Patent Publication Number: US-10765195-B2

Title: Shoulder support for a motor

Description:
TECHNICAL FIELD 
     The present invention concerns a shoulder support for a motor. More specifically, the present invention refers to a shoulder support, of the backpack type, for a motor actuating a tool like, for example, a strimmer, a hedge trimmer, a pruner, a blower/aspirator, an atomizer or other gardening tools. 
     PRIOR ART 
     As known, in order to carry out some gardening operations, portable devices are often used. For example, to cut shrubs, bushes and grass in difficult-to-reach locations strimmers, in particular so-called shoulder-harnessed strimmers. 
     The devices of the prior art comprise a gardening tool actuated by a power group that comprises a motor connected to a shoulder support that the operator wears through shoulder straps. 
     The shoulder support foresees a back-plate fixed to the shoulder straps, and a frame for supporting the motor fixed to the back-plate. 
     The shoulder support comprises a connection body, for the connection of the motor to the frame, connected to the frame by means of at least one resilient support element that allows the oscillation of the connection body with respect to the frame itself. 
     Thanks to such a provision it is possible to limit or prevent the transmission of the vibrations of the motor to the operator. 
     However, during use of the strimmer, both with the motor operating and with the motor turned off, due to the oscillations of the motor the centre of mass of the assembly formed by the motor and the shoulder support can change and move with respect to the frame. 
     Moreover, the resilient support element of the connection body is subjected to substantial shearing stresses that can cause early wearing and breaking thereof. 
     There is therefore a need to limit the stresses acting on the resilient element so as to limit the maintenance interventions of the resilient element itself. 
     The purpose of the present invention is to provide a shoulder support for a motor having structural and functional characteristics such as to avoid the aforementioned drawback with reference to the prior art, in the context of a simple and rational constructive solution. 
     Such purposes are accomplished by the characteristics of the invention given in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention. 
     SUMMARY OF THE INVENTION 
     The invention, particularly, provides a shoulder support for a motor comprising a frame, a connection body adapted for being rigidly connected to the motor and a resilient support element adapted for connecting the connection body to the frame. 
     According to the invention, the shoulder support comprises an abutment element configured to limit an oscillation of the connection body with respect to the frame. 
     Thanks to such a solution, it is possible to limit the oscillation of the connection body (and with it of the motor) with respect to the frame improving the stability of the shoulder support and of the operator. 
     Moreover, by limiting the oscillation of the connection body with respect to the frame, the stress that acts on the resilient support element is reduced, reducing the wearing thereof and limiting the need for maintenance interventions. 
     According to an aspect of the invention, the abutment element can be configured to limit the oscillation of the connection body with respect to a substantially vertical direction. 
     In this way, it is possible to limit specific stresses acting on the resilient support element of the connection body, for example the shearing stresses. 
     In particular, thanks to such a solution it is possible to limit the stresses acting on the resilient support element that in use are accentuated by the weight force acting on the motor. 
     According to another aspect of the invention the frame can be L-shaped and can comprise a first portion (at the back and substantially vertical in use) and a second portion (substantially horizontal in use) undercut with respect to the first portion. Moreover, the connection body and the abutment element can be connected to the second portion. 
     Thanks to such a solution a shoulder support is provided of simple design and manufacture. Moreover, the abutment element is made with a robust, efficient, rational and low-cost solution, located close to the resilient support element to be limited. 
     Moreover, the second portion of the frame can comprise a through opening and the connection body can be vertically aligned with the through opening and, moreover, the abutment element can be configured to at least partially block the through opening. 
     In this way, in use, the abutment element is on the trajectory followed by the connection body during the oscillation with respect to the frame so as to effectively limit the oscillation (vertical, i.e. substantially parallel to the through axis of the opening) of the connection body itself. 
     According to a further aspect of the finding, the abutment element is fixed to the second portion of the frame on the opposite side with respect to the motor. 
     In this way the abutment element is adapted for effectively counteracting the vertical thrust due to the weight force and to the vibrations of the motor making contact with the connection body on the opposite side to the part of the connection body facing the motor without the need for structural modifications of the connection between motor and connection body. 
     According to another aspect, the abutment element can be arranged a distance from the connection body comprised between 3 mm and 6 mm. 
     In this way, it is possible to contain the size of the oscillation of the connection body below a limit value so as to avoid excessive stresses on the resilient support element. 
