US2333765A - Starting device for internal combustion engines - Google Patents

Description

0. CELIO Nov. 9, 1943.

STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Feb. 10. 1942 2 Sheets-Sheet 1 Fig.1.

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STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Feb. 10, 1942 Z SheetS-Sheet 2 6 1 1 26 B 6S 3'] Flg.4. 24 71 63 1 VS 56 S 72 ea 69 67' l 54 25 27 b6 6443 2 40 7s Patented Nov. 9, 1943 I STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Orlando Celio, Soleure, Switzerland, assignor to Scintilla Ltd., Soleure, Switzerland, a corporation of Switzerland Application February .10, 1942, Serial No. 430,290 In Switzerland April 10, 1941 10 Claims.

ring. For this purpose, in the devices heretofore known, the starting motor is driven vforwards or backwards with full or reduced torque, while the pinion is axially pressed by a spring against the gear ring to be brought into engagement with the same as soon as it attains a .suitable angular position. The pinion remains in such positions only during a very short period of time so that a spring of considerable strength is required .to bring it timely into engagement. But this considerable axial pressure of the pinion against the gear ringvery often results in an undesirable wear of the front faces of these parts.

The object of this invention'is to provide means for bringing the pinion into engagement with the gear ring without starting the motor, the pinion being only displaceable against a small resistance. In the case of a greater resistance, the attempt to bring the pinion into engagement shall be vain, and on giving up the attempt, the pinion shall automatically attain an angular position difiering from the one in which it was before starting this attempt so as .to give .a possibility of success for the following attempt.

According to the invention, the pinion is coupled for rotation with an axially displaceable pinion carrierand axially slidable relative thereto against a force which is effective in the engaging direction and tending to press said pinion against an abutment on the pinion carrier,,a non-displac'eab'le or only limited axially displaceable intermediate member being provided in the driving connection between the pinion carrier and the rotor of the starting motor, which member is coupled to said rotor by an overrunning clutch enabling the intermediate member to advance relative to said rotor in the operative direction of rotation of the same, and to the pinion carrier by a steep-pitch thread by means of which said member is turned in the said operative direction with respect to the pinion carrier when the latter is axially displaced in engaging direction with respect to the intermediate member.

-Preferably, displacement of the pinion with respect to the pinion carrier is limited in both, the engaging and disengaging direction by suitable abutments. The operating device of the starting motor can then appropriately be made dependent upon the movement of the pinion carrier in such a way as to permit of starting said motor only when the pinion carrier has attained a position in which the entire axial displacement of the pinion with respect to the pinion carrier causes said pinion to engage the gear ring with at least a part of its tooth breadth.

For axially displacing the pinion carrier, the starting device may comprise a shifting member adapted to transmit to the pinion carrier forces which are only effective in the engaging direction along that portion of the path of the pinion carrier through which the latter has to travel from its resting position to a position wherein the pinion engages the gear ring with a part of its tooth breadth. The switching device of the starting motormay be operable by the said shifting member.

In the accompanying drawings an embodiment of the invention is represented by way of example.

Fig. 1 is alongitudinal sectional view of a starting device taken on the line A-A of Fig. 2.

Fig. 2 is a cross sectional view of the same starting device taken on'the line B-B in Fig. 1.

Figs. 3 to 7 show essential parts of the device according to Figs. 1 and 2 in different operating positions.

The casing of the starter is composed of three main parts, i. e. the bearing plate I, the fieldwinding carrier 2 and the switch housing 3, which are firmly held together by longitudinal bolts or screws not shown. The rotor of the starting motor has a hollow shaft 4,, one end of which is journaled on a pin-like extension 5 of the switch housing 3, while its other end is widened out to form a clutch casing 6 which is fixed in any known manner to an end plate 1 supported in the bearingplate l'.

The rotor shaft 4 carries the laminated armature core 8 having thereon the armature winding 9, and the commutator 10. On the surface of the latter slide the carbon brushes l3 and I4 guided in brush holders II and 12; the brush holders are mounted on a partition 15 of the switch housing 3, which partition is shown separating the starting motor from the switch described farther down. The brush holder II and brush I 3 are insulated with respect to the switch housing 3, while the brush holder l2 and brush I I are earthed across the housing 3. In the fieldwinding carrier 2 are fixedly mounted iron pole pieces I! by means of screws l6, and each pole piece carries a field winding l8 wound thereon.

