WO2010055370A1

WO2010055370A1 - Steering angle detection at kingpin

Info

Publication number: WO2010055370A1
Application number: PCT/IB2008/055641
Authority: WO
Inventors: Stéphane MOISY; Vincent Sausset
Original assignee: Aktiebolaget Skf
Priority date: 2008-11-12
Filing date: 2008-11-12
Publication date: 2010-05-20

Abstract

This steering assembly comprises a kingpin (12), a steering knuckle (14) pivotably mounted around the kingpin (12) and means (40) to determine a rotation parameter of the steering knuckle (14) with respect to the kingpin (12). These means (40) include a cover (70) which defines a housing (V70) for a measurement unit (64). The measurement unit (64) includes first and second magnetically coupled elements (41, 60). The cover (70) is provided with first (62, 72) means adapted to hold the first element (60) with respect to the steering knuckle (14) and with second means (74, 80, 90) adapted to exert, on a support member (44) which holds the second element (41 ), an axial effort (E₉₀), parallel to a central longitudinal axis (X₁₂) of the kingpin (12) and directed towards the kingpin (12).

Description

STEERING ANGLE DETECTION AT KINGPIN

TECHNICAL FIELD OF THE INVENTION

This invention relates to a steering assembly for a motor vehicle, such an assembly being used to steer some wheels of the vehicle, generally its front wheels. The invention also relates to a motor vehicle, in particular a truck, equipped with such a steering assembly. Finally, the invention relates to a process for manufacturing a steering assembly for an automotive vehicle.

BACKGROUND OF THE INVENTION

Motor vehicles are equipped with steered wheels whose positions are controlled by a steering assembly piloted by the driver of the vehicle. For some applications, in particular for articulated trucks, it is important to know the actual wheel angle of the steered wheel in order to provide the driver with feed-back information. Because of the location of the steering assembly at the level of the front axle of a vehicle, it is often difficult to implement a sensor next to the steered wheels of a vehicle.

EP-A-O 905 006 discloses a device for controlling the steering angle in trucks, where a transducer is held stationary with respect to a rotating bushing and cooperates with a rod integral with a fixed pin. This known structure is quite difficult to implement insofar as the transducer and the rod must be mounted respectively on the bushing and on the fixed pin in different complex and time consuming operations, which require highly qualified manpower and nevertheless induces the risk that the transducer might not be correctly positioned with respect to the fixed pin.

SUMMARY OF THE INVENTION

The invention aims at solving these problems with a new steering assembly where one can easily and reliably mount means adapted to determine a rotation parameter of a steering knuckle.

To this end, the invention concerns a steering assembly for a motor vehicle, this assembly comprising a kingpin, a steering knuckle pivotably mounted around the kingpin and means to determine a rotation parameter of the steering knuckle with respect to the kingpin, these means including a cover which defines a housing for a measurement unit, wherein the measurement unit comprises first and second magnetically coupled elements and the cover is provided with first means adapted to hold the first element with respect to the steering knuckle and with second means adapted to exert, on a support member which holds the second element, an axial effort, parallel to a central longitudinal axis of the kingpin and directed towards the kingpin.

Thanks to the invention, the cover can be used to locate and hold the two magnetically coupled elements of the angle measurement unit with respect, respectively, to the steering knuckle and to the kingpin. In other words, mounting of the cover on the knuckle induces a corresponding positioning of the first and second magnetically coupled elements, which facilitates the work of an operator installing the rotation parameter determination means on the steering knuckle and on the kingpin.

A rotation parameter of one part with respect to the other is a parameter which is representative of the pivoting movement of one part with respect to the other. Such a parameter can be an angle measuring the angular position of one part with respect to the other, around the central axis of the pin. Such a parameter can also be a speed, a displacement, an acceleration or a vibration.

