Starter drive for an internal combustion engine
United States Patent Toulier 1 1 STARTER DRIVE FOR AN INTERNAL COMBUSTION ENGINE [75] Inventor: Pierre Toulier, Ville DAvray,  
 France [73] Assignee: Societe Anonyme D.B.A., Paris.  
 France [22] Filed: Nov. 15, 1973 [2]] Appl. No.: 415,874  
 [52] US. Cl 74/7 R; 192/35; 192/94; 192/114 R [51] Int. Cl F02n 11/00 [58] Field of Search 74/6, 7 R; 192/35, 36, 192/4194, 114 R; 290/38 R 156] References Cited UNITED STATES PATENTS 2.167.846 8/1939 Martin 192/36 X 2.233.595 3/1941 Elkin 3.465.353 9/1969 Buxton et all...  
 3.496.759 2/1970 Buxton 3.599.496 8/1971 Toulicr 74/7 R (Ll/76W Apr. 8, 1975 Primary E.\-mm&#39;nerAllan D. Hermann Attorney, Agent, or Firm- Remy .1. Van Ophem; Raymond J. Eifler (57] ABSTRACT A starter for an internal combustion engine comprising a helically splined shaft adapted to be rotated by a starter motor. and a moveable portion comprising a sleeve thrcadedly received on the helical splines of the shaft and connected by a one way clutch to a pinion, the moveable portion being associated with the friction drive mechanism which comprises a retarding plate in frictional engagement with the sleeve and a plunger solenoid of which the plunger core. when in its operational position, operates with the plate by means of a connection of the slot and guide-rail type to prevent rotation of the plate while permitting axial motion of the plate, wherein the plunger core comprises an extension directed towards the retarding plate and cooperating with the plate by engagement means which. when the plunger is in its idle position, prevents actual motion of the plate while permitting rotation of the plate.  
 5 Claims, 1 Drawing Figure STARTER DRIVE FOR AN INTERNAL COMBUSTION ENGINE The invention relates essentially to a starter drive for an internal combustion engine.  
  A known starter drive for an internal combustion engine comprises a helically splined shaft rotated by a starter motor. and a movable portion comprising a sleeve threadedly received on the helical splines of the shaft and connected by a one-way clutch to a pinion. The pinion can be made to mesh with a ring gear in the internal combustion engine by driving forward the movable portion of the starter drive, when the sleeve is prevented from rotating while the starter motor is turnmg.  
  The movable portion may be driven forward by means of a mechanism comprising a retarding plate in frictional engagement with the sleeve. and locking means which prevents rotation of the plate but permits axial motion of it. In one known solution these means comprise a solenoid which can be switched on at prac tically the same moment as the starter motor, and  
 which has a plunger capable of co-operating with the plate by means of a connection of the slot and guiderail type.  
  When a starter drive of this type is at rest, that is. when the starter motor is off and the solenoid plunger is not co-operating with the retarding plate. the starter motor armature. i.e., the shaft of the starter drive. may be rotated due to vibration, shocks orjolting. This does not matter provided the movable portion rotates at the same time as the shaft, as the movable portion remains axially fixed. If. however, the inertia ofthis portion prevents it from turning at the same time as the shaft, it may move axially and bring the pinion into contact with the ring gear of the internal combustion engine. This contact is of course liable to damage the starter drive.  
  An object of the invention is to prevent axial motion of the movable portion of the starter motor while the latter is in its idle position.  
  According to the in ention, the plunger core of the solenoid comprises an extension directed towards the plate of the friction mechanism and co-operating with the retarding plate by engagement means which, when the plunger is in its idle position, prevent axial motion of the plate while permitting rotation of the plate.  
  The invention will now be described by way of example with reference to the accompanying drawing in which the single FIGURE illustrates an embodiment of the starter drive of the invention.  
  The starter drive comprises a pinion l2 slidably mounted on a shaft 14. The shaft 14 is rotated by a starter motor 15, and its end is supported by an extension 16 of the starter motor housing. By way of an unidirectional clutch or freewheel generally designated 18 the pinion 12 is coupled to a sleeve 20 whose internal surface bears helical splines 22 which mesh with corresponding splines on the shaft I4. The sleeve 20 and the outer casing of the freewheel 18 may be integral with one another.  
  The pinion l2, freewheel l8 and sleeve 20 form the movable portion of the starter drive, this portion being shown abutting on a stop 24 in the retracted position which it occupies when idle. The connection by means of helical splines enables the movable portion to advance axially so that the pinion 12 can mesh with the ring gear 26 of the internal combustion engine. The advance of the pinion 12 is limited by a stop ring 28.  
