FR2759119A1 - AUTOMOTIVE VEHICLE STARTER COMPRISING AN IMPROVED LAUNCHER - Google Patents

Abstract

The invention proposes a motor vehicle starter, of the type in which a launcher (16) comprises a pinion (18) and is moved axially from rear to front by a control lever (33), of the type in which a rear sleeve (30) of the launcher (16) drives in rotation, via a freewheel device (34), a front sleeve (38) to which the pinion (18) is connected by helical splines (46, 48 ), characterized in that the pinion comprises a sheath (42) which extends it axially towards the rear, and in that the freewheel device comprises an internal ring (38) provided, on an internal face, with helical splines ( 48) which cooperate with complementary grooves (46) arranged on an outer face of the sleeve (42) which is received inside the inner ring (38).

Description

The invention relates to a motor vehicle starter.

  comprising an improved launcher.

  The invention relates more particularly to a motor vehicle starter, of the type in which a launcher is axially movable on a front section of a starter motor shaft between a retracted rest position and an advanced engagement position in which a pinion of the launcher meshes with a ring gear of a flywheel of the thermal engine of the vehicle, of the type in which the launcher comprises a rear bush which is integral in rotation with 1o the motor shaft by means of grooves and which is moved axially from rear in front by a control lever, of the type in which the rear bush rotates, by means of a free wheel device, a front bush which is free in rotation and sliding on the front section of the shaft and which carries the pinion, and of the type in which the pinion is linked to the front sleeve by helical grooves so that when the pinion comes into abutment tooth against tooth against the crown, the pinion and the front sleeve move axially relative to each other against a return spring and the pinion pivots about its axis relative to the front sleeve a sufficient offset angle to allow engagement

  size of the pinion with the ring gear.

  Such a device makes it possible to transform the axial movement of the pinion relative to the rest of the launcher into a movement of angular offset of the pinion around its axis by a value equal to at least one pitch of teeth so that, when the launcher reaches its advanced position under the action of the control lever, the pinion is effectively engaged with the ring gear. In this way, it is possible to cause the starting of the electric motor of the starter so as to rotate the ring gear of the

thermal motor.

  The object of the invention is to propose a starter launcher comprising such a device for angular shifting of the pinion which is

particularly compact.

  To this end, the invention provides a motor vehicle starter, of the type in which a launcher is axially movable on a front section of a starter motor shaft between a retracted position of rest and an advanced engagement position in which a launcher pinion meshes with a ring gear of a flywheel of the vehicle's heat engine, of the type in which the launcher comprises a rear bush which is fixed in rotation with the motor shaft by means of splines and which is moved axially d rearwardly forward by a control lever, of the type in which the rear bushing rotates, by means of a free wheel device, a front bushing which is free in rotation and in sliding on the front section of the shaft which carries the pinion, and of the type in which the pinion is linked to the front sleeve by helical grooves, characterized in that the pinion comprises a sheath which extends it a xially towards the rear, and in that the freewheel device is a roller device lo of which an outer ring forms the rear bushing of the launcher and of which an inner ring comprises, on an internal cylindrical face, helical grooves which cooperate with complementary grooves arranged on an external cylindrical face of a rear end of the pinion sheath which is received inside the

internal ring.

  According to other characteristics of the invention - the helical grooves of the internal ring are of reduced axial length and are arranged at a rear axial end of the ring; - The helical grooves of the pinion sheath extend axially over a length substantially equal to that of the internal ring; - a return spring is arranged between the pinion and the internal ring of the freewheel device to urge the pinion forward, and the rear axial end of the pinion sheath protrudes rearward beyond one face rear transverse of the ring and comprises abutment means which bear against said transverse face to determine an advanced position of rest of the pinion relative to the internal ring; the means of abutment of the pinion against the rear transverse face of the internal ring comprise an elastic stop ring which

  is mounted on the rear axial end of the sleeve.

  Other characteristics and advantages of the invention

  will appear on reading the following detailed description for the

  understanding of which reference will be made to the appended drawings in which FIGS. 1 to 4 are partial views in longitudinal section of a motor vehicle starter in accordance with the teachings of the invention, in which the launcher is shown respectively in the retracted rest position , when the pinion comes into abutment against the ring gear, during the angular offset of the pinion, and at

  when the pinion meshes with the ring gear.

