EP0077346B1 - Torque wrench, with automatic releasing, pseudo-clutching and setting - Google Patents

Description

The present invention relates to hand tools of the “dynamometric wrench” type enabling bolting or screwing of mechanical assemblies to a recommended torque. This proceeds from the predetermined deformation of a spring. The amplitude of deformation of the spring, obtained with each stress, is constant. The torque variation effects are proportional to the length of spring subject to deformation after adjustment.

In general, known tools of this kind such as the one patented under the number FR, A, 1510105 of January 19, 1968 are used with caution, slowly, by successive approaches, watching for the tenuous signal announcing that the torque value desired is reached. Some are very imprecise. Others, very complex and expensive to make, are fragile. Most cannot be used for loosening. None can be mixed with the other components of a tool box without being carefully protected by a bulky box.

• - manifestation d'un pseudo-débrayage de la poignée de manoeuvre de la clef après déclenchement, associé au réarmement automatique de cette dernière.

The essential interest of this study of a dynamometric key lies in the following new improvement:

• - manifestation of a pseudo-disengaging of the key operating handle after triggering, associated with the automatic resetting of the latter.

None of the known embodiments present this provision.

• - a) Le premier consistait à réenclencher manuellement la clef ce qui entraînait la certitude de ne pas dépasser le couple prescrit, avec comme corollaire, une certaine rapidité de l'action de serrage, partiellement infirmée par la nécessité d'effectuer systématiquement à la demande, le réarmement de l'outil.

Previously, in fact, in terms of rearmament after triggering the couple chosi, there were two principles:

• - a) The first consisted in manually resetting the key, which resulted in the certainty of not exceeding the prescribed torque, with as a corollary, a certain speed of the tightening action, partially invalidated by the need to perform systematically on demand. , resetting the tool.

• - oubli de réarmer qui n'apparaît pas immédiatement dans l'application de faibles couples.
• - rupture brusque du couple au moment du débrayage, importante surtout lors de l'application de couples élevés, génératrice de dérapage dangereux pour la main de l'opérateur.
• - b) Le deuxième principe concernait le réen- clenchement automatique de la clef après relâchement de l'effort de serrage. Ce perfectionnement impliquant que le relâchement de l'effort soit produit à l'instant exact du déclenchement, a entraîné la fâcheuse nécessité d'effectuer une approche lente et précautionneuse du couple de serrage choisi, pour éviter son dépassement. D'où perte de temps.

This provision had two shortcomings:

• - forget to rearm which does not appear immediately in the application of low torques.
• - sudden break in torque when disengaging, important especially when applying high torques, generating dangerous skidding for the operator's hand.
• - b) The second principle concerned the automatic resetting of the key after releasing the tightening force. This improvement implying that the relaxation of the force is produced at the exact instant of triggering, has led to the annoying need to carry out a slow and careful approach to the chosen tightening torque, to avoid it being exceeded. Hence a waste of time.

The torque wrench as characterized in claim 1 solves these problems. Indeed, the invention relates to a hand torque wrench, with automatic triggering and rearming, reversible, allowing tightening and loosening of the mechanical bolts comprising; a pivoting handle during operation around the axis with a triggering device comprising a cam integral with the body of the tool and a rocker arm oscillating around an axis integral with the handle, this rocker arm being retained at one end forming notch by the beak of the cam, characterized in that it further comprises a shock-absorbing block consisting of a steel block secured to the handle at its rear end, a force-absorbing spring leaf extending along the body and the handle in contact with the shock absorber block in its rest position at its rear end and at V5 of its length starting from its rear end with a friction roller crimped in the rocker arm at its end opposite to that retained by the beak of the cam in that the cam being made integral with the body by the action of a part of a spring pressing the end of the cam on the threaded end of a screw screwed into the body and used for calibration , and on the other hand by l has cooperation of a buttonhole whose bottom comes to bear against the axis when the handle is stressed, and in that, as during the tightening operation, the pivoting of the handle around its axis relative to the main body drives the rocker arm in its pivoting movement, this pushes, by its friction roller, the leaf spring in the pivoting direction, until, as the cam is integral with the body of the tool and the bottom is supported on the axis, the rocker notch (3) escapes the cam spout the buttonhole guiding the movement of the cam during its erasure to allow the end of the rocker arm (3) to return to its position d origin when the handle returns and ceases its stress on the leaf spring, the latter released coming back to abut its free end on the damping block by pushing back the rocker arm which creates the tactile and audible signal of the triggering of the warning key the operator that the prefixed tightening torque is at complexion.

