FR2894089A1 - Electrical rotating machine e.g. internal combustion engine starter, for motor vehicle, has cylinder head comprising external part with length shorter than that of internal part for increasing external thickness of cylinder head - Google Patents

Abstract

The machine has a cylinder head inserted between a front bearing (21) and rear bearing (9). An external assembling device mounts the rear bearing to the front bearing and clamps the cylinder head between the bearings. The cylinder head has an external part (122) with length shorter than that of an internal part (22) for increasing external thickness of the cylinder head. The assembling device has studs (123) configured such that the parts surround the increased thickness of the cylinder head.

Description

Rotating electric machine, especially a heat engine starter,

external assembly device

  TECHNICAL FIELD OF THE INVENTION The present invention relates to rotating electrical machines, in particular engine starters, comprising a front bearing, a rear bearing, a yoke interposed between the front and rear bearings and an external assembly device for assembling under tension the rear bearing ~ o to the front bearing with clamping of the cylinder head between these bearings.

State of the art

  In motor vehicle starters, an external assembly device 15 is used, comprising tie rods located outside the cylinder head belonging to the stator inductor of the electric motor of the starter. These tie rods intervene between the front bearing and the rear bearing to tighten the cylinder head sandwiched between the bearings. This gives an assembly with a voltage stack, which gives satisfaction because it resists vibration phenomena well.

  It is desirable to increase the performance of the rotating electrical machine. To do this we can think of a solution consisting in passing the tie rods 25 inside the cylinder head. Such a solution leads to increase the overall size of the machine.

Object of the invention

  The object of the present invention is to increase the performance of the rotary electric machine without unduly increasing the overall size of the machine. According to the invention, a rotary electric machine of the aforementioned type is characterized in that the yoke comprises an extra thickness and in that the assembly device is configured to circumvent the excess thickness of the cylinder head.

  Thanks to the invention, the performance of the rotating electrical machine can be improved by locally increasing the thickness of the cylinder head without increasing the thickness of the rotating electrical machine at least at the level of the electrical machine. one of his front and rear bearings.

  Front and rear bearings of the standard type may be used while locally increasing the thickness of the cylinder head because the assembly device is configured to protrude outwardly the excess thickness of the cylinder head.

  This allowance in one embodiment of the permanent magnets or a coil so that the local increase in the thickness of the yoke increases the electromagnetic performance of the stator of the rotating electrical machine.

  In one embodiment, the assembly device comprises assembly members configured to protrude externally the excess thickness of the cylinder head. In one embodiment these assembly members consist of studs.

  In another embodiment, the assembly device comprises bicycle beam-shaped assembly members with a front end provided with a stepped head and a threaded rear end.

  In one embodiment these assembly members are arched.

  In yet another embodiment of the cylinder head comprises between its two axial ends a thicker intermediate portion and the assembly device is configured to circumvent the outer portion of the cylinder head.

  Thus, the yoke being made of ferromagnetic or magnetic material, the thickness of the yoke and therefore the thickness of the magnetic flux passage are locally increased while having a reduced spacing between the studs at the ends thereof.

  Compared to a solution using straight tie rods 1s space is released in favor of a better passage of the magnetic flux in the intermediate portion of the cylinder head, while reducing the bulk at the ends of the bodies of assembly, this size being in particular a function of the reduced size of the ends of the cylinder head.

Brief description of the drawings

  Other characteristics and advantages of the invention will appear in the light of the following description with reference to the appended figures in which: FIG. 1 is an axial sectional view of a thermal motor starter according to the invention provided with an assembly device comprising stud-shaped fasteners; - Figure 2 is a front view along the arrow 2 of Figure 1; Figure 3 is an enlarged view of the inset marked by the arrow 3 of Figure 1; FIG. 4 is a partial view of an alternative embodiment of the figure; FIG. 5 is a partial view of another variant embodiment using an assembly member in the form of a bicycle spoke.

  DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTION In FIG. 1 is shown in axial section a rotary electric machine in the form of a motor starter, here a motor vehicle engine starter.

  This starter comprises an electric motor 10, a launcher 20, a control lever 30 and an electromagnetic contactor 40 extending above the electric motor 10 and parallel thereto.

