FR2865518A1 - Handle reversible movement controlling method for power transmission system, involves rotating movable fulcrum pin around another pin whose axes are parallel by off-centering axes of one pin with respect to another - Google Patents

Abstract

The method involves exerting a driving force (F) on a lever (18) to form a contact between the lever and a contact generator (15), by an electromagnetic actuator. The generator is coupled to a movable fulcrum pin (8) to rotate the pin around a fixed fulcrum pin (11). An axis of the pin (8) is parallel to that of the pin (11) by being off-centered with respect to the pin (11). An independent claim is also included for a control device.

Description

METHOD FOR CONTROLLING REVERSIBLE DISPLACEMENT OF A

  ROTATING ARM AND DEVICE FOR IMPLEMENTING IT.

  The present invention relates to a reversible movement control method of a rotating arm for applying and removing a friction transmission system, and a device for carrying out this method. The invention applies in particular to the power transmission by a friction roller of an upstream pulley, for example a crankshaft pulley of a heat engine, to a downstream pulley, for example a drive pulley of a water pump for cooling the engine.

  In the past, water pumps for cooling motor vehicle engines have been driven either directly by a synchronous chain or belt type distribution mechanism or by a striated belt type transmission mechanism. In both cases, the start of the water pump and the speed of rotation of its motor shaft are respectively dependent on the starting of the heat engine and the speed of rotation at its output, the water pump not stopping operate only when the engine is stopped.

  A major disadvantage of these drive mechanisms is that it is desirable to leave the water pump off, on the one hand, when the engine is cold to accelerate its rise in temperature and, secondly, when the vehicle is subjected to very low external temperatures. It is thus not possible to manage the operation of the water pump according to the needs of the heat engine.

  It has recently been sought to overcome this dependence by proposing to drive the water pump by an auxiliary electric motor directly connected to the latter or a clutch / clutch mechanism of the electromagnetic type, to make it work only in case of need of cooling of the engine.

  A major disadvantage of these latter driving mechanisms lies primarily in their high cost.

  The present invention provides a reversible movement control method of a rotating arm for applying and removing a friction transmission system, which can overcome the aforementioned drawbacks for power transmission of an upstream pulley, for example a pulley crankshaft, to a downstream pulley, for example a driving pulley of a water pump.

  For this purpose, the method according to the invention comprises the exercise of a thrust force in a mobile contact generator during the thrust and coupled to at least one movable pivot on which is mounted said arm, so as to cause said or each pivot movable in rotation about a fixed axis with respect to which it is eccentric, said fixed axis, the axis of said or each movable pivot and said generatrix contact being parallel during said thrust.

  In the present application, the term axis (e.g. fixed axis above) means the geometric axis of symmetry of a mechanical joint which is for example constituted of said movable pivot or a fixed pivot.

  It will be noted that this friction transmission system is advantageously of the type comprising a friction roller, which implies a simplified transmission kinematics in comparison with that of the aforementioned transmission mechanisms of the chain type or striated belt.

  According to another characteristic of the invention, said method comprises a curvilinear guidance of said contact generatrix about said fixed axis during the exercise of said thrust force, to allow the rotation of said or each movable pivot.

  According to another characteristic of the invention, said method comprises the exercise of a restoring force on said arm.

  According to a first embodiment of the invention, said contact generator evolves radially outside said or each movable pivot during rotation of the latter.

  According to another feature of this first embodiment of the invention including the aforementioned curvilinear guidance, said contact generator 30 moves by sliding on a ramp substantially in the shape of a circular arc.

  According to a second embodiment of the invention, said contact generator evolves radially inside said or each movable pivot during the rotation of the latter.

  According to another characteristic of this second mode according to the invention, said fixed axis and said contact generator pass through said or each movable pivot.

  According to another characteristic of this second embodiment according to the invention including the aforementioned curvilinear guidance, said contact generator evolves by sliding or meshing on a substantially arcuate ramp which is formed in said or each movable pivot.

  A control device according to the invention for implementing the aforementioned method comprises: - at least one movable pivot on which said arm is mounted, said or each movable pivot being rotatable about a fixed pivot which is mounted on a frame so that the axis of said fixed pivot is parallel to that of said or each movable pivot and is eccentric vis-à-vis the latter, - a coupling plate adapted to couple said or each movable pivot to said fixed pivot and an actuator mounted on said frame which is adapted to exert a thrust force on a guide rail integral in rotation with said or each coupling plate, so that said actuator forms, in contact with said ramp, a generator of contact which is guided on said ramp during said thrust being parallel to the axis of said or each movable pivot, so as to cause said or each movable pivot in rotation about said fixed pivot.

  It should be noted that this eccentric mounting of the pivot fixed relative to the movable pivot optimizes the work provided by the actuator, so as to limit the power required for the application and removal of the friction transmission system.

  According to another characteristic of this device according to the invention, said guide ramp comprises a guiding surface substantially in the shape of an arc of a circle.

  According to another characteristic of the invention, said device comprises a return means provided for exerting a restoring force on said arm so as to apply said transmission system with a predetermined force.

  It will be noted that the return means used makes it possible to guarantee the power transmission by friction, for example between a crankshaft pulley of a heat engine and a driving pulley of a water pump, by eliminating any risk of breakage of the engine. motor in case of failure of the vehicle electrical system, unlike a motor-driven water pump drive mechanism.

  According to the aforementioned first embodiment of the invention, said control device comprises a lever comprising: a tab forming said coupling plate, on the respective faces of which said fixed pivot and said movable pivot are mounted, and said guide rail which is formed on said lever in a manner offset from said movable pivot, and said actuator comprises at least one finger intended to be actuated in translation to exert said thrust force by forming said generator in contact with said guide rail, so that said finger drives said lever in rotation about said fixed pivot to obtain rotation of said movable pivot.