In the switch housing 3 a magnet coil 19 is located in which an iron core is longitudinally displaceable. The latter carries a plate M on which a leaf spring 22 is fixed by means of rivets 23; the spring 22 is insulated from the plate 2! by a non-conductive intermediate layer Ti and from the rivets 23 by insulating bushes and washers 18. On the ends of said spring, contact blocks 24 and 25 are located which cooperate with contacts 25 and 21 insulatedly fixed to the housing 3. The contact 28 is connected to the positive pole of a source of current by means of a cable 29 and a terminal post 28 which is likewise insulated from the housing 3. To the contact 21 is riveted a strip 30 which extends through a hole in the partition l5 to be connected to one end of the field winding of the starting motor.

The latter is a direct current series wound motor. When the magnet coil I8 is excited and, by the effect of its attractive force on the core 2! presses the contact blocks 24 and 25 against the contacts 26 and 21, respectively, the current flows from the positive pole of the source of current through the cable '29, the terminal post 28, the pair of contacts 26/24, the spring 22 and the pair of contacts 25/21 to the connecting strip 30. From the latter the current will pass through a conductor 3! to the field winding, the coils H) of which are connected to one another by a conductor indicated by 32. The other end of the field winding is connected by a conductor 33 to the insulated brush I3 which transmits the current across the commutator I0 to the armature winding 3. The brush l4 collecting the current on the opposite side of the commutator is earthed; also the negative pole of the source of current must be earthed in this case so that the return of the current is established by earth. The brush l4 might just as well be connected to the negative pole of the source of current by a separate conductor.

In the hollow .rotor shaft 4 and in a likewise hollow journal 34 of. the end plate 1 of the clutch casing are rotatably lodged two bushes 3'! and 38 between a shoulder of the bore in the shaft and the inner end face 35 of the bearing plate I, limiting the bearing of the journal 34; the said bushes are arranged adjacent each other with a slight longitudinal play so as to be axially displaceable in close limits only. The front bush 3'! which abuts the bearing plate I has a smooth cylindrical outer surface and presents on the inside a steep quadruple square thread which extends over the whole length of said bush.

Between the end plate I and a bottom 39 of the clutch casing 3 a ring 40 is supported on the bush31 which is freely rotatable on said bush. Said ring has on its inner working surface, par allel to the axis, several grooves 4|, of which the depth of each increases in the operative direction of rotation of the rotor of the starting motor. In the present example, this operative direction is supposed to be clockwise as indicated by the arrow 42 in Fig. 2 when the starting motor in Fig. l is viewed from the right-hand side. In each one of the grooves 4| lies a steel roller 43. Upon turning the ring 49 relative to the bush 3'! in the operative direction 42. the rollers 43 roll into the part of little depth of the grooves 4| so as to become jammed between the working surface of the bush 3i and the bottom of the grooves, whereby by reason of the friction produced between these surfaces and the rollers torques are transmitted from the ring 40 to the bush 3?. 0n the other hand, when the bush 3'! is turned to advance relative to the ring 40 in the operative direction 42, the rollers 43 roll into the deeper part of the grooves 4! to rest therein without exerting any pressure on the working surface of the bush 3i and the bottom of the grooves. The rollers then transmit no torque between these surfaces, and the bush 3'! is free to advance with respect to the ring 40 in the direction 42.

On the outer surface of the ring 40 and the inner surface of the wall of the clutch casing 6 are provided, parallel to the axis, grooves 44 and 45, respectively, of rectangular cross section. In the clutch casing, between the surfaces mentioned, are disposed several sets of ring shaped friction discs. In each of these sets a steel disc 56, having on its circumference projections 41 which engage the grooves 45 of the casing, is followed by a disc 48 devoid of projections and made of brake covering material (called Ferodo) then by a steel disc 49 having on its inner border projections 50 which engage the grooves 44 of the ring 40, and finally by another Ferodo -disc 48. On the latter bears the first steel disc 46 of the following set and so on. On the side of the end plate I ofv the clutch casing 6, these sets of friction discs are followed by a solid ring 5| of trapezoidal cross section having its thickest portion on the inner border, and finally, there are provided two adjacent conical pressure discs 52 Whose inner borders bear against the inner border of the ring 51 while the outer borders of said discs rest on a shoulder 53 of the end plate 1. These pressure discs are so shaped as to become deformed on assembling the end plate I with the clutch casing 6 thus pressing by the intermediary of the ring 51 the friction discs 46, 48 and 48 against one another with a certain force.