  The electric motor 10 comprises an inductor stator 11 comprising a winding 5, an induced rotor 12 comprising a winding 6, a shaft 7, a collector 8, a rear bearing 9, here metallic, and a brush holder 13. The axis of the shaft 7 defines the axis XX of the motor 10, the collector 8 being in Figure 1 a collector contact metal contact blades axial.

  The induced rotor 12 comprises a body (not referenced) in the form of a packet of notched sheets for mounting conductive segments connected to the metal contact blades of the collector 8 for forming the coil 6.

  The collector 8 and the rotor body are fixed on the shaft 7, here locally knurled 25 in particular for fixing the rotor body by press fitting.

  The inductor stator 11 comprises a metal head 22, 122 which serves to support at least two polar masses 23 around which series-connected windings are mounted to form the winding 5. The masses 23 are fixed inside the 22, 122 via screws 24 with conical head. In this embodiment, the cylinder head 22, 122 is in two coaxial parts of axis XX in contact with each other. These two parts are tubular and are made of ferromagnetic material, for example sheet metal. The polar masses 23 are also made of ferromagnetic material, for example soft iron.

  In this figure 1 the section of the parts 22, 122 is circular so that these two tubular portions are in the form of a cylindrical tube. In a variant, the section of the tubular parts is of square or rectangular or polygonal shape.

  In Figure 1 the inner portion 22 in the form of tube has the locations provided for the fastening screws 24 of the first holes (not referenced) in correspondence with second holes (not referenced) 15 formed in the outer portion 122 of tubular form. The second holes are initially cylindrical and are deformed, for example by punching, to form chamfers receiving the conical heads of the fixing screws 24. These chamfers make it possible to immobilize the outer part 122 with respect to the inner part 22 while having a good contact between the two parts 22, 122. Of course the diameter of the second holes is initially smaller than the diameter of the first holes.

  In this embodiment, the outer portion 122 is slotted longitudinally, that is to say axially, to facilitate its assembly by axial threading on the inner portion 22 closed. This inner portion 22 is made from a tube or alternatively by rolling a sheet and stapling the rolled ends thereof.

  Of course, in a variant, the structures are reversed, the inner part 22 being split and the outer part 122 closed.

  In all cases the chamfers associated with the heads of the screws 24 allow a restriction of the outer part 122 or an expansion of the inner part 22.

  According to one characteristic, the outer portion 122 is axially shorter in length than the inner portion 22 for forming an excess thickness, obtaining good electromagnetic performance, reducing the weight and radial bulk of the inductor stator 11 as described below. .

  The yoke 22, 122 here has an intermediate portion delimited by the outer portion 122 and two axial ends, which protrude on either side of the central portion and which belong to the inner portion 22.

  According to one characteristic, the thickness of the yoke is locally increased to the level of the intermediate portion thereof delimited by the outer portion 122. This thickness corresponds to the addition of the thicknesses of the portions 22, 122. In FIG. yoke 22, 122 thus has locally, here generally centrally, an excess thickness, ie a maximum thickness, at the level of the screws 24, the polar masses 23 and the winding 5 of the inductor stator which allows a good flow passage magnetic when the coil 5 is electrically powered. Of course the axial length of the outer portion 122 is determined accordingly.

  In the embodiment of FIG. 1, the parts 22, 122 being of tubular cylindrical shape, the diameter D of the cylinder head 22, 122 is therefore maximum at its intermediate portion delimited by its outer part 122 covering the coil. 5 and therefore the polar masses 23. Here the outer portion 122 extends in axial projection on either side of the winding 5 of the type of that described in document EP A 0 749 194 to which reference will be made for more details. .

  The diameter of the yoke 22, 122 is equal to that of the inner portion 22 at each of its axial ends. This diameter is reduced to each of the axial ends of the cylinder head. Thus, for a given size of the inner portion 22 space is released in favor of the inductive ferromagnetic material circuit, called the iron circuit, which improves the performance of the starter.

  The rear bearing 9 is shaped to form a rear bearing for the rear end of the shaft 7 and a closing cap for the rear end of the yoke formed by the rear end of the inner portion 22. This bearing 9 , here based on aluminum, belongs to a metal housing 120 comprising a hollow front bearing 21, here based on aluminum, and the metal yoke 22, 122 interposed axially clamping between the bearings 21.9.

  The front bearing 21 is configured to be mounted on a fixed part of the vehicle and has for this purpose perforated ears 121 (Figure 2) for the passage of fasteners. This front bearing 21 is also configured to serve as a housing for the lever 30 and has at the front a nose 130.