  According to another advantageous characteristic of this first embodiment according to the invention, said ramp has a concave surface with a radius of curvature greater than that of the free end of said or each finger, so that said finger remains in contact with said ramp. during the exercise of said thrust force.

  According to another preferred feature of this first embodiment according to the invention, said lever comprises two identical longitudinal members which each comprise said guide ramp and which are interconnected by a cross member extending on each side of said leg.

  According to another advantageous feature of this first embodiment of the invention, said biasing means is a compression spring bearing against said frame and against an end sleeve which is provided with said arm and which is mounted around said movable pivot.

  According to another advantageous characteristic of this first mode according to the invention, the distance separating the respective axes of said movable pivot and said fixed pivot is less than or equal to the distance separating said generatrix of contact from the axis of said fixed pivot. As a result, the control device according to the invention has an increased compactness.

  According to the aforementioned second embodiment of the invention, the control device comprises an eccentric mechanism comprising: an eccentric disk formed by said or each movable pivot and constituting said or each coupling plate, said or each disk; being traversed by said fixed pivot and being slidably mounted in a recess passing through said arm so as to be pivotally mounted on said frame, said guide rail being formed in said or each disc, and - a thrust member provided to exert said force of thrust that includes said actuator and which is intended to form said generator in contact with said or each guide ramp, so that said thrust member causes said or each disk in rotation about said fixed pivot by guiding said contact generator on said or each ramp, for obtaining rotation of said arm.

  According to a first embodiment of this second embodiment according to the invention, said thrust member advantageously comprises a bent rod intended to be actuated in translation, a free end of which is adapted to cooperate with said guide ramp of said eccentric disc, which has a shape of an arc of a circle.

  According to another feature of this first form of said second mode according to the invention, said biasing means is a tension spring connecting said frame to said arm.

  According to another advantageous characteristic of the invention common to said first mode and to this first form of said second mode, said actuator comprises an electromagnet for obtaining said thrust force.

  As a result of this coupling to an electromagnet a very fast movement of said thrust member, i.e. said finger or said bent rod.

  Note that this electromagnetic actuator induces a limited power consumption, which is relatively high during the duration of the movement of the actuator (a few hundred milliseconds) but very low in a retracted position of the friction transmission system in contact with the pulley motor, for example with the belt of the crankshaft pulley, following removal of the water pump drive pulley.

  It will also be noted that the control device according to the invention incorporating said lever or said eccentric mechanism makes it possible to multiply the force of the electromagnet and that, depending on the location of the moving axis (ie the application of the force of the actuator), it is possible to vary the transmission ratio between the force provided by the electromagnet and that obtained on the pivot.

  According to a second embodiment of this second mode according to the invention, said actuator further comprises a gear which is mounted facing said eccentric disk or between said two eccentric disks, said gear comprising a control screw and one or two end gears each meshing with a toothed element, said or each toothed element being coupled to the guide ramp of said or each eccentric disk, for obtaining said thrust force.

  According to this second embodiment according to the invention, it will be noted that said arm preferably comprises two parallel rods interconnected and ending respectively in two rings enclosing said eccentric discs, such that said rods are driven together in pivotally pivoting about said fixed pivot of said disks respectively in contact with said rings.

  According to a first exemplary embodiment of this second form according to the invention, said thrust member is advantageously constituted by a thrust finger adapted to cooperate transversely with the guide ramp of said eccentric disk.

  According to another advantageous characteristic of this first example according to the invention, said control screw meshes with a toothed wheel provided on one of its faces with a pinion which meshes with a fixed rack fixed to said frame and which is provided coaxially with said or each thrust finger, so that the rectilinear movement of said pinion on said rack is converted into a rotation of said or each eccentric disk by guiding said or each thrust finger on said or each ramp.

  According to this first example according to the invention, it will be noted that said arm could comprise a single rod ending in a ring enclosing a single eccentric disk, so that this rod is pivotally driven by rotary sliding of said disk to contact of said ring.

  According to a second exemplary embodiment of this second form according to the invention, said thrust member is advantageously constituted by two coaxial fingers interconnected which are provided on either side of said gear and which are respectively adapted to cooperate transversely with the guide rails of said eccentric discs.

  According to another advantageous characteristic of this second example according to the invention, said control screw meshes with a gear wheel provided on its respective faces with two coaxial pinions and of different diameters which mesh respectively with a fixed rack fixed to said frame and with a rack mobile parallel to said fixed rack and secured to said thrust fingers, so that the pinion meshing with said movable rack moves the latter in a direction opposite to that of the advance of the pinion meshing with said fixed rack to obtain a translation movement of said toothed wheel along said fixed rack with a reduced force which is converted into a rotation of the two eccentric discs by guiding the two thrust fingers on the respective guide rails of said discs.

  According to another advantageous characteristic of the invention relating to said first and second examples, the guide ramp of said or each disk has a shape of curvilinear slide substantially in an arc whose edge is intended to cooperate by sliding with said or one of said pushing fingers.

  According to a third exemplary embodiment of this second form according to the invention, said thrust member is advantageously constituted by said end gears which meshing respectively with said toothed elements, which are formed by the respective guide ramps of said eccentric discs and present each a form of wheel sector with internal teeth.

  According to another advantageous characteristic of this third example according to the invention, said control screw meshes with a drive gear provided on its respective faces with two coaxial and identical driving gears which mesh respectively with two driven gears which are parallel to said wheel. driving gear, which driven wheels are each provided coaxially on one of their faces with a driven pinion meshing with the guide ramp of the adjacent disc, so that the rotation of said driven gear wheels is converted into a rotation of the two discs eccentric by guiding said pinions carried on the respective guide ramps of said disks.

