Starter device

Description

Background of the Invention

[0001] This invention relates to a starter device in which rotation of the armature shaft of a DC motor is applied through a speed reducer or directly to the output shaft, and rotation of the output shaft is transmitted through an over-running clutch to a pinion thereby to start the engine.

[0002] Fig. 2 is a longitudinal sectional view showing essential components of a conventional starter device which has been disclosed, for instance, by Japanese Utility Model Application Publication No. 53727/1980 or US-A-4 902 905 which forms the basis for the preamble of claim 1. In Fig. 2, reference numeral 1 designates a DC motor, the armature shaft 2 of which is extended into an output shaft 3; 4, a helical spline gear formed on the output shaft 3, the helical spline gear being made up of a plurality of elongated grooves or keyways 4a spaced at equal angular intervals and a plurality of auxiliary through keyways 4b each formed between two adjacent keyways 4a; 5, a stopper formed on the output shaft with an annular groove 6 between the stopper 5 and helical spline gear 4, the stopper 5 having through keyways 5a which communicate with those 4b of the helical spline gear 4 (the helical spline gear 4 and the stopper 5 shown in Fig. 3 in more detail); 7, the front bracket of the DC motor 1; and 8, a partition board.

[0003] Further in Fig. 2, reference numeral 10 designates an over-running clutch mounted on the output shaft 3. The over-running clutch 10 comprises a clutch outer 11 and a clutch inner 12. The clutch outer 11 has helical spline keys 11a formed in its inner cylindrical wall which are engaged with the keyways 4a of the helical spline gear 4 of the output shaft 3. The clutch inner 12 transmits rotation in one direction with the aid of a plurality of rollers 13. The clutch inner 12 has a cylindrical portion 12a extended forwardly, and a pinion 14 is cut integral with the cylindrical portion 12a. The cylindrical portion 12a of the clutch inner 12 is supported through a bearing 15 on the front bracket 7, and supports the front end portion of the output shaft 3 through a bearing 13. Since the cylindrical portion 12a of the clutch inner 12 is supported through the bearing 15 as was described above, the outside diameter thereof should be equal to or larger than the outside diameter of the pinion 14. Thus, the clutch inner is relatively large in weight.

[0004] Further in Fig. 2, reference numeral 17 designates an electro-magnetic switch mounted on the front bracket. When the exciting coil (not shown) of the electro-magnetic switch 17 is energized, the plunger 18 is magnetically retracted or moved backwardly. The plunger 18 is engaged with the upper end portion of a shift lever 19 in the form of a fork, the lower end portion of which is engaged with the over-running clutch 10 to move the latter in an axial direction. That is, when the shift lever 19 is turned counterclockwise, the over-running clutch 10 is moved forwardly; and when it is turned clockwise, the clutch is moved backwardly. Further in Fig. 2, reference numeral 20 designates a torsion spring which is adapted to restore the shift lever 19 by turning it clockwise, and thereby to return the plunger 18 to its original position; and 21, the ring gear of the engine with which the pinion 14 meshes when moved forwardly.

[0005] The above-described over-running clutch 10 is mounted on the output shaft 3 as follows: The helical spline keys 11a of the clutch outer 11 are passed through the through keyways 5a of the stopper 5 and then the through keyways 4b of the helical spline gear 4. Thereafter, at a small diameter clearance groove 3a formed in the rear end portion of the output shaft 3, the clutch outer 11 is turned by a half pitch of the keys 11a until the keys 11a are set in alignment with the keyways 4a of the helical spline gear 4 on the output shaft 3. Under this condition, the clutch outer is moved forwardly, so that the clutch outer and the output shaft are coupled to each other by helical spline engagement. In this case, the front end faces of the keys 11a of the clutch outer 11 abut against the rear end step of the stopper 5, thus inhibiting the forward movement of the clutch outer 11.

[0006] Now, the operation of the starter device thus constructed will be described. Upon energization of the exciting coil (not shown) of the electro-magnetic switch 17, the plunger is moved inwardly, to turn the shift lever 19 counterclockwise in Fig. 2. As a result, the over-running clutch 10 is moved forwardly to cause the pinion 14 to mesh with the ring gear 21. When the plunger 18 is moved backwardly as was described above, the movable contact of the electromagnetic switch is also moved backwardly, to engage with the pair of stationary contacts thereof, thus completing the armature circuit of the DC motor 1. As a result, the armature is rotated, and the rotation of the armature shaft 2; that is, the rotation of the output shaft 3 integral with the armature shaft 2 is transmitted through the over-running clutch 10 to the pinion 14 to rotate the ring gear 21, thereby to start the engine.

