EP1609621A1 - Drawing compass with means to lock the legs in position - Google Patents

Abstract

The compass has an eccentric lever (9) rotatably mounted around an axle (11) parallel to a plane of branches (3, 4) of the compass. The lever slides in a direction orthogonal to the plane of the branches. A blocking screw (8) acts directly or indirectly on articulation disks (6, 7) of the branches and/or on a rod (5) connected kinematically to the disks (6, 7) so as to block the rotation of the branches.

Description

The present invention relates to drawing instruments technical and academic, and relates in particular to a drawing compass with locking means of the spacing of its branches to avoid a Unexpected spacing of the branches especially during the tracing of a circle.

Such compasses are described for example in the documents of US Patent Nos. 3,584,384, 3,662,468, US 0 533,819, US 2,928,180, US Pat. FR 2 106 709, GB 2 278 316 or DE 178 912. Spacer locking branches is done for example by screwing the yoke in the case of a compass with friction cheeks, or by pinching the axis of a baluster in the case of a baluster compass: the axis of the baluster crosses the branches of the compass in their middle part to form an isosceles triangle with the top of the compass. These techniques impose bulky compasses, require a significant effort and are inconvenient to use, especially by the children.

GB 10 452 A discloses a drawing compass less cumbersome than these, because it includes locking means of the spacing of its branches provided at the yoke clevis branches: a locking screw is slidably mounted from one side of the clevis in a direction orthogonal to the plane of the branches. According to a tightened by means of a knurled nut screwed on the locking screw, the latter acts on the articulation disks of the branches or on a linked organ kinematically to these articulation disks so as to lock in rotation the two branches of the compass.

Here, unscrewing or screwing the knurled nut ensures both the adjustment of the initial resistance of the branches to the gauge, and the unlocking or locking the spacing of the arms of the compass.

The initial resistance of the branches to the gap corresponds to the effort to exert to remove the branches of the compass from each other, when their spacing is not locked, that is to say typically when adjusting the tracing radius.

Indeed, it is important for the setting of the tracing radius to be sufficiently precise, that the opening of the branches is sufficiently flexible for a easy handling, fast and accurate, but slightly braked to avoid a spacing of branches unwanted when drawing a circle.

The initial resistance of the branches to the gauge must therefore be adjusted very finely to obtain both flexibility of opening and "braking". However, it is very difficult to fine-tune this parameter by means of a knurled nut which must be unscrewed or screwed very precisely.

Once you have successfully adjusted the knurled nut so that the opening of the branches is both flexible and slightly braked, it remains to lock the gap to keep constant, for tracing, the radius of tracing chosen and adjusted previously.

For this, it is necessary to screw the knurled nut. So, we lose the benefit of the adjustment, made in the previous step, of the resistance of branches at the gap. When setting another tracing radius, it will be necessary to again "grope" with the knurled nut to regain flexibility and "braking" when opening branches.

In addition, the screwing of the knurled nut, to lock the gap, can generate parasitic friction which causes a very slight rotation of branches, and therefore a slight adjustment of the chosen tracing radius previously.

The present invention aims to avoid these disadvantages by providing a compact, ergonomic design compass, inexpensive to manufacture, and the locking or unlocking of the spacing of the branches is achieved simply and easily, especially by children, without risk of distorting setting of the chosen tracing radius or disrupting the initial resistance of the branches at the gap.

For this purpose, the subject of the invention is a drawing compass whose branches are articulated by respective sectors or disks in a clevis, at which locking means are provided the spacing of the branches having a locking pin capable of sliding from one end of the screed, in a direction orthogonal to the plane of branches, and which acts, directly or indirectly, on sectors or disks articulation of the branches and / or on an organ kinematically linked to these sectors or hinge discs so as to block in rotation the two compass arms, an eccentric lever being pivotally mounted, on the side of a wing of the yoke, around an axis parallel to the plane of the branches, and able to sliding said locking pin for locking or unlocking in rotation branches of the compass.

