EP2950744A1

EP2950744A1 - Torque wrench

Info

Publication number: EP2950744A1
Application number: EP14709521.0A
Authority: EP
Inventors: François HUGUELET
Original assignee: HL Technology SA
Current assignee: HL Technology SA
Priority date: 2013-01-29
Filing date: 2014-01-28
Publication date: 2015-12-09
Also published as: CH707490A1; WO2014117282A1; US20160059395A1

Abstract

The invention relates to a torque wrench (10) comprising a grasping handle (11) and two heads, respectively (12 and 13), that each have a clamping tool (14 and 15) arranged at the two opposite ends of the torque wrench. Each of the clamping tools (14 and 15) is provided as a rotatable socket (16) engaged in an annular part (17) that is secured to the corresponding head (12, 13). The rotatable socket (16) comprises a central opening (18) defined by a hexagonal faceted wall (19). The invention also comprises a spring element that corresponds to the head (12) and consists of a single spring leaf (22). In a stressed position, the free end of the spring leaf (22) engages the flank (29) of a tooth (21) and locks the rotatable socket (16). Said socket can be freed after the buckling of the spring leaf (22).

Description

DYNAMOMETRIC KEY Technical field

The present invention relates to a torque wrench, in particular a torque wrench for fixing or loosening an object, in particular a dental implant or the like, this wrench comprising a handle and at least one integral clamping tool. at least one end of said grip handle, said clamping tool being rotatable about its central axis and having an inner opening limited by a faceted wall adapted to the profile and dimensions of said object.

Prior art

Torque wrenches of this type are already known which are produced according to the concept of ratchet wrenches comprising a rotating clamping tool with a central opening defined by a faceted wall and having an outer wall provided with peripheral notches. Furthermore, these keys generally comprise balls or pins each biased by a spiral spring in a direction of engagement in said peripheral notches to provide a non-return lock and a maximum torque of said rotary clamping tool.

Often the number of mechanical parts necessary to allow the torque wrench to perform its function of limiting the tightening torque, is high, which poses a problem of space because of the limited space available for example for an orthodontic application .

On the other hand, the adjustment of the stress of the spiral springs is delicate and proves unreliable over time. Indeed, the tension of a spiral spring of small dimension does not remain constant over time and can vary depending on the conditions of use, especially the temperature. Other types of torque wrenches with a view to simplifying these known systems have been developed and are illustrated in particular by the US Pat. No. 5,224,403 and the European Patent Application EP 1 731 114 A1. The first describes a torque wrench for dental use and which comprises a ring provided with peripheral teeth in which can engage respectively a single ball, biased by an axially movable rod when pushed by a user, via an adjusting mechanism acting on an axial spring. The adjustment mechanism is arranged to exert a more or less strong thrust on the spring, one end of which bears on the ball.

The second has substantially the same configuration, but comprises, in place of the ball mechanism, spring and push rod, a leaf spring whose end enters directly into the cavities separating the teeth of the ring gear to exert a retaining torque on said crown. This mechanism is not very accurate and subject to rapid wear.

In addition, the current torque wrenches are not able to fulfill both its main function which is that of a torque limiter for fixing and tightening an object, but also secondary functions as a key to ratchet and unscrewing key.

As a result, the current torque wrenches have both structural and functional disadvantages. For some, because of their complexity, their assembly is long and delicate so that the manufacturing costs are extremely high, for others their construction is not suitable for medical and dental use because of the constraints of hygiene and imposed in these areas. Presentation of the invention

The present invention proposes to overcome all the disadvantages mentioned above by producing a torque wrench, in particular for the placement of objects such as dental implants, this torque wrench being of simple design, which allows an easy and economical manufacturing, which is easy to adjust and whose setting is reliable over time regardless of the conditions of use. 'use.