[0007] The above-described conventional starter device is however disadvantageous in the following points: That is, in the starter device, the cylindrical portion 12a of the clutch inner 12 is large in outside diameter, and therefore the clutch inner is large in weight, as a result of which the pinion 14 is not smoothly engaged with the ring gear 21. In order to mount the over-running clutch 10 on the output shaft 3, the helical spline keys 10a of the clutch outer 11 are engaged with the keyways 4a after passing through the through keyways 4b, and then the clutch outer is moved forwardly. Hence, it is necessary to space the rear end of the clutch inner 12 from the stopper 5 as much as L, and accordingly the over-running clutch 10 is extended forwardly as much, with the result that the starter device is relatively large in axial length.

SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of this invention to eliminate the above-described difficulties accompanying a conventional starter device. More specifically, it is an object of the invention to provide a starter device in which the clutch inner is reduced in weight to allow the pinion to smoothly engage with the ring gear of the engine, and the over-running clutch is decreased in length, with the result that the starter device itself is reduced in axial length.

[0009] According to the invention there is provided a starter device comprising:
   an output shaft to which rotation of the armature shaft of a DC motor is transmitted, said output shaft having a helical spline gear;
   an over-running clutch including a clutch outer coupled to said output shaft through said helical spline gear, and a clutch inner which is coupled to said clutch outer through rollers to transmit rotation in one direction to a pinion provided on the front end portion thereof, said over-running clutch being adapted to move said pinion forwardly and backwardly; and
   a stopper formed on said output shaft in front of said helical spline gear, to stop the forward movement of said clutch outer at a predetermined position, said clutch inner having a cylindrical portion extended forwardly which is supported through a bearing on the front bracket of said DC motor, said cylindrical portion having an inner periphery on/in which a bearing is mounted/fitted in such a manner that a portion of said output shaft in front of said stopper is forwardly movably supported by said bearing;
   characterised in that the inside diameter of said cylindrical portion of said clutch inner, at which
said bearing is fitted, is slightly larger than the outside diameters of said helical spline gear and stopper on said output shaft so as to allow said cylindrical portion to cover at least a portion of said helical spline gear and stopper.

[0010] In the starter device to be described below, the cylindrical portion of the clutch inner covers the helical spline gear and the stopper for the clutch outer which are formed on the output shaft, so that the overrunning clutch is reduced in length. Furthermore, since the cylindrical portion of the clutch inner is smaller in outside diameter than the rear end portion thereof, the clutch inner is reduced in weight as much, with the result that the axial moving member can be readily moved in the forward direction, thus allowing the pinion mounted on it to smoothly mesh with the ring gear of the engine.

Brief Description of the Drawings

[0011] 

Fig. 1 is a longitudinal sectional view showing essential components of one example of a starter device according to this invention;

Fig. 2 is also a longitudinal sectional view showing essential components of a conventional starter device; and

Fig. 3 is an enlarged diagram showing a helical spline gear and a stopper formed on the output shaft of the starter device shown in Fig. 2.

Detailed Description of the Preferred Embodiment

[0012] Fig. 1 is a longitudinal sectional view showing essential components of one example of a starter device according to this invention. The starter device, as shown in Fig. 1, comprises a DC motor 30, from the armature of which an armature shaft 31 is extended. A small gear, namely, a sun gear 31a is cut integral with the front end portion of the armature shaft 31. The starter device further comprises: a yoke 31; an intermediate bracket 33 which supports the front end portion of the armature shaft 31 through a bearing 34; and a front bracket 35 coupled to the yoke 32 through the intermediate bracket 33.

[0013] Further in Fig. 1, reference numeral 36 designates an output shaft coupled through a steel ball 37 to the front end of the armature shaft 31 in such a manner that the former 36 is coaxial with the latter 31. A helical spline gear 37 is formed on the middle portion of the output shaft. The output shaft has an annular groove 38 and a stopper 39 for the clutch outer in front of the helical spline gear 37. The helical spline gear 37 is made up of a plurality of elongated grooves, namely, keyways 37a spaced at equal angular intervals, and through keyways 37b each formed between two adjacent keyways 37a. The stopper 39 has a through cut 39a which is communicated with the through keyways 37b. The output shaft 36 has a clearance groove 36b smaller in diameter at the rear of the helical spline gear 37.

