Abstract:
Motorized carriage ( 1 ) that is able to move in translation along a longitudinal axis (X) along a horizontal rail, said carriage ( 1 ) comprising at least one wheel ( 4 ), in particular of the friction wheel type, that is driven in rotation by an electric motor ( 5 ) and is mounted so as to pivot about a transverse axis (Y) on a holder ( 3 ) which carries said motor ( 5 ), said carriage ( 1 ) comprising a chassis ( 2 ) incorporating guide means ( 23, 24 ) mounted so as to slide on the chassis ( 2 ) along a vertical axis (Z) orthogonal to the longitudinal axis (X) and transverse axis (Y) and cooperating with elastic stressing means ( 25, 26 ) that are designed to move the guide means ( 23, 24 ) in the direction of the rail, where the holder ( 3 ) is in sliding contact with said guide means ( 23, 24 ) along the longitudinal axis (X) and vertical axis (Z), this sliding contact being designed to convert a movement of the holder ( 3 ) along the longitudinal axis (X) into a concurrent movement of the holder ( 3 ) along the vertical axis (Z) in the direction of the rail. Said carriage ( 1 ) can be used in video surveillance systems.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a motorized carriage capable of being displaced in translation along a horizontal rail. 
         [0002]    More particularly, it relates to a carriage including at least one wheel, in particular of the frictional wheel-type, driven in rotation by an electric motor and pivotally mounted on a support which carries said motor. 
       BACKGROUND 
       [0003]    The invention finds a particular, but non-limiting, application in the field of video surveillance systems integrating a suspended carriage movable in translation on a horizontal rail, where the carriage supports at least one camera mounted on its frame. 
         [0004]    In the field of motorized carriages, the wheel(s) is/are driven in rotation by the electric motor and roll(s) and remain(s) in contact on the horizontal rail. When rolling, each wheel applies a force along a vertical axis (perpendicular to the rail) and, in a conventional manner, a balance is sought between the adherence and the pressure of each rail on the rail. 
         [0005]    Indeed, a low pressure allows limiting the noise and the wear of the components (in particular of the wheels) but limits the adherence of the wheel on the rail, resulting in a risk of skidding of the wheel and consequently in a loss of the driveability of the carriage. 
         [0006]    Conversely, a significant pressure of the wheel guarantees the adherence but generates rapid noise and a wearing of the components (in particular of the wheels). Moreover, with a high pressure of the wheel on the rail, part of the energy deployed by the motor is used to overcome the deformation of the materials, thereby an overconsumption of energy. 
         [0007]    Furthermore, retaining either one of the two solutions, the low-pressure solution (in order to gain silence, limit wear and energy consumption) or the high-pressure solution (in order to enhance adherence and driveability), ultimately turns out to be limited because the rail often presents dimensions subject to variations, even slight variations, and such variations of the dimensions ineluctably make the pressure of the wheel on the rail vary. 
       BRIEF SUMMARY 
       [0008]    The present disclosure aims in particular to solve all or part of these drawbacks, by proposing a motorized carriage which presents a significant longevity while limiting the wear of its components, and a use which is as silent as possible. 
         [0009]    To this end, it proposes a motorized carriage capable of being displaced in translation along a longitudinal axis along a horizontal rail, said carriage including at least one wheel, in particular of the frictional wheel-type, driven in rotation by an electric motor and pivotally mounted along a transverse axis on a support which carries said motor, said carriage being characterized in that it includes a frame integrating guide means slidably mounted on the frame along a vertical axis orthogonal to the longitudinal and transverse axes and cooperating with elastic stressing means shaped to displace the guide means towards the rail, where the support is in sliding contact on said guide means along the longitudinal and vertical axes, this sliding abutment being designed to convert a displacement of the support along the longitudinal axis into a concomitant displacement of the support along the vertical axis towards the rail. 
         [0010]    Thus, thanks to this sliding assembly, the invention allows making the pressure of the wheel on the rail vary depending on the force required to the displacement of the carriage. Indeed, when the carriage is stopped or moving at constant speed, the support is not displaced longitudinally and in this case, the elastic stressing means are slightly stressed so that the wheel applies a reduced pressure whereas, when the carriage is in a braking or in an acceleration phase, then the support is displaced longitudinally and in this case, the elastic stressing means are considerably stressed under the effect of the thrust exerted by the support which slides both longitudinally and vertically on the guide means, which results in an increased thrust of the wheel against the rail. 
         [0011]    Thanks to the invention, the carriage allows exploiting at best the power of the motor while limiting the energy consumption and the wear of the components as much as possible. 
         [0012]    The stressing means allow maintaining the contact between the wheel and the rail at a given minimum pressure when the carriage is stopped or moving at a constant speed, in particular in the aforementioned rest position of the support, and at an increased pressure when the carriage is in a braking or in an acceleration phase. 