This object is achieved by the torque wrench according to the invention as defined in the preamble and characterized in that said rotary clamping tool comprises a peripheral wall provided with teeth, substantially concentric with said faceted wall, in that said grip sleeve carries at least one leaf spring having a fixed first end, mounted in said gripping sleeve at a determined distance from said clamping tool and a second free end, bearing against said peripheral wall provided with teeth, said leaf spring being movable between a first position, said constraint position, in which the second end bears against a sidewall of one of the teeth of said peripheral wall of said clamping tool, this constraint position being maintained as long as the force applied by the user to the handle is less than a predetermined threshold, and a second position, called the released position, in the said second end has unhooked from the side of said tooth of said peripheral wall of said clamping tool, following a buckling of said leaf spring under the effect of a force applied by the user on the handle, this force being at least equal to said predetermined threshold.

According to an advantageous variant, said gripping handle carries two leaf springs each having a fixed first end, mounted in said gripping sleeve at a determined distance from said clamping tool and a second free end, bearing against said peripheral wall provided with teeth, said leaf springs being movable between a first position, said stress position, in which the second free end of each of said leaf springs rests against a sidewall of one of the teeth of said peripheral wall of said clamping tool, this position of stress being maintained as long as the force applied by the user on the handle is less than a predetermined threshold, and a second position, called the released position, in which their second free end has respectively unhooked with respect to the sides of said teeth of said peripheral wall of said clamping tool, following a buckling of said spring blades under the effect of a force applied by the user on the handle, this force being at least equal to said predetermined threshold.

Advantageously, said handle can carry a head at each of its opposite ends, each of these heads comprising a clamping tool, one of said clamping tools being equipped with a single leaf spring and the other tool clamping being equipped with two leaf springs.

According to one of the variants, said at least one spring blade is mounted at one of its ends on a fixed stud in the handle of said torque wrench and having a free end, is housed in a recess in the handle to allow buckling said leaf spring under the effect of a stress applied to said handle.

According to another variant, said spring blade is substantially tangential with respect to said peripheral wall of said clamping sleeve.

Preferably, each of the leaf springs comprises one of its ends mounted on a fixed stud in the handle of said torque wrench, said fixed studs being offset laterally relative to each other and said leaf springs being housed in said release formed in the handle to allow the buckling of said leaf springs under the effect of a stress applied to said handle gripping.

Advantageously, said clamping tool can be made as a rotating sleeve having a general shape of a cylindrical ring open on its two faces so that the clamping tool can be engaged on said object by one or the other in such a way that the torque wrench has a ratchet function. In a particularly advantageous manner, said teeth comprise an asymmetrical profile, one of the flanks of each of said teeth being substantially parallel to said leaf spring in the stress position and the other side of each of said teeth being substantially perpendicular to said leaf spring in position of constraint.

Brief description of the drawings

The present invention and its main advantages will become more apparent in the description of various embodiments, with reference to the accompanying drawings, in which: FIG. 1 shows a plan view of an advantageous embodiment of the torque wrench according to the invention , this key being represented in its so-called "constraint" position, FIG. 2 is a plan view of the embodiment of FIG. 1 of the torque wrench according to the invention, this key being represented in its so-called " 3 is an enlarged view of the head with a leaf spring of the torque wrench shown in its so-called stress position, FIG. 4 is an enlarged view of the head with a leaf spring of the torque wrench shown in FIG. position called released, Figure 5 is an enlarged view of the head with two leaf springs of the torque wrench shown in its so-called contrain position and FIG. 6 is an enlarged view of the two-leaf spring head of the torque wrench shown in its so-called released position. Best ways to achieve the invention

With reference to FIG. 1, the torque wrench 10 shown comprises a gripping handle 11 and two heads, respectively 12 and 13, each carrying a clamping tool 14 and 15 disposed at the two opposite ends of the torque wrench 10. not shown, the torque wrench 10 could have only one head with a single clamping tool. Each of the clamping tools 14 and 15 is in the form of a rotatable bushing 16 housed in an annular piece 17 secured to the corresponding head 12, 13. The rotating bushing 16 has a central opening 18 delimited by a faceted wall 19, this wall being for example hexagonal or having a surface adapted to the profile of an object to be clamped, for example a dental implant or the like. The sleeve has the shape of a relatively flat tubular cylindrical ring, which has the same opening on both sides. As a result, the clamping sleeve is reversible and can be engaged on an object by its two faces. The primary purpose of this faceted wall is to allow clamping during the introduction of the object, this clamping being effected in a controlled manner by the torque limiting function of the torque wrench 10. The rotary sleeve 16 comprises by elsewhere a peripheral wall 20 provided with teeth 21 intended to cooperate with a spring element to limit the tightening torque of the object to be clamped.