Owing to' the friction between these discs, a certain torque is transmitted from the clutch casing E5, coupled for rotation with the discs 46 by the engagement of the grooves 45 and projections 41, to the ring 40 which is connected to the discs 49 by the grooves 44 and projections 50. If, on the other hand, the torque to be transmitted increases, the friction discs 46, 48 and 49 begin to slide relative to each other so that the effective torque imparted to the bush 3? can in no case exceed a certain value.

In the bushes 31 and 38 is arranged a sleeve 54 forming a part of a pinion carrier, the whole of which is designated by the numeral 55. The sleeve 54 is provided on the outside over a part of its length with a steep pitch thread 56 corresponding to and engaging the female square thread of the bush 3'! The direction of the helix of this steep pitch thread is such that upon displacing the pinion carrier 55 to the right in Fig. l. of the drawings the bush is turned in the operative direction 42 (Fig. 2) with respect to said pinion carrier. The inside of the sleeve 54 forms a guide for the shank 51 of a pinion 58 which shank is formed integral with said pinion and provided with splines 59 extending parallel to the axis and engaging corresponding grooves on the inside of said sleeve; the pinion 58 is thus coupled for rotation with the pinion carrier 55 but can slide axially with respect to the same.

The pinion carrier 55 is formed, on the one side with a spindle 50 extending through a longitudinal bore in the pinion 58 and the shank 51. The free end of said spindle carries an abutting nut 6| screwed thereon and secured by a pin 62. Between the bottom 63 of the pinion carrier 55 and the front face 64 of the pinion shank 51 is interposed a relatively weak compression spring .65 tending to press the pinion against the abut ting nut (H. The stroke of the pinion against the pressure of the spring 85 is limited by a shoulder 66 on the spindle '60.

On the other side, the pinion carrier 55 is formed with a shank 61 to which a spring plate -68 is secured. Upon said spring plate rests one end of a compression spring 65 hearing with its other end on the bottom -18 of the bush 38 and tending to shift the pinion carrier inwards, that is to the left in Fig. l. The inward'rnovement of the pinion carrier is limited by its bottom 6-3 abutting the front face of the bottom 18 of the bush 38, and the outward movement is limited by the spring plate 68 abutting the back face of said bottom.

The iron core 20 of the switch for-ms the shifting member controlling the operating means of the pinion of the starting device. The said core is provided with a peg ll guided in an axial bore of the pin-like extension of the switch housing 3, The front face 12 of said peg lies in the path of the end face 13 of the shank 67 of the pin-ion carrier. The length of the peg H is such that the switch cannot be closed unless the pinion carrier has attained a certain position upon its outward movement Owing to the :coaction of the faces 12 and 13, only forces tending to displace. the pin-ion carrier outwardly can be transmitted from the iron core '20 to said pinion carrier. Moreover, the stroke of the iron core is limited by a face 14 of the switch housing in such a manner, that said iron core is allowed to displace thepinion carrier into a certain position only and not to the end of its outward path.

The fly-wheel of the engine to be started by the starting device described, is designated by the numeral 15. a gear ring 16 the teeth of which, regarding pitch and shape. correspond with those of the pinion 58, when inoperative, the pinion is in the position shown in Fig. 1. To bring the pinion into Said fly-wheel is formed with i attracts the iron 500118 .28, and the peg H of the latter displaces the pinion carrier in the ensgaging direction of the pinion 58 thereby compressing ,the spring '69. The pinion 58 which is pressed by the spring 85 against the abutting nut alil and which,,at first, encounters no resistance is :also shifted in the engaging direction. Let it, for instance, be supposed that owing to their inertia, .or for some other reason, the pinion carrier 55 and the pinion 58 do, at first, not rotate about their axis, The bush 31 is then turned through the steep pitch thread 56 of the pinion carrier in the operative direction '42; during this turning movement, the rotor shaft 4 carrying the armature :8 remains stationary as the overrunning clutch formed by the rollers 43 in the grooves 4| enables the bush 31 to be advanced relative to the ring 48 in the said operative direction. In this manner, the parts of the device, at first, attain the position shown in Fig 3, in which the face of the plnion'58 has reached that of the gear ring 1.6.