  According to another advantageous characteristic of the invention relating to the aforesaid second form and to its exemplary embodiments, said control screw is an endless screw coupled to an output shaft of an electric motor for its rotation drive.

  According to another advantageous characteristic of the invention relating to the aforementioned second form and to its exemplary embodiments, said return means comprises a compression spring bearing against said frame and against one of said rings. Note that one could use a torsion spring acting in the same way on said arm, instead of the compression spring.

  In general, it will be noted that the devices according to said first or second embodiment of the invention have a small footprint and a simple structure (low number of parts) and robust with, consequently, a reduced manufacturing cost in comparison with existing devices.

  Other characteristics, advantages and details of the present invention will emerge on reading the following description of several examples of embodiment of the invention, given for illustrative and not limiting, said description being made with reference to the accompanying drawings, among which: Figure 1 is a front view and cut away of a transmission installation including a control device according to a first embodiment of the invention in relation to a friction roller arm applied to two pulleys, the figure 2 is a detail view in perspective and in cutaway of a control box of the device of FIG. 1, FIG. 3 is a perspective view of a lever of the control device according to the invention contained in the housing of the FIG. 2 is a top view of a transmission installation including a control device according to a first form of a second embodiment of the invention; FIG. 5 is a broken cross-sectional view along the plane VV of FIG. 4, FIG. 6 is a perspective view of the control device of FIGS. 4 and 5, in one phase. FIG. 7 is a perspective view of the device of FIGS. 4 and 5, in a phase of retraction of the roller from one of the pulleys, FIG. 8 is a partial perspective view of the pulley. a transmission installation including a control device according to a first example according to the invention of a second form relating to the second embodiment, FIG. 9 is a partial perspective view in transparency of the control device of FIG. 8, FIG. 10 is a perspective view of a transmission installation including a control device according to a second example according to the invention of the second form relating to the second embodiment, FIG. 11 is a partial perspective view. and in transparency of the control device of FIG. 10, FIGS. 12 and 13 are two further partial perspective views of the control device of FIG. 10, FIG. 14 is a top and perspective view of a transmission installation. including a control device according to a third example according to the invention of the second form relating to the second embodiment, and FIG. 15 is a view from above and in perspective of the control device of FIG. 14, FIG. a view from below and in perspective of the control device of FIG. 15, and FIG. 17 is a view from above and in perspective of a control device according to an alternative embodiment of FIGS. 14 to 16. The installation of FIG. transmission 1 illustrated in Figure 1 comprises a friction roller 2 intended to be applied to both a downstream pulley 3, formed in this embodiment of a driving pulley of a water pump, and on an upstream pulley 4, consisting in this example of a crankshaft pulley 5 of a heat engine block 6, or to be removed from the downstream pulley 3 while remaining applied to the belt 5 of the upstream pulley 4.

  The roller 2 is mounted by its axis 2a on a support arm 7 which is itself mounted on a movable pin 8, via a sleeve 9 which is integral with the free end of the arm 7 and which is mounted freely in rotation on the mobile pin 8. It

  The mobile pin 8 is movable in rotation, under the control of a control device 10, around a fixed pivot 11 mounted on a housing 12, which, shown cutaway in Figure 1, is mounted on the engine block 6 by fixing means 13. The axis 11a of the fixed pivot 11, visible in Figure 3, is parallel to the axis 8a of the movable pin 8 being eccentric with respect thereto, as will be detailed below.

  The control device 10 illustrated in FIGS. 1 and 2 essentially comprises, in addition to the mobile pivot 8, the fixed pivot 11 and the housing 12: an actuator 14 of the electromagnetic type also mounted on the housing 12 and adapted to exert a force F of pushing on a lever 18 so as to form in contact therewith a contact generator 15 coupled to the movable pin 8 and parallel to the latter, so as to cause the mobile pivot 8 to rotate about the fixed pivot 11, the actuator 14 consisting of a thrust member 16 coupled to an electromagnet 17 for translational driving thereof, - the lever 18 which is provided with both the fixed pivot 11 and the movable pivot 8 and on which is formed a guide ramp 23 for to contain the generatrix of contact 15, so that the force F is exerted thereon perpendicularly to the axis of rotation of the movable pin 8, and - a return means 19 consisting of a compression spring abutting against the housing 12 and against a bearing surface 9a of which the sleeve 9 is provided, this return means 19 being designed to exert a restoring force on the arm 7, so as to apply the roller 2 to the belt 5 of the upstream pulley 4 and on the downstream pulley 3 with a predetermined intensity force.

  The controller 10 is illustrated in more detail in FIG.

  The traction / thrust member 16 has in this example a U-shaped fork whose core 20 is fixedly mounted on the core 17a of the electromagnet 17 and whose wings 21 form two thrust fingers surrounding the electromagnet 17 The fingers 21 have their respective rounded ends, to cooperate with the guide ramp 23 during the exercise of the aforementioned thrust force.

  With reference to FIGS. 2 and 3, it can be seen that the lever 18 is provided, at a first end adjacent to the fixed pivot 11, with a tab 22 which is provided with the mobile pivot 8 and the fixed pivot 11 on its respective faces and at a second end intended to contain the contact generatrix 15, the guide ramp 23 in the form of a concave surface which is adapted to receive the ends of the fingers 21 of the actuator 14. In this embodiment, the lever 18 comprises two identical longitudinal members 24 which each have this ramp 23 and which are interconnected by a crossmember 25 at the first end, this crossmember 25 being provided at right angles to the tab 22.

  The tab 22 thus forms a coupling plate of the mobile pivot 8 to the fixed pivot 11.

