Abstract:
A device configured to operably couple a steering column to a steering gear housing. The device includes a shaft, a clamping collar and a clamping screw. The clamping collar includes two arms arranged relative to one another so as to define a cavity. The cavity presents an entry zone and a coupling zone into which the shaft is inserted, the shaft first entering the entry zone then entering the coupling zone. The shaft is secured in position by tightening the clamping screw to a set torque, the entry zone being dimensioned in relation to the coupling zone so as to inhibit achieving the set torque of the clamping screw when the shaft is inserted into the entry zone only, and not the coupling zone.

Description:
TECHNICAL FIELD 
     The invention relates to a device for connecting two shafts together. The device for connecting according to the invention is intended in particular, but not exclusively, to be implemented in a steering system to couple means for controlling, and more particularly a steering column, to a steering gear housing. 
     BACKGROUND 
     In a motor vehicle, the means for controlling of the steering system comprise a steering wheel and a steering column comprising a steering shaft integral with the steering wheel. The steering gear housing comprises a pinion gear meshing with a rack arranged along a steering cross shaft connected on either side to the steering wheels by a set of steering tie-rods, with the translation of the cross shaft driving the rotation of the steering wheels of the motor vehicle. 
     The steering shaft of the steering column is connected to the pinion of the steering gear housing by an intermediate transmission shaft. The steering column and the intermediate transmission shaft on the one hand as well as the intermediate transmission shaft and the steering gearbox on the other hand are then respectively connected by a device for connecting comprising a clamping collar, commonly referred to as jaw or universal joint. 
     The clamping collar conventionally comprises per se two arms arranged relative to one another in such a way as to delimit a cavity to receive an end portion of one of the shafts to be coupled with the other shaft. The clamping arms each comprise a hole for the passage of a clamping screw intended to clamp the clamping arms around the end portion of the shaft according to a set torque. 
     In order to provide a sufficient clamping of the screw and as such apply sufficient tension in the connection sought, i.e. the connection between the steering column and the intermediate shaft and/or the connection between the intermediate shaft and the steering gearbox, and as such allow for a resistance in terms of dynamic endurance for the connection, it is required that the clamping collar be sufficiently engaged on the shaft concerned by the coupling. 
     However, in certain circumstances, it occurs that the clamping collar is not sufficiently engaged on the shaft, with the end portion of the shaft not reaching the holes for the passage of the jaw. As the clamping screw is able to be arranged through the holes for passage, the coupling is apparently carried out. However, as the shaft is not sufficiently engaged in the clamping collar, the maintaining of the latter on the shaft is not ensured. 
     In order prevent a poor engagement or insufficient engagement of the clamping collar on a shaft, it is provided in conventional connection devices to match the collar with additional parts that do not authorise the passage of the clamping screw in the holes for the passage of the collar as long as the latter is not fully engaged. By way of example, patent application EP0128813 can be mentioned. Here, the additional part implemented in this document is an elastic member consisting of a curved blade. The blade is arranged on the jaw of the universal joint in such a way that the curved end of the blade is arranged through holes for the passage of the clamping screw. The setting in place of the clamping screw is then prevented as long as no shaft is introduced into the bore of the jaw. 
     The adding of an additional part gives rise however to problems of encumbrance and cost. 
     It is also common to prevent a poor engagement of the collar on a shaft to proceed with a machining of the chamfer type or to create a counterbore centered on the shaft. 
     The additional machining does however have for consequence to reduce the contact zones between the shaft and the jaw, which is detrimental for the resistance in terms of dynamic endurance in a steering system of the transmission gearbox/intermediate transmission shaft and intermediate transmission shaft/steering column connection. 