  An external connecting device is provided for assembling under tension the rear bearing 9 to the front bearing 21 with clamping of the yoke 22, 122 between these bearings. This device provides a voltage stack resistant to vibration.

  In this embodiment this device comprises external connecting members in the form of pins 123 external to the breech 22, 122, only one of which is visible in FIG. 1. These studs are used for fixing the rear bearing. 9 and the yoke 22, 122 at the front bearing 21, the rear bearing 9, having through holes for the studs 123 mounted outside the yoke 22, 122 clamped between the rear bearing 9, constituting a piece of pressure, and the front bearing 21, constituting a reaction piece.

  Here two studs 123 diametrically opposed are provided as visible in Figure 2. Alternatively there is provided three studs or more. In one embodiment these studs are distributed circumferentially in a regular manner.

  Each studs 123 comprises two threaded ends, respectively a front end 124 and a rear end 125, an intermediate section 126 and two connecting sections 127, 128. In FIG. 1, the connection sections 127, 128 are inclined. ~ o The inclined section 127 connects the front threaded end 124 to the intermediate section 126, while the inclined section 128 connects the intermediate section to the rear threaded end 128. The intermediate portion 126 projecting radially from the ends 124, 125, which are closer to the axis XX of the electric motor 10 also constituting the axis of the yoke 22, 122. Here the distance between the two intermediate parts of the two studs 123 is greater than the diameter D of the part 122 of the breech 22, 122.

  The studs 123 thus have a cambered shape and outwardly contour the intermediate portion of the 22.12 thicker yoke.

  The front bearing 21 has tappings 129 at its rear end for screwing the threaded ends before 124 of the pins 123. The rear bearing 9 is ribbed and has two radially projecting lugs 91 and diametrically opposite (Figure 2). Each tab 91 is perforated for the passage of the threaded rear end 125 of the bolt 123 concerned (Figure 1). Nuts 92 are provided for screwing each onto a threaded rear end 125 of a stud 123. The nuts 92 bear against the back of a tab 91 directly or indirectly, via a washer, for example a elastic washer with axial action. It will be noted that indexing means 96 are provided for angularly indexing the rear bearing 9 with respect to the front bearing 21. These means here consist of markings made on the bearings 21, 9 which are made to coincide as visible at FIG. 2. The tabs 91 are in the embodiment shown generally at 90 with respect to the lugs 121. The same is true of the threads 129.

  The brush holder 13 is fixed by pinching a plate 110 between the bearing 9 and the adjacent rear axial end of the inner portion 22 of the yoke 22, 122. This plate 110 belongs to the brush holder 13 and has an opening Central through which the rear end of the shaft 7 passes. The plate 110 serves to support at least two brush guide cages 14 of transverse orientation. Here it is provided four cages 15 so four brushes, one of which is visible at 14 in Figure 1 and its associated cage 15. Two brushes are electrically connected by non visible braids rear bearing connected to the mass via the cylinder head. The other two brushes are also connected to the winding 5 by non-visible braids. The cages are distributed circumferentially in a regular manner. Each cage 15 is closed on the opposite side to the manifold 8 by a plug (not referenced figurel) and serves as a receptacle for a brush 14 mounted to slide axially in this cage 15. Each brush 14 is associated with a spring (not referenced figurel) which bears on the cap of the cage 15, with a centering stud, and on the brush 14 to urge it in contact with the blades of the collector 8. These conductive blades are carried by a body of the collector made of electrically insulating material, such as plastics material.

  In the embodiment of FIG. 1, the shaft 7 of the electric motor 10 is distinct from the output shaft 70 of the starter and a speed reducer is interposed between the shaft 7 and the output shaft 70, of which the front end is rotatably mounted in the front bearing 21 via a bearing 140, here in the form of the needle bearing, mounted in a bore (not referenced) made in the nose 130 of the front bearing 21 of the housing 120. io Similarly, the rear end of the shaft 7 of the motor 10 is rotatably mounted in the rear bearing 9 via a bearing 142, here in the form of the needle bearing, mounted in the central bore formed in the rear bearing 9 closed at the back by a hood 94.

  The front ends of the shaft 7 and rear of the shaft 70 are in the extension of one another, the axes of the shafts 7, 70 being merged. The rear end of the output shaft 70 is provided with a blind bore (unreferenced) into which the reduced (unreferenced) front end (6) of the shaft 7 is engaged with the intervention of a sliding bearing ( not referenced).

