EP1609621B1 - 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 technical drawing instruments and school, and relates in particular to a drawing compass provided with means for locking the spacing of its branches to prevent an unexpected spacing of the branches especially during the tracing of a circle.

Such compasses are described for example in the documents of US Patents 3,584,384 , US 3,662,468 , US 0 533 819 , US 2,928,180 , FR 2,106,709 , GB 2,278,316 or DE 178 912 . The locking of the spacing of the branches is carried out for example by screwing the yoke in the case of a friction-cheeked compass, or by pinching the axis of a baluster in the case of a compass to baluster: 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 considerable effort and are inconvenient to use, especially by children.

In particular, the US Patent 3,584,384 aforesaid shows a baluster compass, whose two branches are directly articulated to each other on an axis, without true clevis, and are also connected to each other by a connecting rod located at a distance from their hinge axis. One of the arms of the compass carries, at a distance from the zone of articulation of the branches, a locking system which comprises a locking pin passing through the branch and itself traversed by the connecting rod, and a lever cooperating with this locking pin, the lever being hinged about another axis directly carried by said branch. The locking pin is oriented and slides relative to the compass leg that it passes in a direction orthogonal to the plane of the branches. The axis of pivoting of the lever, which axis is carried by the branch considered, extends parallel to the plane of the branches.

The document GB 10 452 A . D. 1909 discloses a drawing compass less cumbersome than the latter, since it comprises means for locking the spacing of its branches provided at the yoke of articulation of the branches: a locking screw is slidably mounted on each side. part of the screed in a direction orthogonal to the plane of the branches. Depending on a tightening performed by means of a knurled nut screwed to the locking screw, it acts on the articulation disks of the branches or on a member kinematically connected to these articulation disks so as to lock in place. rotation the two branches of the compass.

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

The initial resistance of the branches to the spacing corresponds to the effort to exert to separate the branches of the compass from one another, when their spacing is not locked, that is to say, typically when adjusting tracing radius.

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

The initial resistance of the branches to the gap must therefore be adjusted very finely to obtain both flexibility of opening and "braking".

However, it is very difficult to finely adjust 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. Thus, the benefit of the adjustment, made in the previous step, of the resistance of the branches to the gap is lost. When setting another tracing radius, it will be necessary to "grope" again with the knurled nut to find flexibility and "braking" at the opening of the branches.

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

The present invention aims to avoid these disadvantages by providing a compact design compass, ergonomic, inexpensive to manufacture, and the locking or unlocking of the spacing of the branches is simply and easily performed, especially by children, without risk to falsify the setting of the chosen tracing radius nor to disrupt the initial resistance of the branches to the spacing.

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 the level of which means are provided for locking the spacing of the branches comprising a blocking pin capable of sliding right through the yoke, in a direction orthogonal to the plane of the branches, and which acts, directly or indirectly, on the sectors or articulation disks of the branches and / or on a member kinematically connected to these sectors or articulation discs so as to lock in rotation the two arms of the compass, this compass being characterized by the fact that the locking pin is made in the form of a locking screw whose head is supported on a wing of the yoke, and on the tail of which screw, on the side of the other wing of the yoke, is screwed a nut, and by the fact that an eccentric lever is pivotally mounted, on the side of this other wing of the screed, on the 'nut around an axis parallel to the plane of the branches, and is able to slide the axis or screw of slide the axis or locking screw for locking or unlocking the rotation of the arms of the compass.

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

The locking pin is made in the form of a locking screw whose head is supported on one wing of the yoke, and on the tail of which screw, on the side of the other wing of the yoke, is screwed a nut on which the eccentric lever is pivoted.

In the unlocked position of the compass, there is a functional play between the clevis and the joints of the branches of the compass, game that allows the free opening of the compass. The tightening of the yoke by the locking screw eliminates this functional clearance and prevents, by friction, to separate the branches from one another.

The unscrewing or screwing of the nut, support of the eccentric lever, makes it possible to adjust the initial resistance of the branches to the distance, independently of the unlocking or locking of the spacing of the branches. After unlocking, we always find the resistance initially set.

Once the tracing radius has been set, the spacing is locked progressively by exerting a slight effort on the lever, and without having to let go of the compass, thus without risk of distorting the setting of the tracing radius.

The two branches can be articulated on separate, parallel and spaced axes, the hinge sectors of the branches being toothed on their periphery so as to mesh with one another, the axis or locking screw being located outside the area 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 hinge axes.

The two branches can also be articulated along the same axis about the axis or locking screw which passes through their articulation disks, each in friction with one of the wings of the yoke under the action of said axis or locking screw, this which prevents the spread of branches.

