Steering system rack with steering pinion insertion zone

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 a rack for a steering system.

Background Art

[0002] The steering system of a vehicle has the purpose of enabling a driver to control the trajectory of the vehicle by changing the direction angle of the vehicle's wheels using a steering wheel.

[0003] There is a steering system that changes the rotation of the vehicle's wheels by a mechanical assembly composed of a steering pinion that meshes with a rack. The rack is slidably mounted longitudinally within a steering casing. Both ends of the rack are coupled to two steering rods outside the casing, and these steering rods are respectively connected to the left and right steering wheels of the vehicle.

[0004] The rack includes a tooth portion formed by teeth and a tooth back portion located on the opposite side of the tooth portion. The tooth portion extends in the longitudinal direction of the rack.

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

[0006] Those skilled in the art know that the characteristics of the tooth portion are determined by evaluation (measurement) using a gauge. That is, the characteristics of the tooth portion are determined with respect to a gauge that is substantially disposed in the recess between two teeth, in other words, in the recess of the tooth portion.

[0007] A gauge is a calibrated instrument capable of making measurements. In this example, the gauge is, for example, a sphere having a predetermined diameter.

[0008] In other parts 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 a virtual circle that at least partially circumscribes the cross-section of the rack in a plane intersecting (orthogonal 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 disposed between two consecutive teeth of the rack, the pitch of the tooth portion is the length between the two centers of the two gauges disposed 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 height of the tooth root is the dimension between the tooth root and the center of the rack, the height of the tooth is the dimension between the top and the center of the rack clarify the characteristics of the rack.

[0009] During the operation of the vehicle, a force that counteracts the contact between the steering pinion and the rack is applied.

[0010] In order to permanently maintain the meshing of the rack with respect to the steering pinion, it is known to use a so-called "push" device that elastically acts on the back surface of the rack in the pinion region to strongly press the tooth portion of the rack against the tooth portion of the pinion. In this way, the clearance between the steering pinion and each tooth portion of the rack is limited by the pressing, and it is also possible to control the sliding force of the rack in the steering casing by this pressing.

Summary of the Invention

Problems to be Solved by the Invention

[0011] The drawback caused by using a so-called "push" device is that adjustment of the pressing is required after the assembly of the steering pinion and the rack.

[0012] Furthermore, the "push" device may fail, and many patent documents regarding the improvement of this device are known.

[0013] Finally, such a device includes the volume, cost, and mass that manufacturers of steering systems seek to reduce.

[0014] Therefore, there is a need for a mechanical assembly composed of a steering pinion that can be assembled quickly and easily and meshes with a rack with reduced volume and mass.

Means for Solving the Problem

[0015] One embodiment relates to a rack for a steering system, the rack comprising 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 the longitudinal axis of the rack. The insertion zone extends on an 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 positioned opposite the insertion zone. As a feature, the height of a gauge disposed in the insertion recess is smaller by an offset distance than the height of a gauge disposed in the functional recess.

[0016] In the remaining part of this specification, two elements are considered "identical" only if they differ from each other by the manufacturing tolerances generally accepted in the art.

[0017] The rack according to the present invention comprises a functional zone that forms the tooth portion of the rack and extends in the longitudinal direction of the rack.

[0018] Each tooth of the rack includes a first flank, a second flank, and a top connecting the first flank and the second flank. Each tooth is spaced from adjacent teeth by a recess.

[0019] The characteristics of the tooth portion are determined with respect to a gauge disposed substantially in the recess between two teeth, i.e., the recess of the tooth portion.

[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 a virtual circle that at least partially inscribes the cross-section of the rack in a plane intersecting (orthogonal 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 disposed between two consecutive teeth of the rack, the pitch of the teeth is the length between the two centers of two gauges disposed in two consecutive recesses, and the pitch of the rack is fixed or variable, the outer profile of the teeth in the longitudinal cross-section of the rack includes at least the top of the teeth and a first flank and a second flank connected to the top, the tooth root is the point of the recess closest to the center of the rack, the height of the tooth root is the dimension between the tooth root and the center of the rack, the height of the teeth is the dimension between the top and the center of the rack to clarify the characteristics of such a rack.

[0022] The functional zone extends along the longitudinal direction of the rack. The height of all gauges disposed in the functional recesses is the same.

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

[0024] The insertion zone enables the assembly of an innovative steering pinion and rack. In fact, according to this invention, first the rack is placed in the steering casing so that the clearance (play) between the rack and the steering casing is substantially the same as the clearance ultimately desired during the operation of the assembly in the vehicle. Next, the steering pinion is inserted into the steering casing in the insertion zone.