Advantageously, the key is equipped with a force receiving spring constituted by a straight leaf spring, of rectangular section, of constant width, but thick, decreasing allowing a better staggering of the graduations.

Preferably the torque wrench being equipped with 3 assorted sets composed of 3 leaf springs of different thicknesses associated one by one with a fixing band and a slider adapted to the 3 different thicknesses of leaf spring, these 3 sets being removable, allows with a single mount whose vernier is engraved with 3 parallel scales to cover a wide range of performances.

In addition, the translation generated by the rotation to the left or to the right of the adjusting screw varies the height of the cam spout allowing the calibration of the leaf springs according to the graduations of the body, and the subsequent recalibration of the key. depending on wear.

The device combines with the automatic resetting system, a simple pseudo-declutching device which allows safely for the operator's hand (without untimely slippage) greater tightening speed, greatly limiting the risk of exceeding the imposed torque. This improvement brings the appreciable double advantage of saving time and reducing the nervous tension of the user.

Its exceptionally audible trigger signal is accompanied by a characteristic and unequivocal tactile message.

As a receiving spring, it employs a straight blade of great length (the size adopted allows precision and longevity) of rectangular section, of constant width but of decreasing thickness along a slope calculated so that the staggering of the vernier graduations traversed by the slider, that is to say closer to an arithmetic progression, than that obtained using a blade of constant section (graphical representation board 2/2) hence greater clamping precision in the area of heavy loads.

Thanks to the removability of three of its components: the spring fixing hoop (9), the slider (10) and the leaf spring (8) of which it is advisable to have a set of different thicknesses, it allows with a single frame ensuring a very wide range of tightening values (ranging from 0, 200 kg to 12 kg for example).

The proven robustness of its handle / body articulation allows it to ensure, without risk, the loosening of the bolts as much as the dynamometric elements are not stressed.

Its fully protected mechanism protects it from misadjustments or damage, it can be mixed with other tools without special precautions and withstands damage and impact without damage.

An adjustment screw (which can, if necessary, be made inviolable by the means existing for carburetor jets for example) allows the tool to be recalibrated according to wear.

Finally, this reversible tool ensures both right tightening and left tightening. He is precise and faithful. Its construction is simple (reduced number of components and large adjustment tolerances). His reduced head and slim body allow him the best access.

The accompanying drawing shows the general appearance (face and profile) of the tool as well as the detail of the mechanism at rest.

CINEMATIC:

When the tool is in the working position and the user exerts traction on its handle (5) in the tightening direction, the latter pivots by a small amplitude around the axis (P-P ') which associates it with the body (1). In doing so, it drives by the axis (T-T ') the rocker arm (3) which, pushed back at its end (14) by the spout (12) of the cam (2) wedged in the body (1) by l 'antagonistic effect of the axis (C-C') fixed in the body (1) retaining this cam (2) by the bottom (17) of the buttonhole (15) and by the action of the spring (6) now l 'end (16) of the cam (2) pressing against the threaded end of the screw (7), deforms the leaf spring (8) away from the body (1) of the tool at the point of contact the friction roller (13) with which it is provided at the other end. This movement also has the effect of moving the free end of the leaf spring (8) away from the damper block (4) by a few millimeters.

When the torque selected by the slider (10) is reached, the rocker arm (3) escapes the spout (12) of the cam (2).

Simultaneously, the leaf spring (8) releases part of the accumulated force by pushing back the rocker arm (3) through its point of contact with the roller (13), and its return effect is stopped at its free end by the shock absorber block (4).

