Abstract:
The invention relates to a portable device ( 1 ) for amplifying an axial force applied to a tool, which includes: means ( 100 ) for linking the device to a user; means ( 2 ) for guiding the tool ( 4 ) it translation along a longitudinal axis (X); means for actuating the tool, including a drain ( 5 ) provided with a motor ( 6 ) and a rope ( 7 ) rigidly connected to the tool ( 4 ) and forming at least one turn ( 8 ) around the drum ( 5 ); and means for controlling the actuating means in order to apply a force to the tool in response to a force provided by the user via a control member. The means ( 100 ) for linking, tile device to the user and the means ( 2 ) for guiding the tool ( 4 ) in translation allow the tool ( 4 ) to rotate freely about the longitudinal axis (X) and about at least one axis (Z, Y) extending in a plane (P) which is normal to the longitudinal axis (X).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the field of force amplifiers, and more specifically to portable force amplifiers applied to operations on construction sites and/or civil engineering sites. 
       BACKGROUND TO THE INVENTION 
       [0002]    Devices for amplifying force comprising a horizontal frame which is fixed to a wall of a building and which carries an arm extending in a vertical direction are already familiar. The lower extremity of the arm includes an interface for receiving a tool such as a drill, a screw-driver or a riveter. The user operates the device by actuating a control unit provided with a vertical force sensor. When the device for amplifying force detects a vertical control force on the sensor, it then controls an actuator (generally a jack) in such a way as to apply a vertical force to the tool that is proportional to the force applied to the control unit. 
         [0003]    Also familiar from document WO2012/149402 is a device for amplifying a lifting force comprising a tracked platform supporting a lifting arm operated by a user. A suchlike device permits the easy amplification of a vertical force, but it is ill-adapted to the amplification of forces comprising a majority horizontal component. 
         [0004]    The implementation of civil engineering works such as rafts, roads or even building slabs frequently requires a product (concrete, bitumen, etc.) to be “drawn” with the aid of a rake with the aim of leveling its surface. Such-like movements place demands on the back and the arms of the operators and are a source of numerous traumas and industrial accidents. The variable direction of the force (the inclination of the rake in relation to the ground changes as its movement progresses) does not allow the adaptation of the amplifiers of mono axial forces that are familiar to a suchlike application. 
         [0005]    No device exists, therefore, which allows the force to be applied to a rake to be supplemented, at least partially, and which allows rapid movement of the user as the task of raking proceeds. Finally, the entirety of the known force amplifiers contain delicate mechanisms (control unit, actuators) which are not adapted to the particularly challenging conditions encountered when working on a construction site. 
       OBJECT OF THE INVENTION 
       [0006]    The invention has as its aim to reduce the forces to be provided by an operator during on-site raking operations while maintaining the satisfactory mobility of the operator in the course of these operations. 
       SUMMARY OF THE INVENTION 
       [0007]    For this purpose, a portable device is proposed for amplifying an axial force applied to a tool, comprising: 
         [0008]    means for linking the device to a user; 
         [0009]    means for guiding the tool in translation along a longitudinal axis; 
         [0010]    means for actuating the tool along the longitudinal axis comprising a drum provided with a motor and a rope rigidly connected to the tool and forming at least one turn around the drum; 
         [0011]    means for controlling the actuating means for applying an assistance force to the tool in response to an actuating force provided by the user via a control unit; 
         [0012]    wherein the means for linking to the user and the means for guiding the tool in translation allow the tool to rotate freely about the longitudinal axis and about at least one axis extending in a plane which is normal to the longitudinal axis. 
         [0013]    Thus, the device makes it possible to assist the operation of a tool such as a rake, both when being pulled and when being pushed, while maintaining the degrees of freedom necessary for the accomplishment of the raking tasks. The motorization with the aid of a drum driving a rope is robust, simple, light and economical, while at the same time guaranteeing a reliable transmission of force. 
         [0014]    The invention also applies to a lower exoskeleton provided with a device for the amplification of force according to the invention. 