According to further aspects of the invention, which are advantageous but not compulsory, the steering assembly might incorporate one or several of the following features:

- The cover, the first and second magnetically coupled elements, the first means, the second means and the support member belong to a sub-assembly mountable onto the steering knuckle and the kingpin in one step. This highly facilitates manufacturing of a steering assembly or maintenance operations, insofar as the operator only has to manipulate one sub-assembly in order to equip the steering assembly with a complete set of rotation parameter determination means.

- The cover is provided with retaining means to hold at least the first and second magnetically coupled elements, the first means, the second means and the support member within an internal volume of this cover. - The sub-assembly can be mounted with respect to the steering knuckle and the kingpin by screwing of the cover on the steering knuckle.

- The cover is provided with a thread adapted to cooperate with a corresponding thread of the steering knuckle in order to screw the cover on the steering knuckle.

- The surface of the support member and the corresponding surface of the kingpin are frustroconical and complementary to each other.

- The support member and the cover are respectively mounted on the inner ring and on the outer ring of a bearing. - An elastic effort transmitting member is located between the cover and the surface of the support member.

- This effort transmitting member can be located between the cover and the bearing. Alternatively, the support member is made of a first part and a second part which can move axially one with respect to the other, whereas the effort transmitting member is located between the first and second parts of the support member.

- The effort transmitting member is an elastically deformable washer.

- The first means include a printed circuit board immobilized within the cover, the first element being mounted on and connected to this printed circuit board.

- The printed circuit board is held within the cover by mechanical means. Alternatively or in addition, the printed circuit board is overmoulded, at least on one side, within the cover.

The invention also concerns a motor vehicle, in particular a truck, having a steered wheel supported by a steering knuckle pivotably mounted around a kingpin, wherein this vehicle includes at least one steering assembly as mentioned here-above.

Such a motor vehicle is more economical and more reliable than the ones of the prior art. Finally, the invention concerns a process for manufacturing a steering assembly for a motor vehicle, this steering assembly comprising a kingpin, a steering knuckle pivotably mounted around the kingpin and means to determine a rotation parameter of the steering knuckle with respect to the kingpin, these means including a cover which defines a housing for a measurement unit, wherein this process includes at least the following steps: a) mounting within the cover a holding means which holds a first element, amongst two magnetically coupled elements belonging to the measurement unit, b) mounting within the cover a support member which holds the second element, amongst the two magnetically coupled elements, and c) mounting the cover, equipped with the holding means and the support member, on the steering knuckle in such a way that the cover exerts, on the support member and parallely to a central longitudinal axis of the kingpin, an axial effort directed towards the kingpin, this axial effort pressing a surface of the support member against a corresponding surface of the kingpin.

Thanks to the process of the invention, the rotation parameter determination means can be mounted in one operation, by manipulating only the cover, which is very fast and reliable and does not require a highly qualified manpower.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on the basis of the following description which is given in correspondence with the annexed figures and as an illustrative example, without restricting the object of the invention. In the annexed figures:

- figure 1 is a longitudinal cut of a steering assembly according to the invention - figure 2 is an enlarged view of detail Il on figure 1

- figure 3 is a view similar to figure 2 prior to mounting a sub-assembly on the steering knuckle and king pin of the steering assembly

- figure 4 is a cut view along line IV-IV on figure 3, at a smaller scale

- figure 5 is a perspective exploded view of the part of the steering assembly shown on figure 4

- figure 6 is a cut view corresponding to the lower part of figure 3 for a steering assembly according to a second embodiment of the invention

- figure 7 is a cut view along line VII-VII on figure 6, at a smaller scale and - figure 8 is a perspective exploded view of the part of the assembly represented on figures 6 and 7.

DETAILED DESCRIPTION OF SOME EMBODIMENTS The steering assembly 10 represented on figures 1 to 5 belongs to a truck T and includes a kingpin 12 and a steering knuckle 14 which supports a steered wheel 16 partially represented in dashed lines on figure 1. Steering knuckle 14 forms a shaft 18 which defines an axis of rotation Xi₈ for wheel 16.