[0014] The starter device further comprises a planetary gear type speed reducer 40 which is designed as following. A plurality of planet gears 41 are engaged with the sun gear 31a and supported through bearings 43 by support pins 42, which are fixedly embedded in a carrier 36a which is a flange formed on the output shaft 36 the rear end. An internal gear frame 44 is fixedly secured inside the front bracket 35, and has an internal gear 44a cut integral with the inner cylindrical wall. The internal gear 44a is engaged with the planet gears 41 to revolve them. The front end portion of the internal gear frame 44 supports the rear end portion of the output shaft 36 through a bearing 46 inserted thereinto.

[0015] The starter device further comprises an overrunning clutch 47 which includes a clutch outer 48 and a clutch inner 49. The clutch outer 48 has helical spline keys 48a which are engaged with the keyways 37a of the helical spline gear 47 on the output shaft 36. The clutch inner 49 is coupled to the clutch outer 48 through rollers 50 to transmit rotation in one direction. The clutch inner 49 has a middle portion 49a the inside diameter of which is made slightly larger than the outside diameters of the helical spline gear 37 and the stopper 39 so as to cover the latter 37 and 39. The outside diameter of the middle portion 49a is larger than that of the rear end portion of the clutch inner, so as to reduce the weight of the clutch inner. The clutch inner 49 is supported through a bearing 52 on the front bracket 35. Further in Fig. 1, the reference numeral 51 designates an engaging ring having a rear end provided with an engagement projection 51b, the engaging ring 51 and clutch outer 48 together defining an annular engagement groove 51c between the engagement projection 51b and the clutch outer 48; and 57 designates a snap ring mounted on the output shaft 36 to abut against the rear end of the clutch outer 48.

[0016] Further in Fig. 1, reference numeral 54 designates a pinion coupled to the front end portion of the clutch inner 49 by spline connection. A stopper 55 holds the pinion 54 at the front end, which is urged forwardly by a compression spring 56.

[0017] The overrunning clutch 47 thus constructed is mounted on the output shaft 36 as follows: The helical spline keys 48a of the clutch outer 48 of the overrunning clutch 47 are moved to the clearance groove 36b after passing through the through cuts 39a of the stopper 39 and through the through keyways 37b of the helical line gear 37. Under this condition, the clutch outer 48 is turned as much as a half of the pitch of the helical spline keys 48a until the keys are set in alignment with the keyways 37a of the helical spline gear 37 of the output shaft 36. Thereafter, the clutch outer is moved forwardly, so that the clutch outer and the output shaft are coupled to each other by spline connection. Under this condition, a snap ring 57 is fitted on the output shaft 36 to determine the rearward position of the clutch outer 48. When, under this condition, the overunning clutch 47 is moved forwardly, then the front end faces of the keys 48a of the clutch outer 48 abut against the stopper 39, thus determining the forward movement of the clutch outer.

[0018] The starter device further comprises a shift lever 58 having a lower end part engaged within the annular lug groove 51c for moving the overrunning clutch 47 forwardly and backwardly. More specifically, the shift lever 58 is turned clockwise or counterclockwise respectively by the backward or forward movement of the hook coupled to the plunger of an electromagnetic switch (not shown) (sic). A closing member 59 of rubber is fitted in a cut formed in the front bracket 35.

[0019] The operation of the starter device thus designed is the same as that of the above-described conventional starter device except that, in the former, the rotation of the armature shaft 31 is transmitted through the planetary gear type speed reducer to the pinion 54.

[0020] As was described above, the embodiment includes the planetary gear type speed reducer 40; however, it should be noted that the technical concept of the invention is applicable also to a starter device in which no planetary gear type speed reducer is employed, and the extension of the armature shaft is employed as the output shaft.