         [0015]    Other characterizing features and advantages of the invention will be appreciated from a perusal of the following description of particular non-restrictive embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Reference is now made to the accompanying figures, in which: 
           [0017]      FIG. 1  is a schematic representation in a perspective view of a first embodiment of an amplifying device according to the invention; 
           [0018]      FIG. 2  is a detailed schematic view of a force sensor of the amplifying device in  FIG. 1 ; 
           [0019]      FIG. 3  is a partial schematic representation in a perspective view of a second embodiment of the invention; 
           [0020]      FIG. 4  is a schematic plan view of the device in  FIG. 3 ; 
           [0021]      FIG. 5  is a schematic representation in plan view of a third embodiment of the amplifying device according to the invention; 
           [0022]      FIG. 6  is a detailed view of the device in  FIG. 5 ; 
           [0023]      FIG. 7  is a schematic representation in a perspective view of the device in  FIG. 5 ; 
           [0024]      FIG. 8  is a schematic representation in a perspective view of a fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    With reference to  FIGS. 1 and 2 , the amplifier device, generally designated as 1, is mounted on a belt  100  intended to be worn by the user and comprises: 
         [0026]    a semi-cylindrical gutter  2  for guiding the handle  3  of a rake  4  in translation along a longitudinal axis X; 
         [0027]    a drum  5  driven in rotation by a motor  6  about an axis Z, in this case horizontal; 
         [0028]    a rope  7  making three turns  8  around the drum  5  and of which the two extremities  7 . 1  and  7 . 2  are connected to the handle  3  of the rake  4 ; 
         [0029]    a cylindrical control sleeve  9  extending around the gutter  2  and the handle  3  which rests thereon. 
         [0030]    The sleeve  9  is connected to a force sensor  10  measuring the longitudinal force applied along the axis X to the sleeve  9 . The force sensor  10  transmits to a processing unit  11  an electrical signal that is proportional to the measured force and to its direction via a rope  12  wound around an idler pulley  13  mounted on the drum  5 . As can be seen in  FIG. 1 , the longitudinal axis X extends substantially perpendicularly to the axis Z of rotation of the drum  5 . 
         [0031]    The force of assistance in translation of the handle  3  of the rake  4  along the axis X may thus be controlled by the application of a torque to the motor  6  triggered by a displacement of the control sleeve  9 . The displacement of the control sleeve  9  being proportional to the control force exerted axially thereon, the assistance force exerted on the handle  3  of the rake  4  is thus dependent on the control force. Depending on whether the sleeve  9  is pulled from the extremity of the tool towards the drum (arrow  14  in  FIG. 1 ) or whether the sleeve  9  is pushed (arrow  15  in  FIG. 1 ), the force of the motor on the rake  4  is a push (rotation of the drum  5  in the direction  16 ) or a pull (rotation of the drum  5  in the direction  17 ). 
         [0032]    The rake  4  remains easy to operate because the following degrees of freedom are left free within amplitudes that are compatible with the tasks to be performed, being substantially equal to [−45°; +45°]: 
         [0033]    rotation of the rake  4  about the longitudinal axis X (represented by the arrow  18  in  FIG. 1 ); 
         [0034]    rotation of the gutter  2  and thus of the rake  4  about the axis Z of rotation of the drum  5  (represented by the arrow  19  in  FIG. 1 ); 
         [0035]    rotation of the gutter  2  and thus of the rake  4  about an axis Y perpendicular to a plane P tangent to the drum  5  at its point of contact with the gutter  2  (represented by the arrow  20  in  FIG. 1 ). 
         [0036]    The axes Y and Z are perpendicular to one another and extend in a plane which is normal to the longitudinal axis X. 
         [0037]    The gutter  2  may be coated advantageously with a coating made of Teflon facilitating the sliding of the handle  3  of the rake  4 . 
         [0038]    In operation, the user puts on the belt  100  in such a way that the drum  5  is situated in proximity to one of his hips. The user grasps the sleeve  9  with one hand, and the other hand may or may not grasp the gutter  2 . The hand holding the sleeve  9  as well as the other hand, as the need arises, exerts guiding forces in the plane which is normal to the axis X. When he wishes to move the rake  4  along the longitudinal axis X, the user exerts a control order in the form of a force  21  applied to the sleeve  9 . The processing unit  11  detects the direction and the intensity of the control force  21  applied to the sleeve  9  and then controls the motor  6  in order to apply a working torque  22  to the drum  5 . The direction and the intensity of the working torque  22  are dependent on the direction and the intensity of the force  21  exerted on the sleeve  9 . The operator remains in control of the position of the rake  4  along the axis X, as in all the other directions, since the drum exerts a sliding force although it is not subject to a position or a given trajectory. 