     According to another aspect of the invention the abutment element can comprise a plate fixed to the frame. 
     Thanks to such a solution, the abutment element is made with a robust, efficient, rational and low-cost solution. 
     According to another aspect, the plate can be equipped with a central hole. 
     In this way, it is possible for an operator to access the connection body to carry out installation and/or maintenance operations of the connection between the motor and the connection body. 
     According to a further aspect of the invention, the resilient support element can comprise a spring (or a plurality of springs). 
     In this way, the connection body is suspended in oscillation at the frame by means of simple, effective and low-cost resilient support elements. 
     A further aspect of the invention provides a power group comprising a shoulder support as described above and a motor connected to the connection body of the shoulder support. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the invention will become clearer from reading the following description provided as a non-limiting example, with the help of the figures illustrated in the attached tables. 
         FIG. 1  is a view from below of the shoulder support and of the motor group. 
         FIG. 2  is the section according to the plane II-II of  FIG. 1 . 
         FIG. 3  is an enlargement of the section according to the plane III-III of  FIG. 1 . 
     
    
    
     BEST EMBODIMENT OF THE INVENTION 
     With particular reference to such figures, a shoulder support for supporting a motor  2  adapted for actuating a gardening tool  3 , of the type known in the field, like for example a strimmer, a hedge trimmer and similar tools is globally indicated with  1 . 
     The motor  2  can be of any type adapted for the actuation of the gardening tool  3 , for example of the endothermal or electric type, and is contained in a case  20  equipped with a lower portion  21  connected to the shoulder support  1 , as will be described more clearly hereinafter. 
     Moreover, the motor  2  is equipped with a power take off  22  connected to the gardening tool  3 . 
     For the purposes of the present invention the components and the operation of the gardening tool  3  will not be illustrated in detail since they are already known by those skilled in the art. 
     The shoulder support  1  comprises a back-plate  10  for example substantially rigid, which is adapted for being associated with the back of an operator through shoulder straps  11 . 
     The back-plate  10  comprises a shaped body to come into contact with the back of the operator to which a frame  12 , for example substantially rigid, is fixed, which is adapted for supporting the motor  2 . 
     With reference to  FIG. 2 , the frame  12  is fixed to the back-plate  10  in a removable manner through engagement/disengagement means  13 , for example of the type described in European Patent EP 1 577 602 B1 to the same Applicant and referred to as a whole here for reference. 
     In practice, the engagement/disengagement means  13  are such as to allow the operator to quickly release the frame  12  and the motor  2  from the back-plate  10  when needed, for example in the case of a fire of the motor  2  itself. 
     According to other embodiments not shown, the frame  12  can be irremovably fixed to the back-plate  10 , for example not ruling out the possibility that the back-plate  10  and the frame  12  can be made in a single piece. 
     With reference to  FIG. 2 , the frame  12  is substantially L-shaped and comprises a first portion  120 , fixed to the back-plate  10 , and a second portion  121  undercut with respect to the first portion  120  and to which the motor  2  is connected at the top. 
     In particular, in use, the first portion  120  is adapted for being arranged substantially vertically (i.e. substantially parallel to the plane of the back-plate  10 ), whereas the second portion  121  is adapted for being arranged substantially horizontally (i.e. substantially perpendicular to the plane of the back-plate  10 ). 
     In the illustrated example, the frame  12  is made in a single piece, for example by moulding of plastic materials. 
     This does not rule out the possibility that in other embodiments the first portion  120  and the second portion  121  of the frame  12  can be made in separate bodies. 
     The first portion  120  of the frame  12  has a profile tapering upwards and is equipped with a lower end constrained to the second portion  121  and a free upper end for example equipped with gripping means. 
     The engagement/disengagement means  13  are for example connected in an area of the first portion  120  intermediate between the free end and the constrained end thereof. 
     The second portion  121  of the frame  12  comprises a through opening  122  with substantially vertical through axis (i.e. parallel to the plane of the back-plate  10 ). 
     The through opening  122  defines a housing seat for a connection body  14  that allows the connection of the motor  2  to the frame  12 . 
     The motor  2  is, therefore, supported by the connection body  14  substantially vertically aligned with the through opening  122 . 
     With particular reference to  FIG. 1 , the second portion  121  of the frame  12  comprises a pair of parallel and spaced prongs  123  between which the through opening  122  is defined. 
     Each prong  123  is fixed canti-levered to the first portion  120  of the frame  12  and is equipped with a first end constrained to the first portion  120  itself and a second free end. 