  The speed reducer here consists of an epicyclic gear comprising, a sun gear (not referenced) formed on the front end of the shaft 7, a planet carrier (not referenced) integral with the rear end of the shaft 70 and a fixed ring 72 toothed internally. The satellites 73, mounted to rotate about axes (not referenced) integral with the planet carrier, meshing with the sun gear and with the ring gear 72. In Figure 1 the toothing of the ring is fixed. As an alternative, shock absorbers occur between the internal toothing and the fixed outer periphery of the ring gear 72. Here the speed reducer is of the type described in EP 0 708 239 to which reference will be made for further details. The gearbox therefore comprises a base plate 74 carrying a support 75 for pivoting mounting of the lever 30, here made of plastic, having two wings (not referenced) disposed on either side of the support 75 with a hole, and that the wings of the lever 30 for mounting a hinge pin 76 for the lever 30. The support 75 and the ring gear internally 72 are made of plastic and extend on either side of the base plate 74 having holes for anchoring the support 75 and the ring 72 by overmoulding as disclosed in the aforementioned EP 0 708 239 to which reference will be made.

  The outer periphery of the ring 72 is provided with a plurality of stiffening ribs distributed circumferentially here in a regular manner. These ribs are of axial orientation. Some of these ribs 195 are thicker and serve to center the front end of the cylinder head 22, 122, that is to say the centering of the inner portion 22 of the cylinder head 22, 122. The inner periphery of the part 22 is therefore in intimate contact with the outer periphery of the ribs 195. Screws 196 serve to assemble the front bearing 21 with a tank 38 belonging to the contactor 40. This tank 38 is closed by a cover 39 in lo electrically insulating material . The base plate 74 is sandwiched between the front bearing 21 and the bottom of the tank 38, the screws 196 passing through the plate 74. Washers 197, 198 serve to wedge axially in one direction the entire plate 74-crown 72 In the other axial direction this assembly is wedged by the planet carrier. A bearing (not referenced) intervenes radially between the outer periphery of the rear end of the shaft 70 and the inner periphery of the aforementioned assembly delimited by the edge of the hole (not referenced) that includes this assembly for passage of the 70. A 199 is seen in a closing plate of the rear end of the internally hollow ring 72. This plate 199 is fixed on the ring 72 by press fitting on studs 296 protruding axially that has the rear end of the ring 72. The plate 199 has for this purpose holes for passage of the pins 296. One of these The plate 199 also has an external radial flange (not referenced) to cooperate with local deformations (not referenced) of the portion 22 for axial wedging of the plate 199. Thus the crown can be filled with grease for the lubrication of the satellites 73 and the sun gear.

  The shaft 70 has at its outer periphery helical splines in engagement with the complementary helical grooves belonging to the inner periphery of the launcher 20 traversed by the shaft 70.

  In this figure 1 these flutes bear the reference 77.

  This launcher 20 comprises a groove (not referenced) for receiving the fork-shaped lower end of the lever 30, as well as a pinion (not referenced) intended to mesh with a starting ring (not shown) connected rigidly or of elastic way to the crankshaft of the engine. The support 21 has for this purpose a passage for the starter ring and also serves as a support for the contactor 40 via the base plate 74.

  The shaft 70 also carries a stop to limit the movement of the launcher 20. The stop is adjacent to the nose 130 of the front bearing 21 and is here in two parts 32, 33, one of these parts consisting of a retaining circlip of the other part 33 forming the stopper itself.

  The contactor 40 comprises within it, that is to say within the assembly 38-39, a coil 44 comprising at least one winding, a fixed core 47, a moving element comprising a control rod 45 and a movable contact 46, a movable core 41 hingedly connected to the upper part of the lever 30 as well as electrically conductive springs and contact terminals 42, 43 carried by the insulating cover 39. One 42 of the terminals is electrically connected at the positive terminal of the vehicle battery and the other 43 at the winding 5 of the stator via a cable 144 passing through the cylinder head through a wire pass 145.