  Axial motion of the movable portion of the starter drive is produced by a friction mechanism which retards the sleeve 20 when the starter motor 15 begins to turn. The friction mechanism comprises a tubular element 30 slidably mounted on the sleeve 20 and biased on to the outer casing of the freewheel 18 by a spring 32 placed round the sleeve 20, this spring being compressed between a thrust washer 34 and a collar 38 which. with balls 36 which separate this collar from the tubular element 30, forms a low-friction abutment bearing. The friction mechanism also comprises a dished annular element or retarding plate 40 whose central opening is provided with slots 42 engaging corresponding projections formed round the tubular element 30, adjacent one end of this element which includes a flange 44. A spring 46 urges the dish 40 on to the flange 44 thereby urging the entire movable portion of the starter drive towards its idle position. The frictional force tending to retard rotation of the sleeve 20 occurs when the dish 40 and the element 30 to which it is connected are prevented from rotating while remaining capable of axial movement. To this end. the dish 40 includes a peripheral ring of teeth 48, with slots therebetween, and a plunger solenoid 50 mounted on the housing 16 is provided with a plunger 52 ending in a guide-rail type bar 54 parallel to the shaft 14. When the solenoid 50 is supplied with current. the plunger 52 descends and the bar 54 engages between two teeth in the ring of teeth 48.  
  The bar 54 comprises an arm 56 which points towards the shaft 14 and bends back towards the interior of the dish 40, ending in a claw 58. The claw 58 is designed to grip a rim 60 formed on the edge of the dish 40 and flanged inwards, the rim 60 being gripped when the solenoid 50 is switched off, that is. when the starter drive is in the idle position illustrated in the FIGURE.  
  When a starter switch (not shown) is operated in a known manner to work the starter drive. the starter motor 15 and solenoid 50 are switched on almost simultaneously. Since the plunger descends, the claw 58 escapes from the rim 60 of the dish. whereas the bar 54 engages between two of the teeth 48 formed on the dish. The assembly including the dish 40 and tubular element 30 is then prevented from rotation. and the re tarding action exerted by this assembly on the movable portion enables the latter to move axially until the pinion 12 meshes with the ring gear 26, as stated above. The dish 40 and tubular element 30 move at the same time as the movable portion of the starter drive until the dish 40 abuts on the housing 16. During this movement. the teeth 48 on the dish move along the bar 54. The starter switch is released when the internal combustion engine has been started. as the pinion 12 is rotated to a speed exceeding the speed at which it is driven by the shaft 14 by way of the sleeve 20 and freewheel IS. The pinion 12 then disengages from the ring gear 26, and the movable portion of the starter drive moves back into its idle position, the return motion being assisted by the return spring 46. As soon as the starter switch is released, however. the plunger of the solenoid 50 returns into the position illustrated. so that, as the movable assembly of the starter drive resumes its idle position, the rim 60 of the dish 40 passes over the claw 58, on which it catches. As shown in the FIGURE. chamfers formed on the leading edges of the rim and the claw facilitate the passage of the rim 60 over the claw 58.  
  The engagement system comprising the claw 58 connected to the bar 54 and the rim 60 on the dish 40 is provided to prevent the movable portion of the starter drive from moving axially while the drive is inoperative. In the absence of special precautions such axial motion is liable to occur because the armature of the starter motor 15, and therefore the shaft 14, may rotate due to vibrations. shocks or joltingt If so, the inertia of the movable portion prevents it from being rotated at the same speed as the shaft 14, and it shifts axially. If the pinion 12 then comes into contact with the ring gear 26 of the internal combustion engine while the latter is running the starter drive is likely to be damaged. This risk is not entirely eliminated in known starter drives in which only the return spring 46 prevents axial motion of the movable portion of the drive. The engagement system comprising the claw S8 and rim 60, however. removes this risk entirely.  
  Advantageously, in a starter drive embodying the invention the height of the claw 58 is less than the dis tance separating the teeth 48 from the bar 54, so that disengagement occurs before the bar meshes with the teeth I claim:  
  I. A starter drive for an internal combustion engine comprising a helically splined shaft adapted to be rotated by a starter motor. and a movable portion com prising a sleeve threadedly received on the helical splines of the shaft and connected by a one-way clutch to a pinion. the movable portion being associated with a friction drive mechanism which comprises a retarding plate in frictional engagement with the sleeve and a plunger solenoid of which the plunger core, when in its operating position, co-operates with the plate by means of a connection of the slot and guide-rail type to prevent rotation of the plate while permitting axial motion ofthe plate wherein the plunger core comprises an extension dirccted towards the retarding plate and C0 operating with the plate by engagement means which. when the plunger is in its idle position, prevents axial motion of the plate while permitting rotation of the plate 2. A starter drive as claimed in claim I, wherein the engagement means comprise a claw formed at the end of the extension and directed radially outwards. and a rim formed on the plate and flanged inwards.  
  3. A starter drive as claimed in claim 2, wherein the claw and/or the rim have inclined leading edges facilitating passage of the rim over the claw when the movable portion of the starter drive returns to its idle position.  
  4. A starter drive as claimed in claim 2, wherein the heights of the claw is less than the distance separating the elements of the connection of the slot and guiderail type in the position occupied by these elements when the plunger is in its idle position.  
  5. A starter drive as claimed in claim 3, wherein the height of the claw is less than the distance separating the elements of the connection of the slot and guiderail type in the position occupied by these elements when the plunger is in its idle position