Steering pinion and rack assembly adjustment system

Abstract

To provide a machine assembly that can be promptly and easily assembled and is constituted by a steering pinion engageable with a rack, the volume and mass of which are reduced.SOLUTION: A steering system rack (1) includes a functional zone (Zf) provided with a plurality of functional teeth (2). The functional teeth define a plurality of functional recessed portions (Ef) between the two continuous functional teeth and include an insertion zone (Zi) extending on the extension of the functional zone (Zf). The insertion zone (Zi) includes at lease one insertion tooth (2), and defines at lease one insertion recessed portion (Ei,Et) between at least one insertion tooth (2) and the functional tooth (2) located opposed to the insertion zone (Zi). A height (Ht1,Ht2,Hi) of a gauge (3) disposed in the insertion recessed portion (Ei, Et) is smaller than a height (Hf) of a gauge (3) disposed in the functional recessed portion (Ef) by an offset distance.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the field of steering systems, and more particularly to racks for steering systems. [Background technology]

[0002] The purpose of a vehicle's steering system is to allow the driver to control the vehicle's trajectory by using the steering wheel to change the directional angle of the vehicle's wheels.

[0003] A steering system uses a mechanical assembly consisting of a steering pinion that meshes with a rack to change the rotation of the vehicle's wheels. The rack is mounted in a steering casing so that it can slide longitudinally. The ends of the rack are connected to two steering rods on the outside of the casing, and these steering rods are connected to the left and right steered wheels of the vehicle, respectively.

[0004] The rack includes a toothing formed by teeth and a tooth back surface located opposite the toothing, the toothing extending in the longitudinal direction of the rack.

[0005] Each tooth further includes a first flank, a second flank, and a crest connecting the first flank and the second flank, and each tooth is spaced from an adjacent tooth by a recess.

[0006] The person skilled in the art knows how to determine the characteristics of a toothing by evaluation (measurement) with a gauge, i.e. the characteristics of the toothing are determined with respect to a gauge that is placed substantially between two teeth, in other words in the recess of the toothing.

[0007] A gauge is a calibrated instrument capable of making measurements, in this example the gauge is for example a sphere with a given diameter.

[0008] Elsewhere in this specification: the longitudinal axis of the rack is an axis extending along the length of the rack; The center of the rack is the center of an imaginary circle that is at least partially inscribed in a cross section of the rack on a plane that intersects (is perpendicular to) the longitudinal axis of the rack, The height of the gauge is the dimension between the center of the rack and the top of the gauge, and the gauge is placed between two consecutive teeth of the rack; The pitch of the teeth is the distance between the centers of two gauges arranged in two consecutive recesses, and the pitch of the rack is fixed or variable; The tooth root is the point of the recess closest to the center of the rack, The tooth bottom height is the dimension between the tooth bottom and the center of the rack, The tooth height is the dimension between the top and the center of the rack. This clarifies the characteristics of the rack.

[0009] During vehicle operation, forces are applied that counteract contact between the steering pinion and rack.

[0010] To maintain the permanent meshing of the rack with the steering pinion, it is known to use so-called "push" devices that act elastically on the back of the rack in the pinion area, forcing the rack teeth against the pinion teeth. This pressing restricts the clearance between the steering pinion and the rack teeth and also makes it possible to control the sliding force of the rack in the steering casing. Summary of the Invention [Problem to be solved by the invention]

[0011] A drawback of using so-called "push" devices is that the push-in force needs to be adjusted after the steering pinion and rack are assembled.

[0012] Furthermore, the "push" device is subject to failure and there are many patents known regarding improvements to this device.

[0013] Finally, such devices involve volume, cost, and mass that steering system manufacturers seek to reduce.

[0014] Therefore, there is a need for a mechanical assembly comprising a rack and mating steering pinion that can be quickly and easily assembled and has reduced volume and mass. [Means for solving the problem]

[0015] One embodiment relates to a rack for a steering system, the rack having a functional zone and an insertion zone. The functional zone includes a plurality of functional teeth, the functional teeth defining a plurality of functional recesses between two consecutive functional teeth, the functional recesses being configured to cooperate with a steering pinion, and the functional zone extending along a longitudinal axis of the rack. The insertion zone extends in the extension of the functional zone and includes at least one insertion tooth, defining at least one insertion recess between the at least one insertion tooth and a functional tooth located opposite the insertion zone. Characteristically, the height of a gauge disposed in the insertion recess is smaller than the height of the gauge disposed in the functional recess by a certain offset distance.