Steering knuckle 14 is pivotably mounted around kingpin 12 which is considered to be fixed with respect to the chassis of truck T for this description. Xi₂ denotes the central longitudinal axis of kingpin 12, this axis being vertical when truck T rests on a horizontal surface. Two ball bearings 20 and 22 allow the pivoting movement of knuckle 14 around axis X12.

24 denotes the lower end of kingpin 12. Next to lower end 24, steering assembly 10 is provided with means 40 adapted to determine a rotation parameter, such as a rotation angle, between steering knuckle 14 and kingpin 12.

These means include a permanent magnet 41 inserted within a central recess 42 of a shaft 44 which forms a support member for magnet 41. Opposite to recess 42, shaft 44 has a an external frustroconical surface 46 centered on a central axis X₄₄ of shaft 44 which is aligned on axis X12 when means 40 are mounted on items 12 and 14.

On the other hand, kingpin 12 has at its lower end 24, a recess 26 of a shape adapted to accommodate the part of shaft 44 which is opposite to recess 42. The radial surface 28 of recess 26 is frustroconical and centered on axis Xi₂. α denotes the semi top angle of surface 46, whereas β denotes the semi top angle of surface 28. The values of angles α and β are equal so that surfaces 46 and 28 are complementary and that shaft 44 can be partly housed in recess 26 when surfaces 46 and 28 lie one against the other. A magnetic sensor 60, e.g. in the form of a Hall effect cell, is installed in the vicinity of magnet 41 at an axial distance di of this magnet sufficiently small to allow sensor 60 to detect any rotation of magnet 41 . Sensor 60 is mounted and connected to a printed circuit board 62 which is held fast within a synthetic cover 70 thanks to three screws 72 inserted within corresponding holes 63 of board 62 and screwed in corresponding bores 73 of cover 70. Magnet 41 and sensor 60 belong to a measurement unit 64 which permits to determine a parameter representative of the rotation of steering knuckle 14 with respect to kingpin 12, around axis X12.

V₇₀ denotes the internal volume of cover 70. Items 41 , 60 and 62 are installed within volume V₇₀. An elastically deformable washer 80 is located within volume V₇₀ and lies against an internal shoulder 74 of cover 70.

A ball bearing 90 is also located within volume V₇₀ and shaft 44 is press- fitted on the inner ring 92 of ball bearing 90. The balls 94 and the outer ring 96 of ball bearing 90 are mounted around inner ring 92 and surrounded by a globally cylindrical part 76 of cover 70.

A retaining ring 100 is also mounted within volume V₇₀ and is held in position with respect to cover 70 thanks to three screws 102, inserted within corresponding holes 103 of ring 100 and screwed in corresponding bores 75 of cover 70.

When retaining ring 100 is held in position by screws 102 within volume V₇₀, elements 41 to 96 are held in position within this volume, so that cover 70 equipped with items 40, 44, 60, 62, 80 and 90 forms a sub-assembly 200 which can be easily manipulated by an operator in order to be mounted onto steering knuckle 14 and kingpin 12.

Cover 70 has an external collar 78 and an external thread 79 which surround the opening O₇₀ of volume V₇₀ through which the respective items mentioned here- above can be introduced within this volume.

On the other hand, the lower end 30 of steering knuckle 14 is provided with an internal thread 32 adapted to cooperate with external thread 79 of cover 70.

A plug or electrical connector 110 is connected to printed circuit board 62 via several electric cables 112. A resin potting 120 is moulded within cover 70 and fills volume V₇₀ between printed circuit board 62 and the end 71 of cover 70 opposite to external thread 79. Printed circuit board 62 is overmoulded in potting 120 on its side opposite to magnet 41. Actually, if printed circuit board 62 is provided with one or several holes or if it does not extend up to the inner surface of cover 70, a part of the potting 120 can extend in the volume between board 62 and washer 80, so that board 62 is overmoulded within cover 70 on its opposite sides. This constitutes an alternative to the fastening of circuit 62 within cover 70 via screws 72. Alternatively, both methods can be used, namely printed circuit board 62 can be held within cover 70 by screws 72 and by potting 120 on one side or on both sides of this circuit.