  In known manner, when the coil 44 of the contactor 40 is electrically powered, for example following actuation of the ignition key, a magnetic field is generated which moves the movable core 41 towards the fixed core 47. After catching up a clearance the movable core 41 acts on the control rod 45 to move the movable contact 46 towards the terminals 42, 43 and against the force exerted by a breaking spring 48. The movable core 41 during its This movement causes the lever 30, which pivots about its axis 76, to move the launcher 20 toward the stop 32,33. This core 41 initially extends in axial projection relative to the tank 38 and is connected, in known manner, to the lever 30 via a connecting rod (not referenced) and a spring 50, said spring tooth against tooth. Another spring 49, called return spring, acts between the bottom of the tank 38, made of ferromagnetic material, to return the core 41 to its initial position. At the end of a determined travel the movable contact 46 comes into contact with the terminals 42, 43 so that the electric motor 10, powered electrically via the cable 144, rotates and rotates the starter pinion 20 via the helical splines 77 to start the engine, the starter gear 20 then meshing with the aforementioned starter ring. The axial movement of the launcher is limited by the stop 32, 33. When the motor 10 turns the winding 5 is electrically powered and the winding 6 and the cylinder head 22, 122 is traversed by a magnetic field, which can be intense because the yoke 22, 122 is thicker at the pole masses 23 and the winding 5.

  FIG. 1 shows an annular flange of axial orientation belonging to the rear bearing 9. This flange is directed towards the front bearing 21. The outer periphery of this flange 95 is in intimate contact with the inner periphery of the end. rear of the inner portion 22 of the yoke 22, 122. Thus the yoke 22, 122 is centered by the ribs 195 of the ring 72, secured to the front bearing 21 via the plate 74, and the flange 95, here ring-shaped , of the rear bearing 9.

  The plate 74 is pinched axially between the rear face of the front bearing 21 and the front face of the cylinder head 22, 122. The plate 110 of the brush holder 13 is clamped between the rear face of the rear end of the cylinder head 22, 122 and the front face of the rear bearing 9, constituting a closing cap of the rear end of the cylinder head.

  All this stack of parts is kept under tension by the two studs 123 according to the invention.

  Thanks to the base plate 74, the output shaft 70 and the launcher 20 can be mounted in advance in the front bearing 21 and the switch 40 can be mounted on the front bearing 21. Similarly, the cylinder head 22 can be equipped in advance. 122 of its components 5, 23,24 and realize in advance the induced rotor 12 without mounting the rear bearing on the shaft 7.

  Then, in a first mounting step, the threaded front ends 124 of the external studs 123 are screwed into the threads 129 of the bearing 21.

  In a second mounting step the front end of the shaft 7 is threaded into the bearing mounted in the blind hole of the rear end of the shaft 70.

  In a third mounting step the studs 123 are discarded by means of a spacer tool without deforming them, that is to say by acting on the elasticity of the tie rods 123, to mount the bolt equipped and put it on the ribs 195 of the crown 72.

  In a fourth mounting step, the spacer being removed, the threaded rear ends 125 of the studs are threaded into the holes of the tabs 91, the rim 95 penetrating into the rear end of the cylinder head during this step, and finally screw nuts 92 to energize the stack of parts 74, 22-122, 110, 9. In this operation the indexing means 96 is used.

  At the end of the fourth step the cylinder head is clamped between the rear face of the front bearing 21 and the front face of the rear bearing 9

  In this embodiment the studs 123 are deformed in advance to form the intermediate section 126.

  In a variant, the studs 123 are deformed after screwing them into the front bearing 21 for forming the sections 126.

  Here the section of the studs 123 is circular, these studs 123 having a diameter D '. In a variant, the section of the studs is rectangular, square or polygonal outside the threaded ends. Alternatively one can achieve a combination of these embodiments. For example, the section of the intermediate section may be square and that of at least one circular connection section or vice versa.

  Of course, the present invention is not limited to the described embodiments.

  Thus the variant gearbox does not comprise a base plate, the ring 72 having a radial extension for the articulation of the lever as described in document FR A 2 863 018 to which reference will be made. It will be appreciated that the solution of FIG. 1 makes it possible to release space between the front end of the yoke 22, 122 and the tank 38 of the contactor 40. Thus, it is possible to easily mount a sealing pad, for example of the type of that described in document FR A 2 863 018, so that the solution is transversely compact.