Thus, the inventive idea is to dissociate the functions of unlocking or locking the spacing of the arms of the compass, and adjusting the initial resistance of the branches to the gap. In a way ergonomic, a simple gesture of raising or lowering the lever eccentric, without screwing or unscrewing, slides the locking pin for unlock or lock the spread of the branches.

In a first embodiment, the locking pin is made in the form of a locking screw whose head is supported on a wing of the clevis, and on the tail of which screw, on the side of the other wing of the clevis, is screwed a nut on which is mounted pivoting the eccentric lever.

In the unlocked position of the compass, there is a functional game between the clevis and the joints of the branches of the compass, a game that allows the free opening of the compass. Tightening the clevis by the locking screw removes this functional game and prevents, by friction, to spread the branches one from the other.

Unscrewing or screwing of the nut, support of the eccentric lever, allows to adjust the initial resistance of the branches to the gap, independently of the unlocking or locking of the spacing of branches. After unlocking, we always find the resistance initially set.

Once the tracing radius has been set, the gap lock is done gradually by exerting a small effort on the lever, and without have to release the compass, so without risk of distorting the adjustment of the radius of tracing.

The two branches can be articulated on separate axes, parallel and spaced, the sectors of articulation of the branches being toothed on their periphery so as to mesh with each other, the axis or screw of blocking being situated outside the zone of articulation sectors sandwiched between the wings of the yoke under the action of said axis or locking screw, which prevents the free rotation of the branches around their axes of articulation.

The two branches can also be articulated according to a same axis around the axis or locking screw that runs through their disks hinge, each in friction with one of the wings of the yoke under the action said axis or locking screw, which prevents the spacing of the branches.

In this context, it is possible to insert between the disks hinge plate forming a friction cheek and having a light central, of oblong shape along the median axis of the screed, intended to be traversed by the axis or locking screw, said plate being surmounted by a rod of substantially cylindrical shape for axially sliding inside of the screed. The tightening then applies to both the joints of the compass branches and on this plate forming friction cheek.

The articulation discs each comprise, on their faces in vis-à-vis, a pin designed to slide in a groove in an arc arranged on the articulation disc vis-à-vis, crossing, if necessary, a corresponding oblong hole on the friction plate.

Being immobilized in rotation by its cylindrical rod, the plate forming friction cheek transmits movement from one branch to the other branch who performs a symmetrical movement. At the same time, thanks to the form oblong, along the median axis of the screed, the central light of the plate, the rod of the latter slides axially inside the clevis of the compass.

In another embodiment of the invention, the locking pin has an opening slidably traversed by a rod of mobile transmission axially inside the clevis in the plane of branches, and provided to allow a symmetrical separation of the branches relative to the median axis of the yoke, the locking pin being able to block in translation the transmission rod by friction on the wall of its opening.

According to one possibility, the transmission rod comprises a first portion of substantially cylindrical shape for sliding axially inside the clevis through the opening of the axis of blocking, and a second shaped portion adapted to engage between the sectors or articulation disks of the branches. Especially in the latter case, the two branches can be articulated on separate axes, parallel and spaced, the disks or sectors of articulation of the branches being toothed on their periphery so as to mesh with the second portion toothed or ringed transmission rod.

Thus, by actuating the eccentric lever, the opening on the locking pin, and slidably traversed by the transmission rod, is shifted so that the transmission rod is off-center and can no longer slide freely inside the screed. It's by blocking the stem of transmission which is blocked, indirectly, the separation of the branches of the compass.

In another aspect, for the sake of ergonomics and compactness, the clevis and the eccentric lever have complementary shapes of so that the lever can be folded on the screed up to embed itself by example in the locking position of the spacing of the branches.