The resulting shock constitutes the expected tactile and auditory signal. At this stage the leaf spring (8) supports a residual tension lower than the nominal torque displayed since its free length increased while its torsion decreased. Consequently, the body (1) of the tool retains its angular position, while even carried away by its momentum, the operator's hand only accentuates the rotational movement of the handle (5). This subsidiary effect is limited by the rise in tension of the leaf spring (8) and, at the end of the stroke, by the contact of the safety stop with the body (1) of the tool. It is during this period that the physiological reflex intervenes to interrupt the tightening action.

The released handle (5) is then pushed back to its starting position by the reaction of the free end of the leaf spring (8) on the damping block (4). At the same time the rocker arm (3) also maintained by it, in the initial position, that is to say in support by its roller (13) and the base of its beak clears in passing the beak (12) of the cam (2) which slides in its buttonhole (15), compresses its return spring (6) and finally comes back out under its plane of contact with the spout (14) of the rocker arm (3). The return movement of the handle (5) is stopped at this instant by the contact of the stop which is integral with the corresponding notch milled in the body (1) of the tool.

In conclusion, the guiding idea of the preceding study was to popularize, by simplifying its construction and its use, by widening its possibilities, a hand tool still little known and little used, made more and more necessary by the evolution of technique in mechanical engineering.

Claims (4)

1. Hand torque wrench with automatic releasing and setting, reversible, permitting to tight and untight the mechanical nuts and bolts including: a handle (5) turning during the iperation around the axis (P-P') with a releasing device including a cam (2) solidary with the body (1) of the tool and a tripper device (3) oscillating a handle (5) solidary (T-T'), this tripper device being rehold at an extremity forming catch (14) by the end of the cam (12) characterized by the fact that this device includes moreover (12), a silent bloc (4) consisting of a handle (5) solidary steelen bloc (5) in its posterior extremity, a spring strip (8) receiving pull extending along the body (1) and the handle (5) in contact with silent bloc (4) in its resting position of posterior extremity and'/₅ of its lenght beginning from its posterior extremity with a friction pulley (13) crimpped in the tripper device (3) in its opposed extremity to the one rehold by the end (12) of the cam (2) by the fact the cam (2) being rehold solidary with the body (1) the action on one hand, by a spring (6) plating the extremity (16) of the cam (2) on the threaded extremity of a screw (7) screwed in the body (1) and serving at the calibrating and, on the other hand, by the cooperation of a hole (15) which the bottom (17) supports the axis (C-C') when the handle (5) is sollicitated and by the fact, like as while the releasing operation, the turning of the handle (5) around its axis (P-P') reporting to the main body (1) draws the tripper device (3) in its turning movement, this one pushes, by its friction pulley (13) the spring strip (8) in the sense of the turning until, when the cam is solidary the tool'body and which the bottom (17) is supported on the axis (C-C'), the catch (14) of the tripper device (3) espaces from the end (12) of the cam (2) the hole guiding the movement of the cam within its thrawing back to permit the ex- tremoty (12) of the tripper device (3) to retake its original position within the return of the handle (5) and stop its constraint on the spring strip (8), this one freed butting again with its free extremity of the silent bloc (4) repushing the tripper device (3) which makes the tactile and sonorous signal of the key releasing to advertise the operator that the fixed torque of tightening is obtained.

2. Torque wrench according to claim 1 characterized by the fact it is equiped with a re- ceaving pull spring strip (8), straight, rectangulary section, with a constant width, degressif thickness permitting a better graduation degreession.

3. Torque wrench according to claim 1 characterized by the fact that it is equiped by 3 assemblies composed of 3 spring strip (8) with different thickness associated one to another by a hoop (9) a slide (10) adapted to the 3 different thickness of the spring strip (8), this 3 assemblies being removable, permetting with a single frame which vernier is ingraved of 3 parallels ladders to obtain big performances.

4. Torque wrench according to claim 1 characterized by the fact that it permits owing to the generated translation by the rotary motion on the left or on the right of the correction screw (7) to make the highness of the end (16) of the cam (2) varies permetting the standardizing of the spring strip (8) in function of the degressions of the body (1) and the ulterior standardizing of the key in function of the attribution.

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