor will, on account of the fastening point of the link arm, follow a path that runs a long way in front of the helmet, which gives rise to torque forces that give the operator the sensation that the helmet is going to fall off his head.
When the visor is raised and lowered, the spring force must be overcome, which also gives rise to torque forces which act on the helmet. The operator also has to brake the visor when it approaches the raised and the lowered position in order that the visor does not bang in front of the face of the operator or up on the top of the helmet.
In order that the visor does not, in the raised position, interfere with the fastening points of the ear protectors, these have been moved to the rear region of the helmet. As conventional protective helmets do not have a rear region that allows ear protector fastening, the helmet must be specially made, which increases construction costs.
The object of the present invention is to provide a link arm mechanism of the type indicated in the introduction, which eliminates the abovementioned disadvantages of the known link arm mechanism.
This is achieved by virtue of the fact that the first end of the link arm is connected in an articulated manner to the visor at a fastening point arranged in a region above a lower edge of a window arranged in the visor.
Such a link arm mechanism allows the operator to work undisturbed, without the link arm having any irritating effect. By means of the link mechanism, the visor can be mounted on a conventional protective helmet or head frame without the usual fastening points of the ear protectors above the ear region of the operator having to be moved.
The invention will be explained in greater detail below with the aid of exemplary embodiments shown in the appended drawings, in which:
Fig. 1 shows a side view of a link mechanism according to a first exemplary embodiment arranged on a protective helmet where the visor is in the lowered position,
Fig. 2 shows a side view of the link mechanism according to the first exemplary embodiment where the visor is in the raised position,
Fig. 3 shows a front view of the link mechanism with the visor removed,
Fig. 4 shows a side view of the link mechanism according to the first exemplary embodiment where the visor is in an intermediate position,
Fig. 5 shows a side view of the link mechanism according to the first exemplary embodiment arranged on a head frame, and
Fig. 6 shows a side view of a link mechanism according to a second exemplary embodiment arranged on a protective helmet.
Fig. 1 shows a link mechanism 1 according to a first exemplary embodiment, which is arranged on an item of
headgear in the form of a protective helmet 2. The link mechanism 1 supports a welding visor 4 which has been placed in a lowered position so as to protect the face and the eyes of an operator (not shown) who is wearing the helmet 2 on his head. The visor 4 is provided with a window 6 which is intended to be located in front of the eyes of the operator. The window 6 is delimited by a lower edge 5, an upper edge 7 and side edges 9.
The link mechanism 1 comprises a link arm 8 which, at a first end 10, is connected in an articulated manner to the visor 4 by means of a first articulation 12, which first articulation 12 is arranged on the visor 4 at a fastening point 14 located above the window 6. In this way, the link arm 8 will not fall within the field of vision of the operator. It is also possible to divide the first end of the link arm 8 into two parts, which is described below, each part being fastened on both sides of the window 6 in a region above the lower edge 5 of the window 6.
A second end 16 of the link arm 8 is connected in an articulated manner to a holder 18 at a second articulation 20, which holder 18 extends from one side of the helmet 2 to a second side of the helmet 2. The holder 18 is attached to the helmet 2 by means of, for example, screws 22. Alternatively, the holder 18 can be attached to the helmet 2 by means of a snap-fastening arrangement (not shown) .
In a front region of the helmet 2 , located close to the forehead (not shown) of the operator, the holder 18 comprises a first and a second metal plate 24 and 28 respectively made of magnetic material, which plates are intended to interact with a permanent magnet 30 arranged on the link arm 8. In the lowered position of the visor 4, the permanent magnet 30 bears against the first metal plate 24 and fixes the visor 4 in the lowered position. In order for it to be possible to
adjust the position of the visor 4' in front of the face of the operator, a third metal plate 32 made of magnetic material is arranged on an inner side of the visor 4, in a region above the fastening point 14 of the first end 10 of the link arm 8. The third metal plate 32 can be adjusted in the direction towards and the direction away from the visor 4 by means of a threaded spindle 34. In the lowered position of the visor 4, the third metal plate 32 bears against the permanent magnet 30 which is arranged on the link arm 8.
Fig. 2 shows the visor 4 in a raised position. The visor 4 is then located on top of the helmet 2. This position of the visor 4 is suitable when the operator takes a break from welding in order, for example, to carry out adjustments on the article being welded. When the operator raises the visor 4, the first and the third metal plates 24 and 32 respectively will be released from the permanent magnet 30. Furthermore, the link arm 8 will be rotated about the articulations 12 and 20 respectively. The movement ends when the permanent magnet 30 reaches the second metal plate 28, the contact between the second metal plate 28 and the permanent magnet 30 then fixing the visor 4 in the raised position.
According to the embodiment shown, the permanent magnet 30 is mounted pivotably in the link arm 8, which makes it possible for the permanent magnet 30 to bear flat against the metal plates 24, 28 and 32 respectively. Fig. 3 shows how the permanent magnet 30 is mounted on a spindle 38 in a recess 40 of the link arm 8. Fig. 3 shows the link mechanism 1 in a front view, where the visor 4 has been removed. The link arm 8 is essentially plate-shaped and the first end 10 is divided into two parts. The second end 16 of the link arm 8 is, on account of the recess 40, also divided into two parts. It is also possible for the first end 10 to extend over
the entire width (not shown) of the link arm 8. The link arm 8 is preferably made of a rigid plastic or metal material so that good torsional rigidity of the link mechanism 1 is obtained.
For the purpose of clarity, Fig. 4 shows the visor 4 in an intermediate position. In this intermediate position, the pivotable permanent magnet 30 does not bear against any of the metal plates 24, 28, 32, as a result of which it is easy for the operator to move the visor 4 into the lowered or the raised position.
Fig. 5 shows a side view of the link mechanism 1, where the holder 18 is arranged on a head frame 44 made of bands 42, which is intended to be arranged on the head of the operator. In this case, the head frame 44 constitutes an item of headgear for the operator.
As has been stated above, the metal plates 24, 28 and 32 respectively are arranged on the holder 18 and the visor 4 respectively and the permanent magnet 30 is arranged on the link arm 8. However, the situation can be reversed, that is to say that a metal plate made of magnetic material is arranged on the link arm 8 and permanent magnets are arranged on the holder 18 and the visor 4 respectively.
Fig. 6 shows a second exemplary embodiment of the link mechanism 1'. Instead of metal plates 24, 28, 32 and a permanent magnet 30, use is in this case made of a snap arrangement 46, in which a pivotable plate 48 with two first and second projections 50, 52 directed essentially away from one another are arranged. The holder 18 comprises in this case a first and a second indentation 54, 56 adapted to accommodate, in the raised and lowered positions respectively of the visor 4, the projections 50, 52 arranged on the pivotable plate 48. A third indentation 57 is arranged on the threaded spindle 34, which third indentation 57 is
adapted to accommodate, in the lowered position of the visor 4, the first projection 50 arranged on the pivotable plate 48.
In Fig. 6, a pair of ear protectors 58 has been drawn in to show that these do not interfere with the raised visor 4. The ear protectors 58 are arranged on the helmet 2 in a conventional manner.