FR2473806A1 - Small electric motor for vehicle windscreen wipers - has gear casing fitted to motor casing with bearing plate providing seat for roller bearing - Google Patents

Abstract

The motor has gears located in a gear casing with a bearing plate that closes the pot-shaped motor casing containing the motor armature. The bearing plate has a seat for the roller bearing of the armature's shaft. A slide is held against an end stop on the motor casing and against the roller bearing by a screw passing through the bearing plate. The motor casing has a hole (33) open towards the upper edge. One section of the edge of the hole acts as end stop acting in the direction of the bearing plate (38). The slide (37) is angled and its outer limb (38) extends in the long direction of the motor casing and lies in the hole.

Description

 The present invention relates to a small electric motor, in particular for a wiper on board a motor vehicle, comprising a pot-shaped motor casing containing the motor rotor, a transmission casing having a bearing flange which closes the casing. of the motor and on which is formed a housing for a bearing serving as a bearing for the rotor shaft, and at least one latch which a screw, passing through the flange, holds against a stop on the casing of the motor and against the bearing.

 For such small engines, various constructions are known in which locks carry out both the mutual assembly of the engine casing and the transmission casing as well as the fixing of the bearing in the bearing flange of the transmission casing.

 Thus, in a known embodiment, the latches are produced in the form of flat plates. So that the latches can have a grip on the motor casing, two handles or pierced lugs are formed thereon, protruding beyond its edge, and the outer ends of the latches are placed in the openings of these lugs . This construction allows the bolts to be given such length that they end with the outer surface of the motor housing. Furthermore, such a design however implies a greater loss of material during the manufacture of the motor casing, which is normally formed from a sheet.

 This is why, in another embodiment, we have come to locks having a hook shape. The locks come out of the motor casing through a recess in an outer edge of the flange, then bend at ninety degrees, relative to their direction of insertion during assembly, and run along the outside. of the engine casing over a certain distance, then enter, through a terminal portion which is also bent at ninety degrees, into a recess in the engine casing.

In this way, the handles or lugs protruding beyond the upper edge of the engine casing are avoided, and the loss of material over the height of these lugs is therefore avoided. But then, the locks have a complicated shape, so that their manufacture is expensive.

 The object of the present invention is to produce a small electric motor in which latches are used for assembling the transmission casing and the motor casing as well as for immobilizing a bearing in a flange ending the engine casing, so that this assembly of the casing to the casing and this immobilization of the bearing can be carried out with relatively simple locks, without there being any significant loss of material during manufacture.

 According to the invention, this object is achieved, in the case of a small electric motor of the type indicated above, by the fact that the envelope of the motor has at least one recess open on the upper edge of this envelope, by the fact that at least a portion of the edge of this recess is constituted as a stop acting in the direction of the flange, and by the fact that each lock has the shape of an angle iron of which an outer wing is oriented in the direction of the length of the motor casing and is located in said recess.

 With a small electric motor according to the invention, there is no need for any tab pierced on the casing of the engine, so that the losses of material, which such tabs would imply, are avoided. Furthermore, the locks are simplified compared to the hook-shaped locks, since they are now produced in the form of a simple angle. This simple embodiment is authorized in the first place by the fact that the recesses in the envelope of the engine are with open edge. By giving the recesses an appropriate configuration, it is easy to form the stops by which the outer wings of the latches catch on the casing of the motor.

 Advantageous embodiments of the invention are indicated in the description which follows. Thus, it is particularly advantageous that the locks are right angle brackets. The inner wing can then be perpendicular to the screw, so that if, in accordance with an advantageous embodiment, the screw passage is provided with a helical thread such that the locks serve at the same time as nut for the screws , this screw passage then crosses the inner wing perpendicularly and is therefore easy to drill.

 If the small electric motor according to the invention is such that the distance between the passage of the screw in the inner wing of a bolt and the outer surface of the outer wing is at most equal to the radial distance between the passage of the screw in the flange and the external surface of the motor casing, it is then ensured that the external wing of the latches will not protrude beyond the periphery of the motor casing.

 If the shape of the recesses in the envelope of the engine and the shape of the outer wing of the locks are very substantially complementary, the recesses are then almost entirely closed by the outer wings of the locks, so that the interior of the engine is then protected against soiling.

 In a very advantageous embodiment, each recess has the shape of a rectangle in which at least one projection of the envelope projects, which projection is bordered by a lower surface which is advantageously oriented parallel to the plane of the flange.