         [0013]    According to one feature, the support includes at least one bearing element mounted to slide on a corresponding guide part integrated to the guide means (and therefore to the frame), where the or each bearing element presents a bearing surface called front bearing surface adapted to come into sliding abutment on a guide ramp called front guide ramp provided on the corresponding guide part, where the front bearing surface and the front guide ramp extend in respective planes parallel to the transverse axis and inclined with respect to the longitudinal and vertical axes. 
         [0014]    Thus, the aforementioned sliding assembly is made between the bearing element and the guide part, along the bearing surface which bears and slides against the guide ramp. 
         [0015]    Advantageously, the or each bearing element presents a bearing surface called rear bearing surface adapted to come into sliding abutment on a guide ramp called rear guide ramp provided on the corresponding guide part, where the rear bearing surface and the rear guide ramp are symmetrical to the front bearing surface and to the front guide ramp respectively along planes orthogonal to the longitudinal axis. 
         [0016]    In this conformation, the sliding abutment is ensured in both directions of displacement of the carriage, whether it is a forward displacement with the front bearing surface bearing and sliding against the front guide ramp, or a backward displacement with the rear bearing surface bearing and sliding against the rear guide ramp. 
         [0017]    In a particular embodiment, the or each guide part presents front and rear guide ramps which converge towards a peak of the guide part, and the or each bearing element presents front and rear bearing surfaces which converge towards a hollow bottom of the bearing element. 
         [0018]    Alternatively, the or each guide part presents front and rear guide ramps which converge towards a hollow bottom of the guide part, and the or each bearing element presents front and rear bearing surfaces which converge towards a peak of the bearing element. 
         [0019]    In a general manner, the or each guide part has a shape complementary to the corresponding bearing element. When the peak of one of the parts (the guide part and the bearing element) bears on the hollow bottom of the other, then the support is in a position called rest position and the wheel applies a minimum pressure. 
         [0020]    According to another feature, the or each guide part is in the form of a beveled or conical part cooperating with a bearing element having a complementary shape, or conversely, the or each bearing element is in the form of a beveled or conical part cooperating with a guide part having a complementary shape. 
         [0021]    According to one possibility of the invention, the or each guide part is slidably mounted on the frame along the vertical axis. 
         [0022]    According to another possibility of the invention, the elastic stressing means cooperate with the or each guide part so as to displace in translation the corresponding guide part in the direction of pressing the guide part against the corresponding bearing element of the support for pushing said support towards the rail. 
         [0023]    In a particular embodiment, the or each guide part is slidably mounted inside the hollow guide secured to the frame, and the elastic stressing means include at least one elastic member, in particular of the spring-type, interposed between a bottom wall of the guide and the corresponding guide part. 
         [0024]    In accordance with another advantageous feature of the invention, the support includes a first bearing element slidably mounted on a first guide part and a second bearing element slidably mounted on a second guide part, the first bearing element and the first guide part being shifted along the longitudinal axis with respect to the second bearing element and to the second guide part, in particular on either side of the wheel. 
         [0025]    Thus, the sliding assembly of the support is made on two guide parts, for a balance of the forces and an optimum control of the sliding. 
         [0026]    The present invention also concerns the feature according to which the support includes a central portion carrying the motor and on which the or each wheel is pivotally mounted, and the first and second bearing elements extend on either side of said central portion so as to cooperate in sliding abutment with the first and second guide parts. 
         [0027]    The invention also relates to a video surveillance system integrating a suspended carriage movable in translation on a horizontal rail, where the carriage is in accordance with the invention and supports at least one camera mounted on its frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Other features and advantages of the present invention will appear upon reading the detailed description hereinafter, of a non-limiting example of implementation, made with reference to the appended figures in which: 
           [0029]      FIG. 1  is a schematic side view of a support cooperating with two guide parts slidably mounted in guides secured to a frame for a carriage in accordance with the invention; 
           [0030]      FIGS. 2 to 4  are schematic side views of a carriage in accordance with the invention integrating the elements of  FIG. 1 , when the carriage is respectively in a forward acceleration phase ( FIG. 2 ), in a stop phase or in a constant speed movement phase ( FIG. 3 ) and in a backward acceleration phase ( FIG. 4 ). 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    For the following description, reference will usefully be made to the reference mark (X, Y, Z) presenting:
       a longitudinal axis X extending horizontally from backward to forward with reference to the direction of displacement of the carriage;   a transverse axis Y extending horizontally from the right to the left and orthogonal to the longitudinal axis;   a vertical axis Z extending from the bottom to the top and orthogonally to the horizontal plane (X, Y).       