     In particular, in the illustrated example, the prongs  123  are constrained to one another by a curved cross member  124  fixed to the free ends of each prong  123 . 
     In practice, the prongs  123 , the curved cross member  124  and the first portion  120  of the frame  12  delimit the through opening  122  of the second portion giving them a substantially a doughnut shape, for example ogival or oval. 
     The connection body  14  is vertically aligned with the through opening  122  of the second portion  121  of the frame  12 , for example inserted with enough radial clearance inside the substantially cylindrical space defined by the through opening  122 . 
     In the illustrated example, the connection body  14  is partially received in the seat defined by the through opening  122 , i.e. it is at least partially contained in the axial bulk of the through opening  122 . 
     In greater detail, the figures illustrate the connection body  14  in a rest position in which it is at least partially contained in the axial bulk of the through opening  122  so as to project at the top with respect to an upper surface  125  of the second portion  121  of the frame  12 . 
     Moreover, in the illustrated example, the connection body  14  is arranged a non-zero distance from the plane on which a lower surface  126  of the second portion  121  of the frame  12  lies, i.e. between a lower end of the connection body  14  and the lower surface  126  of the second portion  121  of the frame  12  an interspace  127  is defined. 
     The connection body  14  is adapted for being rigidly connected to the motor  2 , in particular to the lower portion  21  of the case  20 . 
     The connection body  14  comprises a substantially conical or cylindrical central stump  140 , from which a plurality of radial projections  141  extends with respect to an axis of the connection body  14  itself passing through the central stump  140  and adapted, in use, for being arranged substantially vertically. 
     In the illustrated example the radial projections  141 , four in number, are arranged equally angularly spaced apart around the central stump  140 , and are adapted for allowing the connection of the connection body  14  to the frame  12  as will be described more clearly hereinafter. 
     In the central stump  140  of the connection body  14  a through bush (in the axial direction) is formed that is adapted for receiving a fastening pin  15  of the motor  2 . 
     The pin  15  comprises a head  150  fixed to the lower portion  21  of the case  20  of the motor  2 , and a stem  151  received in the through bush of the central stump  140 , of the connection body  14 , for example through the interposition of one or more ball bearings  152 . 
     The stem  151  of the pin  15  comprises a threaded end, opposite the head  150 , which projects at the bottom from the central stump  140  of the connection body  14  and on which a nut  153  is screwed to clamp the pin  15  to the connection body  14  itself and therefore for the rigid (firm) connection of the motor  2  to the connection body  14 . 
     The connection body  14  is connected to the frame  12  by means of at least one resilient support element configured to support, in a floating manner, the connection body  14  with respect to the frame  12  inside the housing seat defined by the opening  122 , and to allow an oscillation of the connection body  14  itself with respect to the frame  12 . 
     For example, the connection body  14  is connected to the frame  12  by means of at least one spring  16 . 
     In particular, in the illustrated example, the connection body  14  is connected to the frame  12  by means of a plurality of springs  16 , for example helical, arranged with radial axis with respect to the connection body  14  itself. 
     The springs  16  are arranged equally spaced apart and with axis substantially perpendicular to the axis of the connection body  14 . In other words, the axes of the springs  16  lay on a plane that in use is adapted for being arranged substantially transversally to a vertical direction. 
     Each spring  16  comprises a first end fixed to the frame  12  and a second end fixed to the connection body  14 . 
     In particular, in the illustrated example, each first end of the springs  16  is fixed to the second portion  121  of the frame  12  at an inner wall of the through opening  122  (for example through threaded attachment members), and each second end of the springs  16  themselves is fixed to a respective radial projection  141  of the connection body  14 . 
     The springs  16  are configured to allow the oscillation (floating) of the connection body  14  substantially along any direction. 
     For example, the springs  16  are configured to allow the oscillation of the connection body  14  along any direction substantially perpendicular to the axis of the connection body  14 , i.e. a direction parallel to the plane in which the axes of the springs  16  themselves lie (in which the springs  16  are mainly biased by traction/compression). 
     In particular, the springs  16  are configured to allow the oscillation of the connection body  14  along a substantially vertical direction, i.e. substantially transversal to the axes of the springs  16  themselves (in which the springs  16  are biased mainly by shearing as well as by traction/compression). 