The rectangular shape of the recess allows the latches to be manufactured in the press, with simple tools and without great loss of material, from metal strip whose width corresponds substantially to that of the recess. The preferred shape of the lower surface bordering the protrusions protruding into the recess ensures that, during and after the fixing of the transmission casing by tightening of the screws cooperating with the latches, the motor casing must not withstand, in the circumferential direction, that zero or weak forces compared to those which would appear in the case of an oblique lower surface.

 There is also provision, in the axial direction of the motor casing, between the outer wing of a lock and the recess, as well as between this lock and the flange, a clearance which guarantees that the lock will be sure to contact between the motor housing and the ball bearing.

 According to other features of the invention, it is provided that a support fixed to the flange is located below the inner wing of a lock and at least near the origin of the wings of the lock and retains the lock against the flange during assembly, and that the support is a core oriented transversely to the direction of movement of the locks during assembly.

 These characteristics serve above all to simplify the mounting of the engine casing and the transmission casing by giving each lock a certain guide against the flange. In addition, these features eliminate the possibility of a lock falling into the motor housing during assembly. Similarly, the configuration by which the stroke of a bolt is limited inwards, contributes to the speed and s-implicity of the mounting of the small motor.

The invention will be better understood and other characteristics will appear from the following description and the accompanying drawings in which - Figure I shows an elevational view of a small engine
electric, partially cut off - Figure 2 shows a side view of the motor in Figure 1
after rotating to ninety degrees; and - Figure 3 shows a top view of a lock of a small
motor according to the invention.

 In FIGS. 3 or 2, the permanent magnets located inside the envelope JO of the motor, as well as the rotor or armature also arranged in this envelope, are not shown because these elements are of no importance for the understanding of the invention. In addition to its casing 10, the motor comprises a casing 11 in which a reduction gear is arranged with a belicoldal worm screw thread (not visible in the figures) formed on the part of the rotor shaft 12 projecting into the casing] 1, and with a toothed wheel] 3 meshing on this net. This reducer reduces the speed of rotation of the shaft 12 to a speed of rotation suitable for an output shaft intended for the actuation of a wiper device. On the toothed wheel 13, a conductive track 14 is fixed on which contact springs rub. These contact springs constitute, with the conductive track 14, a switch for permanent stop position.

 The casing 10 of the engine has a cylindrical shape, like a pot, and is made by winding a sheet. The housing 11 of the reducer consists of a housing A5, also in the form of a pot, for the toothed wheel 13, housing whose open side is closed by a cover 16, of a channel 17 oriented in the longitudinal direction of the casing 10 and tangentially bordering the housing 15 to which it is open, the worm being in this channel 17, and a bearing flange 18 whose outside diameter coincides with the outside diameter of the casing 10 of the motor , which is closed on the reduction side by this bearing flange # 8.

 On the flange 18, a passage 22 is formed centrally for the shaft 12 of the motor. Starting from this passage 22, a hemispherical cup 23, turned towards the casing 10 of the engine, is formed on the flange. Stepped towards the outside, this cup is followed by a cylindrical housing 24. This configuration makes it possible to place either a spherical bearing in the cup 23, or, as provided for the small engine according to the invention, a ball bearing 25 in the cylindrical housing 24.

 The ball bearing 25 has an inner ring 26 fixedly mounted on the shaft 12 and stopped axially by two stop rings 29. This ball bearing 25 also has an outer ring 27 whose outer surface is in contact with the surface of the housing 24, and balls 28 between the two rings.

 The casing 10 of the motor has two recesses 33 which are open on the upper edge 32 and are arranged in diametrically opposite locations of the casing 10. The recesses 33 have the shape of a rectangle in which protrude from two lateral edges , projections 34 of the casing 10 which are also rectangular.

This geometry has the result that the two surfaces 35, delimiting the two projections 34 downward, are parallel to the plane of the flange 58 and perpendicular to the longitudinal direction of the casing 10 of the engine. Above the recesses 33, over a width corresponding to that of these recesses 33, the edge 36 of the flange 18 is perforated.

 The recesses 33 serve, in combination with two latches 37, to fix the flange 18 to the casing 10 of the engine. The latches 37 have the shape of an angle or square at right angles having an outer wing 38 and an inner wing 39. The shape of the wing 38 is very substantially complementary to the shape of the recesses 33. Its width, which is also the width of the inner wing 39 coincides with the width of the recesses 33. Two notches 40 receive the projections 34. In the longitudinal direction of the casing 10, the dimensions of the recesses 33, of the notches 41 in the flange 18, and latches 37, are such that there is an axial play. This is intended to ensure that the outer wing 38 will always come to bear against the projections 34, and that the inner branch 39 will always come to rest against the outer ring 27 of the ball bearing 25.