  As illustrated schematically in Figure 2, the lower part of the control unit 12 is provided, below the sleeve 9, a connecting member 27 connecting the sleeve 9 to the arm 7 and advantageously comprising a rubber sealing bellows.

  It can be seen in FIG. 3 that the mobile pivot 8 and the fixed pivot 11 are mounted on the lug 22 in such a way that the axis 8a of the mobile pivot 8 is parallel to the axis 11a of the fixed pivot 11 while being eccentric by report to the latter. More specifically, the lever 18 is advantageously such that the lever arm relative to the generatrix 15 is much greater than the lever arm b relative to the movable pin 8, which has the effect of optimizing the work of the actuator 14 while providing a satisfactory compactness of the control device 10 in the housing 12. Tests have shown that in a preferred embodiment of the control means 10, the lever arm a is substantially equal to 4.3 times the arm of lever b.

  The controller 10 according to this first embodiment of the invention operates as follows.

  In the idle state of the actuator 14 illustrated in FIGS. 1 and 2, in which the thrust member 16 occupies a bearing position on the contact generatrix 15 of the lever 18 corresponding to a maximum end position, the roller 2 is applied in contact with the belt 5 of the upstream pulley 4 and the downstream pulley 3. The force of this application is predetermined by the stiffness of the compression spring 19 being compressed by the bearing 9a of the sleeve 9. There is thus transmitting the rotational movement of the upstream pulley 4 to the downstream pulley 3 and therefore, in the example described, driving the water pump pulley 3 by the rotation of the pulley 4 of the crankshaft.

  To remove the roller 2 from the rim of the downstream pulley 3, the electromagnet 17 is actuated so that it causes a thrust signal (ie reduction of stroke) of the fingers 21 of the member 16 in the direction of the arrow F, which has the effect of pivoting the lever 18 on its fixed pivot 11 in the direction FI of the clockwise due to the thrust exerted on the guide ramp 23 via the contact generatrix 15. The result is a plane rotation of the movable pin 8 about the fixed pivot 11 vis-à-vis which it is slightly eccentric and, therefore, the sleeve 9 in the same FI direction, which has the effect of reducing the compression spring 19 in a compression position and thus move the arm 7, so as to remove the roller 2 of the downstream pulley 3.

  It will be noted that the guide ramp 23 makes it possible to obtain the rotation of the mobile pivot 8, and therefore of the lever 18, from the translational force of the fingers 21 of the thrust member 16.

  Advantageously, the roller 2 removed from the pulley 3 is held in contact with the belt 5 of the upstream pulley 4 of the crankshaft, which makes it possible to limit the transmission of jerks at the time of the subsequent recovery of the transmission of power consisting of to reapply the roller 2 on both the belt 5 of the upstream pulley 4 and the downstream pulley 3.

  This application of the roller 2 on the downstream pulley 3 is achieved by releasing the thrust signal via the electromagnet 17, which has the effect of reversing the direction of the aforementioned movements.

  The angle between the force vectors F applied on the movable axis 15 and lever arm of this effort F is substantially equal to 90, which has the effect of facilitating the pivoting of the arm 7.

  It will be noted that in the case of a maintenance operation 5 of the installation 1, for example to replace the belt of the upstream pulley 4, the arm 7 can be moved directly.

  The transmission systems 101 to 401 according to alternative embodiments of the invention which are illustrated in FIG. 4 and following will be described using numerical references successively increased by 100 with respect to those of elements described with reference to FIGS. 3 and having the same function, if not the same structure.

  The installation 101 of FIG. 4 comprises a friction roller 102 intended to be applied both to a downstream pulley 103 and to the belt 105 of an upstream pulley 104 (see FIGS. 6 and 7), or to be withdrawn from the downstream pulley 103 remaining applied on this belt 105.

  The roller 102 is mounted by its axis 102a on a support arm 107 which is itself pivotally mounted on a movable pin 108, which is rotatable under the control of a control device 110 around a fixed pivot 111 mounted on a frame 112 (see Figures 4 and 5).

  As for the first embodiment mentioned above, the control device 110 comprises an electromagnetic type actuator 114 adapted to exert a thrust force on a contact generator 115 coupled to the mobile pivot 108, so as to drive the mobile pivot 108 in rotation around the fixed pivot 111.

  The control device 110 is in fact an eccentric mechanism comprising, in addition to the mobile pivot 108 and the fixed pivot 111: the actuator 114, which comprises a bent rod 116 actuated in thrust by an electromagnet 117, a disk of eccentric constituted by the movable pivot 108, which is pivotally mounted on the frame 112 by the fixed pivot 111 which passes therethrough eccentrically, and in which is formed a guide ramp 123, on which the bent rod 116 is mounted movably in sliding and which is intended to contain the contact generatrix 115, so that the translational force of the bent rod 116 on the ramp 123 causes the eccentric 108 to rotate about the fixed pivot 111, and a return means 119 consisting of a tension spring which connects the frame 112, via a fixing means 119a, to the free end 107a of the support arm 107 and which is provided to exert a restoring force on the arm 107, so as to maintain the roller 10 2 on the belt 105 of the upstream pulley 104.

  More precisely, FIG. 4 shows that the guide ramp 123 has an arcuate shape and extends close to the axis of symmetry of the eccentric disk 108.

  It can be seen in FIG. 5 that the eccentric disc 108 is housed in a recess passing through the arm 107 near the free end 107a of the latter, so as to cause the arm 107 to pivot by sliding during its rotation.

  This eccentric disk thus forms a coupling plate of the mobile pivot 108 to the fixed pivot 111.

  The controller 110 operates in the following manner.