When, contrary to the assumption made, the pinion carrier 55 and pinion 58 are rotated by a small torque while, on the other hand, the bush 31 is prevented from rotating, for example by the friction in the ioverrunning clutch, the pinion carrier and pinion will upon axial displacement be turned in the direction opposed to the operaengagement with the teeth of the .gear ring the pinion carrier and pinion must be displaced outwards in axial direction. But the axial vd-isplacement of the pinion will not comes :under all circumstances to produce this engagement because in many cases the front faces of the teeth 'of the pinion will abut against the front faces of the teeth of the gear ring, and engagement can only take place when the teeth ofthe pinion :are able to slide into the tooth gaps of the gear ring. Consequently, in the mode -of operation two typical principal cases are to be distinguished, according to whether a single outward displacement :of the pinion carrier suffices to bring the pinion into engagement-with the gear ring or to whether it will be necessary to turn said pinion prior to effecting its engagement.

If certain conditions are assumed, in both of these cases the engagement of the pinion will take place as described hereafter. In reality, ther conditions than the ones assumed might prevail in certain parts of the device .so a to cause some other issue of the operation. In general, engagement of the pinion,-as compared with the more unfavourable of the two cases hereinafter considered, will be facilitated by these diverging conditions.

In order to start the engine by means of the starting device, the magnet coil [9 is :putincircuit, for example by closing a switch .in its circuit, not shown in the drawings. This coil thenv til tive direction 42 so as to assume in the axial position in which they are represented in Fig 3 azsomewhat different angular position.

The further course of the engaging operation depends on whether in the attained position of the pinion 58 each tooth of the same is opposite a tooth gap of the toothed gear ring 16 so that upon axial displacement the pinion may immediately be moved into engagement with the gear ring, or whether the face of a tooth or of several teeth of the pinion abut respectively the face or faces of 'a tooth or several teeth of the gear ring.

.If each tooth of the pinion -58 meets a tooth gap of the gear ring 16, pinion carrier 55 and pinion 5B Willbe farther axially displaced by the core 28 which is attracted by the coil 19. Owing to the engagement of the teeth of pinion '58 with the still motionless gear ring 16, the pinion 58 and its carrier 55 are then forcedly prevented from rotating so that the steep pitch thread 56 of the pinion carrier compels the bush 31 to turn in the operative direction '42. The overrunnlng clutch formed by the roller '43 permits the bush 8-! to turn without movement of the armature of the starting motor. I

When the ccre of the :electro-magnet comes in touch with the face 14 limiting its-course, the parts of the starting motor will be in the position 'show-n in Fig. 4. Immediately :before reaching said position, the contact blocks 24 and 25 will come in touch with the stationary contacts 26 and 21, and during the end stroke of the core 20 the spring 2215 bent back to increase the contact pressure. The circuit'of the starting motor is thereby closed and its armature begins to 1'0- tate in the direction of the arrow '42. Through the shaft l and the friction clutch 4652, rotation of the armature is transmitted to the ring 48 which now tends to advance with respect to the bush '3? in the operative direction. The-rollers 43 are then movedinto the part of little depth of the grooves M so as to couple the ring 0 to the bush 3?. The latter is therefore likewise driven by the armaturecf the starting motor.

The pinion 58 and its carrier 55 are still p're vented from rotating by the stationary gear ring 16; consequently, upon rotation of the bush 31, they are displaced still farther outwards in the engaging direction of the pinion. The face 13 of the shank 51 of the pinion carrier is thereby separated from the face 12 of peg H which is rigid with the core 20 of the electro-magnet. The spring plate 68 fast on the pinion carrier 55 finally comes in touch with the bottom of bush 38; the parts are then in the position shown in Fig, 5 wherein the pinion carrier Will not let itself displace any farther in axial direction.

