Abstract:
The invention relates to a test bench that reproduces the performance of a gearbox. The invention consists of: at least one gearshift module ( 2 ) comprising a linear motor ( 12 ) and a ball joint ( 14 ) that can be used to convert a linear motion of the motor ( 12 ) into a rotational motion of a gearshift shaft ( 5 ) and a force sensor ( 17 ) that can be used to measure the force applied to the gearshift shaft ( 5 ). In particular embodiments of the invention, the test bench also comprises a vertical linear selection module or a horizontal selection module. The modules employed can be used to simulate forces as a function of the shift and selection position in a manner that is representative of a gearbox.

Description:
BACKGROUND OF THE INVENTION 
   I. Field of the Invention 
   The technical field of the present invention is that of test benches to simulate gearboxes, for example, vehicle gearboxes. 
   II. Description of Related Art 
   In the field of application of test benches, it is sometimes necessary to simulate a gearbox and this is particularly true of test benches for external control of gearboxes. 
   Test benches using pneumatic rams are currently known in the field of test benches that simulate gearboxes. 
   Such devices have the major disadvantage, on account of the use of pneumatic rams, of lacking in precision and above all of having performance that is limited in terms of responsiveness and in terms of dynamic range. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention overcomes these disadvantages by proposing a test bench that simulates a gearbox making it possible to generate loads equivalent to those of an actual gearbox and reproducing various aspects of behavior, according to the type of gearbox parametrized. 
   The subject of the invention is a test bench of the type that reproduces the behavior of a gearbox, characterized in that it comprises at least one gearshift module consisting of a linear motor and of a ball joint allowing a linear movement of the motor to be converted into a rotary movement of a gearshift shaft, and of a load sensor allowing the load applied to the gearshift shaft to be measured. 
   According to one feature of the invention, the linear motor moves translationally with respect to a slideway along a horizontal axis and the gearshift shaft pivots about a substantially vertical axis. 
   According to another feature of the invention, the test bench comprises a horizontal selection module consisting of a linear motor and of a ball joint allowing a linear movement of the motor to be converted into a rotary movement of a selection shaft, and of a load sensor allowing the load applied to the selection shaft to be measured. 
   According to another feature of the invention, the linear motor moves with respect to a slideway along a horizontal axis, and the selection shaft pivots about its substantially horizontal axis. 
   According to another feature of the invention, the test bench comprises a vertical selection module consisting of a linear motor, a tension/compression load sensor and a compensating means. 
   According to another feature of the invention, the linear motor moves with respect to a slideway along a vertical axis so as to cause the gearshift shaft to move translationally along its substantially vertical axis. 
   One advantage of the device according to the invention is that it allows the behavior of different types of gearbox to be reproduced. 
   Another advantage of the device according to the invention lies in its speed and in its precision when actuating the external controls. 
   Another advantage of the device according to the invention lies in the fact that it uses modules that are independent of one another and can readily be moved. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features, details and advantages of the invention will become more clearly evident from the detailed description given hereinafter by way of indication with reference to the drawings in which: 
       FIGS. 1   a  to  1   c  depict functional diagrams illustrating applications of the test bench according to the invention, 
       FIG. 2  is a perspective depiction of one embodiment of the gearshift module  2 , 
       FIG. 3  is a perspective depiction of one embodiment of the horizontal selection module  3 , 
       FIG. 4  is a depiction in profile of one embodiment of the vertical selection module  4 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The test bench that the present invention proposes to produce is a test bench that simulates a gearbox. More specifically, this test bench needs to reproduce various aspects of behavior corresponding to different types of gearbox. This test bench is particularly intended for gearbox external controls. 
   The gearboxes conventionally used are in the form of an automatic box or of a manual box. 
     FIG. 1   a  illustrates a first type of gearbox simulated by the invention. This type of gearbox is the automatic gearbox type  40 . Mechanically controlled automatic gearboxes  40  are conventionally actuated by an external control  7  comprising a lever  8  moving along a longitudinal segment  41 . The lever  8  therefore allows the mode P, R, N or D to be selected and allows gears to be changed manually (M+ or M−). In this case, only the gearshift module is used. For this type of box, only the gearshift mode corresponding to a torque about a substantially vertical axis needs to be simulated using a gearshift module  2  actuating a gearshift shaft connected to the lever  8 . 
     FIG. 1   b  illustrates a second type of gearbox simulated by the invention. This type of gearbox is the manual gearbox type  42  with combined gear selection and gear shift. Manual gearboxes with combined selection and shifting are conventionally actuated by an external control  7  performed by a lever moving along a gate in the shape of a double “H”. The horizontal bar  44  of the gate corresponds to the neutral position (where no gear is engaged). The movement of the lever  8  in order to select the gear for the gear shift is broken down into a horizontal selection movement along the horizontal axis  44  of the gate and into a gearshift movement, along one of the three vertical axes  41   a ,  41   b ,  41   c  of the gate. The lever  8  is connected at its lower end to two cables  45  and  46  actuating an interconnection module  47 . Movement along the horizontal axis  44  drives the first cable  45 , while a gearshift drives the second cable  46 . The interconnection module  47  (conventionally embodied in the form of a combination of link rods) allows the movements of these two cables  45 ,  46  to be converted into a vertical load and a torque about a vertical axis. 
   The control supplied to the gearbox is therefore a control combining a vertical selection control and a gearshift control. These two controls are transmitted to the box by a single component  5  (cable or shaft, for example). In this type of gearbox, the vertical selection mode, corresponding to a load along a substantially vertical axis, and the gearshift mode, corresponding to a torque about a substantially vertical axis, need to be simulated using a vertical selection module  4  and a gearshift module  2  acting on the same shaft  5 . 
