FR2846267A1 - Automatic engagement device for dynamometric tightening key comprises independent lever arms connected by pressure driving system and inclined zone enabling automatic placing of arms into initial position after disengagement - Google Patents

Abstract

The automatic engagement device (1) for a dynamometric tightening key (2) comprises two independent lever arms (5,8) connected together by a pressure driving system (9). There is an inclined zone (6) enabling the automatic placing of the lever arms into their initial use position when they are disengaged after having exceeded a certain tightening torque.

Description

i The present invention relates to an automatic interlocking device

  for torque wrench.

  This device is an improvement on the current system used in the design of torque wrenches usually of small dimensions, but which could be of larger dimensions. These tightening keys generally consist of a main axis comprising at one end the imprint of the screw or nut to be driven in rotation. This axis has a lever arm, generally located approximately in the middle of its

  length, constituted by a beam fixed integrally to the main axis or forming an integral part of this axis by forming a generally right angle with this axis.

  A second lever arm, located above the first and which generally

  an integral part of the handle of the key is free to rotate about the main axis.

  This second arm allows the main axis to be rotated thanks to

  a point connection with the first lever arm secured to the main axis.

  This temporary link allows the main axis to rotate.

  up to a certain drive torque beyond which the drive is broken.

  This connection is generally constituted by an adjustable pressure device, for example a screw comprising at its end a ball or a nozzle maintained

  in contact pressure on the first arm by means of a compressed spring of adjustable force 20.

  One can imagine any other means of connection between the two arms such as mechanical stops, magnetic, elastic or adhesive connections, etc. When the second lever arm is rotated, it therefore transmits a rotational movement to the main axis by driving the first arm to which it is connected by the connection device. When a certain value of drive torque is reached, the linkage device whose contact force between the two arms, previously set, is exceeded, dissociates and indicates to the user that the

  desired setting value has been obtained.

  Such keys are usually used to adjust the tension of the skins of percussion musical instruments such as snare drums, drums or any other instrument using this tension mode. Of course, such keys

  could be used in any other field of application.

  The disadvantage of existing keys is that the user must switch on, that is to say put the two lever arms back in connection when they are detached in order to be able to use the key again. This is done manually, which forces the user not to forget it, otherwise the system

becomes inoperative.

  These repeated manual interlockings also make it possible to lose a considerable amount of time when re-tuning an instrument for example.

  The invention consists in remedying the problem of engaging the key

  dynamometric by proposing a system operating automatically.

  Thus, according to the invention, the device for engaging the dynamometric tightening keys is characterized in that it comprises means making it possible to automatically return the key to the initial position after it has been triggered when the drive torque has been exceeded. The engagement is then carried out

  automatically as soon as the training effort is released.

  It is composed according to a first characteristic of a lever integral with the axis of rotation whose surface of this lever in contact with the presser drive device 25 has an area inclined relative to the axis of said device. Thus, when the selected training effort exceeds the resistance of the system

  drive, the two lever arms disengage away from each other.

  Previously, the drive pressure system was then in the position of

  rest, by removing contact between the two arms.

  According to the preferred embodiment, the end of the drive system which usually consists of a ball kept under pressure by a spring is then forced to follow the inclined area when the trigger point has been reached. The angle of this contact surface is such that when the user releases the manual rotational drive effort, this results in a sliding force.

  opposite preventing the ball from remaining in a fixed position on this sloping area. 10 This force automatically reposition the ball in the initial position.

  Other characteristics and advantages of the invention emerge from the description

  following with reference to the appended drawings which are given only by way of nonlimiting examples.

  Figures 1 to 5 illustrate a first embodiment of the invention.

  Figure 1 is a complete view of the key in perspective.

  Figure 2 is a drawing of the key seen from the side of the drive device.

  Figure 3 shows the pressure system in the drive position.

  Figure 4 shows the pressure system in the breaking position

  drive, when the ball has escaped from its housing.

  Figure 5 is a perspective view of the main axis with the lever arm

integral with this axis.

  Figures 6 to 8 show an alternative embodiment of the system object of the invention.

  Figure 6 is a view of the complete key in section of this variant.

  Figure 7 is a view of the pressure system of this variant in the drive position. Figure 8 is a view of the pressure system in the drive-out position when the ball has escaped from its housing. Figures 9 and 10 show an alternative embodiment of the pressure system. Figures 11 to 16 show another embodiment of the object system

of the invention.

  Figures 11 and 12 show the spring-loaded drive system

  of traction to return to the initial position.

  Figures 13 and 14 show the same system equipped with compression spring.

  Figures 15 and 16 show the same system equipped with elastic leaf spring 15 for the return to the initial position.

  With reference to these drawings, the invention relates to an automatic engagement device (1) for a torque wrench (2) This key (2) consists of an axis

  main (3) comprising at its end (4) the imprint or the shape of the screw or nut to be rotated in order to tighten or loosen them to an adjustable tightening torque.