[0016] For the remainder of this specification, two elements are said to be "identical" only if they differ from each other by manufacturing tolerances generally accepted in the art.

[0017] The rack according to the invention comprises functional zones which form the teeth of the rack and extend in the longitudinal direction of the rack.

[0018] Each tooth of the rack has a first flank, a second flank, and a crest connecting the first and second flanks, and each tooth is spaced from an adjacent tooth by a recess.

[0019] The characteristics of the toothing are determined with respect to a gauge that is located substantially between two teeth, i.e. in the recess of the toothing.

[0020] The gauge is, for example, a sphere having a center and a predetermined diameter.

[0021] In the remainder of this specification: the longitudinal axis of the rack is an axis extending along the length of the rack; The center of the rack is the center of an imaginary circle that is at least partially inscribed in a cross section of the rack on a plane that intersects (is perpendicular to) the longitudinal axis of the rack, The height of the gauge is the dimension between the center of the rack and the top of the gauge, and the gauge is placed between two consecutive teeth of the rack; The tooth pitch is the distance between the two centers of two gauges placed in two consecutive recesses, and the rack pitch is fixed or variable; The outer shape of the tooth in a longitudinal cross section of the rack includes at least a tooth apex, and a first flank and a second flank connected to the apex, The root is the point of the recess closest to the center of the rack, The tooth bottom height is the dimension between the tooth bottom and the center of the rack, The tooth height is the dimension between the top and the center of the rack. This clarifies the characteristics of the rack.

[0022] The functional zone extends along the longitudinal direction of the rack. All gauges placed in the functional recesses have the same height.

[0023] The insertion zone is located at one end of the functional zone along the longitudinal direction of the rack and is in contact with the functional zone.

[0024] The insertion zone allows for an innovative assembly of the steering pinion and rack assembly. Indeed, according to the invention, the rack is first placed in the steering casing so that the clearance (play) between the rack and the steering casing is substantially the same as the final desired clearance during operation of the assembly on the vehicle. The steering pinion is then inserted into the steering casing in the insertion zone.

[0025] The at least one insertion tooth has the specific function of allowing the steering pinion to be inserted into the rack when the rack is placed in the steering casing. It is therefore clear that the at least one insertion tooth has an outer shape determined in its pre-manufacturing stage so as to ensure that the height of the gauge placed in the insertion recess is lower by an offset distance than the height of the gauge placed in the functional recess.

[0026] The height of the gauge placed in the insertion recess is lower than the height of the gauge placed in the functional recess, thereby reducing the stress acting on the steering pinion and rack assembly, and as a result, it is possible to insert the steering pinion into the rack while the rack is already placed in the steering casing.

[0027] The invention makes it possible to avoid the need to press the rack onto the steering pinion after insertion, for example with a "push" type device: in fact, the final stressing of the steering pinion and rack assembly can be carried out when the steering pinion meshes with the teeth of the functional zone.

[0028] During operation of the assembly on the vehicle, the steering pinion moves only through the functional zone, and movement of the steering pinion into the insertion zone can be limited, for example, by a movement limiter.

[0029] The invention therefore makes it possible to carry out final adjustment of the rack within the steering casing before inserting the steering pinion into said steering casing.

[0030] Unlike a toothless or flat insertion zone, the presence of at least one tooth in the insertion zone according to the present invention allows the cross section of the rack to be maintained in a plane perpendicular to the longitudinal axis of the rack while minimizing the change in the length of the rack. This allows the deformation of the rack during the heat treatment process to remain relatively constant. A toothless or flat insertion zone would cause a significant change in the cross section, which would result in significant deformation during the heat treatment and thus weaken the mechanical properties of the rack.

[0031] Furthermore, for steering systems where there is a mechanical connection between the steering wheel and the steering pinion and rack assembly, the insertion zone according to the present invention allows for angular indexing of the steering pinion with the rack to ensure precise alignment of the steering wheel with the midpoint of the steering pinion and rack assembly.

