GB2120461A

GB2120461A - Electric starter for an internal combustion engine

Info

Publication number: GB2120461A
Application number: GB08214467A
Authority: GB
Inventors: Alfred Bruno Mazzorana
Original assignee: Societe de Paris et du Rhone SA
Current assignee: Societe de Paris et du Rhone SA
Priority date: 1982-05-18
Filing date: 1982-05-18
Publication date: 1983-11-30
Also published as: GB2120461B

Abstract

An electric starter comprises a base plate 1 to which all the elements of the starter are fixed. On one face of the base plate 1 are fixed the casing 2 of the electric motor 3 and the yoke of the solenoid 4. On the opposite face of the base plate is fixed a mounting for the lever 6, which moves the actuator 7. The base plate 1 further supports means for assembly to a unit 16 of the internal combustion engine through lugs 17a on the starter casing 17 so that the starter casing 17 is subjected only to compressive stresses at its lugs. <IMAGE>

Description

SPECIFICATION Electric starter for heat engine comprising a base plate to which all the elements thereof are fixed Electric starters for internal combustion engines generally comprise a casing in which is arranged the nose piece of the starter, i.e. the end bearing of the shaft of its electric motor along which the actuator moves. This casing is often provided with side lugs adapted to fix the starter with respect to the heat engine.

It will be readily appreciated that this overhang assembly necessitates considerable mechanical strength of the casing of the starter and that the fastening of the electric motor and of the contactor with respect to the said casing must be effected with great care to avoid disconnection thereof with respect to the casing further to the effects of vibrations transmitted by the heat engine.

French Patent No. 73 45606 proposes making a coaxial starter, i.e. one whose actuator is actuated by a contactor located to the rear of the electric motor. The latter is associated with a side piece adapted to be assembled with the heat engine in the manner of a conventional flanged electric motor.

Such an assembly is extremely complex, with the result that a starter manufactured according to said prior Patent has virtually no chance of being used, due to its excessive cost price.

The improvements forming the subject matter of the present invention concern a starter whose contactor is adjacent its electric motor, the actuator of the starter in question being actuated by a lever controlled by the contactor in question.

It is an object of the invention to eliminate any stress on the casing of the starter so that the latter can be very light and even made of reinforced plastics material. Moreover, the arrangement according to the invention allows the natural vibrations of the starter to be reduced since it constitutes an assembly of firmly assembled members.

The electric starter according to the invention comprises a substantially flat plate to which are firstly fixed the carcase of the electric motor then the electro-magnetic contactor for actuating the lever controlling the actuator, and finally the members which ensure pivoting of the lever and elastic support of the teeth of the actuator against those of the gear rim of the heat engine. Such a starter is fixed to the clutch casing of the heat engine by means of screws which pass through openings made in lugs on the casing of the starter in question so that this casing is subjected only to compression. Due to the presence of a spacer placed between the base plate and the motor unit, the compressive stresses undergone by the casing may even be completely eliminated.

In order to considerably improve the resistance of the starter to vibrations, the carcase of the electric motor may be welded to the base plate so that the assembly thus produced has a very high natural frequency.

Finally, savings can further be made by eliminating the front plate of the electro-magnetic contactor, said plate being replaced by a part of the base plate which is inserted in the circuit of the contactor in question.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Fig. 1 is a partial view in elevation, with parts torn away, of an electric starter according to the invention.

Fig. 2 illustrates a detail thereof.

Fig. 3 is a view similar to that of Fig. 1, but illustrating a variant.

Fig. 4 is a variant of Fig. 3.

Referring now to the drawings, the starter shown in Fig. 1 essentially comprises a metal base plate 1, on one of the faces of which are centred the carcase 2 of the electric motor 3 as well as the electro-magnetic contactor 4. On the other face of the substantially flat base plate 1 is fixed a stirrup element 5 with respect to which is pivotally mounted the lever 6 for actuating the actuator 7, the return of said lever to initial position being effected by means of a spring 8 also ensuring elastic bearing of the teeth of the pinion 7a of the actuator against those of the gear rim (not shown) of the heat engine.

The base plate 1 is provided with studs 9 forcibly engaged in perforations in this plate and which allow the carcase 2 of the electric motor 3 to be precisely centred. The base plate is also provided with tapped holes 1 a in which are screwed tie-rods 10 adapted for holding the rear bearing (not shown in this Figure) of said electric motor. This bearing is illustrated in Fig. 3 where it is referenced 11. It will be observed that, at the level of each of the holes 1 a, a curved plate 1 2 has been associated with the base plate, for example by welding, said curved plate 12 being tapped so that it constitutes counter-nut for each tie rod 10.

The base plate is further provided with radial lugs 13 retaining a tubular nut 14 adapted to receive a screw 1 5 which passes freely through a part of the unit 1 6 of the heat engine and lugs 1 7a arranged in the casing 1 7 which protects the actuator and its actuating mechanism, and further constitutes in certain cases the second bearing 1 7b of the shaft 1 8 of the electric motor 3.