In this context, it is conceivable to intercalate between the hinge disks a plate forming a friction lug and having a central slot, of oblong shape along the median axis of the yoke, intended to be traversed by the axis or screw blocking, said plate being surmounted by a rod of substantially cylindrical shape for sliding axially inside of the screed. The tightening then applies to both the hinges of the arms of the compass and this plate forming a friction cheek.

The hinge discs each comprise, on their facing faces, a lug designed to slide in an arcuate groove formed on the hinge disc vis-à-vis, crossing, if appropriate a corresponding oblong hole formed on the friction plate.

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

In another embodiment of the invention, the locking pin comprises an opening slidably traversed by a transmission rod movable axially inside the yoke in the plane of the branches, and provided to allow symmetrical spacing. branches relative to the median axis of the yoke, the locking pin being adapted to lock 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 intended to slide axially inside the yoke through the opening of the locking pin, and a second portion of shape adapted to come into taken between sectors or articulation discs of branches. In particular in the latter case, the two branches can be articulated on separate, parallel and spaced axes, the disks or hinge sectors of the branches being toothed on their periphery so as to mesh with the second toothed or annular portion of the rod of transmission.

Thus, by actuating the eccentric lever, the opening formed on the locking pin, and slidably traversed by the transmission rod, is shifted so that the transmission rod is off-axis and can no longer slide freely to the inside the screed. It is by blocking the transmission rod that one blocks, 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 yoke until embedded there for 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:

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

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

As indicated in figure 1 the compass, generally designated by the numeral 1, comprises two branches 3, 4, for example metal, articulated along a joint axis 8 common in a yoke 2 of the compass.

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

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

In the three embodiments illustrated in figures 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 shaft 11 passing through a nut 10 screwed onto the tail of 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 bearing on the outside of the wing 2b of the yoke 2 and acting on the tail of the screw 8.

As illustrated in figure 2 , the branches 3 and 4 are hinged around the locking screw 8, which passes through their hinge discs 6, 7 in their center.

A plate 5b forms a friction flange between the hinge discs 6, 7 and comprises a central lumen 5d, of oblong shape along the median axis of the yoke 2, intended to be traversed by the locking screw 8.

The plate 5b is made in the form of a disc, for example made of plastic, of polyamide type loaded with glass fiber, and surmounted by a cylindrical rod 5a intended to slide axially inside the yoke 2 along its median axis.

The hinge disks 6, 7 each comprise, on their faces facing each other, a lug 6c, 7c designed to slide in a corresponding circular arc groove formed on the hinge disc 6, 7 to face. Each lug 6c and 7c through an oblong hole corresponding 5c formed on the plate 5b.

In the lowered position of the eccentric lever 9 (see figure 3 ), the compass is in an adjustable position, not locked, that is to say that there is a functional clearance (low friction) between the wings 2a, 2b of the yoke 2 and the hinge discs 6 and 7, game that allows to move - or to bring - freely branches 3 and 4 to adjust the radius of a circle or an arc to draw.

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

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

The figure 7 illustrates an embodiment variant close to that of the figure 2 in which the hinge disks 6, 7 engage directly against one another, the lugs 6c and 7c sliding directly in the corresponding circular arc groove of the disc vis-à-vis 7, 6.

In the raised, locking position of the eccentric lever 9, the cams 9a and 9b of the lever 9 press the two articulation disks 6, 7 against one another between the wings 2a, 2b of the yoke 2, so that that, by the friction of the hinge discs 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 Figures 8 and 9 , the two branches 3, 4 are articulated on separate axes 11 and 12, parallel and spaced apart. Each hinge sector 6, 7 branches 3, 4 has a toothing 6b, 7b complementary to mesh with one another.

The locking screw 8 is situated outside the region of the hinge sectors 6, 7, for example on the yoke 2 above these articulation sectors 6, 7 (cf. Fig. 8 ).

In the raised position of the eccentric lever 9, each of the hinge sectors 6, 7 is sandwiched between the flanges 2a and 2b of the yoke 2. The resulting friction prevents the hinge sectors 6, 7 to rotate 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 the branches 3 and 4, namely the effort to be exerted at the end of a branch 3 or 4 to separate the branches from each other, 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, as defined above, is advantageously less than 90 grams-force in the unlocked position of the compass , and greater than 280 grams-force, in locked position.

In the embodiment illustrated in Figures 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 apart.

A locking pin 8 'is slidably mounted, parallel to the hinge pins 12 and 13 of the branches 3, 4, between guide bearings formed in the flanges 2a, 2b of the yoke 2. The locking pin 8' is located outside the area of the hinge sectors 6 ', 7', for example on the yoke 2 above these articulation 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 it comprises, as before, a hinge fork whose two parts active are eccentric to form cams 9a, 9b acting, via the axis 11, on the tail of the locking pin 8 'to slide.

