Method of attaching a cover to an orifice of a power steering system and such a cover

Abstract

Housing (1') of a power steering system, comprising at least one fixing seat (2) for a cover (60), said fixing seat (2) delimiting an orifice, the cover (60) being intended to close the orifice, the fixing seat (2) comprising a support wall (53) for the cover (60), characterized in that the fixing seat (2) also comprises at least one elongation portion (54) arranged outside the support wall (53), the elongation portion (54) being provided with at least one deformation zone (55) configured to be folded down onto the cover (60). Figure 5

Description

Title of the invention: Method for fixing a cover on an orifice of a power steering system and such a cover

[0001] The invention relates to the field of housings for power steering systems in motor vehicles, and more specifically, to a housing, an assembly and a method for fixing a cover to the housing.

[0002] Motor vehicles comprise a steering system provided with a steering wheel driving a steering column. Said steering column is connected to a steering box comprising a rack extending along an axis transverse to an axis of elongation of the vehicle. The rack allows the steered wheels of the vehicle to pivot.

[0003] A power steering system also comprises an assistance device delivering to the rack an assistance force dependent on that given by the driver on the steering wheel. In this way, the force required of the driver to pivot the steering wheel is reduced.

[0004] A known type of electrical assistance device comprises an electric motor connected to a casing 1, as shown in [Fig.2], comprising a worm screw, which drives a toothed wheel fixed on a shaft linked to a pinion of the rack.

[0005] Such a casing 1 generally comprises one or more fixing seats 2, 3 which delimit an access orifice comprising an internal surface 21. The access orifice passes through an external wall 5 of said casing to allow introduction and assembly of all or part of the elements of the casing 1.

[0006] These fixing seats 2, 3 must be closed by means of a cover 6 often provided with an O-ring for example, so as to prevent the intrusion of liquid or foreign bodies, such as gravel, dust, into the casing 1, and thus guarantee the long-term proper functioning of the elements protected by the casing 1.

[0007] Subsequently, we will focus more particularly on the cover 6 located on the fixing seat 2 of the reduction wheel of the casing 1. However, the invention can be applied to any other cover of the power steering system.

[0008] There is a known solution in which the cover 6 is fixed to the casing 1 by means of clips 61, present on the cover 6. Said clips are inserted into a machined groove 51 of the casing 1. More precisely, the groove 51 is machined on the circumference of the internal surface 21 of the orifice 2.

[0009] The use of such a cover 6 has the disadvantage of not being able to visually check the correct insertion of the clips 61 in the groove 51. Thus, it is impossible to check correct insertion and correct holding of the cover 6. In the same way In this way, it is impossible to verify that there has been no degradation during assembly or over time, such as the breakage of a clip 61.

[0010] Furthermore, such a cover 6 requires cooperation with a groove 51 which must be made in the casing 1 after its manufacture. This is therefore an additional operation on the casing 1 which results in an increase in the manufacturing cost.

[0011] The invention aims to remedy all or part of the aforementioned drawbacks by proposing a casing for a power steering system, comprising at least one seat for fixing a cover, said fixing seat delimiting an orifice, the cover being intended to close the orifice, the fixing seat comprising a support wall for the cover, characterized in that the fixing seat also comprises at least one elongation part arranged outside the support wall, the elongation part being provided with at least one deformation zone configured to be folded down onto the cover.

[0012] Thus, the elements intended to hold the cover on the fixing seat, that is to say the elongation part, are outside the orifice, that is to say that an internal surface of the orifice can be perfectly smooth. The casing according to the invention does not require a machining operation between manufacturing and installation of the cover. Only an operation of folding down the deformation zone is carried out after installation of the cover so as to fix the cover permanently on the casing. This allows a saving of time and money compared to the casing of the state of the art.

[0013] The cover is held by means of the deformation zone of the elongation part.

[0014] The fixing solution according to the invention is particularly simple, robust and compact.

[0015] The invention may have one or more of the following features taken alone or in combination.

[0016] According to one embodiment, the fixing seat comprises an internal surface delimiting the orifice, the support wall extending in a direction substantially transverse to the internal surface.

[0017] According to one embodiment, the elongation portion extends in a direction substantially parallel to the internal surface.

[0018] According to one embodiment, the elongation portion continuously surrounds the support wall.

[0019] In this way, the fixing seat is not oriented.

[0020] The at least one deformation zone can be produced at any location of the elongation portion. There is therefore no orientation of the casing, and therefore of the elongation wall, relative to a tool for deforming the deformation zones.

[0021] According to one embodiment, the elongation portion comprises a plurality of deformation zones distributed regularly over the elongation portion.

[0022] Thus the cover is held regularly at several points. Preferably, the elongation part comprises at least two deformation zones.