• la figure 1 est une vue en perpective d'un compas de dessin conforme à un premier mode de réalisation de l'invention
• la figure 2 est une vue en perspective et en éclaté de ce même compas ;
• la figure 3 est une vue en coupe suivant l'axe III-III de la figure 1 du compas précédent en position déverrouillée;
• la figure 4 est une vue similaire à la figure 3 en position verrouillée du compas;
• la figure 5 est une vue schématique, en coupe dans le plan des branches, d'un compas de dessin conforme à un second mode de réalisation de l'invention ;
• la figure 6 est une vue schématique, en coupe selon l'axe VI-VI du compas de la figure 5 ;
• la figure 7 est une vue similaire à la figure 2 d'une troisième forme de réalisation du compas selon l'invention ;
• la figure 8 est une vue schématique, en coupe dans le plan des branches, d'un compas de dessin conforme à un quatrième mode de réalisation de l'invention ;
• la figure 9 est une vue schématique, en coupe selon l'axe VIII-VIII du compas de la figure 8.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing by way of example some embodiments of a compass according to the invention, in which:

• FIG. 1 is a perspective view of a drawing compass according to a first embodiment of the invention.
• Figure 2 is a perspective view and exploded of the same compass;
• Figure 3 is a sectional view along the axis III-III of Figure 1 of the previous compass in the unlocked position;
• Figure 4 is a view similar to Figure 3 in the locked position of the compass;
• Figure 5 is a schematic sectional view in the plane of the branches of a drawing compass according to a second embodiment of the invention;
• Figure 6 is a schematic sectional view along the axis VI-VI of the compass of Figure 5;
• Figure 7 is a view similar to Figure 2 of a third embodiment of the compass according to the invention;
• Figure 8 is a schematic sectional view in the plane of the branches of a drawing compass according to a fourth embodiment of the invention;
• FIG. 9 is a schematic view, in section along the axis VIII-VIII of the compass of FIG. 8.

In all the figures, the corresponding elements are designated by the same references, possibly followed by the sign "prime".

As shown in Figure 1, the compass, designated globally by the reference numeral 1, comprises two branches 3, 4, for example metal, articulated along a joint axis 8 common in a clevis 2 of the compass.

An eccentric lever 9, pivotally mounted on the side of a wing 2b of the clevis 2, makes it possible to lock the spacing of the branches 3, 4.

Equipment such as tip or mine, carried by the ends branches 3, 4 are not represented, not being concerned by the invention.

In the three embodiments illustrated in FIGS. 2, 3, 4, 7, 8 and 9, the eccentric lever 9 is pivotally mounted about an axis 11 parallel to the wing 2b of the yoke 2, this axis 11 passing through a nut 10 screwed on the tail a locking screw 8 whose head is supported on the outer face of the other wing 2a of the yoke 2.

The eccentric lever 9 comprises a hinge fork whose two active parts are eccentric to form cams 9a, 9b taking support on the outside of the wing 2b of the yoke 2 and acting on the tail of the screw 8.

As illustrated in FIG. 2, the branches 3 and 4 are articulated around the locking screw 8, which passes through their articulation disks 6, 7 in their center.

A plate 5b forms a friction cheek between the disks 6, 7 and has a central slot 5d oblong along the median axis of the yoke 2, intended to be traversed by the screw of blocking 8.

The plate 5b is made in the form of a disk, for example in plastic material, polyamide type filled with fiberglass, and topped a cylindrical rod 5a intended to slide axially inside the clevis 2 along its median axis.

The articulation disks 6, 7 each comprise, on their faces vis-à-vis, a lug 6c, 7c provided for sliding in an arcuate groove corresponding circle formed on the hinge disc 6, 7 vis-à-vis. Each lug 6c and 7c passes through a corresponding oblong hole 5c formed on the plate 5b.

In the lowered position of the eccentric lever 9 (see FIG. 3), the compass is in an adjustable, unlocked position, that is, there is a game functional (low friction) between the wings 2a, 2b of the yoke 2 and the discs of articulation 6 and 7, a game which makes it possible to separate - or to bring - freely the branches 3 and 4 to adjust the radius of a circle or an arc to be drawn.