In the example shown, the spring element corresponding to the head 12 consists of a single spring blade 22 and the spring element corresponding to the head 13 consists of two leaf springs 23 and 24. Figure 1 shows the key dynamometric in its position of constraint. The enlarged detail views illustrate the operation of the key and the interaction between the various operational components, in particular the teeth 21 and the leaf springs 22, 23 and 24. The leaf spring 22 is fixed on a fixed stud 25 to one of its ends 26 and bears against a flank of a tooth 21 at its other free end 27. This constraint position is shown in Figure 1 and Figure 3. The spring blade is disposed in a recess 28 formed in the handle 11 to allow the buckling of the blade following a stress applied to the handle during tightening of the object. In operation, when the operator wants to set up and tighten in position an object by means of the clamping tool 14 of the head 12, as long as the force exerted on the handle 11 and which is transmitted to the rotary sleeve 16 is less than a given value, called the threshold, the leaf spring 22 remains substantially straight. The free end 27 bears against a flank 29 of a tooth 21. Each tooth 21 has a flank 29 which is substantially perpendicular to the spring blade when the latter is in the stress position and a flank 30 which is substantially parallel to the spring blade when the latter is in the stress position. Its free end 27 remains in abutment against the side 29 of a tooth 21 and the rotating sleeve is locked in position. When the force applied to the handle 11 by the user exceeds said threshold, the spring blade starts to flare and bend to reach a limit position in which the free end 27 picks up the flank 29 of the tooth 21 against which the blade spring 22 was in abutment, following its bearing against the next tooth 21, in the direction of rotation of the sleeve. This position corresponds to a limiting torque of the rotating sleeve 16 and to a maximum force that can be applied by the user to the handle 11 of the torque wrench. This position called released position is illustrated in Figure 2 and Figure 4. In addition to this main function of torque limiter, the torque wrench 10 has also a first complementary function which is that of a ratchet. This function is fulfilled when the user turns the key in the opposite direction to the one that made it possible to tighten an object, to return to the initial position. During this movement the blade or leaf springs offer little resistance to the rotation of the rotating sleeve 16 and bend during the passage of the teeth 21 one after the other.

A second complementary function is that of unscrewing key. Just turn the key 180 ° around its longitudinal axis. The free end 27 of the spring blade, (or leaf springs, for the variant with two leaf springs) blocks the side 29 of the or two teeth 21, which allows to unscrew the object. Figures 1 and 5 show the head 13 and the clamping tool 15 with two leaf springs 23 and 24 in the stress position and Figures 2 and 6 show the head 3 and the clamping tool 5 with two leaf springs 23 and 24 in the released position. The leaf springs 23 and 24 are respectively fixed on a fixed stud 33 and 34 at one of their end 36 and bear respectively against the side of a tooth 21 at their other free end 43 and 44. This position of stress is represented by Figure 1 and Figure 3.

In operation, when the operator wants to set up and tighten in position an object by means of the clamping tool 15 of the head 13, that is to say use the key for its main function, as long as the force exerted on the handle 11 and which is transmitted to the rotating sleeve 16 is smaller than a given value, the leaf springs 23 and 24 remain substantially straight. Their free ends 43 and 44 remain in abutment against the respective sides of two teeth 21 and the rotating sleeve 16 is locked in position. When the force applied to the handle 11 by the user exceeds said given value, the leaf springs begin to bend, to reach a limit position in which the free ends 43 and 44 respectively unhook from the side of the teeth 21 against which the leaf springs 23 and 24 were in abutment. This position corresponds to a threshold tightening torque of the rotating sleeve 16 and to a maximum force that can be applied by the user to the handle 11 of the torque wrench 10. This so-called released position is illustrated in FIG. 2 and FIG. .