  There is shown in the figures the front axial end of a starter 10, a motor shaft 12 of axis A1 is driven in rotation by an electric motor (not shown). The motor shaft 12 comprises a front section 14 on which is mounted a launcher 16 which comprises, at the front, a pinion 18 intended to mesh with a toothed crown 20

  of the flywheel of a thermal engine of the motor vehicle.

  The front section 14 of the shaft 12 is extended axially by 1o a front axial end 22 which is rotatably mounted in a bearing 24 formed in a nose 26 at the front of the starter casing 12. The nose 26 has a lower opening 28 which allows the meshing of the pinion 18, which is arranged inside the nose 26, with the crown

  toothed 20 which is of course external to the starter 10.

  In known manner, the launcher 16 is axially movable from rear to front between a retracted position of rest shown in the

  Figure 1 and a geared forward position shown in Figure 4.

  The launcher 16 comprises, in addition to the pinion 18, a rear bushing which is linked in rotation with the drive shaft 12 by means of helical grooves 32, and whose axial movement on the shaft 12 is controlled by a control lever 33 articulated around a transverse axis A2 and itself controlled by a starter switch

(not shown).

  In a known manner, the rear bush 30 uniquely rotates the pinion 18 by means of a roller freewheel device 34, an external ring 36 of which is made integrally with the rear bush 30 and including a ring internal 38 forms a front casing of the launcher 16 which is linked in rotation with the pinion 18. The freewheel device with rollers 34 makes it possible to ensure that, when the heat engine of the vehicle starts and that the speed of rotation of the flywheel increases, the pinion 18 cannot rotate the electric motor of the starter at too high a speed which

could damage it.

  Furthermore, the launcher 16 comprises means 40 which make it possible to prevent the electric motor of the starter from causing the rotation of the pinion 18 before the latter is correctly engaged.

with the crown gear 20.

  To this end, the pinion 18 comprises a sheath 42 which extends axially towards the rear and whose rear axial end 44 comprises, on an external face, helical grooves 46 which are intended to cooperate with corresponding grooves 48 arranged on an internal cylindrical surface 50 of the internal ring 38 of the

  roller freewheel device 34.

  The grooves 46 of the sleeve 42, which open at the rear, extend over a length which is substantially equivalent to that of the internal ring 38 but the rear end 44 of the sleeve 42, which is 1o received inside the inner ring 38, protrudes axially towards

the rear beyond it.

  An elastic ring 52 is fixed to the rear of the sleeve 46 so as to be able to abut against a rear transverse wall 54 of the internal ring 38. In fact, a helical compression spring 56 is arranged around the sleeve 42 between the pinion 18 and a front transverse face 58 of the inner ring 38 so as to urge the pinion 18 axially towards the front relative to the sleeve

  rear 30 and to the roller freewheel device 34.

  Thus, when the starter is in its rest position shown in FIG. 1, the elastic stop ring 52 arranged at the rear of the sheath 42 of the pinion 18 bears axially forwards against

  the rear transverse face 54 of the inner ring 38.

  The operation of the starter 10 according to the invention will be

  now described with reference to Figures 2 to 4.

  When the driver of the vehicle wishes to start the heat engine, he requests the starter, the contactor of which causes the control lever 33 to rotate about its transverse axis A2.

  so as to urge the rear bush 30 of the launcher 16 forward.

  As long as the pinion 18 does not encounter any obstacle, the whole of the launcher 16 therefore moves forward to the position shown in FIG. 2 in which a front transverse face 60 of the pinion 18

  arrives at the gear 20.

  If the pinion 18 and the ring gear 20 are arranged angularly with respect to each other so that they meet

  tooth against tooth, the pinion 18 is locked axially forward.

  In this way, when the lever 33 continues to push the rear bush 30 forward, it drives with it the roller freewheel device 34 and in particular its internal ring 38 which then moves axially forwards with respect to the pinion 18, as can be seen more particularly in FIG. 3. This relative movement of the freewheel device 34 relative to the pinion 18 causes the compression of the

spring 56.

  Furthermore, the complementary grooves 46, 48 of the sheath 42 of the pinion 18 and the inner ring 38 being helical, this relative displacement in the axial direction induces a rotational movement which causes an angular offset of the pinion 18 around its

axis A1.