         [0039]    With reference to  FIG. 2 , one particular embodiment of the force sensor  10  is now described in detail. The sensor  10  comprises a parallelepipedic index  30  that is integral with the sleeve  9  and is slidably mounted in relation to the gutter  2 . The index  30  slides on a resistive track  31  that is rigidly connected to the gutter  2 , and of which one extremity is connected to a first strand  12 . 1  of the rope  12 . A second strand  12 . 2  of the rope  12  is connected to a stylus  32  that is rigidly connected to the index  30 , and of which one extremity comes into contact with the track  31 . The index  30  is connected by a first spring  33  to a point  34  on the gutter  2  situated in proximity to a first extremity  9 . 1  of the sleeve  9 . The index  30  is also connected by a second spring  35  to a second point  36  on the gutter  2  situated in proximity to a second extremity  9 . 2  of the sleeve  9 . 
         [0040]    When the user pulls or pushes on the sleeve  9 , he causes the length of the resistive track  31  extending between the stylus  32  connected to the rope  12 . 1  and the extremity of the resistive track  31  connected to the strand  12 . 1  to vary. The resistance measured between the strands  12 . 1  and  12 . 2  makes it easy to determine the value and the direction of displacement of the sleeve  9 . The respective rigidities K 33  and K 35  of the springs  33  and  35  thus permit the intensity of the force exerted on the sleeve  9  to be deduced. This force sensor  10  has proven to be particularly robust and not at all sensitive to the conditions of humidity, dust and impacts that are encountered on construction sites. 
         [0041]    A second particular embodiment of the invention will now be described with reference to  FIGS. 3 and 4 . In this embodiment, the handle  3  of the rake  4  is maintained in the gutter  2  by a dolly  40 . As can be seen in  FIG. 4 , the dolly  40  is rotatably mounted on a shaft  41  parallel to the axis of rotation Z of the drum  5 . The shaft  41  is slidably mounted at its two extremities  42  and  43  respectively on two rods  44  and  45 . The respective extremities  46  and  47  of the rods  44  and  45  are rotatably mounted about the axis Z of rotation of the drum  5  on bearings  56  and  57 . The shaft  41  comprises two abutments, bearing against which are springs  48  and  49  to return the dolly  40  towards a central position. These springs  48  and  49  also allow a translation of the dolly  40  in the direction of the axis Z, in particular in order to assist the winding and the unwinding of the turns  8  on the drum  5 . Springs  50  and  51  respectively bearing against the extremities  52  and  53  of the rods  44  and  45  opposite the extremities  46  and  47  maintain the dolly  40  in contact with the handle  3 . The bearings  54  and  55  of the drum  5  as well as the bearings  56  and  57  of the rods  44  and  45  are integral with a support  58  that is rotatably mounted about a substantially vertical side  60  of a spring-assisted deformable balancing parallelogram  61 . The side  62  of the parallelogram  61  parallel to the side  60  is rotatably mounted about a substantially vertical axis that is rigidly connected to the belt  100 . The balancing of the parallelogram  61  is achieved with the aid of a spring  63  extending between two opposite corners  64  and  65  of the parallelogram  61 . 
         [0042]    When he puts on the belt  100 , the user is freely able to adjust the height of the amplifier device  1 , while maintaining the following degrees of freedom: 
         [0043]    rotation of the handle  3  of the rake  4  about the longitudinal axis X; 
         [0044]    rotation of the gutter  2  and thus the rake  4  about the axis Z of rotation of the drum  5 ; 
         [0045]    rotation of the structure  58  about the vertical side  60  of the parallelogram  61 . 
         [0046]      FIGS. 5 to 7  represent an embodiment in which the dolly  40  is replaced by a bogie  70  comprising two dollies  40 , thereby ensuring improved guiding of the handle  3  in the gutter  2 . In this embodiment, the side  62  of the parallelogram  61  is rotatably mounted about a substantially vertical axis that is integral with a backing plate  110  of a harness  111 . The use of the harness  111  permits better distribution of the forces on the user, more particularly the vertical forces and the torques. 
