Abstract:
A device ( 15 ) for slowing the movement of a door ( 2 ) urged by unidirectional thrust means ( 4 ), including a casing ( 17 ) fixable to a structure (S) and defining a chamber ( 18 ) filled with a viscous fluid, and a rotor ( 31 ). The rotor ( 31 ) includes a disc portion ( 32 ) and a shaft portion ( 33 ) protruding through the lid ( 21 ) of the casing ( 17 ) in such a way as it can be associated with the door ( 2 ). The base surface ( 23   a ) of the chamber ( 18 ) has a recess ( 51 ) operable to house a pivotable arm ( 52 ). The arm ( 52 ) has a pin portion ( 54 ) protruding into the chamber ( 18 ). The lower surface ( 62 ) of the disc portion ( 32 ) of the rotor ( 31 ) has a groove ( 70 ) for engaging the pin portion ( 54 ) of the arm ( 52 ). At one end ( 73 ), the groove ( 70 ) has a cam ( 76 ) dividing it into a return path ( 75 ) and a forward path ( 74 ) for the pin portion ( 54 ) so as to define a locking position for the rotor ( 31 ) in cooperation with the thrust means ( 4 ).

Description:
This is a National Stage entry of International Application PCT/IT2003/000535, with an international filing date of Sep. 8, 2003, which was published as WO 2004/085777 A1, and the complete disclosure of which is incorporated into this application by reference. 
   BACKGROUND OF THE INVENTION 
   A device for slowing the movement of a door, drawer or similar movable member, having releasable locking means. 
   The present invention relates to a device for slowing the movement of a door, drawer or similar member which is movable with respect to a fixed structure and urged by unidirectional thrust means. 
   The present invention relates to a device for slowing the movement of a door, drawer or similar member which is movable with respect to a fixed structure and urged by unidirectional thrust means, of a type described in the preamble to Claim  1 . 
   A device of this type is known from British Patent Application GB-A 2 062 933 and is normally used to smooth the movement of a slidable drawer caused by spring means, as used in certain types of ashtray fitted in the dashboard of motor vehicles, or of pivoted doors, of a type used, for example in tape recorder apparatus. 
   It is also known that such drawers or doors often have latch closure means which are released by a light pressure on the drawer, so that pressure is used to carry out both opening and closing operations. 
   The document U.S. Pat. No. 4,893,522 describes a rotary damper including a cylindrical rotor, a casing with a shaft for insertion into the cylindrical rotor and a cylindrical wall enclosing this shaft, with a viscous fluid between the inner surface of the cylindrical rotor and the casing shaft. A spiral spring is fitted between the cylindrical wall of the casing and the outer surface of the rotor and is wound up by the rotation induced by an applied torque. This device has incorporated latch closure means, including an excursion groove formed either in the inner surface of the casing lid or in an end surface of the cylindrical rotor and having a heart-shaped cam groove at one end and an operating pin either provided on the lid or on the cylindrical rotor, operable to slide along the groove. 
   The document EP-A-0 199 242 describes a device in which the latch closure means include a sphere engaged in a rectilinear groove, formed in the lateral surface of the stator, and urged by a shaped groove formed in the lateral wall of the rotor and having a cam defining a forward path and a return path for the sphere. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is a device for slowing the movement of a door or drawer of a compact type, having the characteristics defined in the Claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A few preferred but non-limitative embodiments of the invention will now be described with reference to the appended drawings, in which: 
     A preferred but non-limitative embodiments of the invention will now be described with reference to the appended drawings, in which: 
       FIG. 1  is a longitudinally sectioned view of the structure of the door of a tape recorder incorporating a slowing device according to the invention; 
       FIG. 2  is a longitudinally sectioned view of an embodiment of a slowing device according to the invention; 
       FIG. 3  is a plan view of a component of the device of  FIG. 2 ; 
       FIG. 4  is a section of the slowing device of  FIG. 2  taken on the line IV-IV of  FIG. 3   
       FIG. 5  is a plan view of another component of the device of  FIG. 2 ; and 
       FIGS. 6-14  are plan views illustrating the operation of the slowing device of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1 , numeral reference  2  designates a door, for example, the door of a tape recorder, pivoted about a hinge  3  fixed to the structure S of this recorder, while  4  indicates a spring which urges the door into its open position. A curved rack  6 , the centre of curvature of which coincides with the pivot axis of the door  2 , is secured to this door. A slowing device  15  of the invention is also secured to the structure S of the recorder, with a rotatable pinion  16  arranged so as to engage the teeth of the rack  6 . 