When pivoting and folding up lever 9 (see 4), the cams 9a and 9b of the lever 9 press the two disks 6, 7 branches 3, 4, the friction cheek 5a and the wings 2a, 2b of the yoke 2, thus ensuring by friction locking the spacing of branches 3, 4.

The branches 3 and 4 then remain locked in the set position previously so that it is possible to make several circles or arcs circle of identical radius.

FIG. 7 illustrates an embodiment variant similar to that of the FIG. 2, in which the articulation disks 6, 7 come directly into taken against each other, the pins 6c and 7c sliding directly into the corresponding circular arc groove of the disc vis-à-vis 7, 6.

In raised position, locking, eccentric lever 9, the cams 9a and 9b of the lever 9 press the two articulation disks 6, 7 one against the other between the wings 2a, 2b of the yoke 2, so that by the friction of the articulation disks 6, 7 between them and against the wings 2a and 2b, the spacing of the branches 3, 4 is prevented.

In the embodiment variant illustrated in FIGS. 8 and 9, the two branches 3, 4 are articulated on separate axes 11 and 12, parallel and spaced. Each sector of articulation 6, 7 of the branches 3, 4 comprises a tooth 6b, 7b complementary to mesh one into the other.

Locking screw 8 is located outside the area of the sectors hinge 6, 7, for example on the yoke 2 above these sectors 6, 7 (see Fig. 8).

In the raised position of the eccentric lever 9, each of the sectors 6, 7 is clamped between the wings 2a and 2b of the yoke 2. The friction resulting prevents the articulation sectors 6, 7 from rotating freely so that the spacing of the branches 3, 4 is prevented.

In the three preceding embodiments, illustrated in Figures 2, 3, 4, 7, 8 and 9, it is possible to adjust the resistance to the spacing of branches 3 and 4, namely the effort to exert at the end of a branch 3 or 4 to separate the branches from one another by screwing or unscrewing the nut 10 on the locking screw 8.

In general, the compass object of the invention is shaped so that the resistance to the separation of the branches, such as defined above, is advantageously less than 90 grams-force in unlocked position of the compass, and greater than 280 grams-force, in locked position.

In the embodiment illustrated in FIGS. 5 and 6, the two branches 3 and 4 are articulated by articulation sectors 6 ', 7' on separate axes 12 and 13, parallel and spaced.

A locking pin 8 'is slidably mounted parallel to the axes 12 and 13 of the branches 3, 4, between guide bearings formed in the wings 2a, 2b of the yoke 2. The locking pin 8 'is located out of the area of articulation sectors 6 ', 7', for example on the yoke 2 above these hinge sectors 6 ', 7' (see Figure 5).

The eccentric lever 9 is pivotally mounted about an axis 11 parallel to the plane of the branches 3, 4, on the side of the wing 2b of the yoke 2, and comprises, as before, a hinge fork of which both active parts are eccentric to form cams 9a, 9b acting by through the axis 11, on the tail of the locking pin 8 'to do it slide.

The locking pin 8 'has in its central zone an opening 8 'a oblong (see Figure 6) through which is able to slide axially, towards the inside of the yoke 2, a first cylindrical portion 5'a a rod 5 ', for example metal.

A second cylindrical portion 5'b of the rod 5 'is corrugated to (see FIG. 5) engage by meshing between the articulation sectors 6 ', 7' comprising for this purpose teeth 6'b and 7'b.

The lifting of the lever 9 exerts a pull on the tail of the locking pin 8 ', therefore the opening 8'a is translated so that the rod 5 'is off-center and prevented from sliding freely in the yoke 2. The rotation of the teeth 6'b and 7'b being thus prevented, the branches 3 and 4 are blocked in rotation.

In the embodiments detailed above, the yoke 2 and the lever 9 have complementary shapes. The eccentric lever 9 can thus fall back on the screed 2 until it fits in, which contributes to the compactness and ergonomics of the compass.

It goes without saying that one would not depart from the scope of the invention, as defined in the appended claims, in particular by applying it to a compass of any design (with friction cheeks, with gearing ...), and in all material (plastics, metals ...).