  In the idle state of the bent rod 116 illustrated in FIG. 6, in which it occupies a bearing position on the guide ramp 123 corresponding to a reduced stroke, the roller 102 is applied in contact with the belt 105 of the upstream pulley 104 and in contact with the downstream pulley 103 with a minimum application force predetermined by the stiffness of the spring 119. There is thus transmission of the rotational movement of the upstream pulley 104 to the downstream pulley 103 and therefore, in the illustrated example, driving the water pump pulley 103 by the rotation of the pulley 104 of the crankshaft.

  The angle between the thrust force vectors F 'applied to the contact generator 115 (see FIG. 4) and the lever arm of this effort F' (connecting the generator 115 to the fixed pivot 111) is provided substantially equal to 90, which has the effect of facilitating the pivoting of the arm 107.

  To remove the roller 102 from the downstream pulley 103, the electromagnet 117 is actuated so that it applies a push signal to the bent rod 116 in the direction of the vector F ', which has the effect of rotating the eccentric 108 on its fixed pivot 111 in the opposite direction F'1 of the needles because of the guide rod 116 on the ramp 123 (see Figures 4 and 7). This results in a combined movement of rotation and translation of the eccentric 108 pivoting about the fixed pivot 111 and, consequently, a sliding pivoting of the arm 107 in the same direction F'1, which has the effect of removing the roller 102 of the downstream pulley 103 and to stretch the tension spring 119, as can be seen in FIG. 7.

  It will be noted that the guide ramp 123 makes it possible to obtain the rotation of the disk 108 around the fixed pivot 111, starting from the translational force applied to the bent rod 116.

  The restoring force exerted by the spring 119 thus stretched only has the effect of keeping the roller 102 in contact with the belt 105 of the upstream pulley 104, which makes it possible to limit the transmission of jerks at the moment of application. subsequent roll 102 on both upstream and downstream pulleys 103, 104.

  This application of the roller 102 on the downstream pulley 103 is achieved by releasing the push signal, which has the effect of reversing the direction of the aforementioned movements.

  The transmission system 201 which is illustrated in FIGS. 8 and 9 is such that the arm 207 comprises, for example, two parallel rods 207a, 207b interconnected and terminating respectively in two rings 207c sandwiching two parallel eccentric discs 208, in such a way that the rods 207a, 207b are driven together in rotation by rotary sliding of the discs 208 respectively in contact with the rings 207c. The control device 210 of this installation 201 essentially comprises: an actuator 214 comprising, on the one hand, a pushing finger 216 intended to form a contact generatrix 215 by transverse sliding on two guide ramps 223 respectively formed in the disks; eccentrics 208, which are pivotally mounted on a frame 212 via a fixed pivot 211 interconnecting them in an eccentric manner and which constitute the movable pivots for the arm 207, and, secondly, a gear mounted between the two disks 208 which comprises a worm 230 of X axis coupled to an output shaft of an electric motor (not shown) for its drive in rotation and which ends with a pinion 231 meshing with a rack 232 fixedly mounted on the building 212; and a return means 219 consisting for example of a compression spring bearing against the frame 212 and against a bearing surface 207d formed on one of the rings 207c (a torsion spring could also be used).

  More precisely, the endless screw 230, of the multi-threaded type, meshes with a toothed wheel 233 provided at right angles to one of its faces of the pinion 231, which is provided coaxially with the pushing finger 216. As can be seen in FIG. 8, the finger 216 passes through the two eccentric disks 208 at right angles via two identical orifices 240 in the shape of an arcuate curvilinear slide which are respectively formed in the disks 208 and whose edges define the guide ramps 223.

  The controller 210 operates as follows.

  When the electric motor is stopped, the roller is in contact with the downstream pulley, for example the water pump pulley, and with the belt of the upstream pulley, for example of the crankshaft pulley. In this mode of operation, the gear is inactive and only the compression spring 219 acts on the rods 207a, 207b of the arm 207 to maintain the roller in contact with the belt and the pulley.

  When the motor is powered, it is understood in Figure 9 that it rotates the worm 230 in the direction Rv with a given torque, which has the effect of driving the toothed wheel 233 in rotation in the direction Rr and to move the pinion 231 in translation on the rack 232 in the direction Tr. This rectilinear movement of the pinion 231 is converted into a rotation of each eccentric disk 208 about the fixed pivot 211 eccentric in the direction Re, by guiding the pin push 216 on each ramp 223. This results in joint pivoting by sliding of the two rods 207a, 207b respectively provided with the rings 207c and, consequently, the arm 207, which results in the removal of the roller from the downstream pulley.

  Note that the rack 232 could be at another location than that illustrated in Figure 9, for example on the side of the worm 230 relative to the gear 231, provided to rotate the electric motor in the opposite direction to obtain the desired direction of rotation of the toothed wheel 233.

  It will also be noted that the control device 210 could comprise only one eccentric disc such as the disc 208, so as to obtain the pivoting of an arm 207 consisting of a single rod 207b provided with a ring 207c enclosing this disc 208.

  When the electric motor is no longer powered, the gear operates in a direction opposite to that of Figure 9 under the pressure of the spring 219, which leads again to the position of the roller in contact with the downstream pulley and with the belt of the upstream pulley.

  The transmission installation 301 which is illustrated in FIGS. 10 to 13 differs only from the installation 201 described above, in that the actuator 314 of its control device 310 comprises: as a pushing member , two coaxial fingers 316 parallel and interconnected which are provided on either side of a gear and which are respectively adapted to cooperate transversely by sliding on guiding ramps 323 identical to the ramps 223, which are formed in disks eccentric 308 rotatably mounted on the frame 312 via the fixed pin 311 therethrough; and as a gear, a worm 330 coupled to an electric motor 335 which meshes with a toothed wheel 333 provided at right angles on its respective faces with two co-axial gears 336, 337 of different diameters which mesh respectively with a fixed rack 338 secured to the frame 312 and with a movable rack 339 parallel to the fixed rack 338 and integral with the thrust pins 316.