[0025] At least one insertion tooth has a specific function of enabling the steering pinion to be inserted into the rack when the rack is disposed within the steering casing. Thus, it is clear that at least one insertion tooth has a profile determined at a pre-manufacturing stage such that the height of the gauge disposed in the insertion recess is lower by an offset distance than the height of the gauge disposed in the functional recess.

[0026] The lower height of the gauge disposed in the insertion recess than the height of the gauge disposed in the functional recess can reduce the stress acting on the assembly of the steering pinion and the rack, and as a result, it becomes possible to insert the steering pinion into the rack with the rack already disposed in the steering casing.

[0027] According to the present invention, after insertion, it becomes possible to eliminate the need to press the rack against the steering pinion using, for example, a "push" type device. In fact, the final stress generation of the assembly of the steering pinion and the rack can be carried out when the steering pinion meshes with the teeth of the functional zone.

[0028] During the operation of the assembly in a vehicle, the steering pinion only moves in the functional zone. The movement of the steering pinion into the insertion zone can be restricted, for example, by a movement limiter.

[0029] Thus, according to the present invention, it becomes possible to perform a final adjustment of the rack within the steering casing before inserting the steering pinion into the steering casing.

[0030] Unlike the toothless insertion zone or the flat insertion zone, in the insertion zone according to the present invention, due to the presence of at least one tooth, it is possible to hold the cross-section of the rack in a plane perpendicular to the longitudinal axis of the rack while minimizing the change in the length of the rack. Thereby, the deformation of the rack during the heat treatment process can be kept somewhat constant. The toothless insertion zone or the flat insertion zone causes a significant change in the cross-section, resulting in significant deformation during heat treatment and thus weakening the mechanical properties of the rack.

[0031] Furthermore, in the case of a steering system having a mechanical connection between the steering wheel and the assembly of the steering pinion and the rack, the insertion zone according to the present invention enables angular indexing of the steering pinion on the rack so as to ensure accurate alignment between the steering wheel and the midpoint of the assembly of the steering pinion and the rack.

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

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

[0034] Thereby, the insertion recess and the functional recess are aligned.

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

[0036] Therefore, the insertion teeth are smaller than the functional teeth.

[0037] According to one embodiment, at least one insertion tooth has the same upper outer shape as the upper outer shape of the functional teeth facing the insertion zone along the longitudinal cross-section of the rack.

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

[0039] The outer shape of the upper part of the tooth is determined by tooth calculation (tooth profile calculation) known to those skilled in the art.

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

[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 that is close to but not necessarily equal to the offset distance with respect to the functional tooth located opposite to the insertion zone.

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

[0043] In an embodiment, the insertion zone includes a plurality of 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 an embodiment, the insertion zone includes an introduction part provided with at least two introduction recesses, and the heights of the gauges arranged in the at least two introduction recesses are the same.

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

[0047] The introduction recess facilitates the 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 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 introduction recess.

[0049] In one embodiment, the transition section is disposed between the functional zone and the introduction section.

[0050] Therefore, the transition section is in contact with the functional zone on one hand and the introduction section on the other hand.

[0051] The transition section facilitates the meshing of the steering pinion in the functional zone by gradually positioning the steering pinion in the operating position, that is, by gradually increasing the stress acting on the assembly of the steering pinion and the rack.

[0052] In one embodiment, the transition section includes at least two transition recesses.

[0053] In one embodiment, the height of the gauge disposed in at least two transition recesses decreases linearly between the height of the gauge disposed in the functional recess and the height of the gauge disposed in the introduction recess.

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

[0055] The present invention will be better understood from the following description. These relate to multiple embodiments of the present invention and are shown as non-limiting examples described with reference to the accompanying schematic drawings.

Brief Description of the Drawings

[0056]

Figure 1

Figure 2

Figure 3a

Figure 3b

Figure 4a

Figure 4b

Figure 5a

Figure 5b

BEST MODE FOR CARRYING OUT THE INVENTION

[0057] Only the elements necessary for understanding the invention are illustrated. For ease of understanding the drawings, the same reference numerals are given to the same elements in each drawing.

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

[0059] The rack 1 includes a tooth portion (tooth row) formed by a plurality of teeth 2, and this tooth portion extends along a longitudinal axis A which is also called the extension axis of the rack 2.

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

[0061] As shown in FIG. 2, the outer shape of the upper part of the tooth 2 in the longitudinal cross-section of the rack 1 includes at least the top, a part of the first flank of the tooth 2, and a part of the second flank of the tooth 2, and the part of the first flank and the part of the second flank are connected to the top. 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 tooth part are determined with respect to the gauge 3 that is substantially disposed between two teeth 2, that is, within the recess E of the tooth part, as shown in FIG. 2.