  The starter may be devoid of speed reducer, the electric motor shaft also constituting the output shaft of the starter. In this case it is possible, as can be seen in FIG. 4, to provide a centering surface 221 on the rear end of the front bearing 21 of the housing 120 to center the front end of the cylinder head, the inner periphery of the front end of the cylinder head. the cylinder head being in intimate contact with the centering bearing 221 formed at the outer periphery of an axial projection 233 of the rear end of the front bearing 21. The shape of the bearing 221 depends on that of the cylinder head.

  In Figure 4 the projection 233 consists of an annular rim of axial orientation of tubular shape and the bearing 221 is cylindrical.

  In this embodiment, the front end of the cylinder head 222 bears against the rear face of the front bearing 21. Of course, the centering can be achieved by means of a piece of plastic material which is pierced centrally for passage of the starter output shaft and mounted in the front bearing. All combinations are possible. Thus the bearing 221 of FIG. 4 can serve to center the breech of FIG. 1.

  We can reverse the structures. For example, in a variant, the flange 95 of the rear bearing 9 is in contact with its inner periphery with the outer periphery of the rear end of the yoke.

  The cylinder head may alternatively be in one part as visible at 222 in FIG. 4. In this case, the outer portion of the cylinder head corresponds to an oversize of the cylinder head made for example by machining. This extra thickness delimits the intermediate portion of the yoke in the same manner as the portion 122 of FIG.

  This yoke may carry permanent magnets in place of the studs 23 and the coil 5, which may alternatively be of another form.

  The starter is in an embodiment configured so that the starter gear is implanted outside the nose 130 of the front bearing.

  The variant switch is carried by the rear bearing 9. In one embodiment, this rear bearing is made of moldable material so that the tank of the contactor can be molded with the rear bearing 9.

  This contactor is in an embodiment coaxial with the electric motor by being implanted in front of it. The presence of the control lever is not essential. In a variant, the launcher and the lever are removed, the rotating electrical machine consisting of an electric motor.

  The rotating electric machine is alternatively a dynamo. In a variant, the stator of the rotating electrical machine is an induced stator.

  The starter variant does not have a launcher and is connected to the crankshaft of the engine of the vehicle by a belt or chain transmission or gears.

  In another embodiment, the brushes 14 are axially oriented relative to the axis of the shaft 7 of the electric motor 10, while the collector with its electrically conductive blades is oriented transversely with respect to this axis. . In this case the brush holder is secured to the bottom of the rear bearing and no plate is pinched between the rear bearing and the rear end of the cylinder head.

  The number of brooms and dowels depends on the applications. Alternatively at least one of the inclined sections 127, 128 is replaced by a generally S-shaped connection section as visible in 227 in Figure 4. Various forms being permitted for the connection sections. In another embodiment, the connection portion 127 is eliminated so that the intermediate section 126 extends to the threaded front portion 124 only the remaining rear connection section, this section possibly having the shape of the section 227. The rear bearing 9 of Fig. 1 may be retained in this embodiment.

  In another embodiment, the rear end of the front bearing comprises perforated lugs in place of the threads 129. The stud is then replaced by a bicycle-shaped assembly member 223 as shown in FIG. Thus this assembly member comprises a threaded rear end 125 as in Figure 1 and a front end 224 with a shouldered and bent head 226 in contact with the edge of the hole 229 of the axially oriented ear 228 belonging to the front bearing 21 In another embodiment, the head 226 is straight and the lug 228 lo is transversely oriented with respect to the axis XX. Of course, at least one of the connection sections of the assembly member 223 may be a section of the type of the section 227 of FIG. 4. The same is true for the connection member 123 in the form of a stud. In still another embodiment of the assembly device comprises connecting members in at least two parts assembled together by an intermediate tensioner, such as a threaded tensioner.

  In FIG. 1 the intermediate section 126 of the arched stud is offset axially with respect to the intermediate part 122 of the cylinder head and in the direction of the rear bearing 9. Thanks to this arrangement, the assembly members 123, 223 are symmetrical, the connecting sections directed in opposite direction being of identical length. Of course it depends on the applications. As a variant, the connection sections are of different length, or even of different section. In one embodiment the sections 126 and the intermediate portion 122, 22 are of the same length. All combinations are possible. The length of the intermediate section 126 is in an embodiment equal to that of the intermediate portion of the yoke.

  In another embodiment, this length of the section 126 is greater than that of the intermediate portion of the yoke.

  In another embodiment, this length of the section 126 is smaller than that of the intermediate portion of the cylinder head.