  The value of this offset depends on the relative axial travel lo of the pinion 18 relative to the inner ring 38 and on the helix angle of the helical grooves 46, 48. It suffices therefore to provide that, during the relative travel of the pinion 18 and the inner ring 38 between the position of contact of the pinion 18 with the crown 20, represented in FIG. 2, and the extreme advanced position of the internal ring 38, represented in FIG. 3, the angular offset of the pinion 18 is equal to at least one tooth pitch so that, along this race, the pinion 18 and the crown 20 find themselves in a relative angular position allowing engagement in the axial direction as shown in the

figure 4.

  Indeed, as soon as a tooth of the pinion 18 is in correspondence with a between-tooth of the crown 20, and vice versa,

  the spring 56 pushes the pinion 18 forward while relaxing.

  Thus, when the rear bush 30 of the launcher 16 reaches its extreme forward position under the action of the lever 33 controlled by the switch, the pinion is certainly engaged with the toothed crown.

  , regardless of their initial relative position.

  The starter contactor can then cause the electric supply to the starter motor to drive the motor shaft 12 in rotation, a movement which is then transmitted to the crown 20 by

Through the launcher 16.

  As can be seen in the figures, the device 40 according to the invention which makes it possible to obtain the angular offset of the pinion 18 is particularly compact. Indeed, the mechanism of complementary helical splines 46, 48 is almost entirely contained in the axial size of the internal ring 38 of a freewheel device with a roller 34 so that the axial length of the launcher 16 is

particularly reduced.

  It can be seen that the axial length of the grooves 48 of the inner ring 38 is particularly reduced so that the raised parts of the grooves 48 are in the form of teeth which are arranged at the rear axial end of the ring 38 and which are likely to slide in the hollow parts of the grooves

46 of the sleeve 42 of the pinion 18.

  The radial size of the device 40 is also very small. Of course, the direction of winding of the helix of the helical grooves 46, 48 must be such that, when the inner ring 38 moves towards the pinion 18, it is biased in the locking direction of the roller freewheel device so that it is the pinion 18 which

1o turns and not the ring 38.

Claims (5)

  1. Motor vehicle starter, of the type in which a launcher (16) is axially movable on a front section (14) of a motor shaft (12) of the starter (10) between a retracted position of rest and an advanced position d meshing in which a pinion (18) of the launcher (16) meshes with a ring gear (20) of a flywheel of the thermal engine of the vehicle, of the type in which the launcher (16) comprises a rear bushing (30) which is integral in rotation with the motor shaft 10 (12) by means of grooves (32) and which is moved axially from back to front by a control lever (33), of the type in which the rear bushing (30) drives in rotation, by means of a freewheel device (34), a front sleeve (38) which is free in rotation and in sliding on the front section (14) of the shaft (12) and which carries the pinion (18), and of the type in which the pinion (18) is linked to the front sleeve (38) by helical grooves (46 , 48), characterized in that the pinion comprises a sheath (42) which extends it axially towards the rear, and in that the freewheel device is a roller device (34) of which an internal ring (38) comprises , on an internal cylindrical face, helical grooves (48) which cooperate with complementary grooves (46) arranged on an external cylindrical face of a rear end (44) of the sleeve   (42) which is received inside the inner ring (38).   2. Starter according to claim 1, characterized in that the helical grooves (48) of the inner ring (38) are of reduced axial length and are arranged at a rear axial end of the ring (38).   3. Starter according to claim 2, characterized in that the helical grooves (46) of the sleeve (42) of the pinion (18) extend axially over a length substantially equal to that of the inner ring (38).   4. Starter according to any one of the claims   previous, characterized in that a return spring (56) is arranged between the pinion (18) and the inner ring (38) of the freewheel device (34) to urge the pinion (18) forwards, and in that the end   rear axial of the sheath (42) of the pinion (18) protrudes rearwardly   beyond a rear transverse face (54) of the ring (38) and comprises abutment means (52) which bear against said transverse face (54) to determine an advanced position of rest of the pinion (18) relative to has the inner ring (38). 5. Starter according to claim 4, characterized in that the means of abutment of the pinion (18) against the rear transverse face (54) of the internal ring (38) comprise an elastic stop ring   (52) which is mounted on the rear axial end (44) of the sleeve (42).