[0021] In the starter device of the invention, the inner diameter of the cylindrical portion of the clutch inner is made slightly larger than the outside diameters of the helical spline gear and the stopper for the clutch outer which are formed on the output shaft, so as to cover them. Therefore, the over-running clutch is reduced in length as much; that is, it is small in axial dimension. Furthermore, since the cylindrical portion of the clutch inner is smaller in outside diameter than the rear end portion thereof, and the pinion is mounted on the front end portion of the clutch inner which is made smaller than the cylindrical portion, the clutch inner is reduced in weight as much, with the result that the axial moving member can be readily moved in the forward direction, thus allowing the pinion mounted on it to smoothly mesh with the ring gear of the engine.

Claims

1. A starter device comprising:
   an output shaft (36) to which rotation of the armature shaft (31) of a DC motor (30) is transmitted, said output shaft (36) having a helical spline gear (37);
   an over-running clutch (47) including a clutch outer (48) coupled to said output shaft (36) through said helical spline gear (37), and a clutch inner (49) which is coupled to said clutch outer (48) through rollers (50) to transmit rotation in one direction to a pinion (54) provided on the front end portion thereof, said over-running clutch (47) being adapted to move said pinion (54) forwardly and backwardly; and
   a stopper (39) formed on said output shaft (36) in front of said helical spline gear (37), to stop the forward movement of said clutch outer (48) at a predetermined position, said clutch inner (49) having a cylindrical portion (49a) extended forwardly which is supported through a bearing (52) on the front bracket (35) of said DC motor (30), said cylindrical portion (49a) having an inner periphery on/in which a bearing, (53) is mounted/fitted in such a manner that a portion of said output shaft (36) in front of said stopper (39) is forwardly movably supported by said bearing (53);
   characterised in that the inside diameter of said cylindrical portion (49a) of said clutch inner (49), at which said bearing (53) is fitted, is slightly larger than the outside diameters of said helical spline gear (37) and stopper (39) on said output shaft (36) so as to allow said cylindrical portion to cover at least a portion of said helical spline gear (37) and stopper (39).

2. A starter device according to claim 1, wherein the outside diameter of said cylindrical portion of said clutch inner is smaller than that of the rear end portion thereof, and the outside diameter of the front end portion extended from said cylindrical portion is smaller than that of said cylindrical portion, and said pinion is mounted on said front end portion.

3. A starter device according to claim 1, wherein:-
   a snap ring (57) is fitted to a rear end part of the output shaft (36) and adapted to receive a rear end of the clutch outer (48) which has returned to a backward position;
   an internal gear frame (44) is secured to said bracket (35) and rotatably supports the rear end part of the output shaft (36) through a bearing (45),
   a shift lever (58) has a lower end part engaged with an annular engagement groove (51c) in an axial direction, and can be turned to move said overrunning clutch (47) to either one of a forward position and the backward position, the annular engagement groove (51c) being provided at a rear side part of the clutch outer (48), and
   the annular egagement groove (51c) in said overrunning clutch (47) is adapted to have a rear end side inner periphery overhung said snap ring (57) when the clutch outer (48) is in the backward position, and the inner periphery is formed to have a larger diameter than an outer periphery of an outer end of the bearing supporting part of said internal gear frame (44).

4. A starter device according to claim 3,
   wherein said clutch inner (49) has a cylindrical portion (49a) extended forwardly which is supported through a bearing (52) on the front bracket (35) of said DC motor (30), said cylindrical portion (49a) having an inner periphery on or in which a bearing (53) is mounted or fitted in such a manner that a portion of said output shaft (36) in front of said stopper (39) is forwardly movably supported by said bearing (53), and
   wherein the inside diameter of said cylindrical portion (49a) of said clutch inner (49) at which said bearing (53) is fitted, is slightly larger than the outside diameters of said helical spline gear (37) and stopper (39) on said output shaft (36) so as to allow said cylindrical portion to cover at least a portion of said helical spline gear (37) and stopper (39).

5. A starting motor according to Claim 3, wherein an engaging ring (51) is engaged with the clutch outer (48) to provide the annular engagement groove (51c).

6. A starting motor according to Claim 5, wherein the engaging ring (51) is engaged with the clutch outer (48) by means of said snap ring (57).

7. A starting motor according to Claim 4, wherein the engaging ring (51) has a rear end provided with an engagement projection (51b).

8. A starting motor according to Claim 7, wherein the annular engagement groove (51c) is formed between the engagement projection (51b) and an enlarged portion rear end of the clutch outer (48).