  More precisely, it can be seen in FIG. 10 that the two rods 307a, 307b of the arm 307 are respectively extended by two identical 307e shells protecting the faces of the friction roller 302, which is shown schematically in this figure in contact with the belt of the pulley. upstream 304 and in contact with the downstream pulley 303 (these pulleys 303, 304 are symbolized by dotted lines).

  11 and 13 show the structure of the two thrust pins 316 and their connection 316a in transparency on either side of the gear, this link 316a having a U-shape. Is also illustrated in Figure 3 the mounting of the movable rack 339, which is mounted movably in translation on a fixed support 339a integral with the frame 312 secured to the fingers 316.

  FIG. 12 shows the meshing of the pinion 336 with the fixed rack 338, along which the toothed wheel 333 is finally provided to move in translation.

  The controller 310 operates as follows.

  When the electric motor 335 is stopped, the roller 302 is in contact with the downstream pulley 303 and with the belt of the upstream pulley 304, the gear then being inactive and only the compression spring 319 acting on the rods 307a. 307b of the arm 307 to keep the roller 302 in contact with the belt and the pulley 303.

  When the motor 335 is powered, it is understood in Figures 12 and 13 that it rotates the worm 330 in the direction RI, which has the effect of driving the toothed wheel 333 in rotation in the direction R2 and move in translation, this toothed wheel 333 with a reduced force along the fixed rack 338, due to the translation of the pinion 336 on the fixed rack 338 in the direction T3 which is attenuated by the translation in the opposite direction T4 of the movable rack 339 on its support 339a via the other pinion 337. This resultant translation of the toothed wheel 333 in the direction T3 is converted into a rotation in the direction R5 of the two eccentric discs 308 around the fixed pivot 311 eccentric (Figure 13) , by guiding the two pushing fingers 316 on the respective guide ramps 323 of the discs 308.

  This results in the sliding joint movement (direction T6 in FIG. 13) of the two rods 307a, 307b respectively provided with the rings 307c and, consequently, with the arm 307, which results in the removal of the roller 302 from the downstream pulley. 303.

  When the electric motor 335 is no longer powered, the gear operates in the opposite direction under the pressure of the spring 319, which again leads to the position of the roller 302 in contact with the downstream pulley 303 and with the belt of the pulley upstream 304.

  The transmission installation 401 which is illustrated in FIGS. 14 to 16 differs only from the installation 301 described above, in that the actuator 414 of its control device 410 comprises: as a pushing member two end gears 416 (only one can be seen in FIGS. 14 to 16) which mesh respectively with toothed guide ramps 423 respectively formed in the eccentric discs 408 and each having an internally toothed wheel sector shape; and as a gear, a worm gear 430 coupled to an electric motor 435 which meshes with a drive gear 433 provided at right angles on its respective faces with two coaxial and identical intermediate gears 436 (one of which is visible at Figures 14 and 15, the other in Figure 16), which meshes respectively with two driven gears 441 which are parallel to the drive wheel 433, these driven wheels 441 are each provided coaxially and at right angles to one of their faces of the same pinion 416 which meshes with the guide ramp 423 of the adjacent disc 408.

  More precisely, FIGS. 14 and 15 show that each toothed guide ramp 423 forms part of the edge of an orifice 440 which is formed in each eccentric disk 408, in particular to allow access to the gear provided between the two disks 408, as will be explained below.

  The control device 410 illustrated in FIG. 17 differs only from that described above with reference to FIGS. 14 to 16, in that the compression spring 419 relating to these figures is replaced by a torsion spring 419 'to two turns which is wound around the ring 407c of a rod 407 and which bears on a part of the frame 412 and on this ring 407c.

  The control devices 410 operate in the following manner.

  When the electric motor 435 is stopped (refer to FIG. 14) the friction roller 402, protected by shells 402e similar to those of FIG. 10, is in contact with the belt of the upstream pulley 404 and with the downstream pulley 403, the gear then being inactive and only the compression spring or torsion 419, 419 'acting on the rods 407a, 407b of the arm 407 to maintain the roller 402 in contact with the belt and the pulley 403.

  When the motor 435 is energized (see FIG. 15), it turns the worm 430 in the direction RI, which rotates in the direction R2 the driving wheel 433 and therefore the intermediate gears 436, which gears 436 respectively entangling the rotation in the direction R3 of the two driven wheels 441, to generate a first gear stage. This last rotation is accompanied by a rotation in the same direction R3 of the final gears 416 which are respectively integral with the driven wheels 441 and which meshes with the guide ramps 423 of the two eccentric discs 408 which leads, in a second reduction stage, the rotation of these deniers in the direction R4 around the eccentric fixed pivot (not shown) by guiding the end gears 416 on the ramps 423.

  This results in the joint sliding movement in the direction T5 of the two rods 407a, 407b respectively provided with the rings 407c and, consequently, the arm 407, which results in the withdrawal of the roller 402 of the downstream pulley 403.

  It will be noted that these two reduction stages (i.e. of reduction) make it possible to minimize the forces of the electric motor 435.

  When the electric motor 435 is no longer powered, the gear operates in the opposite direction under the pressure of the spring 419 or 419 ', which leads again to the position of the roller 402 in contact with the downstream pulley 403 and with the belt the upstream pulley 404.