     In greater detail, the springs  16  are configured so as to allow a vertical oscillation of the connection body  14  that extends below the plane of the lower surface  126  of the second portion  121  of the frame  12 . 
     In other words, the springs  16  are configured so that during the oscillation of the connection body  14  with respect to the frame  12 , the interspace  17  is cancelled (disappears, i.e. becomes of zero axial thickness) and the connection body at least partially projects beyond the plane of the lower surface  126  of the second portion  121  of the frame  12   
     The shoulder support  1  also comprises at least one abutment element connected to one from the connection body  14  and the frame  12  and configured to limit the oscillation of the connection body  14  with respect to the frame  12 . 
     In particular, the abutment element is configured to limit the oscillation of the connection body  14  along a substantially vertical direction, i.e. substantially transversal to the axes of the springs  16 . 
     In practice, in use, the abutment element is configured to limit the oscillation of the connection body  14  in a vertical direction, for example coinciding with the direction of the weight force acting on the motor  2 . 
     In the illustrated example, the abutment element comprises a plate  17  fixed to the frame  12 , in particular to the second portion  121  thereof. 
     In greater detail, the plate  17  is fixed to the second portion  121  so as to be vertically aligned with the through opening  122  and so as to be arranged, in use, along the trajectory followed by the connection body  14  during the oscillation with respect to a substantially vertical direction. 
     In practice, the plate  17  is arranged so as to partially block the through opening  122 . 
     Moreover, the plate  17  is fixed below the second portion  121  of the frame  12  on the side, i.e. on the opposite side with respect to the motor  2 , so that the connection body  14  is arranged between the plate  17  and the motor  2 . 
     In other words, the plate  17  is fixed to the lower surface  126  of the second portion  121  of the frame  12 . 
     In the illustrated example, the plate  17  is arranged substantially zero distance from the lower surface  126  of the second portion  121  of the frame  12  and thus is separated from the connection body  14  by the interspace  17 . 
     The plate  17  is arranged a minimum distance from the connection body  14  comprised between 3 and 6 mm, for example 4.4 mm; such a distance is defined with respect to a rest position of the connection body  14  taken up by it when the motor  2  is turned off and/or when the motor  2  is released from the connection body  14  itself. 
     In other words, when the motor  2  is turned off and/or when the motor  2  is released from the connection body  14  the axial dimension of the interspace  127  (i.e. along a direction parallel to the axis of the through opening  122 ) is comprised between 3 and 6 mm, for example 4.4 mm. 
     The plate  17  is shaped like a circular ring comprising a plurality of radial appendages  170  that allow the attachment to the frame  12 . 
     In the illustrated example, the radial appendages  170 , of which there are three, are equally angularly spaced apart so as to cover a straight angle overall, and are respectively fixed to the prongs  123  and to the curved cross member  124  of the second portion  121  of the frame  12 . 
     The radial appendages  170  are adapted for being fixed to the (lower surface  126  of the) second portion  121  of the frame  12  by means of suitable fastening members  172 . 
     In particular, the fastening members  172  are of the releasable type like for example threaded members. 
     According to other embodiments, the plate  17  could be fixed to the frame  12  in a removable manner, for example it could be made in a single body with the frame  12 . 
     The plate  17  also comprises a central through hole  171 , equipped with an axis substantially parallel to the axis of the through opening  122 , which allows access to the connection body  14 . 
     The central hole  171  of the plate  17  is arranged coaxial to the connection body  14 , for example to the pin  15  and has for example a greater diameter than the maximum diameter of the nut  153  so as to allow access to the connection body  14  by an operator, in particular to allow the attachment of the nut  153  to the pin  15 . 
     According to other embodiments that are not illustrated, the abutment element could comprise at least one body, for example a resilient buffer, fixed to the upper surface  125  of the second portion  121  of the frame  12 , i.e. on the same side as the motor  2  with respect to the frame  12 , so as to be arranged between the frame  12  itself and the motor  2 . 
     Moreover, according to other embodiments that are not illustrated, the abutment element could be fixed at the top to the connection body  14 , for example so as to project above the upper surface  125  of the second portion  121  of the frame  12  (i.e. arranged between the motor  2  and the connection body  14 ) and go into abutment with it during the oscillation of the connection body  14 . 
     The invention thus conceived can undergo numerous modifications and variants, all of which are covered by the inventive concept. 
     Moreover, all of the details can be replaced by other technically equivalent elements. 
     In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to requirements without for this reason departing from the scope of protection of the following claims.