  In still another embodiment a small difference in length exists so that the length of the intermediate section 126 is in this embodiment substantially equal to that of the intermediate portion of the yoke.

  In general, the connecting members 123, 223 are positioned outside the intermediate portion of the yoke, at a short distance from this portion, the ends of these connecting members being configured or shaped to form get closer to the axis of the rotating electrical machine. It will be appreciated the compactness of the solution according to the invention which allows the use of bearings of smaller size. It is therefore possible to use standard bearings of smaller size. The speed reducer is also of small radial size. 2015

Claims (18)

claims   1. A rotary electric machine, in particular a heat engine starter, comprising a front bearing (21), a rear bearing (9), a cylinder head (22,122-222) interposed between the front and rear bearings and an external assembly device for assembling under tension the rear bearing to the front bearing with clamping of the cylinder head between these bearings, characterized in that the yoke (22,122-222) has an extra thickness (122-222) and in that the assembly device (123,129, 91-223,228 , 91 is configured to bypass the overthickness (122,22) of the yoke (22,122-222).   2. Machine according to claim 1, characterized in that the extra thickness (122-222) of the yoke (22,122-222) carries permanent magnets or a coil (5).   3. Machine according to claim 1 or 2, characterized in that the connecting device (123,129, 91-223,228,91) comprises at least two connecting members (123, 223) configured to circumvent externally the excess thickness of the cylinder head . 20   4. Machine according to claim 3, characterized in that the connecting members consist of studs (123) with a front end (124) and back (125) threaded. 25   5. Machine according to claim 4, characterized in that the front bearing (21) comprises threads (129) for screwing the front ends (124) of the threaded bolts (123), while the rear bearing (9) comprises holes for the passage of the rear parts (125) threaded studs (123). 30   6. Machine according to claim 3, characterized in that the connecting members (223) are in the form of a bicycle radius with a front end provided with a shouldered head (226) and a threaded rear end (125).   7. Machine according to claim 6, characterized in that the front bearing (21) has lugs (228) with holes for mounting the heads of assembly members (223), while the rear bearing (9) comprises holes for the passage of the threaded rear parts (125) of the connecting members (223).   8. Machine according to claim 5 or 7, characterized in that the rear bearing (9) has protruding lugs (91), in that each tab is perforated for the passage of a threaded rear end (125) of an assembly member (123,223) and in that nuts (92) are provided for screwing each onto a threaded rear end (125) of an assembly member (123,223).   9. Machine according to any one of the preceding claims, 1s characterized in that the connecting members (123, 223) are arched.   10. Machine according to any one of the preceding claims, characterized in that the yoke (22, 122-22) comprises between its two axial ends a thicker intermediate portion and in that the assembly device comprises d assembly (123, 223) configured to circumvent externally the intermediate portion of the yoke (22, 122).   11. Machine according to claim 10, characterized in that the yoke (22, 122) comprises two coaxial parts of tubular form in contact with each other, namely an inner part (22) and an outer part (122). ) and in that the outer portion (122) is axially shorter for forming the intermediate portion. 30   12. Machine according to claim 10, characterized in that the yoke (222) is in one piece and has an extra thickness for forming the intermediate portion. 15   13. Machine according to any one of claims 10 to 12, characterized in that the connecting members comprise an intermediate section (126) and two connecting sections (127, 128-227) for connecting the intermediate section (126) respectively to the front (124, 224)) and rear (125) ends of the connecting member (123, 223) and that the front (1424, 224) and rear (125) ends are closer to the axis (XX) of the cylinder head (22, 122-222) as the intermediate portion (126).   14. Machine according to claim 13, characterized in that one (127, 128) at least connecting sections to an inclined shape.   15. Machine according to claim 13, characterized in that one (227) at least sections of connection to an S-shape. 16, Machine according to any one of claims 13 to 15, characterized in that the intermediate portions of the connecting members are offset axially with respect to the intermediate portion of the yoke. 20 17. Machine according to any one of the preceding claims, characterized in that it consists of a thermal motor starter comprising an electric motor (10) and in that the cylinder head belongs to the inductor stator (12) that comprises the electric motor. (10). 25 18. Machine according to claim 17, characterized in that it comprises a speed reducer (71) having a ring gear (72) having at its outer periphery ribs (195) for centering the front end of the cylinder head (22, 122). 30