  With reference to any one of the installations 201 to 401 described above, it will be noted that in the case of a maintenance operation of the installation 201 to 401, for example to replace the belt of the upstream pulley 204 to 404, can move the arm 207 to 407 directly at the same time as the eccentric disks 208 to 408 of the actuator 214 to 414 are disengaged via the orifices 240 to 440 formed in these disks 208 to 408, in order to avoid any movement of the gear mechanism due to the pivoting of the arm 207 to 407. Following this maintenance operation, the mechanism is put back in place under the return force of the spring 219 to 419 or 419 '.

  In general, the control devices according to the invention are adapted to transmit the very small torque required for the proper functioning of a water pump - usually up to 3 Nm for a gasoline engine of reduced size, and it should be noted that they are not limited to the transmission of power from an upstream pulley to a downstream pulley by a friction roller, being generally usable for the control of the reversible displacement of an arm provided with a friction transmission system.

Claims (30)

  A method for reversibly moving a rotating arm (7, 107, 207, 307, 407) for applying and removing a friction transmission system (2, 102, 302, 402), characterized in that it comprises the exercise of a thrust force (F, F ', F ") in a contact generator (15, 115) movable during the thrust and coupled to at least one movable pivot (8, 108, 208, 308, 408) on which is mounted said arm, so as to cause said or each mobile pivot in rotation about a fixed axis (11a) vis-à-vis which it is eccentré, said fixed axis, the axis (8a) of said or each movable pivot and said generatrix contact being parallel during said thrust.   2. Control method according to claim 1, characterized in that it comprises a curvilinear guidance of said generatrix contact (15, 115) about said fixed axis (11a) during the exercise of said thrust force (F, F ', F "), to allow rotation of said or each movable pivot (8, 108, 208, 308, 408).   3. Method according to one of claims 1 or 2, characterized in that it comprises the exercise of a restoring force on said arm (7, 107, 207, 307, 407).   4. Control method according to one of claims 1 to 3, characterized in that said generatrix contact (15) evolves radially outside said or each movable pin (8) during the rotation thereof.   5. A control method according to claims 2 and 4, characterized in that said generatrix contact (15) evolves by sliding on a ramp (23) substantially in the form of an arc.   6. Control method according to one of claims 1 to 3, characterized in that said generatrix contact (115) evolves radially within said or each movable pivot (108, 208, 308, 408) during the rotation of this last.   7. Control method according to claim 6, characterized in that said fixed axis and said generatrix of contact (115) through said or each movable pivot (108, 208, 308, 408).   8. Control method according to claim 2 and one of claims 6 or 7, characterized in that said generatrix contact (115) evolves by sliding or meshing on a ramp (123, 223, 323, 423) substantially shaped circular arc which is formed in said or each movable pivot (108, 208, 308, 408).   9. Control device (10, 110, 210, 310, 410) for carrying out the method according to one of the preceding claims, characterized in that it comprises: - at least one movable pivot (8, 108, 208) , 308, 408) on which is mounted said arm (7, 107, 207, 307, 407), said or each movable pivot being rotatable about a fixed pivot (11, 111, 211, 311) which is mounted on a frame (12, 112, 212, 312, 412) so that the axis (11a) of said fixed pivot is parallel to that of said or each movable pivot and is eccentric with respect to the latter, - a coupling plate (22, 108, 208, 308, 408) adapted to couple said or each movable pivot (8, 108, 208, 308, 408) to said fixed pivot (11, 111, 211, 311), and - an actuator (14, 114, 214, 314, 414) mounted on said frame (12, 112, 212, 312, 412) which is adapted to exert a thrust force (F, F ', F ") on a guide ramp ( 23, 123, 223, 323, 423) integral in rotation with said or each plate of coupling (22, 108, 208, 308, 408), so that said actuator forms in contact with said ramp a contact generator (15, 115) which is guided on said ramp during said thrust being parallel to the the axis (8a) of said or each movable pivot (8, 108, 208, 308, 408), so as to cause said or each movable pivot in rotation about said fixed pivot (11, 111, 211, 311).   10. Control device (10, 110, 210, 310, 410) according to claim 9, characterized in that said guide ramp (23, 123, 223, 323, 423) comprises a substantially shaped guide surface. arc.   11. Control device (10, 110, 210, 310, 410) according to claim 9 or 10, characterized in that it comprises a return means (19, 119, 219, 319, 419, 419 ') provided for exerting a restoring force on said arm (7, 107, 207, 307, 407) so as to apply said transmission system (2, 102, 302, 402) with a predetermined force.   12. Control device (10) according to one of claims 9 to 11, characterized in that it comprises a lever (18) 10 comprising: - a tab forming said coupling plate (22), on the respective sides of which said fixed pivot (11) and said movable pivot (8) are mounted, and said guide ramp (23) is formed on said lever (18) offset from said movable pivot (8), and in that said actuator (14) comprises at least one finger (21) intended to be actuated in translation to exert said thrust force by forming said generator (15) in contact with said guide ramp (23), so that said finger drives said lever (18) rotating about said fixed pivot (11) to obtain rotation of said movable pivot (8).   15. Device (10) according to claim 12, characterized in that said ramp (23) has a concave surface of radius of curvature greater than that of the free end of said or each finger (21).   16. Control device (10) according to claim 12 or 13, characterized in that said lever (18) comprises two identical longitudinal members (24) which each comprise said guide ramp (23) and which are interconnected by a cross member (25) extending on each side of said tab (22).   17. Control device (10) according to one of claims 12 to 14, characterized in that said biasing means (19) is a compression spring bearing against said frame (12) and against an end sleeve ( 9) which is provided with said arm (7) and which is mounted around said movable pivot (8).   