9. A starter device according to Claim 8, wherein the engaging ring (51) has an inner diameter formed to be larger than the outer diameter of said snap ring (57) and that of the bearing supporting part of the internal gear frame (44).

Ansprüche

1. Anlasser mit:
einer Ausgangswelle (36), auf welche die Drehung der Läuferwelle (31) eines Gleichstrommotors (30) übertragen wird, wobei die Ausgangswelle (36) ein Schraubenkeilgetriebe (37) aufweist;
einer Freilaufkupplung (47) mit einem Kupplungsaußenteil (48), welches mit der Ausgangswelle (36) über das Schraubenkeilgetriebe (37) gekuppelt ist, und mit einem Kupplungsinnenteil (49), welches mit dem Kupplungsaußenteil (48) über Rollen (50) so gekuppelt ist, daß eine Drehung in einer Richtung auf ein Ritzel (54) übertragen wird, das auf seinem vorderen Endabschnitt vorgesehen ist, wobei die Freilaufkupplung (47) so ausgebildet ist, daß sie das Ritzel (54) nach vorn und hinten bewegen kann; und
einem Anschlag (39), der auf der Ausgangswelle (36) vor dem Schraubenkeilgetriebe (37) vorgesehen ist, um die Vorwärtsbewegung des Kupplungsaußenteils (48) in einer vorbestimmten Position anzuhalten, wobei das Kupplungsinnenteil (49) einen zylindrischen Abschnitt (49a) aufweist, der sich nach vorn erstreckt, und über ein Lager (52) auf der vorderen Stütze (35) des Gleichstrommotors (30) gelagert ist, wobei der zylindrische Abschnitt (49a) einen Innenteilumfang aufweist, auf bzw. in welchem ein Lager (53) angebracht bzw. eingepaßt ist, so daß ein Abschnitt der Ausgangswelle (36) vor dem Anschlag (39) in Vorwärtsrichtung beweglich durch das Lager (53) gehaltert wird;
dadurch gekennzeichnet, daß der Innendurchmesser des zylindrischen Abschnitts (49a) des Kupplungsinnenteils (49), an welchem das Lager (53) angebracht ist, geringfügig größer ist als die Außendurchmesser des Schraubenkeilgetriebes (37) und des Anschlags (39) auf der Ausgangswelle (36), damit der zylindrische Abschnitt zumindest einen Abschnitt des Schraubenkeilgetriebes (37) und des Anschlags (39) abdecken kann.

2. Anlasser nach Anspruch 1, bei welchem der Außendurchmesser des zylindrischen Abschnitts des Kupplungsinnenteils kleiner ist als jener seines hinteren Endabschnitts, und der Außendurchmesser des vorderen Endabschnitts, der von dem zylindrischen Abschnitt ausgeht, kleiner ist als jener des zylindrischen Abschnitts, und das Ritzel auf dem vorderen Endabschnitt angebracht ist.

3. Anlasser nach Anspruch 1, bei welchem:
ein Schnappring (57) auf ein hinteres Endteil der Ausgangswelle (36) aufgepaßt und dazu ausgebildet ist, ein hinteres Ende des Kupplungsaußenteils (48) aufzunehmen, welches in eine rückwärtige Position zurückgekehrt ist;
ein Träger (44) für ein Zahnrad mit Innenverzahnung an der Stütze (35) befestigt ist und das hintere Endteil der Ausgangswelle (36) über ein Lager (45) drehbar haltert,
ein Schalthebel (58) ein unteres Endteil aufweist, das mit einer kreisringförmigen Eingriffsnut (51c) in Axialrichtung im Eingriff steht, und gedreht werden kann, um die Freilaufkupplung (47) entweder in eine vordere Position oder die rückwärtige Position zu bewegen, wobei die kreisringförmige Eingriffsnut (51c) an einem rückseitigen Teil des Kupplungsaußenteils (48) vorgesehen ist, und
die kreisringförmige Eingriffsnut (51c) in der Freilaufkupplung (47) so ausgebildet ist, daß sie einen Innenumfang an der hinteren Endseite aufweist, welcher über dem Schnappring (57) hängt, wenn sich das Kupplungsaußenteil (48) in der rückwärtigen Position befindet, wobei der Innenumfang so ausgebildet ist, daß sein Durchmesser größer ist als ein Außenumfang eines äußeren Endes des Lagerhalterungsteils des Trägers (44) für das Zahnrad mit Innenverzahnung.