[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 a virtual circle in which at least a part of the cross-section of the rack 1 cut by a plane intersecting (orthogonal to) the longitudinal axis A of the rack 1 is 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 tooth part includes a functional zone Z f and an insertion zone Z i and its insertion zone Z i is a transition part P t and an introduction part P i and includes.

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

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

[0069] Functional recess E fThe height H of all the gauges 3 arranged therein f is the same.

[0070] Insertion zone Z i In this, the tooth 2 is referred to as the insertion tooth, and the recess E is referred to as the insertion recess E i 、E t and so on.

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

[0072] Insertion zone Z i includes a plurality of insertion recesses E i 、E t , preferably at least three insertion recesses E i 、E t .

[0073] Insertion recess E i 、E t The height H of the gauge 3 arranged therein i 、H t1 、H t2 is smaller by an offset distance (shift distance, displacement distance, shift distance) than the height H of the gauge 3 arranged in the functional recess E f . f More precisely, the offset distance is included between 20% and 70%, preferably between 30% and 50%, particularly between 35% and 45% of the height H of the gauge 3 arranged in the functional recess E

[0074] f The height H of the gauge 3 arranged therein f .

[0075] According to one embodiment, the height of the bottom of at least one insertion recess E i 、E t is the same as the height of the bottom of the plurality of functional recesses E f .

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

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

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

[0079] According to one embodiment, the outer shape of the upper part of at least one insertion tooth 2 is the same as the outer shape of the upper part of the functional tooth 2 facing the insertion zone Z i along the longitudinal cross-section of the rack 1.

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

[0081] According to one embodiment, the rack 1 according to the present invention is characterized in that the functional tooth 2 facing the insertion zone Z i and at least one insertion tooth 2 have the same outer shape at the upper part. Further, the height H i , H t1 , H t2 of the gauge 3 disposed in the insertion recesses Ei, Et is lower than the height H f of the gauge 3 disposed in the functional recess E f . Therefore, the top of at least one insertion tooth 2 is offset in the direction of the center C of the rack 1 by a distance that is close to but not necessarily equal to the relative offset distance with respect to the functional tooth 2 located facing the insertion zone Z i .

[0082] In the transition part P t , the recess E is referred to as a transition recess E t , while in the introduction part P i , the recess is referred to as an introduction recess E i .

[0083] Introduction recess E i and transition recess E t are insertion recesses E i , E t as well.

[0084] Introduction part P i is provided with at least two introduction recesses E i , and the height H i of the gauge arranged in at least two introduction recesses E i is the same.

[0085] The introduction recess E i facilitates the insertion of the steering pinion 10.

[0086] The height H t of the gauge 3 arranged in at least one transition recess E t1 , H t2 is included between the height H f of the gauge 3 arranged in the functional recess E f and the height H i of the gauge 3 arranged in the introduction recess E i .

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

[0088] Therefore, the transition part P t is in contact with the functional zone Z f on one hand and in contact with the introduction part P i on the other hand.

[0089] Transition part P t facilitates the meshing of the steering pinion 10 in the functional zone Z f by gradually positioning the steering pinion 10 in the operating position, that is, by gradually increasing the stress acting on the assembly of the steering pinion 10 and the rack 1.

[0090] Transition part P tThere are at least two transition recesses E t provided therein.

[0091] The height H t of the gauge 3 arranged in at least two transition recesses E t1 , H t2 is linearly decreasing between the height H f of the gauge 3 arranged in the functional recess E f and the height H i of the gauge 3 arranged in the introduction recess E i .

[0092] Figures 3, 4 and 5 show embodiments of the assembly of the rack 1 and the 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 casings 20, 20', 20''. Figures 3b, 4b and 5b show the position of the steering pinion 10 relative to the rack 1 during the normal operation of the steering system.

[0093] When assembling the assembly of the steering pinion 10 and the rack 1 according to the present invention, first place the rack in the steering casings 20, 20', 20''.

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

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

[0096] According to the third embodiment of Figure 5, the steering casing 20'' is not provided with any specific device for applying a thrust load towards the rack 1.

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

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

[0099] Next, as shown in FIGS. 3a, 4a, and 5a, in the insertion zone Z i and more precisely in the introduction part P i the steering pinion 10 is inserted into the steering casings 20, 20', 20''. In fact, since the height H of the gauge 3 arranged in the introduction recess E i is lower than the height H of the gauge 3 arranged in the functional recess E i f f the stress acting on the rack 1 is reduced, making it possible to insert the steering pinion 10 into the steering casings 20, 20', 20''.