[0032] The subject matter of the present disclosure may include one or more of the following features, either alone or in combination.

[0033] According to one embodiment, the height of the root of the at least one insertion recess is the same as the height of the root of the plurality of functional recesses.

[0034] This allows the insertion recess and the functional recess to be aligned.

[0035] According to one embodiment, the height of the insertion tooth is less than the height of the functional tooth.

[0036] Therefore, the interpositional tooth is smaller than the functional tooth.

[0037] According to one embodiment, at least one insertion tooth has, along a longitudinal cross section of the rack, an upper profile that is identical to the upper profile of the functional tooth facing the insertion zone.

[0038] The outer shape of the upper part of the tooth is the outer shape of the tooth along the longitudinal cross section of the rack, and includes at least the top of the tooth and a part of the first flank and a part of the second flank connected to the top.

[0039] The profile of the top of the tooth is determined by tooth calculations (tooth profile calculations) known to those skilled in the art.

[0040] The rack according to the invention is characterized in that the functional tooth facing the insertion zone and at least one insertion tooth have the same upper profile.

[0041] Furthermore, since the height of the gauge arranged in the insertion recess is lower than the height of the gauge arranged in the functional recess, the top of at least one insertion tooth is offset toward the center of the rack by a distance close to, but not necessarily equal to, the offset distance relative to the functional tooth located opposite the insertion zone.

[0042] In an embodiment, the offset distance is between 20% and 70%, preferably between 30% and 50%, in particular between 35% and 45% of the height of the gauge placed in the functional recess.

[0043] In some embodiments, the insertion zone comprises multiple insertion recesses, preferably at least three insertion recesses.

[0044] Therefore, during insertion, the steering pinion can engage with at least three insertion recesses.

[0045] In one embodiment, the insertion zone comprises a lead-in section with at least two lead-in recesses, and the height of the gauges disposed in the at least two lead-in recesses is the same.

[0046] The introduction recess is also an insertion recess.

[0047] The lead-in recess facilitates insertion of the steering pinion.

[0048] In one embodiment, the insertion zone includes a transition section with at least one transition recess, and the height of the gauge disposed in the at least one transition recess is between the height of the gauge disposed in the functional recess and the height of the gauge disposed in the lead-in recess.

[0049] In some embodiments, a transition section is disposed between the functional zone and the lead-in section.

[0050] The transition section therefore borders on the one hand the functional zone and on the other hand the lead-in section.

[0051] The transition portion facilitates engagement of the steering pinion in the functional zone by gradually placing the steering pinion in an operating position, i.e., by gradually increasing the stress acting on the steering pinion and rack assembly.

[0052] In some embodiments, the transition section comprises at least two transition recesses.

[0053] In some embodiments, the height of the gauge disposed in the at least two transition recesses decreases linearly between the height of the gauge disposed in the feature recess and the height of the gauge disposed in the lead-in recess.

[0054] Another aspect of the invention relates to a steering system including a rack according to the invention.

[0055] The invention will be better understood from the following description, which relates to several embodiments of the invention, given by way of non-limiting example and with reference to the accompanying schematic drawings, in which: [Brief explanation of the drawings]

[0056] [Figure 1] FIG. 1 is a longitudinal cross-sectional view of a rack according to the present invention. [Figure 2] FIG. 2 is an enlarged view of FIG. [Figure 3a]FIG. 3a is a longitudinal cross-sectional view of a steering pinion and rack assembly according to a first embodiment. [Figure 3b] FIG. 3b is a longitudinal cross-sectional view of the steering pinion and rack assembly according to the first embodiment. [Figure 4a] FIG. 4a is a longitudinal cross-sectional view of a steering pinion and rack assembly according to a second embodiment. [Figure 4b] FIG. 4b is a longitudinal cross-sectional view of a steering pinion and rack assembly according to a second embodiment. [Figure 5a] FIG. 5a is a longitudinal cross-sectional view of a steering pinion and rack assembly according to a third embodiment. [Figure 5b] FIG. 5b is a longitudinal cross-sectional view of a steering pinion and rack assembly according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0057] Only those elements necessary for understanding the invention are shown, and to facilitate understanding of the drawings, identical elements are designated by the same reference numerals from one drawing to the next.