   With reference to  FIG. 2 , the device  15  substantially includes a casing  17 , defining internally a substantially cylindrical chamber  18  open at one end, and having a pair of lateral extensions  19  in which through holes  19   a  are formed for engaging fixing means  19   b  (shown in  FIG. 1 ) such as screws, rivets and the like for rigidly securing these extensions  19  to the structure S of the recorder, with the pinion  16  engaged with the rack  6 . The open end of the cylindrical chamber  18  is adapted to be closed by a lid  21  which is fixed to the casing  17  so as to provide a fluid tight seal, for example by gluing or welding. The lid  21  has a central through-hole  22 . The base  23  of the cylindrical chamber  18 , corresponding to the base of the casing  17 , has a pin portion  24  which projects axially from the centre of the base  23  of the chamber  18  inwardly thereof. 
   The device  15  also includes a rotor  31  housed in the chamber  18 . The rotor  31  includes a disc portion  32 , rotatable inside the casing  17 , and a shaft portion  33  which extends axially from the centre of the disc portion  32  and protrudes from the lid  21  of the casing  17 , passing through the central hole  22 . The free end  33   a  of the shaft portion  33  of the rotor  31  is arranged so the pinion  16  can be mounted thereon. The rotor  31  also has a central hole  34 , formed in the base of the disc portion  32  for enabling the rotor  31  to be mounted on the pin portion  24  of the casing  17  and providing thereby an axis of rotation for the rotor. 
   The chamber  18  is filled with a highly viscous fluid of a known type, in such a way that the rotor  31  is fully immersed. The fluid tight seal at the central hole  22  is ensured by an O-ring  41  housed in a circular seat  42  formed around the central hole  22  through the lid  21 . 
   With reference also to  FIGS. 3 and 4  (for the sake of clarity, in  FIG. 3  the casing  17  is shown without the lid  21  and the rotor  31 ), the base surface  23   a  of the chamber  18  has a recess  51  with an arm element  52  housed therein, mounted pivotably on a pin  53  formed in one piece with the base of the recess  51 . The arm element  52  includes an integrally formed elongate body  52   a , with a thickness along the length of the device  15  less than or equal to the depth of the recess  51 . One end  52   b  of the body  52   a  of the arm element  52  is pivoted on the pin  53 , while the other end  52   c  has a pin portion  54  projecting from the base surface  23   a  inwardly of the cylindrical chamber  18 . Due to this configuration, the arm element  52  is able to oscillate in the bottom of the recess  51 , in a plane parallel to the base surface  23   a . The shape of the recess  51  can be different from that shown in  FIG. 3  but it must be able to allow the arm element  52  to pivot sufficiently in order for the device to operate, as will be described later. 
     FIG. 5  is a plan view just of the rotor  31 . It has a pair of vane portions  61  extending radially from diametrically opposite sides of the disc portion  32 . An elongate groove  70  (shown in the broken line) is formed in the lower surface  62  of the disc portion  32  and of the paddle elements  61 , that is the surface opposite the base surface  23   a  so as to extend concentrically with the shaft portion  33  of the rotor  31 . In particular, this groove  70  extends to the edge of the disc portion  32  so it is substantially divided into three portions on the vane portions  61 . The first and second portions  71 ,  72  constitute an end portion and an intermediate portion of a part of the groove  70  concentric with the shaft portion  33  of the rotor  31 . These portions  71 ,  72  are formed in such a way that their radially inner walls  71   a ,  72   a  are blended with the side wall  32   a  of the disc portion  32 . In an improved embodiment (not shown) the portion  72  is provided with flared ends so as to form mouths, the function of which will be explained later. The third portion  73  forms the opposite end of the groove  70  and extends so as to approximately form a ring, with forward and return branches  74 ,  75 , respectively, and a cam portion  76  interposed between them. The radially inner wall of the mouth of the forward branch  74  is connected to the radially outer wall  32   a  of the disc element  32 . 