  This main axis (3) comprises, approximately located at half of its length, an integral lever arm (5) generally forming a right angle with this axis, and the end of which comprises an inclined surface (6) relative to the horizontal. On this inclined surface is produced a hollow form (13) in which is housed

  the end (12) of the drive system.

  On the main axis (3) is assembled a drive handle (7) free to rotate on this axis and comprising a lever arm (8) equipped with the drive system with adjustable pressure force (9). This system (9) generally consists of an assembly composed of a screw (10), a compression spring (11) and a ball (12). The more the screw (10) is turned in the direction which brings it closer to the surface (6), the more the spring (11) compresses and

  transmits greater force on the ball (12).

  By turning the screw (10) in the other direction, on the contrary the force decreases because the spring (11) relaxes. Thus the ball (12) is maintained in more or less strong pressure in the hollow form ( 13) which creates the connection between the two lever arms (5) and (8) and allows the axis (5) to be rotated when the user turns the drive handle (7) When the tightening torque reaches a value greater than the resistance of the pressure system, the ball (12) compresses the spring (11) and escapes from the form

  hollow (13), which separates the two lever arms (5) and (8).

  By inertia, the ball (12) is then in contact with the inclined surface (6) which informs the user that the system has been triggered. This indication materializes by the sensation in the hand of the relaxation of the rotary drive which is accompanied by a perceptible noise caused by the ball (12) which escapes from

  its support position in the hollow form (13).

  The user then releases the rotational force on the drive handle and therefore, the pressure exerted on the ball (12) by the compressed spring (11) 25 causes it to slide over the sloping area (6) and returns it to the initial drive position in the hollow form (13). Interlocking therefore takes place from

  automatically when the user releases the rotation effort.

  According to another embodiment (Figures 6,7 and 8), the drive system consists of a screw + spring + ball (9) assembly which is fixed and not adjustable on a

lever arms.

  In this case, conversely, the hollow form (13) is produced on a movable part (16) and it is this which allows the pressure adjustment on the ball (12) while approaching or moving away from the latter. This movable part (16) has an inclined surface (6) around the hollow form (13) allowing, as before, the return

  automatic ball (12) to its initial drive position.

  Whatever the embodiment, it is necessary to add 10 movement limitation stops (18) to the device so that the ball (12) does not escape from the

inclined surface.

  According to another embodiment (Figures 9 and 10), the drive system does not have a hollow shape on the inclined area (6) to receive the ball (12). In this case, in the driving position, the ball (12) is in contact with the edge of the lever arm (5) making abutment against this arm which allows its training when the user turns the handle (7 ). As soon as the drive torque reaches a value greater than the resistance of the pressure system, the ball (12) rises on the inclined zone (6) by compressing the spring (11) which separates the two arms

lever (5) and (8).

  The user then feels the triggering of the device and releases the training effort, which allows the ball to return to the initial position and the engagement

  automatic device as before.

  According to another embodiment, the automatic engagement of the device

  can be obtained by a spring system operating in tension (Figures 11 and 12), in compression (Figures 13 and 14) or by elastic deformation (Figures 15 and 16).

  Of course, the invention is not limited to the embodiments described and shown by way of examples, but it also includes all the equivalents

  techniques and their combinations.

Claims (8)

  1. Interlocking device (1) for a torque wrench (2) comprising two independent lever arms (5) and (8) interconnected by a drive pressure system (9), characterized in that it includes means making it possible to automatically return the two lever arms (5) and (8) to the initial position of use as soon as these two arms have separated after tripping of the connection system (9) due to the overshoot of its resistance to a certain couple of pre-set tightening.   2. Automatic engagement device (1) for a dynamometric tightening key (2) according to claim -1- characterized in that it comprises an inclined zone (6) on one of the two lever arms (5) or (8) or on an element of these two arms which allows the pressure system (9) to be in contact with this inclined zone (6) when the key is released and the two arms (5) and (8) are dissociate. 3.Automatic engagement device (1) for a torque wrench (2) according to claim -2- characterized in that the pressure system (9) slides over the inclined area (6) to return automatically to its   initial training position when the user releases the rotational force.   4.Automatic engagement device (I) for torque wrench   (2) according to claim -1- characterized in that the connection system (9) returns to the initial position by means of tension springs (19) after tripping.   5.Automatic engagement device (1) for a torque wrench (2) according to claim -1- characterized in that the connection system (9) returns to the initial position by means of compression springs (20) after tripping . 6.Automatic engagement device (1) for a torque wrench (2) according to claim -1- characterized in that the connection system (9)   returns to the initial position by means of an elastic element (21) after tripping.   7.Automatic engagement device (1) for a torque wrench (2) according to claims 1 to 6 characterized in that its operation   produces a sensation in the user's hand accompanied by a perceptible noise,   which indicates that the trip has been completed.   8.Automatic engagement device (1) for a torque wrench (2) according to claims 1 to 7 characterized in that it comprises stops movement limitation (18).