4. Anlasser nach Anspruch 3, bei welchem das Kupplungsinnenteil (49) einen zylindrischen Abschnitt (49a) aufweist, der sich nach vorn erstreckt und durch ein Lager (52) auf der vorderen Stütze (35) des Gleichstrommotors (30) gehaltert wird, wobei der zylindrische Abschnitt (49a) einen Innenumfang aufweist, auf oder in welchem ein Lager (53) angebracht oder eingepaßt ist, auf solche Weise, daß ein Abschnitt der Ausgangswelle (36) vor dem Anschlag (39) in Vorwärtsrichtung beweglich durch das Lager (53) gehaltert wird, und
bei welchem der Innendurchmesser des zylindrischen Abschnitts (49a) des Kupplungsinnenteils (49), an welchem das Lager (53) angebracht ist, geringfügig größer ist als die Außendurchmesser des Schraubenkeilgetriebes (837) und des Anschlags (39) auf der Ausgangswelle (36), damit der zylindrische Abschnitt zumindest einen Abschnitt des Schraubenkeilgetriebes (37) und des Anschlags (39) abdecken kann.

5. Anlasser nach Anspruch 3, bei welchem ein Eingriffsring (51) mit dem Kupplungsaußenteil (48) im Eingriff steht, um die kreisringförmige Eingriffsnut (51c) zur Verfügung zu stellen.

6. Anlasser nach Anspruch 5, bei welchem der Eingriffsring (51) mit dem Kupplungsaußenteil (48) über den Schnappring (57) im Eingriff steht.

7. Anlasser nach Anspruch 4, bei welchem der Eingriffsring (51) ein hinteres Ende aufweist, welches mit einem Eingriffsvorsprung (51b) versehen ist.

8. Anlasser nach Anspruch 7, bei welchem die kreisringförmige Eingriffsnut (51c) zwischen dem Eingriffsvorsprung (51b) und einem hinteren Ende des vergrößerten Abschnitts des Kupplungsaußenteils (48) vorgesehen ist.

9. Anlasser nach Anspruch 8, bei welchem der Eingriffsring (51) einen Innendurchmesser aufweist, der größer ist als der Außendurchmesser des Schnappringes (57) und jener des Lagerhalterungsteils des Trägers (44) für das Zahnrad mit Innenverzahnung.

Revendications

1. Dispositif de démarrage comportant :
   un arbre de sortie (36) auquel est transmise la rotation de l'arbre d'induit (31) d'un moteur (30) à courant continu, ledit arbre de sortie (36) ayant un engrenage (37) à cannelures hélicoïdales,
   un embrayage à roue libre (47) comportant un embrayage extérieur (48) relié audit arbre de sortie (36) par l'intermédiaire dudit engrenage (37) à cannelures hélicoïdales, et un embrayage intérieur (49) qui est relié audit embrayage extérieur (48) par l'intermédiaire de galets (50) pour transmettre la rotation dans une seule direction à un pignon (54) agencé sur sa partie formant extrémité avant, ledit embrayage à roue libre (47) étant adapté pour déplacer ledit pignon (54) vers l'avant et vers l'arrière, et
   un dispositif d'arrêt (39) formé sur ledit arbre de sortie (36) en avant dudit engrenage à cannelures hélicoïdales (37), destiné à stopper le mouvement vers l'avant dudit embrayage extérieur (48) au niveau d'une position prédéterminée, ledit embrayage antérieur (49) ayant une partie cylindrique (49a) s'étendant vers l'avant qui est supportée par l'intermédiaire d'un palier (52) situé sur l'étrier avant (35) dudit moteur (30) à courant continu, ladite partie cylindrique (49a) ayant une périphérie intérieure sur/dans laquelle un palier (53) est monté/agencé d'une manière telle qu'une partie dudit arbre de sortie (36) située en avant dudit dispositif d'arrêt (39) est supportée de manière mobile vers l'avant par ledit palier (53),
   caractérisé en ce que le diamètre intérieur de ladite partie cylindrique (49a) dudit embrayage intérieur (49), au niveau de laquelle ledit palier (53) est agencé, est légèrement plus grand que les diamètres extérieurs dudit engrenage à cannelures hélicoïdales (37) et du dispositif d'arrêt (39) situés sur ledit arbre de sortie (36) de manière à permettre à ladite partie cylindrique de recouvrir au moins une partie dudit engrenage à cannelures hélicoïdales (37) et du dispositif d'arrêt (39).