   A recess  77  is formed in the cam portion  76 , in front of which a cuspid branch  78  is extended which interconnects the two branches  74 ,  75  of the groove  70 . The cuspid branch  78  defines two sharp bends  79 ,  81  at its ends, substantially opposite the recess  77  of the cam portion  76 . 
   The groove  70  is engageable by the pin portion  54  of the arm element  51 , which moves along the groove when the rotor  31  is rotated relative to the casing  17 . After passing through the portions  71 ,  72 , the pin portion  54  engages in succession the branches  75  and  74  of the groove  70 , accompanied by the movement of the arm element  52 , thereby accomplishing locking and release operations in the manner of the pressure latch system described with reference to the prior art. 
     FIGS. 6 to 14  illustrate the operation of the device according to the invention. 
   From the latched position ( FIG. 6 ) in which the pin portion  54  engages the recess  77  of the cam portion  76 , pressure applied on the door  2  causes a slight clockwise rotation of the rotor  31 , by means of the rack  6  engaged with the pinion  16 , thereby causing the pin portion of the arm to be moved away from the recess (see  FIG. 7 ) until it reaches the bend  79 , beyond which clockwise rotation is prevented (see  FIG. 8 ). The arm element  52  pivots slightly anti-clockwise, following the movement of the pin portion  54  induced by the rotor  31 . 
   When pressure on the door  2  is released, the spring  4  urges it until it is fully open. The movement transmitted to the rotor  31  causes it to rotate anti-clockwise, whereby the pin portion  54  (see  FIG. 9 ) passes along the forward branch  74 , the intermediate portion  72  and the end portion  71  until it reaches the end of travel position defined by the end portion  71  (see  FIG. 10 ). In addition to slowing the movement of the rotor  31 , and therefore of the door  2 , the viscosity of the viscous fluid prevents the pin portion  54  and the arm portion  52 , which pivot clockwise while moving along the forward branch  75 , from moving away radially from the path of the groove  70  in the portion in which this is interrupted (see  FIG. 9 ). 
   If pressure continues to be exerted on the door  2 , the rotor  31  rotates clockwise (see  FIG. 11 ) and the pin portion  54  returns along the groove  70  until it is diverted by the cam portion  76  into the return branch  75 , whereby the arm element  52  reaches its position of maximum clockwise travel (see  FIG. 12 ). The mouth of the forward branch  74  is much narrower than that of the return branch  75 , in order to reduce the possibility of the pin element  54  entering this branch by mistake when it reaches the end portion  73  of the groove  70 . 
   If pressure on the door  2  is continued, the rotor  31  rotates until the pin portion  54  engages the bend  81  of the return branch  75 , which prevents further rotation (see  FIG. 13 ). 
   If pressure is released, the action of the spring  4  causes the rotor  31  to rotate slightly anti-clockwise (see  FIG. 14 ) and, thanks to the configuration of the cuspid branch  78 , the pin portion  54  is guided to the recess  77  of the cam portion  76 , once again locking the rotor  31  into the starting position shown in  FIG. 1 . 
   It will be appreciated that, although it has internal latch means, the slowing device according to an embodiment of the invention has a structure which is more compact and is simpler to manufacture than the prior art, wherein the axial depth of the casing can be of only a few millimeters, while maintaining the high reliability of the device. In particular, the Applicant has made the portion  73  of the groove  70  with an angular extent of around 10-20° in a device with a diameter of around 1.5 cm. In this way, by fitting this device with the rack  6 , it is possible to activate the release mechanism with an angular movement of the door of only a few degrees. 
   It is understood that the invention is not limited to the embodiments described and illustrated here, but that the shape and arrangements of parts, construction and operating details can be modified. For example, the arm element could be mounted on the disc portion of the rotor, while the groove could be formed in the base of the chamber itself. Alternatively, it is possible to arrange these latch means between the upper surface of the disc portion and the lower surface of the casing lid, or on both sides of the disc portion. 
   The groove  70 ,  70 ′,  70 ″ can of course be orientated as a mirror image of that described, thereby causing the device to be locked or released by rotation in the opposite sense to that described above. 
   In addition, the device according to the first embodiment can be coupled with a rectilinear rack in order to control the movement of a slidable drawer.