     FIG. 1   c  illustrates a third type of gearbox which is the manual gearbox type with separate gear selection and gearshift  43 . Manual gearboxes in which the gears are selected and shifted separately are conventionally actuated by an external control  7  performed by a lever moving along a gate in the shape of a double “H”. The horizontal bar  44  of the gate corresponds to the neutral position (where no gear is engaged). The movement of the lever  8  in order to select the gear for the gear shift is broken down into a horizontal selection movement along the horizontal axis  44  of the gate and into a gearshift movement, along one of the three vertical axes  41   a ,  41   b ,  41   c  of the gate. The control supplied to the gearbox is therefore a control combining a horizontal selection control and a gearshift control. These controls are transmitted to the gearbox separately by the two distinct cables  48 ,  49  acting on shafts  5  and  6 . In this type of gearbox, the horizontal selection mode, corresponding to a torque about a substantially horizontal axis, and the gearshift mode, corresponding to a torque about a substantially vertical axis, need to be simulated using a horizontal selection module  3  and a gearshift module  2  acting on two distinct components (shafts or cables). 
   The test bench according to the invention allows these three types of gearbox to be simulated by using a gearshift module  2 , a horizontal selection module  3  and a vertical selection module  4 . 
     FIG. 2  is a perspective depiction of one embodiment of the gearshift module  2 . In this embodiment, the gearshift module  2  consists of a plate  10  secured to the frame of the test bench (not depicted in its complexity), of a horizontal slideway  11  secured to the plate  10 , of a linear motor  12  able to move along the slideway  11  along a horizontal axis, and of an arm support  13 , supporting an arm  15  by means of a ball joint  14 . The arm  15  is secured to a control shaft  5  by a pivot connection provided by means of an axis substantially perpendicular to the axis Z of the control shaft  5 . A guide device  18  secured to the plate  10  assists in guiding the rotation of the control shaft  5  about its substantially vertical axis Z, for example by means of a rolling bearing. The gearshift module  2  also comprises a load sensor  17  allowing the load applied to the gearshift shaft  5  to be measured. It may, for example, be possible to use a tension/compression sensor  17  positioned between the arm support  13  and the ball joint  14 . 
   Embodying the gearshift module  2  in this way allows the horizontal linear movement of the motor  12  to be converted into a rotary movement of the shaft  5 . 
   Use of a horizontal linear motor is particularly advantageous because such a motor is not disturbed by the forces generated by its own weight, allowing it to move very quickly and very precisely and therefore to subject the gearshift shaft  5  to rapid and very precise rotational movements. Such precision could not be achieved using a rotary motor or a device embodied using rams. 
     FIG. 3  is a perspective depiction of one embodiment of the horizontal selection module  3 . In this embodiment, the horizontal selection module  3  consists of a unit  20  secured to the frame of the test bench, of a slideway  21  secured to the unit  20 , of a linear motor  22  able to move along the slideway  21  along a horizontal axis, and of an arm support  23 , supporting a substantially vertical arm  25  by means of a ball joint  24 . The arm  25  is secured to a horizontal selection gear selection shaft  6 . Rolling bearings  28  secured to the unit  20  support the gear selection shaft  6  while at the same time leaving it free to rotate about its axis. The horizontal selection module  3  also comprises a load sensor  27  allowing the load applied to the selection shaft  6  to be measured. It may, for example, be possible to use a tension/compression sensor  27  positioned between the arm support  23  and the ball joint  24 . 
   Embodying the horizontal selection module  3  in this way allows the horizontal linear movement of the motor  22  to be converted into a rotary movement of the gear selection shaft  6  about a horizontal axis. 
     FIG. 4  is a profile view of one embodiment of the vertical selection module  4 . In this embodiment, the vertical selection module  4  consists of a unit  30  secured to the frame of the test bench, of a slideway  31  secured to the unit  30 , of a vertical linear motor  32  able to move along the slideway  31  along a vertical axis, and of a connecting rod support  33  supporting a substantially vertical connecting rod  35  by means of a ball joint  34 . The connecting rod  35  is secured to the control shaft  5 . A sleeve  38  secured to the unit  30  supports the shaft  5  while at the same time leaving it free to rotate and to effect a translational movement along and about its axis Z. A tensile/compressive load sensor  37  positioned for example between the support  33  and the ball joint  34  allows the vertical loads supplied to the gearshift shaft  5  to be measured. 
   Embodying the vertical selection module  4  in this way allows the vertical linear movement of the motor  32  to be transmitted to the shaft  5  while at the same time compensating for any discrepancies using the connecting rod  35  which constitutes a compensating means. This exemplary embodiment also depicts the arm  15  of the gearshift module  2 . In this particular embodiment, the gearshift shaft  5  is no longer guided by the guide device  18  secured to the plate  10  (these two items being depicted in  FIG. 2 ) but is guided by a sleeve  38  secured to the unit  30 . The sleeve  38  guides the control shaft  5  in terms of translation and in terms of rotation along and about its substantially vertical axis Z. 
   In this embodiment of the invention, the vertical selection module  4  is used in combination with the gearshift module  2  in the context of the simulation of a gearbox in which the gear selection and gear shift are combined. These two modules  2  and  4  therefore allow the control shaft  5  to be subjected to a load and to a torque along and about its axis Z. 
   The modules  2 ,  3  and  4  are advantageously independent of one another so that they are positioned on the test bench or omitted from the test bench according to the type of gearbox that is to be reproduced. The modules used allow the loads to be simulated as a function of position during gear selection and gearshift in a way that is representative of the behavior of a gearbox.