 
         [0035]    The motorized carriage  1  in accordance with the invention is intended to be displaced from forward to backward, and from backward to forward, on a horizontal rail (not represented) extending parallel to the axis X. 
         [0036]    The carriage  1  includes a frame  2  and a support  3  slidably mounted on the frame  2 , as well as at least one wheel  4  driven in rotation by an electric motor  5 . 
         [0037]    The wheel  4 , of the frictional wheel-type, is intended to roll on the rail, under the effect of the rotation exerted by the motor  5 . The wheel  4  is pivotally mounted along the axis Y on the support  3 , and the motor  5  is in turn carried by this support  3 . 
         [0038]    The support  3  includes a movable plate  30  presenting a central portion on which are mounted the wheel  4  and the motor  5 , and two arms  31 ,  32  extending on either side of the central portion  30  along the axis X, a first arm  31  of which forming a first bearing element and a second arm  32  forming a second bearing element. 
         [0039]    The support  3  is symmetrical with respect to a midplane parallel to the plane (Y, Z), and each arm  31 ,  32  presents a V D-shaped end. 
         [0040]    The first arm  31  presents a front bearing surface  311  extending in a plane parallel to the axis Y and inclined with respect to the axes X and Z. The second arm  32  also presents a front bearing surface  321  extending parallel to the front bearing surface  311 . 
         [0041]    The first arm  31  presents a rear bearing surface  312  extending in a plane parallel to the axis Y and inclined with respect to the axes X and Z, where the rear bearing surface  312  is symmetrical to the front bearing surface  311  along a plane orthogonal to the axis X. The second arm  32  also presents a rear bearing surface  322  extending parallel to the rear bearing surface  312 . 
         [0042]    Thus, each arm  31 ,  32  presents two front  311 ,  321 , and rear  312 ,  322  bearing surfaces which converge towards a hollow bottom of the arm  31 ,  32  so as to define a          V          shape. The bearing surfaces  311 ,  312 ,  321 ,  322  comprise upper surfaces, in other words oriented upwards, opposite to the rail which is at the bottom. 
         [0043]    Because of the symmetry of the support  3 , the front bearing surface  311  of the first arm  31  is closer to the central portion of the plate  30  than the rear bearing surface  312 , and conversely, the rear bearing surface  322  of the second arm  32  is closer to the central portion of the plate  30  than the front bearing surface  321 . 
         [0044]    The frame  2  includes a first and a second hollow guides  21 ,  22  each defining internally a housing  210 ,  220  extending along the direction Z and plugged at the top (or upper) portion by a bottom  211 ,  221 . 
         [0045]    The frame  2  includes a first guide part  23  slidably mounted in the first guide  21  along the axis Z, and a second guide part  24  slidably mounted in the second guide  22  along the axis Z. 
         [0046]    Each guide part  23 ,  24  is in the form of a beveled or conical part terminated by a tip or a peak oriented downwards, towards the rail. 
         [0047]    Each guide part  23 ,  24  presents two opposite guide ramps  231 ,  232 ,  241 ,  242  which converge towards the peak. 
         [0048]    The first guide part  23  presents a front guide ramp  231  extending parallel to the front bearing surface  311  of the first arm  31 , and a rear guide ramp  232  extending parallel to the rear bearing surface  312 . 
         [0049]    The second guide part  24  presents a front guide ramp  241  extending parallel to the front bearing surface  321  of the second arm  32 , and a rear guide ramp  242  extending parallel to the rear bearing surface  322 . 
         [0050]    The frame  2  also includes a first and a second springs  25 ,  26  mounted respectively in the first and second guides  21 ,  22 , the first spring  25  being interposed between the bottom  211  and the first guide part  23  so as to push the first guide part  23  downwards (towards the rail), and the second spring  26  being interposed between the bottom  221  and the second guide part  24  so as to push the second guide part  24  downwards. 
         [0051]    The first arm  31  passes through the first guide  21  before penetrating inside its housing  210  and cooperating in sliding abutment with the first guide part  23 , the front bearing surface  311  being adapted to come into sliding abutment on the front guide ramp  231 , whereas the rear bearing surface  312  is adapted to come into sliding abutment on the rear guide ramp  232 . 
         [0052]    Similarly, the second arm  32  passes through the second guide  22  before penetrating inside its housing  220  and cooperating in sliding abutment with the second guide part  24 , the front bearing surface  321  being adapted to come into sliding abutment on the front guide ramp  241 , whereas the rear bearing surface  322  is adapted to come into sliding abutment on the rear guide ramp  242 . 
         [0053]    The support  3  can present the following three distinct positions, respectively a rest position, a forward-motion position and a backward-motion position. 