     SUMMARY OF THE DISCLOSURE 
     The invention aims to overcome these problems by proposing a device for connecting making it possible to prevent the clamping and the axial maintaining, by the clamping screw, of the clamping collar on the shaft when the latter is not sufficiently engaged in the collar. To this effect, and according to a first aspect, the invention proposes a device for connecting a steering column to a steering gear housing, with the device comprising a shaft defining an axis of insertion and a direction of insertion, having an end portion and a clamping portion situated to the rear of the end portion in the direction of insertion, a clamping collar comprising two arms arranged relative to one another in such a way as to delimit a cavity able to guide the shaft according to the axis of insertion in the direction of insertion into a position of engagement and to keep the shaft in the position of engagement, with each arm comprising a hole, and a clamping screw of the arms onto the shaft in the position of engagement according to a set torque, with the holes of each arm being aligned with one another in order to define with the clamping portion an axis of passage of the clamping screw perpendicular to the axis of insertion, the cavity comprising a coupling zone and an entry zone situated to the rear of the coupling zone in the direction of insertion, the entry zone being dimensioned in relation to the coupling zone in such a way as to prevent the clamping of the clamping screw according to a set torque when the end portion is situated in the entry zone. 
     Conventionally, the set tightening torque corresponds to an optimum tightening torque that makes it possible to generate a deformation of the arms of the clamping collar at the limit of yielding. 
     Advantageously, the entry zone has a section that is greater than that of the coupling zone. 
     The presence of an enlarged zone preceding the coupling zone in the direction of insertion of the shaft into the cavity of the clamping collar, makes it possible as such to suppress the bearing zones transmitting the forces of the arms  10 ,  11  onto the shaft  2  during the clamping of the screw. So, as the portion of the shaft  2  arranged in the entry zone  5  is no longer in contact with all or a portion of the internal surfaces of the clamping collar, the forces of the collar as a reaction to the clamping of the screw are not transmitted to the shaft. The set tightening torque therefore cannot be achieved. 
     Advantageously, the coupling zone and the entry zone have, in the lower portion, one or several bearing surfaces of the shaft. 
     Advantageously, the bearing surfaces of the entry zone are arranged in the extension of the bearing surfaces of the coupling zone ( 4 ) according to an axis parallel to the axis of insertion. 
     Advantageously, the entry zone is vertically offset in relation to the axis of insertion. This as such makes it possible to preserve lower bearing surfaces on the zone of the coupling zone but also on the entry zone. The expression “vertically offset” means an offsetting situated in a plane perpendicular to the clamping axis and passing through the axis of insertion. The presence of lower bearing surfaces makes it possible to provide for the resistance in dynamic endurance of the collar when the latter is assembled with the shaft. 
     Advantageously, the entry zone is horizontally offset in relation to the axis of insertion. The expression “horizontally offset” means an offsetting situated in a plane parallel to the clamping axis and passing through the axis of insertion. 
     According to an advantageous embodiment, it can be provided that the entry zone is offset both vertically and horizontally. 
     Advantageously, the holes open into the coupling zone, in the vicinity of the entry zone. 
     Advantageously, the cavity comprises an end defining a docking surface in the entry zone, with the entry zone ( 5 ) having a length substantially equal to the distance of the holes with the docking surface. 
     Advantageously, the entry zone forms a counterbore. This configuration has for advantage to simplify the manufacturing of the clamping collar. 
     According to another alternative embodiment, the entry zone has a chamfered profile. This configuration has for advantage to facilitate the continuous mounting of the clamping collar on the shaft. 
     According to a second aspect, the invention relates to a clamping collar intended to be implemented in a device for connecting a steering column to a steering gear housing such as described hereinabove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention shall appear when reading the following description, made in reference to the annexed drawings, wherein: 
         FIG. 1  shows a diagrammatical view in perspective of a device for the connecting of a steering column to a gear housing according to a first embodiment of the invention; 
         FIG. 2  shows a front view of the device for connecting of  FIG. 1 ; 
         FIG. 3  shows a cross-section view according to the axis of the device for connecting of  FIG. 1 ; 
         FIG. 4  shows a diagrammatical view in perspective of a device for connecting according to a second embodiment of the invention; 
         FIG. 5  shows a front view of the device of  FIG. 4 ; 
         FIG. 6  shows a diagrammatical view in perspective of a device for connecting according to a third embodiment of the invention; 
         FIG. 7  shows a front view of the device for connecting of  FIG. 6 ; 
         FIG. 8  shows a cross-section view according to the axis VIII-VIII of the device of  FIG. 6 ; 
         FIGS. 9, 11, 13 and 15  show alternatives of the coupling profile implemented in the device for connecting; and 
         FIGS. 10, 12, 14, 16  show front views of the devices for connecting shown respectively in  FIGS. 9 and 11 . 