Consequently, the torque of the bush 31, received from the armature 8 of the starting motor through the friction clutch 46-52, is, transmitted from said bush to the pinion carrier 55 by the thread 56 and is also imparted to the pinion 58. The torque acting on the pinion 58 transmits to the gear ring 16 of the fly-wheel a circumferential force which cranks the engine shaft and thereby sets the engine in motion.

After the engine has commenced running under its own power, it may impart to the pinion 58 a speed'being higher than the speed of the armature shaft 4. This is possible without any reaction on said shaft because, on the one hand. the overrunning clutch formed by the rollers 43 permits the bush 3'! to advance with respect to the ring 48 rotating with the armature speed in the operative direction. On the other band, also the pinion carrier 55 is able to advance to a certain angle with respect to the bush 3! while being axially displaced in the disengaging direction of pinion 58. This axial displacement of the pinion carrier 55 which is likewise imparted to the pinion 55 ensues of the action of spring 69, and it is certainly limited by the face 12 of peg H. The latter is at first in the position according to Figs. 4 and 5. But as soon as the operator has ascertained correct running of the engine, he will have to switch off the current flowing in the magnet coil IS. The pinion carrier 55 is then retracted by spring 69 into the position shown in Fig. 1 thereby shifting the magnet core and peg ll back to the initial position. The switch contacts 24/26 and /21 are then separated whereby the circuit of the starting motor is interrupted and the latter stopped, Also the pinion carrier 55 and pinion 58 cease to turn as soon as the latter is entirely disengaged from the gear ring 16.

Should in the position of the parts represented. in Fig. 3, a tooth of pinion 58 clash against a tooth of the gear ring 16 so as to prevent said pinion from being displaced any farther in the engaging direction, the further displacement of the magnet core 28 and pinion carrier 55 will compress the spring 65 lying between said pinion carrier and the pinion shank 51. If the turning movement of the pinion 58 and hence of the pinion carrier 55 is impeded by the friction produced between said pinion and the gear ring 16, the bush 3"! will be turned in the operative direction 42; that is to say the rollers 43 remain in the deeper part of the grooves 4| so that said turning movement may take place when the armature shaft 4 remains stationary. The parts then attain the position represented in Fig. 6 in which the shoulder 66 of spindle 6D abuts against the face 64 of pinion shank 51. Any farther displacement of the pinion carrier 55 and hence of the magnet core 20 in engaging direction of the pinion will then be impossible. Also the contact blocks 24 and 25 are not able to reach their stationary counter-contacts 26 and 21 respectively, so that the circuit of the starting motor cannot be closed. In this way, rotation of the pinion 58 by the starting motor is prevented so long as said pinion has not been engaged with the gear ring Hi.

If the operator finds that the starting motor does not commence operation, he will switch of! the current of the magnet coil I9. The spring 69 then tends to displace the pinion carrier in the disengaging direction of the pinion. The bush 31 being prevented by the effect of the overrunning clutch between said bush and the ring 40 from turning in opposition to the operative direction 42 when the armature shaft 4 remains stationary, the pinion carrier 55 and pinion 58 are compelled by said return displacement to turn in the operative direction. During said turning movement, the friction between pinion 58 and the gear ring 15 will have to be overcome by the pressure of spring 69. But owing to the slight force with which the spring 65 presses the pinion axially against the gear ring '18, the said friction is of little importance and not apt neither to impede the return of the pinion carrier 55 nor to produce an essential wear on the pinion 58 and the gear ring 16.

Upon this turning of the pinion 58, it may happen that the teeth of the latter arrive in front of the tooth gaps of the toothed rim. The spring 65 then again displaces the pinion 58 in engaging direction so that its teeth come into engagement with those of the gear ring 16 on a small portion of their length. In this case, the pinion is prevented from turning farther and,

" consequently, the axial return movement of the pinion carrier is interrupted. A further switching on of the magnet coil l9 then causes the pin ion to be brought into the position shown in Fig. 4, and the engine may be started without further delay.