Claims (10)

Drawing compass whose branches (3, 4) are articulated by sectors or articulation disks (6, 6 ', 7, 7') respectively in a yoke (2), at which locking means are provided. the spacing of the branches (3, 4) comprising a locking pin (8, 8 ') able to slide right through the yoke (2), in a direction orthogonal to the plane of the branches (3, 4), and which acts, directly or indirectly, on the sectors or articulation disks (6, 6 ', 7, 7') of the branches (3, 4) and / or on a member (5, 5 ') kinematically connected to these articulation sectors or discs (6, 6 ', 7, 7') so as to block the two arms in rotation (3, 4) of the compass (1), characterized in that an eccentric lever (9) is mounted pivoting, on the side of a wing (2b) of the yoke (2), about an axis (11) parallel to the plane of the branches (3, 4), and is capable of sliding said locking pin (8, 8 ') for locking or unlocking the branches (3, 4) in rotation compass. Drawing compass according to claim 1, characterized in that the locking pin is in the form of a locking screw (8) whose head is supported on a flange (2a) of the yoke (2), and on the tail of which screw (8), on the side of the other wing (2b) of the yoke (2), is screwed a nut (10) on which is pivotally mounted the eccentric lever (9). Drawing compass according to claim 1 or 2, characterized in that the two branches (3, 4) are articulated on separate axes (12, 13) parallel and spaced, the hinge sectors (6, 7) of the branches (3, 4) being toothed on their periphery so as to mesh with one another, the axis or locking screw (8) being situated outside the region of the articulation sectors (6, 7) enclosed between the wings (2a, 2b) of the yoke (2) under the action of said axis or locking screw (8). Drawing compass according to claim 1 or 2, characterized in that the two branches (3, 4) are articulated along the same axis about the axis or locking screw (8) which passes through their articulation disks (6, 7), each in friction with one of the wings (2a, 2b) of the yoke (2) under the action of said axis or locking screw (8). Drawing compass according to Claim 4, characterized in that a friction plate (5b) is provided between the articulation disks (6, 7) and has a central slot (5d) of oblong shape according to the median axis of the yoke (2), intended to be traversed by the axis or locking screw (8), said plate (5b) being surmounted by a rod (5a) of substantially cylindrical shape for sliding axially to the inside the screed (2). Drawing compass according to claim 4 or 5, characterized in that the articulation disks (6, 7) each comprise, on their facing faces, a lug (6c, 7c) designed to slide in a groove in a circular arc formed on the hinge disc (6, 7) vis-à-vis, crossing, if necessary, an oblong hole (5c) corresponding formed on the plate (5b) forming a friction cheek. Drawing compass according to claim 1, characterized in that the locking pin (8 ') has an opening (8'a) slidably traversed by a transmission rod (5') movable axially inside the clevis (2) in the plane of the branches (3, 4), and provided to allow a symmetrical spacing of the branches (3, 4) relative to the median axis of the yoke (2), the locking pin (8). ') being able to block in translation the transmission rod (5') by friction on the wall of its opening (8'a). Drawing compass according to claim 7, characterized in that the transmission rod (5 ') comprises a first portion (5'a) of substantially cylindrical shape intended to slide axially inside the yoke (2) through the opening (8'a) of the locking pin (8 '), and a second portion (5'b) of shape adapted to engage between the sectors or articulation disks (6', 7 ') branches (3, 4). Drawing compass according to claim 8, characterized in that the two branches (3, 4) are articulated on separate, parallel and spaced axes, the disks or articulation sectors (6, 7) of the branches (3, 4). being toothed on their periphery so as to mesh with the second portion (5'b), toothed or annealed, of the transmission rod (5 '). Drawing compass according to one of claims 1 to 9, characterized in that the yoke (2) and the eccentric lever (9) have complementary shapes so that the lever (9) can be folded onto the yoke (2). until recessed, for example in the locking position of the spacing of the branches (3, 4).

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