The locking pin 8 'has in its central zone an oblong opening 8'a (see figure 6 ) through which is axially slidable, in the direction of the interior of the yoke 2, a first cylindrical portion 5'a of a rod 5 ', for example metallic.

A second cylindrical portion 5'b of the rod 5 'is corrugated to (see figure 5 ) meshingly engage between the hinge sectors 6 ', 7' having for this purpose 6'b and 7'b teeth.

The lifting of the lever 9 exerts traction 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. rotation of the teeth 6'b and 7'b being thus prevented, the branches 3 and 4 are locked in rotation.

In the embodiments detailed above, the yoke 2 and the lever 9 have complementary shapes. The eccentric lever 9 can be folded on the yoke 2 until it recesses, 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, gearing, etc.) , and in any material (plastics, metals ...).

Claims (9)

1. Drawing compass, the legs (3, 4) of which are articulated by respective articulation sectors or discs (6, 6', 7, 7,') in a clevis (2) at which means for locking the legs (3, 4) in position are provided, comprising a locking pin (8, 8') able to slide right through the clevis (2) in a direction orthogonal to the plane of the legs (3, 4) and which acts directly or indirectly on the articulation sectors or discs (6, 6', 7, 7') of the legs (3, 4) and/or on a member (5, 5') connected kinematically to these articulation sectors or discs (6, 6', 7, 7') so as to prevent rotation of the two legs (3, 4) of the compass (1), characterized in that the locking pin is produced in the form of a locking screw (8, 8'), the head of which bears against one arm (2a) of the clevis (2), and a nut (10) is screwed onto the shank of said screw (8, 8') at the other arm (2b) of the clevis (2), and in that an eccentric lever (9) is pivotably mounted, at this other arm (2b) of the clevis (2), on the nut (10) so as to pivot about a pin (11) parallel to the plane of the legs (3, 4) and is able to cause the locking pin or screw (8, 8') to slide in order to prevent or allow rotation of the legs (3, 4) of the compass.
2. Drawing compass according to Claim 1, characterized in that the two legs (3, 4) are articulated on separate, parallel and spaced-apart pins (12, 13), the articulation sectors (6, 7) of the legs (3, 4) having indentations on their peripheries so as to mesh in one another, the locking pin or screw (8) being located outside the area of the articulation sectors (6, 7) gripped between the arms (2a, 2b) of the clevis (2) under the action of said locking pin or screw (8).
3. Drawing compass according to Claim 1, characterized in that the two legs (3, 4) are articulated about the same axis around the locking pin or screw (8) which passes through their articulation discs (6, 7), in each case in frictional contact with one of the arms (2a, 2b) of the clevis (2) under the action of said locking pin or screw (8).
4. Drawing compass according to Claim 3, characterized in that a plate (5b) forming a friction flange and having an oblong central slot (5d) along the mid-axis of the clevis (2) is interposed between the articulation discs (6, 7) through which plate the locking pin or screw (8) is designed to pass, said plate (5b) having a more or less cylindrical rod (5a) mounted on it which is intended to slide axially inside the clevis (2).
5. Drawing compass according to Claim 3 or 4, characterized in that the articulation discs (6, 7) each comprise on their opposing surfaces a peg (6c, 7c) designed to slide in a circular arcuate groove made on the opposing articulation disc (6, 7), passing through, if necessary, a corresponding oblong hole (5c) made in the plate (5b) forming a friction flange.
6. Drawing compass according to Claim 1, characterized in that the locking pin (8') has an opening (8'a) through which a transmission rod (5') that can move axially inside the clevis (2) in the plane of the arms (3, 4) slides, and provided so as to allow symmetrical positioning of the legs (3, 4) with respect to the mid-axis of the clevis (2), the locking pin (8) being able to prevent the transmission rod (5') from undergoing translational movement by friction on the wall of its opening (8'a).
7. Drawing compass according to Claim 6, characterized in that the transmission rod (5') has a more or less cylindrical first portion (5'a) intended to slide axially inside the clevis (2) through the opening (8'a) in the locking pin (8') and a second portion (5'b) having a form designed to be engaged between the articulation sectors or discs (6', 7') of the legs (3, 4).
8. Drawing compass according to Claim 7, characterized in that the two legs (3, 4) are articulated on separate, parallel and spaced-apart pins, the articulation sectors or pins (6, 7) of the legs (3, 4) having indentations on their peripheries so as to mesh with the second portion (5'b), which has indentations or is ringed, of the transmission rod (5').
9. Drawing compass according to one of Claims 1 to 8, characterized in that the clevis (2) and the eccentric lever (9) have complementary forms such that the lever (9) can hinge down on the clevis (2) so as to fit therein, for example in the position locking the legs (3, 4) in position.

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