16. Control device (10) according to one of claims 12 to 15, characterized in that the distance (b) between the respective axes of said movable pivot (8) and said fixed pivot (11) is less than or equal to the distance ( a) separating said contact generatrix (15) from the axis (11a) of said fixed pivot (11).   17. Control device (110, 210, 310, 410) according to one of claims 9 to 11, characterized in that it comprises an eccentric mechanism comprising: an eccentric disk formed by said or each movable pivot ( 108, 208, 308, 408) and constituting said or each coupling plate, said or each disk (108, 208, 308, 408) being traversed by said fixed pivot (111, 211, 311) and being slidably mounted in a recess extending through said arm (107, 207, 307, 407) so as to be pivotally mounted on said frame (112, 212, 312, 412), said guide rail (123, 223, 323, 423) being formed in said each disc, and - a thrust member (116, 216, 316, 416) provided to exert said thrust force (F ') that comprises said actuator (114, 214, 314, 414) and which is intended to form said generator at the contact (115) of said or each guide rail (123, 223, 323, 423), so that said thrust member (116, 216, 316, 416) drives the or each disc (108, 208, 308, 408) rotated about said fixed pivot (111, 211, 311) by guiding said contact generator (115) to said or each ramp (123, 223, 323, 423) for obtaining rotation of said arm (107, 207, 307, 407).   18. Control device (110) according to claim 17, characterized in that said thrust member (116) comprises a bent rod intended to be actuated in translation, a free end of which is adapted to cooperate with said guide ramp (123). ) in the form of an arc of said eccentric disk (108).   19. Control device (110) according to claim 18, characterized in that said biasing means (119) is a tension spring connecting said frame (112) to said arm (107).   20. Control device (10, 110) according to one of claims 9 to 19, characterized in that said actuator (14, 114) comprises an electromagnet (17, 117) for obtaining said thrust force (F, F ' , F ").   21. Control device (210, 310, 410) according to claim 17, characterized in that said actuator further comprises a gear which is mounted opposite said eccentric disk (208) or between said two eccentric discs. (208, 308, 408) said gear comprising a control screw (230, 330, 430) and one or two end gears (231, 336 and 337, 416), each meshing with a toothed element (232, 338 and 339, 423), said or each toothed element being coupled to the guide ramp (223, 323, 423) of said or each eccentric disk for obtaining said thrust force.   22. Control device (210, 310) according to claim 21, characterized in that said thrust member is constituted by a thrust pin (216) or two coaxial push fingers (316) connected to each other which are provided on either side of said gear, said or each finger (216, 316) being adapted to cooperate transversely with the guide ramp (223, 323) of said one or of said eccentric discs (208, 308); .   23. Control device (210) according to claim 22, characterized in that said control screw (230) meshes with a toothed wheel (233) provided on one of its faces with a pinion (231) which meshes with a fixed rack (232) integral with said frame (212) and which is provided coaxially with said or each thrust pin (216), such that the rectilinear movement (Tr) of said pinion (231) on said fixed rack (232) is converted into a rotation (Re) of said or each eccentric disk (208) by guiding said or each thrust finger (216) on said or each ramp (223).   24. Control device (310) according to claim 22, characterized in that said control screw (330) meshes with a toothed wheel (333) provided on its respective faces with two coaxial pinions (336) of different diameters which mesh with each other. respectively with a fixed rack (338) integral with said frame (312) and with a movable rack (339) parallel to said fixed rack and secured to said thrusting fingers (316), so that the pinion (336) meshing with said rack mobile (339) moves the latter in a direction (T4) opposite that of the advance (T3) pinion (336) meshing with said fixed rack (338) to obtain a translational movement (T3) of said toothed wheel (333) with a reduced force along said fixed rack (338) which is converted into a rotation (R5) of the two eccentric disks (308) by guiding both push fingers (316) on the ramps of guides (323) respe ctives of said disks (308).   25. Control device (210, 310) according to one of claims 22 to 24, characterized in that the guide ramp (223, 323) of said or each disc (208, 308) has a substantially arcuate curvilinear slide shape circle whose one edge is intended to cooperate by sliding with said one or one of said thrust fingers (216, 316).   26. Control device (410) according to claim 21, characterized in that said thrust member is constituted by said end gears (416) which meshing respectively with said toothed elements, which are formed by the respective guide ramps (423) of said eccentric discs (408) and each have a shape of wheel sector with internal toothing.   27. Control device (410) according to claim 26, characterized in that said control screw (430) meshes with a drive gear (433) provided on its respective faces with two coaxial and identical drive gears (436) meshing with each other. respectively with two driven gearwheels (441) which are parallel to said driving gearwheel (433), which driven wheels are each provided coaxially on one of their faces with a driven gear (416) meshing with the guide rail ( 423) of the adjacent disk (408), such that the rotation (R3) of said driven gears (441) is converted into a rotation (R4) of the two eccentric disks (408) by guiding said driven gears (416). on the respective guide rails (423) of said disks (408).   28. Control device (210, 310, 410) according to one of claims 21 to 27, characterized in that said control screw (230, 330, 430) is a worm coupled to an output shaft of an engine electric (335, 435) for its rotational drive.   29. Control device (210, 310, 410) according to one of claims 21 to 28, characterized in that said arm (207, 307, 407) comprises two parallel rods (207a and 207b, 307a and 307b, 407a and 407b). interconnected and terminating respectively with two rings (207c, 307c, 407c) enclosing said eccentric discs (208, 308, 408), such that said rods are driven together in pivotal manner by rotary sliding about said fixed pivot ( 211, 311) of said disks respectively in contact with said rings.   30. Control device (210, 310, 410) according to one of claims 21 to 29, characterized in that said biasing means comprises a compression spring or torsion (219, 319, 419, 419 ') bearing against said frame (212, 312, 412) and against one of said rings (207c, 307c, 407c).