         [0047]    With reference to  FIG. 8 , the amplifying device  1  is integrated into a lower exoskeleton  80 . The lower exoskeleton  80  comprises two lower members  81  and  82  extending respectively in a plane parallel to the right leg  110  and a plane parallel to the left leg  111  of the user. The lower member  81  is articulated on a segment of hip  83  and comprises a segment of thigh  84  articulated on a segment of tibia  85 , at the extremity of which is articulated a foot  86  on which the foot  112  of the user is fixed. The articulations between the segments of hip  83 , the segment of thigh  84  and the segment of tibia  85  are motorized and controlled by a processing unit  87  of the lower exoskeleton  80 . The lower segment  82  comprises in a homologous manner a segment of thigh  88  articulated on the one hand on the segment of hip  83  and on the other hand on a segment of tibia  89 , at the extremity of which is articulated a foot  90  on which the foot  113  of the user is fixed. In the embodiment represented in  FIG. 6 , the sleeve  9  receives a handle  9 . 3  permitting the user not to have to bend over in order to actuate the sleeve  9 . 
         [0048]    The processing unit  87  controls the motorizations of the articulations of the lower exoskeleton  80  depending on the movements of the legs  110  and  111  of the user and on the information received by the processing unit  11  of the amplifying device  1 . The processing unit  87  is thus able to arrange the blocking—or the application of balancing forces calculated by the processing unit  87 —of a single lower member or the two lower members  81  and  82  during actuation of the rake  3  in order to relieve the stresses on the legs and the back of the user. 
         [0049]    The expression rope is used here to designate a flexible component of solid or tubular section having a circular, flat or other form, with the ability to be made up of sub-elements that are articulated with one another, for example a chain or a belt. 
         [0050]    Of course, the invention is not limited to the embodiments described above, but encompasses any variant falling within the scope of the invention as defined by the claims. 
         [0051]    In particular, 
         [0052]    although the amplifying device is mounted on a belt or a harness comprising a backing plate in this case, the invention is applicable to other means for linking to a user, for example a harness lacking a backing plate, braces or possibly a second handle rigidly connected to the trough; 
         [0053]    although the rake is guided in translation by a semi-cylindrical trough in this case, the invention also applies to other means for guiding in translation, for example a plurality of coaxial sliding bushes, one or a plurality of pins in a slide or a trough of triangular or some other form; 
         [0054]    although the translation of the handle of the rake relative to the trough is assured by friction on a coating having a low coefficient of friction in this case, the invention also applies to other means of sliding, for example pulleys or rollers, that are integral with one or the other of the handle and the trough; 
         [0055]    although the device has been described in relation to the actuation of a rake in this case, the invention also applies to other types of tools, for example a scraper, a roller or a float; 
         [0056]    although the axis of driving of the drum is horizontal in this case, the invention also applies to actuating means comprising a drum of which the axis is oriented differently, for example an axis that is vertical or oriented in any direction; 
         [0057]    although the rope makes three turns around the drum in this case, the invention also applies to a different number of turns, for example a single turn, two turns or more than three turns; 
         [0058]    although the control of the actuating means is exerted by the user on a sleeve in this case, the invention also applies to other types of means of control, for example a handle, a rotary knob or a joystick; 
         [0059]    although the sensor of force is of the resistive type in this case, the invention also applies to other means for the detection and/or measurement of a force applied to a control, for example a deformation gauge, an optical sensor facing towards a segmented track, a rope connected to an incremental rotary encoder. The sensor may transmit the information either by wire or wirelessly, for example according to a Wi-Fi or Bluetooth protocol; 
         [0060]    although the index of the force sensor is moved back into position with the aid of springs in this case, the invention also applies to other types of elastic means, for example elastomer blocks, Belleville washers, one or a plurality of gas springs; 
         [0061]    although the control of the motorization of the drum is performed by a processing unit in this case, the invention also applies to other means for control, for example a three-way hydraulic or pneumatic valve or an electric speed variator.