2. Dispositif de démarrage selon la revendication 1, dans lequel le diamètre extérieur de ladite partie cylindrique dudit embrayage intérieur est plus petit que celui de la partie formant extrémité arrière de celui-ci, et le diamètre extérieur de la partie formant extrémité avant s'étendant à partir de ladite partie cylindrique est plus petit que celui de ladite partie cylindrique, et ledit pignon est monté sur ladite partie formant extrémité avant.

3. Dispositif de démarrage selon la revendication 1, dans lequel :
   un circlip extérieur (57) est agencé sur une partie formant extrémité arrière de l'arbre de sortie (36) et adapté pour recevoir une extrémité arrière de l'embrayage extérieur (48) qui retourne vers sa position vers l'arrière,
   un châssis à engrenage intérieur (44) est fixé audit étrier (35) et supporte de manière rotative la partie formant extrémité arrière de l'arbre de sortie (36) par l'intermédiaire d'un palier (45),
   un levier de déplacement (58) comporte une partie formant extrémité inférieure en prise avec une gorge de prise annulaire (51c) dans une direction axiale, et peut être tourné pour déplacer ledit embrayage à roue libre (47) vers l'une ou l'autre des positions vers l'avant ou vers l'arrière, la gorge de prise annulaire (51c) étant agencée au niveau de la partie latérale arrière de l'embrayage extérieur (48), et
   la gorge de prise annulaire (51c) située dans ledit embrayage à roue libre (47) est adaptée pour avoir une périphérie intérieure formant côté d'extrémité arrière surplombant ledit circlip extérieur (57) lorsque l'embrayage extérieur (48) est dans la position arrière, et dont la périphérie intérieure est formée pour avoir un diamètre plus grand que la périphérie extérieure de l'extrémité extérieure de la partie dudit châssis à engrenage intérieur (44) supportant le palier.

4. Dispositif de démarrage selon la revendication 3, dans lequel ledit embrayage intérieur (49) a une partie cylindrique (49a) s'étendant vers l'avant qui est supportée par l'intermédiaire d'un palier (52) situé sur l'étrier avant (35) dudit moteur à courant continu (30), ladite partie cylindrique (49a) ayant une périphérie intérieure sur laquelle ou dans laquelle un palier (53) est agencé ou monté d'une manière telle qu'une partie dudit arbre de sortie (36) située en avant dudit dispositif d'arrêt (39) est supportée de manière mobile vers l'avant par ledit palier (53), et dans lequel le diamètre intérieur de ladite partie cylindrique (49a) dudit embrayage intérieur (49) auquel le palier (53) est fixé, est plus large que les diamètres extérieurs desdits engrenage à cannelures hélicoïdales (37) et dispositif d'arrêt (39) sur ledit arbre de sortie (36), de façon à permettre à ladite partie cylindrique de couvrir au moins une partie desdits engrenage à cannelures hélicoïdales (37) et dispositif d'arrêt (39).

5. Dispositif de démarrage selon la revendication 3, dans lequel un anneau de prise (51) est en prise avec l'embrayage extérieur (48) pour fournir la gorge de prise annulaire (51c).

6. Dispositif de démarrage selon la revendication 5, dans lequel l'anneau de prise (51) est en prise avec l'embrayage extérieur (48) à l'aide dudit circlip (57).

7. Dispositif de démarrage selon la revendication 4, dans lequel l'anneau de prise (51) a une extrémité arrière munie d'une saillie de prise (51b).

8. Dispositif de démarrage selon la revendication 7, dans lequel la gorge de prise annulaire (51c) est formée entre la saillie de prise (51b) et une extrémité arrière formant partie agrandie de l'embrayage extérieur (48).

9. Dispositif de démarrage selon la revendication 8, dans lequel l'anneau de prise (51) a un diamètre intérieur formé pour être plus grand que le diamètre extérieur dudit circlip (57) et en ce que le papier supporte la partie du châssis à engrenage intérieur (44).

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