The present invention is not limited to the embodiments described, but may undergo various modifications or variations. Torque key embodiments operating on the same principle, but having only one head equipped with one or two leaf springs could be realized. The choice of the spring blade as well as the geometry of the teeth of the peripheral wall of the rotary sleeve, make it possible to define the threshold of the tightening torque of the torque wrench.

Claims

claims

A torque wrench (10), in particular a torque wrench for fastening or loosening an object, in particular a dental implant or the like, the wrench having a handle (11) and at least one clamping tool (13, 14) integral with at least one end of said handle (11), said clamping tool being rotatable about its central axis and having an inner opening (18) limited by a faceted wall (19) adapted to the profile and dimensions of said object, characterized in that said rotary clamping tool (13, 14) comprises a peripheral wall (20) provided with teeth (21), substantially concentric with said faceted wall (19), in that said gripping sleeve (11) carries at least one spring blade (22, 23, 24) having a fixed first end (26) mounted in said gripping sleeve (11) at a determined distance from said gripping tool and a second free end (27), in support of said peripheral wall (20) provided with teeth (21), said leaf spring (22, 23, 24) being movable between a first position, said stress position, in which the second end bears against a side of one of the teeth (21) of said peripheral wall (20) of said clamping tool (13, 14), said constraint position being maintained as long as the force applied by the user on the handle (11) is less than a predetermined threshold, and a second position, said released position, in which said second end (27) has unhooked from the side of said tooth (21) of said peripheral wall of said clamping tool, following a buckling of said spring blade under the effect a force applied by the user on the handle, this force being at least equal to said predetermined threshold.

2. torque wrench according to claim 1, characterized in that said gripping handle (11) carries two leaf springs (23, 24) each having a fixed first end (26), mounted in said gripping handle at a determined distance from said clamping tool and a second free end (27), bearing against said peripheral wall (20) provided with teeth (21), said leaf springs (23, 24) being movable between a first position, said position of constraint, in which the second free end of each of said leaf springs bears against one side of one of the teeth (21) of said peripheral wall of said clamping tool, this position of stress being maintained as long as the force applied by the user on the handle is less than a predetermined threshold, and a second position, said released position, in which their second free end has respectively unhooked relative to the sides of said teeth of said peripheral wall of said clamping tool, following a buckling of said blades springs under the effect of a force applied by the user on the handle, this force being at least equal to said predetermined threshold.

3. Torque wrench according to any one of claims 1 or 2 characterized in that the handle (11) carries a head (12, 13) at each of its opposite ends, each of these heads comprising a clamping tool ( 14, 15), one of said clamping tools being equipped with a single spring blade (22) and the other clamping tool being equipped with two leaf springs (23, 24).

4. Torque wrench according to claim 1, characterized in that said at least one leaf spring (22, 23, 24) mounted at one of its ends on a fixed pad (25) in the handle of said torque wrench and having one end free is housed in a clearance formed in the handle (11) to allow the buckling of said leaf spring under the effect of a stress applied to said handle.

5. Torque wrench according to claim 4, characterized in that said at least one leaf spring (22, 23, 24) is substantially tangential to said peripheral wall (20).

6. Torque wrench according to claim 4, comprising two leaf springs, characterized in that each of the leaf springs (23, 24) comprises one of its ends mounted on a fixed stud (16) in the handle (11) of said torque wrench, said fixed studs being offset laterally with respect to each other and said leaf springs being housed in said clearance in the handle to allow the buckling of said leaf springs under the effect of a stress applied to said handle gripping.

7. Torque wrench according to any one of the preceding claims, characterized in that said clamping tool is a rotary sleeve (16) having the general shape of a cylindrical ring open on both sides so that the tool clamping can be engaged on said object by one or the other side so that the torque wrench has a ratchet function.

8. Torque wrench according to any one of the preceding claims, characterized in that said teeth (21) comprise an asymmetrical profile, one of the flanks of each of said teeth being substantially parallel to said leaf spring in the stress position and the another sidewall of each of said teeth being substantially perpendicular to said leaf spring in the stress position.