So far as the teeth of pinion 58 do not engage tooth gaps of the gear ring I5 when the pinion 58 is turned by the axial return movement of the pinion carrier 55, the pinion will finally be withdrawn from the gear ring 16 by the abutting nut 6| of the pinion carrier. The pinion carrier and pinion then continue to turn in the operative direction 42, thereby moving farther in disengaging direction so as to attain, finally, the position represented in Fig. 7 in which the bottom 63 of the pinion carrier abuts against the bottom 10 of bush 38. v In Fig. 7 the pinion carrier 55 and pinion 58 are in the same axial positions as in Fig. 1 but in different angular positions, the pin ion carrier which upon its axial displacement in the engaging direction of the pinion was not to be rotated having been turned upon its axial displacement in the opposite direction.

By once more switching on the magnet coil H! in the starting position according to Fig. 7, the attempt to bring the pinion into engagement is repeated. On account of the new angular position of the pinion carrier and pinion, this new attempt may have a more favourable issue than the unsuccessful attempt which was made in they starting position shown in Fig. 1. If not. a still other angular position of the pinion will result as new starting position for the third attempt, and so on.

The pitch of thread 56 must be so chosen that the angle through which the pinion 5B is turned at each unsuccessful operating attempt. differs from the pitch angle of the pinion and the whol multiples of said pitch angle, respectively. Experlence has proved that on considering this with the engine, of a starting motor, .an axially displaceable pinion carrier, an abutment on said carrier, a pinion driven by the starting motor and adapted to be brought into engagement with said gear ring, said pinion being coupled for rotation with said carrier and axially slidable relative thereto, spring means acting upon said pinio'nin the engaging direction for counteracting said slid- I .1

ing movement and tending'to press said pinion against said abutment, an intermediatemembe'r interposed between the pinion carrier and the rotor of the starting motor, coupling means connecting said rotor to said intermediate member and enabling the latter to advance relative tosaid rotor in the operative direction of rotation of the same, and coupling means-between said member and the pinion carrier for turning saidmember in the said operative direction with respect to said carrier when the latter is axiallydisplaced in engagingdirection with respect to the intermediate member.

2. A starting device for internal combustion engines, the combination with a gear ring turning with the engine',-of a starting motor, an axially displaceable pinion carrier, an abutment on said carrier, a pinion driven by the starting motor and adapted to be brought into engagement with said gear ring, said pinion being coupled for rotation t with said carrier and axially slidable relative thereto, spring means acting upon said pinion in the engaging direction for counteracting said sliding movement and tending to press said pinion against said abutment, an intermediate member interposed between the pinion carrier and the rotor of the starting motor, an overrunning clutch coupling formed on said rotor and intermediate member, respectively, and adapted to permit said member to be advanced relative to said rotor in the operative direction of rotation of the same, and a steep-pitch thread coupling formed, respectively, on the intermediate member and the pinion carrier and active to turn said member in the said operative direction with respect to the pinion carrier when the latter is axially displaced in engaging direction with respect to the intermediate member.

3. A starting device for internal combustion engines, the combination with a gear ring turning with the engine, of a starting motor, an axially displaceable pinion carrier, an abutment on said carrier, a pinion driven by the starting motor and adapted to be brought into engagement with said gear ring, said pinion being coupled for rotation with said carrier and axially slidable relative thereto, spring means acting upon said pinion in the engaging direction for counteracting said sliding movement and tending to press said pinion against said abutment, an intermediate member interposed between the pinion carrier and the rotor of the starting motor, an overrunning clutch coupling formed on said rotor and intermediate member, respectively, and adapted to permit said member to be advanced relative to said rotor in the operative direction of rotation of the same, a steep-pitch thread coupling formed, respectively, on the intermediate member and the pinion carrier and active to turn said member in the said operative direction with respect to the pinion carrier" when the latter. is axially d'isplacedfjnf riigaging directionwith respect to the intermediate member, and a shifting member for axiallyois-j' placing the pinion carrier and adapted to" tiafisfmi't to said oarrier forces which are only effective in the engaging direction along that portion of the path or the pinion carrier througl'iwhich the latter has to' travel from its resting'positior'i to a positionwherein the pinion engages the gear ring with at least a part of ii'lstooth breadth.