 The inner wing 39, the shape of which appears particularly clearly in FIG. 3, is guided laterally through the walls 45 of the flange 18. In the vicinity of its free end, the wing 39 is lowered in steps from the two ribs. During assembly, these steps 46 meet stops 47 projecting from the walls 45 of the bushing, which has the effect of limiting the pressing of the latch inwards. Below the inner wings 39 of the latches 37 are, projecting inwards from the walls 45, supports 48 which are connected to each other by a core 49 and which extend, from an area close to the origin of the wings 38 and 39, towards the free end of the inner wing 39.

 In the inner wing 39 of each latch 37, a hole 50 is arranged with an inner belicoidal thread 51. The hole 50 is aligned with an opening 52 in the flange 18 This opening 52 is crossed by a screw 53 pressed against the flange 18, by means of an elastic stop washer 54, and screwed into the wing 39.

The latches 37 therefore also serve as nuts for the screws 53.

 The distance between the hole 50 in the wing 39 and the outer surface of the outer wing 38 is approximately equal to the radial distance between the opening 52 and the outer surface of the casing 10 of the engine. The outer surface of the wing 38 is therefore flush with the outer surface of the envelope 10.

 During assembly, the latches 37 are placed on the supports 48, then they are moved in the casing 20 of the motor, until they are in abutment. The supports 48 prevent the latches from falling into this envelope 10. Then, the screws 53 are introduced through the openings 52 in the flange 18, then they are brought into the threads 53 and they are tightened. During this operation, the outer wings 38 of the latches 37 bear against the projections 34 in the recesses 33, and the inner wings 39 meet the ball bearing 25 which bears against the flange 18. Thus, the casing 11 of the reduction gear and the casing 10 of the engine are assembled to each other in a simple manner. The ball bearing 25 is immobilized in the housing 24.

 Of course, the embodiment described is in no way limitative of the invention.

Claims (10)

 1. Small electric motor, in particular for a windscreen wiper on board a motor vehicle, comprising a pot-shaped motor casing containing the motor rotor, a transmission casing having a bearing flange which closes the motor casing and on which is formed a housing for a bearing serving as a bearing for the rotor shaft, and at least one latch which a screw, passing through the flange, holds against a stop on the casing of the motor and against the bearing, this motor being characterized in that its envelope (10) has at least one recess (33) open on the upper edge (32), in that at least a portion (35) of the edge of this recess (33) is formed as a stop acting in the direction of the flange (18), and in that each lock (37) has the shape of an angle iron of which an outer wing (38) is oriented in the longitudinal direction of the casing (10) of the motor and is located in said recess (33).  2. Engine according to claim 1, characterized in that the angle iron is a right angle bracket whose inner wing (39) is oriented perpendicular to the longitudinal direction of the envelope (10) of the engine.  3. Motor according to one of claims I or 2, characterized in that each lock (37) constitutes the nut of the associated screw (53).  4. Motor according to any one of claims 1 to 3, characterized in that the distance between the passage (50) of the screw in the inner wing (39) of a latch (37) and the outer surface of the 'outer wing (38) is at most equal to the radial distance between the passage (52) of the screw in the flange (J8) and the outer surface of the casing (10) of the engine.  5. Motor according to any one of claims 1 to 4, characterized in that the shape of the recesses (33) in the casing (10) of the engine and the shape of the outer wing (38) of the latches (37) are very noticeably complementary.  6. Motor according to any one of claims I to 5, characterized in that each recess (33) has the shape of a rectangle in which projects at least one projection (34) of the envelope, which projection is bordered by a lower surface (35) which is advantageously oriented parallel to the plane of the flange (18).  7. Engine according to one of claims 4 or 5, characterized in that there is a certain clearance, in the axial direction of the casing (] O) of the engine, between the outer wing t38) of a latch t37) and the recess (33), as well as between this latch (37) and the flange (18) #.  8. Motor according to any one of claims 1 to 7, characterized in that a support (48,49), fixed to the flange (18), sue located below the inner wing (39) of a lock (37) and at least near the origin of the wings (38,39) of the lock and retains the lock (37) against the flange (J8) during assembly.  9. Motor according to claim 8, characterized in that the support is a core (49) oriented transversely to the direction of movement of the latches (37) during assembly.  10. Motor according to any one of claims 1 to 9, characterized in that, at its end and in the vicinity of this end, the inner wing (39) of a latch (37) is preferably narrowed in the form of step (46) by which it abuts against the flange (18).