     
    
    
     For increased clarity, identical or similar elements of the various embodiments are marked with identical reference signs in all of the figures. 
     DETAILED DESCRIPTION 
     In relation with  FIGS. 1 to 3 , a device a described for connecting making it possible to assemble a steering column with a steering gear housing. More particularly, the device for connecting is implemented to couple the intermediate transmission shaft with the axis of the pinion of the steering gearbox and/or the intermediate transmission shaft with the steering shaft of the steering column. 
     In the embodiment described, the device for connecting comprises a shaft  2 , a clamping collar  1  arranged to be mounted onto the shaft  2  and means for clamping comprising a screw  16  allowing for the clamping of the clamping collar  1  around the shaft  2  according to a set torque. As shall be seen further on, the clamping according to a set torque is obtained when the shaft  2  is sufficiently engaged in the collar. 
     According to the invention, the shaft  2 , which defines an axis of insertion YY and a direction of insertion, has an end portion  20  and a clamping portion  22 . As shall be seen further on, the clamping portion  22  corresponds to the portion with which the clamping screw is placed into contact in order to provide for the clamping of the collar  1  onto the shaft  2 . The clamping portion  22  is situated to the rear of the end portion  20  in the direction of insertion. In other words, when the clamping collar  1  is engaged on the shaft  2 , the end portion first docks the clamping collar  1 . 
     The clamping collar  1  comprises two arms  10 ,  11  connected to one another by a connecting portion  12 . The arms  10 ,  11  are arranged with the connecting portion  12  in order to delimit a cavity  3  able to receive the shaft  2 , and in particular the clamping and end portions  20 ,  22  of the shaft  2 . 
     Each arm  10 ,  11  comprises a hole  14 ,  15  for the passage of the clamping screw  16  intended to clamp the arms  10 ,  11  onto the clamping and end portions of the shaft  2 . The holes  14 ,  15  are aligned with one another according to a clamping axis XX perpendicular to the axis of insertion of the cavity  3  corresponding to the axis of insertion of the shaft  2  when the latter is positioned in the cavity  3 . 
     The cavity  3  according to the invention is arranged to have two adjacent zones  4 ,  5 . As shall be seen further on, one of the zones  5  is arranged in relation to the other zone  4  in order to prevent the clamping of the clamping screw  16  according to the set torque when the clamping collar  1  is insufficiently engaged on the shaft  2  (this will be referred to in what follows as entry zone or fault-preventing zone), with the other zone  4  providing for the coupling of the clamping collar  1  onto the shaft  2  (this will be referred to in what follows as coupling zone). 
     According to the invention, the coupling zone  4  is intended to receive the clamping and end portions  20 ,  22  of the shaft  2 . In this configuration wherein the two portions  20 ,  22  are arranged in the coupling zone  4 , the clamping collar  1  is considered as correctly, or at least sufficiently engaged, on the shaft, in order to allow for the clamping of the screw  16  according to the set torque. 
     In order to provide a satisfactory connection between the clamping and end portions  20 ,  22  of the shaft  2  and the coupling zone  4  of the clamping collar  1 , and as such provide for the transmission of the torque between the two shafts connected by the device for connecting, the coupling zone  4  has a profile that is complementary with that of the clamping and end portions  20 ,  22  of the shaft  2 . In the embodiment described, the coupling zone  4  comprises two lateral notched walls  40 ,  41  able to cooperate with flats with complementary notched shapes arranged on the lateral surfaces of the end portion  20  of the shaft  2 , with the two lateral notched walls  40 ,  41  being connected to one another by an upper connecting wall  42  in the shape of an arc of a circle corresponding to the shape of the upper surface of the end portion  20  of the shaft  2 . It is of course obvious that the coupling zone  4  is not limited to such a configuration and that any shape or profile making it possible to provide for the coupling of the clamping collar  1  with a shaft can be implemented without however leaving the scope of the invention. For example, and advantageously, a coupling zone  4  can be provided of which the lateral  40 ,  41  and upper  42  walls are provided with splines  400  ( FIGS. 9, 10 ). A coupling zone  4  can also be provided having a six-section wall ( FIGS. 15 and 16 ). In this application, walls designate the entry and coupling zones, the internal surfaces of these zones. 