Thus the starter illustrated in Fig. 1 is fixed via its base plate 1 without its casing 1 7 being subjected to stresses other than compression at its lugs 1 7a. As illustrated in Fig. 2, a tubular spacer 19 could be engaged in each of the lugs in question, the ends of which spacer would rest on the one hand against the part of the unit 16 of the heat engine and on the other hand against the base plate 1 so that the tightening of each screw 1 5 in no way concerns the casing 17. The latter could then be very light and may even be made of reinforced plastics material which, of course, leads to substantial savings.

At the level of the shaft 18 of the motor 3, the base plate 1 comprises a truncated dish-element 1 b surrounding said shaft and with the walls of which cooperates a conical elastomeric block 20 made fast with the channeled sleeve 7b of the actuator 7. In this way, and as has been described in a prior Patent filed by Applicants, the dish constitutes an intermediate bearing for the shaft 1 8 so that its vibrations are very substantially reduced.

Fig. 3 illustrates a variant embodiment of a starter applying the improvements according to the invention, in which the tubular nuts 14 do not exist since the fixing screw 1 5 is screwed in part 16 of the motor unit. There again, although this has not been shown, a tubular spacer 1 9 may be placed between the base plate 1 and said motor unit to eliminate any compression of the lugs 1 7a of the casing 17.

Similarly, the shaft 1 8 passes through the base plate 1 in a bore comprising a conical widening 1c in which bears a part 7c, of complementary shape, made on the channeled sleeve 7b of the actuator 7.

In example shown, the carcase 2 of the electric motor 3 is made of material similar to that of the base plate 1, i.e. is advantageously made of steel, with the result that this carcase may be welded with respect to the corresponding face of said plate with a view to constituting an assembly having a very high natural frequency so that the tie rods 10 are under much less stress. This embodiment thus leads to obtaining an electric machine which is highly resistant to vibrations and to dismantlings.

According to the variant of Fig. 3, the base plate 1 further constitutes an element of the magnetic circuit of the contactor 4 and the yoke 4a thereof may then advantageously be welded beneath the plate as provided for the carcase 2 of the electric motor 3. It may also be assembled by means of screws 21 ensuring fixing of the casing 1 7 but the solution employing welding of the yoke 4a of the contactor 4 represents the preferred embodiment.

Fig. 4 illustrates an assembly in which the base plate 1 is provided with rivets 22 passing through perforations 1 d and of which the head 22a is in abutment against the face of said plate 1 which receives the stirrup 5 whilst the end of its shank projects slightly beyond its other face. By appropriate choice of the metal constituting the rivets 22, the end of the shank thereof may be welded to the carcase 2 of the electric motor and/or to the yoke 4a of the contactor 4. Of course, the perforations 1 dare distributed to this end on the base plate 1. The latter may then be made of a material which is not weldable to the carcase and to the yoke. The stirrup 5 may also be fixed in the same way to the base plate 1.

An arrangement has thus been produced which enables a starter to present a very high natural frequency due to the mass constituted by its base plate, the carcase of the electric motor and the yoke of the contactor and whose fixation makes it possible on the one hand considerably to lighten the casing protecting its actuator and to ensure an energetic fixing with respect to the motor unit on which the starter is mounted.

The preceding description has of course been given only by way of non-limiting example and replacement of the details of execution described by any other equivalents wouid not depart from the scope of the invention.

Claims

1. An electric starter for internal combustion engine, of the type comprising an actuator controlled by a lever which is pivoted by means of a contactor disposed parallel to the electric motor of said starter whose carcase is associated with a base plate, wherein the casing forming the bearing of the shaft of its electric motor is provided with lugs compressed between the base plate and the unit of the heat engine by fixing means known per se such as screws.

2. A starter as claimed in Claim 1, wherein the carcase of the electric motor is welded to the base plate.

3. A starter as claimed in Claim 1, wherein spacers are placed in the lugs on its casing with a view to absorbing the compressive stresses of the fixing screws which also pass through radial lugs on the base plate.

4. A starter as claimed in Claim 1 , wherein the radial lugs on the plate are tapped with a view to receiving the fixing screws directly.

5. A starter as claimed in Claim 1, wherein its base plate comprises means in which are screwed the fixing screws which pass through the lugs on the casing of the starter as well as a part of the unit of the heat engine.

6. A starter as claimed in Claim 5, wherein the means are tubular nuts fastened to the lugs of the base plate.

7. A starter as claimed in Claim 1, wherein the base plate further forms a means for fixing the assembly tie rods of the rear bearing of the electric motor.

8. A starter as claimed in Claim 1, wherein its base plate constitutes a part of the magnetic circuit of the contactor.

9. A starter as claimed in Claim 1 , wherein its base plate comprises means for centering the actuator when it is in rest position with a view to constituting a third bearing for the shaft of the electric motor.

10. A starter as claimed in any one of the preceding Claims, wherein the members fastened to the base plate are assembled by welding to the end of the shank of the rivets which passes through said plate whilst their heads abut against the face of this plate opposite the member which these rivets immobilise.

1 An electric starter substantially as described hereinabove and illustrated in the accompanying drawings.