[0058] The present invention relates to a rack 1 for a steering system, as shown in FIG.

[0059] The rack 1 comprises a toothing (row of teeth) formed by a plurality of teeth 2, which extend along a longitudinal axis A, also called the axis of extension of the rack 2.

[0060] Each tooth 2 has a top, a first flank (first side face) and a second flank (second side face), and the first flank and the second flank are each connected to the top at a predetermined angle.

[0061] 2, the outer shape of the upper part of the tooth 2 in a longitudinal cross section of the rack 1 includes at least a crest, a portion of the first flank of the tooth 2, and a portion of the second flank of the tooth 2, and the portion of the first flank and the portion of the second flank are connected to the crest. The outer shape of the upper part of the tooth 2 is determined by tooth profile calculations known to those skilled in the art.

[0062] The characteristics of the toothing are determined with respect to a gauge 3 which is placed substantially between two teeth 2, i.e. in a recess E of the toothing, as shown in FIG.

[0063] The gauge 3 is, for example, a sphere having a center and a predetermined diameter.

[0064] The center C of the rack 1 is the center of an imaginary circle in which a cross section of the rack 1 cut by a plane intersecting (orthogonal to) the longitudinal axis A of the rack 1 is at least partially inscribed.

[0065] The height H of the gauge 3 is the dimension between the center C of the rack 1 and the top of the gauge 3, and the gauge 3 is located between two consecutive teeth 2 of the rack 1.

[0066] The teeth are in functional zone Z f and insertion zone Z i and its insertion zone Z i is the transition part P t and introductory part P i Includes:

[0067] Two successive teeth 2 are spaced apart by a recess E.

[0068] Functional Zone Z f In this case, tooth 2 is called a functional tooth, and the recess is called a functional recess E. f Functional recess E f is configured to cooperate with the steering pinion 10 during normal operation of the steering system. f extends along the longitudinal axis A of the rack 1.

[0069] Functional recess E fAll gauges 3 placed at height H f are identical.

[0070] Insertion Zone Z i In this case, tooth 2 is called the insertion tooth, and recess E is called the insertion recess E. i , E t It is called.

[0071] Insertion Zone Z i is the functional zone Z f Insertion Zone Z i is located along the longitudinal axis A of the rack 1 in the functional zone Z f The insertion zone Z is located at one end of the i is the functional zone Z f It is in contact with.

[0072] Insertion Zone Z i has multiple insertion recesses E i , E t , preferably at least three insertion recesses E i , E t Includes:

[0073] Insertion recess E i , E t Height H of gauge 3 placed at i , H t1 , H t2 is the functional recess E f Height H of gauge 3 placed at f is smaller by a certain offset distance (shift distance).

[0074] More precisely, the offset distance is the functional recess E f Height H of gauge 3 placed at f between 20% and 70%, preferably between 30% and 50%, in particular between 35% and 45% of the total.

[0075] According to one embodiment, at least one insertion recess E i , E t The height of the tooth root is determined by the multiple functional recesses E f The height of the tooth base is the same as that of the

[0076] Therefore, the insertion recess E i , E t and functional recess E f are aligned with.

[0077] According to one embodiment, the height of the insertion tooth 2 is less than the height of the functional tooth 2 .

[0078] Therefore, the interpositional tooth is smaller than the functional tooth.

[0079] According to one embodiment, the contour of the top of the at least one insertion tooth 2 is such that it is aligned with the insertion zone Z along the longitudinal section of the rack 1. i The outer shape of the upper part of the functional tooth 2 facing the functional tooth 1 is the same as that of the upper part of the functional tooth 2 facing the functional tooth 1.

[0080] The outer shape of the upper part of the tooth 2 is the outer shape of the tooth 2 in a longitudinal cross section of the rack 1, and includes at least the apex, a portion of the first flank and a portion of the second flank of the tooth, which are connected at the apex.

[0081] According to one embodiment, the rack 1 according to the invention has an insertion zone Z i The functional tooth 2 facing the insertion recess Ei and at least one insertion tooth 2 have the same upper outer shape. i , H t1 , H t2 But functional recess E f Height H of gauge 3 placed at f , so that the top of at least one insertion tooth 2 is located in the insertion zone Z i , and is offset in the direction of the center C of the rack 1 by a distance close to, but not necessarily equal to, the relative offset distance with respect to the functional tooth 2 located opposite it.