     Moreover, the coupling zone  4  and the clamping and end portions  20 ,  22  of the shaft  2  are dimension in such a way as to offer sufficient clearance in order to allow for the engagement of the clamping collar  1  on the shaft  2  while still providing for the good resistance of the latter. 
     In the embodiment described, each arm  10 ,  11  further comprises extensions  100 ,  110  forming one or several zones having lower bearing surfaces  101 ,  111  on the coupling zone  4 . As such, when the clamping collar  1  is in place on the shaft  2 , the clamping and end portions  20 ,  22  of the shaft  2  received in the coupling zone  4  are bearing respectively against the lateral walls  40 ,  41  and the upper wall  42  of the cavity  3  as well as against the lower bearing surfaces  101 ,  111 . 
     According to the invention, the entry zone  5  is dimensioned in relation to the coupling zone  4  in order to form a fault-preventing zone  5 . More particularly, the entry zone  5  is dimensioned in such a way as to prevent the clamping of the clamping screw  16  according to the set torque when the clamping collar  1  is insufficiently engaged on the shaft  2  ( FIG. 3 ), i.e. when the end portion is not engaged into the coupling zone. 
     More particularly, the entry zone  5  has a section that is greater than that of the coupling zone  4 . The presence of an enlargement preceding the coupling zone  4  in the direction of insertion of the shaft  2  in the cavity  3 , makes it possible as such to suppress the bearing zones transmitting the forces of the arms  10 ,  11  on the shaft  2  during the clamping of the screw. As such, the portion of the shaft  2  arranged in the entry zone  5  cannot be maintained or clamped by the portions of the arms  10 ,  11  delimiting the entry zone  5 . 
     Advantageously, the holes  14 ,  15  open into the coupling zone  4 , in the vicinity of the entry zone  5 . According to a preferred embodiment, the clamping collar  1  has an end defining a docking surface  17  in the entry zone  5 , with the entry zone ( 5 ) having a length substantially equal to the distance of the holes  14 ,  15  with the docking surface  17 . 
     The presence of an enlargement of the cavity  3  on holes  14 ,  15  and the positioning of these holes  14 ,  15  in relation to this enlargement makes it possible to reduce assembly errors while preventing the clamping of the clamping collar  1  on the shaft  2  when the latter is not sufficiently introduced into the cavity  3 . 
     As such, in the case where the end portion of the shaft is not sufficiently introduced into the clamping collar  1  ( FIGS. 3 and 8 ), the clamping screw, even if it can be engaged in the holes for passage  14 ,  15 , cannot clamp the arms  10 ,  11  of the clamping collar onto the shaft  2 , as no force can be transmitted between the walls of the entry zone  5  and the shaft  2 . Note that if the shaft  2  is engaged in the clamping collar  1  in such a way that the end portion  20  interferes slightly with the holes  14 ,  15 , the setting in place of the clamping screw  16  will displace the end portion  20  in the entry zone which then cannot be clamped to the set torque. Also note that, in the configuration wherein the end portion  20  is engaged in the coupling zone  4  but the clamping portion  22  is partially or not engaged in the coupling zone in such a way that the clamping portion  22  does not define with the holes  14 ,  15  an axis of passage for the clamping screw  16 , the portion of the shaft positioned facing the holes  14 ,  15  will form a fault-preventing means preventing the setting into place of the clamping screw in the holes. 
     Advantageously, the clamping portion  20  of the shaft comprises a peripheral groove for positioning and immobilizing  21  provided to be positioned facing the holes  14 ,  15  of the clamping collar  1  when the shaft is correctly engaged in the cavity  3 , i.e. when the end portion  20  and the clamping portion  22  are both situated in the coupling zone  4  of the clamping collar  1 . The groove  21  makes possible, with the clamping screw  16  when the latter passes through the holes  14 ,  15  of the arms  10 ,  11 , the retaining of the shaft in the collar. 