[0100] Next, the steering pinion 10 rotates along the rack 1 so as to pass through the transition part P t . The transition part P t gradually applies stress to the assembly of the steering pinion 10 and the rack 1. Finally, the steering pinion 10 is located in the functional zone Z f as shown in FIGS. 3b, 4b, and 5b. And the insertion zone Z i prevents (prohibits entry of) the steering pinion 10, for example by a travel limiter.

[0101] ​​According to the present invention, for example, it is no longer necessary to press the rack 1 against the steering pinion 10 by a "push" type device 30 adjusted after the placement of the steering pinion 10. In fact, the final stress is applied when the steering pinion 10 meshes with the teeth 2 of the functional zone Z f This occurs when the steering pinion 10 meshes with the teeth 2 of the functional zone Z f within. During the operation of the assembly in the vehicle, the steering pinion 10 only moves within the functional zone Z

[0102] The present invention has been described with reference to specific embodiments, but it is obvious that modifications and changes can be made to these examples without departing from the overall scope of the invention defined by the claims. In particular, the individual features of the various illustrated / described embodiments can be combined in additional embodiments. Therefore, the description and drawings should be construed as illustrative rather than restrictive.

[0103] Also, it is obvious that all the features described with respect to the method are applicable to the device alone or in combination, and conversely, all the features described with respect to the device are applicable to the method alone or in combination.

Claims

1. A rack (1) for a steering system, A functional zone (Z) having a plurality of functional teeth (2) ｆ ), wherein the functional teeth define a plurality of functional recesses (E) between two consecutive functional teeth ｆ ), and the functional recesses (E) ｆ ) are configured to cooperate with a steering pinion (10), and the functional zone (Z) ｆ ) extends along the longitudinal axis (A) of a rack (1). on the extension of the functional zone (Z ｆ ), an insertion zone (Z ｉ ) is provided, and the insertion zone (Z ｉ ) includes at least one insertion tooth (2), and at least one insertion recess (E ｉ , E ｉ , E ｔ ) is defined between the at least one insertion tooth (2) and the functional tooth (2) located opposite to the insertion zone (Z ｉ ). The height (H ｉ , H ｔ ) of the gauge (3) disposed in the insertion recess (E ｔ１ , H ｔ２ , H ｉ ) is smaller by an offset distance than the height (H ｆ ) of the gauge (3) disposed in the functional recess (E ｆ ), and the rack (1) is characterized by this.

2. In the rack (1) according to Claim 1, The at least one insertion tooth (2) has an upper outer shape of the functional tooth (2) positioned opposite to the insertion zone (Z ｉ ), and a rack (1) having the same upper outer shape in the longitudinal cross-section of the rack (1).

3. In the rack (1) according to Claim 1 or 2, The offset distance is between 20% and 70%, preferably between 30% and 50%, particularly between 35% and 45% of the height (H ｆ ), of the gauge (3) arranged in the functional recess (E ｆ ), of the rack (1).

4. In the rack (1) according to any one of Claims 1 to 3, The insertion zone (Z ｉ ) includes a plurality of insertion recesses (E ｉ , E ｔ ), preferably including at least three insertion recesses (E ｉ , E ｔ ) of the rack (1).

5. In the rack (1) according to Claim 4, The insertion zone (Z ｉ ) includes an introduction part (P ｉ ) having at least two introduction recesses (E ｉ ), and a rack (1) in which the heights (H ｉ ) of the gauges (3) arranged in the at least two introduction recesses (E ｉ ) are the same.

6. In the rack (1) according to Claim 5, The insertion zone (Z ｉ ) includes a transition part (P ｔ ) having at least one transition recess (E ｔ ), and the height (H ｔ , H ｔ１ ) of the gauge (3) arranged in the at least one transition recess (E ｔ２ ) is between the height (H ｆ ) of the gauge (3) arranged in the functional recess (E ｆ ) and the height (H ｉ ) of the gauge (3) arranged in the introduction recess (E ｉ ), a rack (1).

7. In the rack (1) according to Claim 6, The transition section (P ｔ ) is disposed between the functional zone (Z ｆ ) and the introduction section (P ｉ ), and a rack (1).

8. In the rack (1) according to Claim 6 or 7, The transition portion (P ｔ ) has at least two transition recesses (E ｔ ), and the rack (1).

9. In the rack (1) according to Claim 8, The height (H ｔ , H ｔ１ ) of the gauge (3) arranged in the at least two transition recesses (E ｔ２ ) is linearly reduced between the height (H ｆ ) of the gauge (3) arranged in the functional recess (E ｆ ) and the height (H ｉ ) of the gauge (3) arranged in the introduction recess (E ｉ ), and a rack (1).

10. A steering system comprising the rack (1) according to any one of Claims 1 to 9.

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