[0023] Alternatively, the deformation zones are continuous over the elongation portion.

[0024] According to one embodiment, the casing is made of aluminum.

[0025] Thus, the casing is light and strong.

[0026] The invention also relates to an assembly comprising a casing according to the invention, and a cover held on the orifice by means of at least one deformation zone folded down on said cover.

[0027] The cover comprises a retaining edge coming into contact with the support wall. When the retaining edge continuously surrounds the cover, the latter can be positioned without taking into account its orientation relative to the fixing seat. Positioning of the cover is therefore facilitated.

[0028] The invention also relates to a method for fixing a cover to a fixing seat of a casing according to the invention, said cover comprising a protective wall surrounded at least partially by a holding edge, the method comprising a step of inserting the cover into the orifice so that the holding edge of the cover is in contact with the at least one support wall, the method comprising a deformation step in which the at least one deformation zone is folded back onto the holding edge.

[0029] The method according to the invention comprises a step of inserting the cover during which the cover closes the orifice of the fixing seat. There is no need to orient the cover relative to the orifice. This step is therefore particularly simple. The cover must be inserted into the orifice so that the holding edge is in contact with the at least one support wall.

[0030] The method then comprises a deformation step making it possible to permanently fix the cover on the orifice. The elongation part comprises the at least one deformation zone which is intended to be deformed. Before deformation, the deformation zone is not differentiated from the elongation part which has a component in a direction parallel to the orifice strictly greater than a thickness of the holding edge of the cover.

[0031] Thus when the cover is inserted into the orifice, the elongation part, and therefore the deformation zones, protrude, or exceed the cover.

[0032] It is then possible to exert pressure on the deformation zones of the elongation part so as to fold the deformation zone onto the holding edge. There is plastic deformation of the elongation part, i.e. of the casing.

[0033] Finally, the cover is held on the fixing seat by means of the deformation zones which block the cover in the orifice. There is no addition of material or part to fix the cover. Only the material already present at the fixing seat, and more particularly at the elongation part is deformed to fix the cover. The method is therefore economical.

[0034] Such a fixing method allows a visual check of the correct insertion and correct holding of the cover since the deformation zones are positioned outside the orifice. In addition, it does not require any specific groove in the casing.

[0035] According to one embodiment, the deformation step is carried out by means of a mechanical material folding process.

[0036] Such a method may be a crimping, punching, scoring or any other known material pushing method. A mechanical method does not involve external heating of the material, so the method is very safe since there is no risk of burning. In addition, it is quick to carry out. Finally, it does not present any thermal deformation of the material which thus retains its internal structure.

[0037] Alternatively, the deformation step is carried out by means of a thermal material folding process.

[0038] According to one embodiment, during the deformation step, the deformation zone is folded back by exerting pressure in a direction substantially parallel to the support wall.

[0039] It is possible to exert pressure on the deformation zones of the elongation part in a direction substantially parallel to the support wall so as to crush the deformation zone on the holding edge.

[0040] According to one embodiment, during the deformation step, the deformation zone is folded back by exerting pressure in a direction substantially transverse to the support wall.

[0041] Thus the deformation zones of the elongation part are folded on the holding edge.

[0042] According to one embodiment, after deformation, the deformation zone has a shape chosen from: triangle, circle, square.

[0043] The shape of the deformation zone after deformation is linked to the shape of the tool used to carry out the deformation step.

[0044] The invention will be better understood, thanks to the following description, which relates to an embodiment according to the present invention, given by way of non-limiting example and explained with reference to the appended schematic drawings, in which:

[0045] [Fig. 1] is a perspective representation of a cover according to the state of the art;

[0046] [Fig.2] is a representation of a housing of a power steering system comprising the cover of [Fig.l];

[0047] [Fig.3] is a sectional view of the steering system housing after completion of a step of inserting the cover according to the invention;

[0048] [Fig.4] is a perspective view of the steering system housing after a rea carrying out a step of deformation of the cover according to the invention;

[0049] [Fig.5] is a sectional representation of an enlargement of the casing according to [Fig.4]

[0050] The casing 1' comprises an outer wall 5' which may be metallic or made of material rigid plastic. It houses a gear mechanism not shown in the figures.

[0051] The mechanism is preferably a reducer comprising a reduction wheel and a worm screw which provides mechanical transmission between a steering assistance motor and a movable member, such as a rack or a steering column. The steering column makes it possible to modify the yaw orientation (steering angle) of the vehicle's steered wheels.

[0052] The casing 1' comprises several fixing seats 2, 3, 4 comprising an internal surface 21' delimiting an orifice which passes through the external wall 5' of said casing 1' to allow introduction and assembly of all or part of the elements of the casing 1'. The fixing seats 2, 3, 4 have a substantially circular shape.