4. A starting device' for internal combustion engines, the combinationwith' a; gear'ring turn; ing with the engine, of a starting'motor, an axially displaceable ion carrier, an abutmentoii said carrier, a p tor and adapted t o be" brought into en agement with said gear ring, said p'inion' being coupled m1 rotation with said carrier and axially slidable relative thereto, spring means acting upon said pinion in the enga ing direction for counteracting said sliding movement and tending to press said pinion against said abutment, an intermedr ate member interposed between the pinion carrier and the rotor of the" starting m'otorl. an overrunning clutch couplin'g' formed onsaid roto'r'an'd intermediate in'emberjrespectively, and adapted to" permit said member to be advanced relative to said rotor in the operative direction or rotation of the' same, a steep pitch tlir'ea'd coupling" formed, respectively, on;.,13ne intermediate member and the pinion carrier and active to turn said member in the said operative direction with respect to the pinion carrier when the latter is axially displaced in engaging direction with respect to the intermediate member, a shifting member for axially displacing the pinion carrier and adapted to transmit to said carrier forces which are only eiiective in the engaging direction along that portion of the path of the pinion carrier through which the latter has to travel from its resting position to a position wherein the pinion engages the gear ring with a part of its tooth breadth, and a switching device for the starting motor, said device being operable by the shifting member and dependent upon the movement of the pinion carrier in such a manner as to permit of starting said motor only when the pinion carrier has attained a position in which the entire axial displacement of the pinion with respect to the pinion carrier causes said pinion to engage the gear ring with at least a part of its toothed breadth.

5. A'starting device as claimed in claim 1, wherein the displacement of the pinion with respect to the pinion carrier is limited also in the disengaging direction by an abutment.

6. A starting device as claimed in claim 4, wherein the displacement of the pinion with respect to the pinion carrier is limited also in the disengaging direction by an abutment.

7. In a turning gear for starting internal combustion engines, the combination of a ring gear turning with the engine; a motor having a shaft; a pinion coaxial with said shaft and axially shiftable relatively thereto to move into and out of mesh with said ring gear; a one way drive between the motor shaft and pinion comprising n driven by the starting moas an incident to the limited relative axial shift of said member in one direction; means for biasing said axially shiftable member in a direction to disengage the pinion; means for shifting said member in a direction to engage said pinion; and a controller for said motor arranged to be operated by the last named means and serving to operate the motor only after the pinion has entered meshing engagement.

8. In a turning gear for starting engines, the combination of a ring gear turning with the engine; a motor having a shaft; a pinion coaxial with said shaft and axially shiftable relatively thereto to move into and out of mesh with said ring gear: a one way drive between the motor shaft and the pinion comprising an intermediate transmitting member which normally turns with and shifts axially with the pinion, but is capable of limited axial reciprocation relatively thereto, a spring resisting such relative motion but adapted to yield if the pinion clashes with the ring gear, an over-running clutch and a quick pitch thread serially connecting the motor shaft and pinion through the intermediate member, so arranged that limited axial reciprocation of the intermediate member causes the clutch to over-run and thereby changes the angular position of the pinion relatively to the shaft; and means for shifting said intermediate member in a direction to cause the pinion to mesh with the ring gear.

9. The combination defined in claim 8 in which the range of limited axial reciprocation and the quick pitch thread are so correlated that the change of angular position controlled thereby differs from the tooth interval of the pinion and from multiples thereof.

10. In a turning gear for starting engines, the

combination of a ring gear turning with the en-.

gine; a motor having a shaft; a pinioncoaxial with said shaft and axially shiftable relatively thereto to move into and out of mesh with said ring gear; a one way drive between the motor shaft and the pinion comprising an intermediate transmitting member which normally turns with and shifts axially with the pinion, but is capable of limited axial reciprocation relatively thereto, a spring resisting such relative motion but adapted to yield if the pinion clashes with the ring gear, an over-running clutch and a quick pitch thread serially connecting the motor shaft and pinion through the intermediate member, so arranged that limited axial reciprocation of the intermediate member causes the clutch to over-run and thereby changes the angular position of the pinion relatively to the shaft; means for shifting said intermediate member in a direction to cause the pinion to mesh with the ring gear; and a controller for said motor actuated by the last named means and serving to energize the motor only after meshing engagement has occurred.

ORLANDO CELIOi

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