     In the embodiment shown in  FIGS. 1 and 2 , the entry zone  5  is formed by a counterbore  50  or cylindrical housing with a section greater than the section of the coupling zone  4 . 
     In  FIG. 2 , the entry zone  5  has a vertical offset in the direction of the upper portion of the collar  1  in relation to the axis of insertion YY of the coupling zone. 
     The vertical offsetting is provided in such a way as to provide in the entry zone  5  bearing surfaces  101  arranged in the extension of the bearing surfaces  111  of the coupling zone  4 . This as such makes it possible to preserve the resistance in endurance of the collar/shaft connection. This also makes it possible to facilitate the mounting of the collar  1  on the shaft  2 . 
     As the lower bearing zone of the entry zone  5  is retained, an enlargement then occurs on only the lateral and upper walls of the entry zone  5 . Note that the enlargement can extend over the entire height of the lateral walls as shown in  FIGS. 1, 2, 9 and 10  or, as shown in  FIGS. 4, 5, 11, 12 , over a portion only of the height of the lateral walls. The extent of the enlargement on lateral walls of the entry zone  5  will be determined in such a way as to provide both the fault-preventing for the shaft when the latter is not sufficiently engaged in the jaw and the resistance in endurance of the collar/shaft connection. 
     The presence of a counterbore  50  upstream of the coupling zone  4  as shown in  FIG. 2 , wherein the lateral and upper bearing zones have been suppressed and the lower bearing zone  101  retained makes it possible to prevent any transmission of force from the collar on the end portion  20  of the shaft  2  arranged in the entry zone  5  during the clamping of the screw while maintaining a resistance in endurance of the clamping collar  1 /shaft  2  connection equivalent to that of a conventional clamping collar with the shaft. 
     According to a particular embodiment shown in  FIGS. 4 and 5 , the entry zone  5  has a counterbore  50  that is offset vertically and horizontally. This vertical and horizontal offsetting has for advantage, in addition to suppressing any bearing zone on the lateral and upper walls of the counterbore, the arranging of an axial abutment  51  on the engagement surface. This axial abutment has for function, in cooperation with the shoulder arranged on the shaft  2 , to allow for a stoppage in translation of the clamping collar on the shaft  2 . Note that the shoulder is arranged on the shaft  2  so that when the shoulder  16  is stopped by the axial abutment  51 , the groove for positioning and immobilizing  21  is positioned facing the holes  14 ,  15 . 
     According to another embodiment shown in  FIGS. 6, 7 and 8 , an entry zone  5  can be provided having a chamfered profile  55 . 
     The chamfered profile shown in  FIGS. 6 and 8  shows a vertical and horizontal offset of the profile in relation to the axis of insertion of the coupling zone  4 , with the lower bearing zones being retained. Such a profile makes it possible, as the one shown in  FIGS. 4 and 5 , to remove any lateral and upper bearing zones while still retaining an axial abutment. It is of course obvious that a chamfered profile can be provided having only a vertical offset without however leaving the scope of the invention. 
     The characteristics and advantages described hereinabove for an entry zone formed of a counterbore also apply to an entry zone having a chamfered profile. 
     In the embodiments shown in the figures, the collar is comprised of a single-block part. It is of course obvious that the clamping collar is not limited to such a configuration. 
     In the embodiments shown in  FIGS. 1 to 7 , the extensions  100 ,  110  of the arms  10 ,  11 , and therefore the bearing surfaces  101 ,  111 , resulting from a folding of material at 180 degrees. It is of course obvious that the bearing surfaces can be carried out by any other manner without however leaving the scope of the invention. 
     In particular, and as shown in  FIGS. 9 to 15 , the extensions  100 ,  110  of the arms  10 ,  11 , and therefore the bearing surfaces  101 ,  111 , can result from a folding of material at 90 degrees but also from a half-cut  120  in the material on the external surfaces of the arms  10  and  11  followed by a displacement of material  121  by punching on the internal surfaces of the arms towards the interior of the entry zone  5 . 
     The invention is described in what precedes by way of example. It is understood that those skilled in the art are able to carry out different alternatives of the embodiment of the invention without however leaving the scope of the invention.