[0082] Transition part P t Now let's move to recess E. t On the other hand, the introduction P i Introduce the recess in recess E i It is called.

[0083] Introduction recess E i and transition recess E t is the insertion recess E i , E t It is also.

[0084] Introduction part P i There are at least two entry recesses E i and at least two introduction recesses E i The height H of the gauge placed at i are identical.

[0085] Introduction recess E i This makes it easier to insert the steering pinion 10.

[0086] At least one transition recess E t Height H of gauge 3 placed at t1 , H t2 is the functional recess E f Height H of gauge 3 placed at f and the introduction recess E i Height H of gauge 3 placed at i Included between and.

[0087] Transition part P t is the functional zone Z f and introductory part P i It is located between.

[0088] Therefore, the transition part P t On the other hand, functional zone Z f On the other hand, the introduction part P i and come into contact with them.

[0089] Transition part P t The steering pinion 10 is gradually brought into its operating position, i.e., the stress acting on the steering pinion 10 and rack 1 assembly is gradually increased, so that the functional zone Z f This facilitates engagement of the steering pinion 10.

[0090] Transition part P thas at least two transition recesses E t is provided.

[0091] At least two transition recesses E t Height H of gauge 3 placed at t1 , H t2 is the functional recess E f Height H of gauge 3 placed at f and the introduction recess E i Height H of gauge 3 placed at i It decreases linearly between

[0092] Figures 3, 4 and 5 show embodiments of the assembly of rack 1 and steering pinion 10 in different steering casings 20, 20', 20''. More specifically, Figures 3a, 4a and 5a show the position of the steering pinion 10 relative to the rack 1 when inserted into the steering casing 20, 20', 20''. Figures 3b, 4b and 5b show the position of the steering pinion 10 relative to the rack 1 during normal operation of the steering system.

[0093] When assembling the steering pinion 10 and rack 1 assembly according to the present invention, the rack is first placed in the steering casing 20, 20', 20''.

[0094] According to a first embodiment of FIG. 3, the steering casing 20 is provided with a "push" device 30 pre-adjusted to exert a force towards the rack equal to the force that would be exerted during normal operation.

[0095] According to a second embodiment of Figure 4, the steering casing 20' is provided with a spring 30' which exerts a predetermined force towards the rack 1. Said spring 30' is not adjustable.

[0096] According to the third embodiment of FIG. 5, the steering casing 20 ″ does not have any specific device for applying a thrust load towards the rack 1 .

[0097] In each embodiment, the rack 1 is slidably mounted within a steering casing 20, 20', 20''.

[0098] In each embodiment, the insertion zone Z i allows for an innovative assembly of the steering pinion 10 and the rack 1. In fact, according to the invention, as shown in Figures 3a, 4a and 5a, the rack 1 is first placed in the steering casing 20, 20', 20'' so that the clearance (play) between the rack 1 and the steering casing 20, 20', 20'' is approximately the same as the final clearance (play) desired during operation of the assembly on the vehicle.

[0099] Next, as shown in Figures 3a, 4a and 5a, the insertion zone Z i In more detail, the introduction P i In this case, the steering pinion 10 is inserted into the steering casing 20, 20', 20''. i Height H of gauge 3 placed at i But functional recess E f Height H of gauge 3 placed at f 4. Since the rack 1 is lower than the steering casing 20, 20', 20'', the stress acting on the rack 1 is reduced and the steering pinion 10 can be inserted into the steering casing 20, 20', 20''.

[0100] Next, the steering pinion 10 passes through the transition point P t The rack 1 rotates along the transition point P. t This gradually stresses the steering pinion 10 and rack 1 assembly. Finally, the steering pinion 10 is in the functional zone Z as shown in Figures 3b, 4b and 5b. f And the insertion zone Z i For example, the steering pinion 10 is restricted (prohibited from entering) by a travel limiter.