         [0054]    A rest position, illustrated in  FIG. 3 , is a position in which the peak of each guide part  23 ,  24  is in the bottom of the corresponding arm  31 ,  32 , with the front bearing surface  311  bearing on the front guide ramp  231 , the rear bearing surface  312  bearing on the rear guide ramp  232 , the front bearing surface  321  bearing on the front guide ramp  241 , and the rear bearing surface  322  bearing on the rear guide ramp  242 . 
         [0055]    A forward-motion position, illustrated in  FIG. 2 , is a position in which the support  3  has been displaced longitudinally forwards (arrow DV) resulting, on the one hand, into a sliding of the front bearing surfaces  311 ,  321  against the front guide ramps  231 ,  241  and, on the other hand, into a detachment of the rear bearing surfaces  312 ,  322  vis-à-vis the rear guide ramps  232 ,  242 , so that:
       in a situation where the wheel  4  would not rest on a rail, the support  3  is guided in translation vertically downwards concomitantly with its longitudinal displacement forwards;   in a situation where the wheel  4  rests (rolls) on a rail which is fixed, the support  3  cannot be displaced vertically downwards (towards the rail), and in this case, the longitudinal displacement of the support  3  forwards is converted into a vertical thrust of the guide parts  23 ,  24  upwards (arrows P), thereby stressing the springs  25 ,  26 , so that the pressure applied by the wheel  4  against the rail is increased.       
 
         [0058]    A backward-motion position, illustrated in  FIG. 4 , is a position in which the support  3  has been displaced longitudinally backwards (arrow DV) resulting, on the one hand, into a sliding of the rear bearing surfaces  312 ,  322  against the rear guide ramps  232 ,  242  and, on the other hand, into a detachment of the front bearing surfaces  311 ,  321  vis-à-vis the front guide ramps  231 ,  241 , so that:
       in a situation where the wheel  4  would not rest on a rail, the support  3  is guided in translation vertically downwards concomitantly with its longitudinal displacement backwards;   in a situation where the wheel  4  rests (rolls) on a rail which is fixed, the support  3  cannot be displaced vertically downwards (towards the rail), and in this case, the longitudinal displacement of the support  3  backwards is converted into a vertical thrust of the guide parts  23 ,  24  upwards, thereby stressing the springs  25 ,  26 , so that the pressure applied by the wheel  4  against the rail is increased.       
 
         [0061]    The following description relates to the operation of the carriage in an acceleration or in a braking phase. 
         [0062]    When the drive wheel  4  starts rotating or accelerates, driven by the motor  5 , it tends to displace the movable plate  30  along the axis X (forwards or backwards). As explained before, any displacement of the support  3  along the axis X results in a displacement of the guide parts  23 ,  24  along the axis Z, so that we get in the forward-motion or backward-motion position described above, and the support  3  presses the drive wheel  4  further against the rail. 
         [0063]    Thus, the more the motor  5  accelerates, and the further the support  3  is displaced along the axis X and therefore the more the guide parts  23 ,  24  are pushed upwards, and therefore the more the adherence of the drive wheel  4  on the rail increases, thereby allowing to avoid any skidding. 
         [0064]    During the acceleration of the carriage  1 , the pulling forces provided by the motor  5  are significant, thereby increasing the pressure of the wheel  4  on the rail and therefore the adherence of the wheel  4 . 
         [0065]    The following description relates to the operation of the carriage in a steady state phase, in other words in a stop phase or in a constant speed movement phase. 
         [0066]    When the carriage  1  is displaced at a uniform speed, the rail being horizontal, the motor  5  simply has to compensate the losses of speed due to the frictions. Thus, the pulling forces provided by the motor  5  are low and therefore the displacement of the support  3  along the axis X is almost zero, so that we get in the rest position described above. Hence, the pressure of the wheel  4  on the rail is minimum and is determined by the stiffnesses of the springs  25 ,  26 , thereby limiting the deformation of the rail and therefore the energy losses. Thus, the energy consumption of the motor  5  decreases as well as the wear of the drive wheel  4 , of the motor  5  and of the bearings. 
         [0067]    In conclusion, the above-described carriage  1  allows displacing a carriage  1  on a rail while optimizing, on the one hand, the use of the power of the motor  5  and, on the other hand, the lifespan of the components involved in the transmission of the movement. Furthermore, this system with the support  3  and the guide parts  23 ,  24  is strictly mechanical and does not consume energy for the regulation of the pressure of the wheel  4  with the driveability needs. Finally, it guarantees the possibility of obtaining the maximum speed of the carriage  1  for a given motor, the acceleration and braking efficiency of the carriage  1  (when the latter is performed by the motor), the proper positioning of the carriage  1  on the rail during the acceleration and braking phases, the easiness of handling the carriage  1  during maintenance, an optimum setting when the dimensions of the rail vary.