[0053] Subsequently, we will focus more particularly on the cover 60 making it possible to close the orifice of the fixing seat 2 positioned on the reduction wheel.

[0054] The casing 1' comprises the fixing seat 2 of the cover 60, the fixing seat 2 comprises the internal surface 21' delimiting the orifice, a support wall 53 extending in a direction substantially transverse to the internal surface 21' and an elongation portion 54 extending substantially in the direction of the internal surface 21'. The support wall 53 and the elongation portion 54 are formed in a thickness of the external wall 5'. The internal surface 21' does not have any recess or indentation. It is cylindrical.

[0055] The cover 60 comprises a substantially circular protective wall 603 having a diameter substantially equal to the diameter of the orifice 2. The protective wall 603 is extended in a plane in which the protective wall 603 extends by a retaining edge 602. The retaining edge 602 continuously surrounds the protective wall 603.

[0056] The protective wall 603 is surrounded by an insertion edge 601 which extends in a direction substantially transverse to the protective wall 603. The insertion edge 601 comprises a location 604 intended to receive an O-ring seal (not shown).

[0057] A method of fixing according to the invention the cover 60 on the orifice 2 comprises a step of inserting the cover 60 into the orifice of the fixing seat 2 as shown in [Fig. 3]. In this step, the cover 60 is inserted into the orifice so that the insertion edge 601 is in contact with the internal surface 21' and the holding edge 602 of the cover 60 is in contact with the support wall 53. Thus the protective wall 603 completely covers the orifice.

[0058] A length of the cover 60 in a direction parallel to the protective wall 603 is strictly greater than a dimension of the orifice measured between two opposite internal surfaces 21', and strictly less than a dimension of the orifice measured between two opposite internal surfaces 21' increased by the elongation wall 54. In other words, the length of the cover 60 in a direction parallel to the protective wall 603 is strictly greater than a dimension of the orifice measured between two opposite internal surfaces 21', is less than or equal to a dimension of the orifice measured between two support walls 53.

[0059] The method then comprises a deformation step. During this step, deformation zones 55 of the elongation portion 54 are crushed by means of an anvil in the direction of the internal surface 21' towards the holding edge 602. The deformation zones 55 are regularly distributed over the circumference of the cover. Alternatively, the deformation zones could be continuous over the circumference of the cover 60. The deformation zones 55 have a square shape.

[0060] Figures 4 and 5 illustrate the casing 1' after carrying out the fixing method according to the invention.

[0061] Of course, the invention is not limited to the embodiment described and shown in the attached figures. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Claims

1. Housing (1') of a power steering system, comprising at least one fixing seat (2) for a cover (60), said fixing seat (2) delimiting an orifice, the cover (60) being intended to close the orifice, the fixing seat (2) comprising a support wall (53) for the cover (60), characterized in that the fixing seat (2) also comprises at least one elongation portion (54) arranged outside the support wall (53), the elongation portion (54) being provided with at least one deformation zone (55) configured to be folded down onto the cover (60).

2. Housing (1') according to claim 1, in which the fixing seat (2) comprises an internal surface (21') delimiting the orifice, the support wall (53) extending in a direction substantially transverse to the internal surface (21').

3. A casing (1') according to claim 2, wherein the elongation portion (54) extends in a direction substantially parallel to the inner surface (21').

4. A housing (1') according to any one of claims 1 to 3, wherein the elongation portion (54) continuously surrounds the bearing wall (53).

5. A housing (1') according to any one of claims 1 to 4, wherein the elongation portion (54) comprises a plurality of deformation zones (55) distributed regularly over the elongation portion (54).

6. Assembly comprising a casing (1') according to any one of claims 1 to 5, and a cover (60) held on the orifice by means of at least one deformation zone (55) folded down on said cover (60).

7. Method for fixing a cover (60) on a fixing seat (2) of a casing (1') according to one of claims 1 to 5, said cover (60) comprising a protective wall (603) surrounded at least partially by a holding edge (602), the method comprising a step of inserting the cover (60) into the orifice so that the holding edge (602) of the cover (60) is in contact with the at least one support wall (53), the method comprising a deformation step in which the at least one deformation zone (55) is folded over the holding edge (602).

8. The method of claim 7, wherein the deforming step is produced using a mechanical material folding process.

9. Method according to claim 7 or 8, wherein during the deformation step, the deformation zone (55) is folded down by exerting pressure in a direction substantially parallel to the support wall (53).

10. Method according to claim 7 or 8, wherein during the deformation step, the deformation zone (55) is folded down by exerting pressure in a direction substantially transverse to the support wall (53).

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