[0101] According to the invention, it is no longer necessary to press the rack 1 against the steering pinion 10, for example by means of a "push" type device 30 which is adjusted after the steering pinion 10 is placed. In fact, the final stress is applied when the steering pinion 10 is in the functional zone Z f During operation of the assembly on the vehicle, the steering pinion 10 is engaged in the functional zone Z f The invention therefore makes it possible to adjust the rack 1 within the steering casing 20, 20', 20'' before inserting the steering pinion 10.

[0102] While the present invention has been described with reference to particular embodiments, it will be apparent that modifications and variations can be made to these examples without departing from the overall scope of the invention as defined by the claims. In particular, individual features of the various embodiments shown / described can be combined in additional embodiments. Accordingly, the description and drawings should be interpreted as illustrative rather than restrictive.

[0103] It is also clear that all features described with respect to the method may be applied to the apparatus alone or in any combination, and conversely, all features described with respect to the apparatus may be applied to the method alone or in any combination.

Claims

1. 1. An assembly and adjustment system for a steering pinion and rack assembly for a steering system, comprising: The assembly and adjustment system comprises a rack (1) and a gauge (3), which is a spherical instrument for measuring the teeth of the rack (1); The rack (1) A functional zone (Z) with multiple functional teeth (2) ｆ ), and the functional teeth have a plurality of functional recesses (E ｆ ) and the functional recess (E ｆ ) is configured to cooperate with the steering pinion (10), and said functional zone (Z ｆ ) extends along the longitudinal axis (A) of the rack (1), The functional zone (Z ｆ ) extending on the extension of the insertion zone (Z ｉ ), and said insertion zone (Z ｉ ) has at least one insertion tooth (2), and the at least one insertion tooth (2) and the insertion zone (Z ｉ At least one insertion recess (E) is provided between the functional tooth (2) and the functional tooth (2) located opposite to the functional tooth (2). ｉ , E ｔ ) is defined, The insertion recess (E ｉ , E ｔ The height (H) of the gauge (3) is the dimension between the top of the gauge (3) placed on the rack and the center of the rack. ｔ１ , H ｔ２ , H ｉ ) is the functional recess (E ｆ The height (H) of the gauge (3) ｆ ) by the offset distance, The assembly adjustment system, wherein the at least one insertion tooth (2) has an upper outer shape of the functional tooth (2) located opposite the insertion zone (Z i ) that is identical to an upper outer shape of the rack (1) in a longitudinal cross section.

2. 2. The assembly and adjustment system according to claim 1, The offset distance is ｆ The height (H) of the gauge (3) ｆ ) assembly adjustment system that is between 20% and 70% of the

3. 2. The assembly and adjustment system according to claim 1, The insertion zone (Z ｉ ) are inserted into a plurality of recesses (E ｉ , E ｔ ) assembly adjustment system.

4. 4. The assembly and adjustment system according to claim 3, The insertion zone (Z ｉ ) has at least two introduction recesses (E ｉ ) with an introduction part (P ｉ ), and said at least two introduction recesses (E ｉ The height (H) of the gauge (3) ｉ ) are identical assembly adjustment systems.

5. 5. The assembly and adjustment system according to claim 4, The insertion zone (Z ｉ ) has at least one transition recess (E ｔ ) with a transition section (P ｔ ), and said at least one transition recess (E ｔ The height (H) of the gauge (3) ｔ１ , H ｔ２ ) is the functional recess (E ｆ The height (H) of the gauge (3) ｆ ) and the introduction recess (E ｉ The height (H) of the gauge (3) ｉ ) assembly adjustment system.

6. 6. The assembly and adjustment system according to claim 5, The transition portion (P ｔ ) is the functional zone (Z ｆ ) and the introduction part (P ｉ ) and an assembly adjustment system located between them.

7. 6. The assembly and adjustment system according to claim 5, The transition portion (P ｔ ) has at least two transition recesses (E ｔ ) an assembly adjustment system.

8. 8. The assembly and adjustment system according to claim 7, The at least two transition recesses (E ｔ The height (H) of the gauge (3) ｔ１ , H ｔ２ ) is the functional recess (E ｆ The height (H) of the gauge (3) ｆ ) and the introduction recess (E ｉ The height (H) of the gauge (3) ｉ ) and linearly decreasing assembly adjustment system.

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