On figures 3 and 4, the ends of cables 112 are not represented within potting 120, for the clarity of the drawings. When manufacturing steering assembly 10, it is possible to connect printed circuit board 62, which bears magnetic sensor 60, to plug 110 via cables 112. It is then possible to immobilize printed circuit board 62 within cover 70 thanks to screws 72 and/or potting 120. It is then possible to install, within volume V₇₀, washer 80 and ball bearing 90 already equipped with shaft 44 provided with magnet 41. Then, retaining ring 100 is installed to hold ball bearing 90 within volume V₇₀. In this manner, one constitutes sub-assembly 200 made of items 40, 44, 60, 62, 70, 72, 80, 90, 100, 102, 110, 112 and 120.

When one wants to determine and monitor the angle of rotation between steering knuckle 14 and kingpin 12, around axis Xi₂, it is possible to screw this sub-assembly on the lower end 30 of steering knuckle 14, thanks to threads 79 and 32. In other words, sub-assembly can be mounted in one screwing step on end 30, thus installing the rotation parameter determination means 40 in proper working conditions. This brings assembly 200 in the configuration of figures 1 and 2, where cover 70 exerts on washer 80, via shoulder 74, an effort E₇₀ parallel to axes Xi₂ and X₄₄ which are then aligned. Effort E₇₀ can, therefore, be qualified as axial. It is transmitted by washer 80 to outer ring 96 as en effort E₈o and, from there, to balls 94 and inner ring 92. This axial effort E₈o becomes an axial effort E₉₀ exerted by bearing 90 on shaft 44 whose external surface 46 is thus firmly pressed against the internal surface 28 of recess 26, by an axial effort E₄₄. All efforts E₇₀, E₈o, E₉₀ and E₄₄ are parallel to axes Xi₂ and X₄₄.

The axial effort E₇₀ exerted by cover 70 onto washer 80 is forwarded through ball bearing 90 as an axial effort E₈o, which is itself forwarded to shaft 44 as an axial effort E₉₀, this effort being applied as an axial effort E₄₄ spread on surfaces 46 and 28, with the result that an adherence force exists between these surfaces, thus preventing rotation of shaft 44 with respect to kingpin 12.

Therefore, thanks to the screwing of cover 70 on steering knuckle 14, shaft 44 is made fast in rotation with kingpin 12. Thereafter, upon rotation of steering knuckle 14 around axis Xi₂, cover 70 is driven in rotation around axis Xi₂ since it is fast with steering knuckle 14. This implies that sensor 60 rotates with steering knuckle 14. On the other hand, magnet 40 remains stationary with kingpin 12 since shaft 44 is pressed within recess 26, so that magnetic sensor 60 detects a rotation of magnet 40 with respect to sensor 60.

The use of elastic washer 80 allows to compensate for variations in the dimensions of items 12, 14, 44, 70 and 90, which is advantageous. The intensity of effort E₄₄ can be limited by the elasticity of washer 80.

In the second embodiment of the invention represented on figures 6 to 8, the same elements as in the first embodiment bear the same references and are not described in a detailed way. One describes hereafter only the differences with the first embodiment.

The main difference between this embodiment and the previous one is that shaft 44 is here made of a first part 441 which bears a permanent magnet 41 and a second part 442 which is supposed to come into contact with the radial inner surface of a recess of the kingpin. To this end, second part 442 is provided with a frustroconical external surface 46 adapted to cooperate with a radial surface of a kingpin similar to surface 28 of the first embodiment. An elastic washer 80 is arranged axially between parts 441 and 442 which can slide one with respect to the other along a longitudinal axis X₄₄ of shaft 44.

Part 441 has two tabs 443 and 444 respectively provided with an oblong hole 445 or 446 where a pin 447 crossing second part 442 is engaged. Pin 447 is also received within a hole 448 of part 442 which extends perpendicularly to axis X₄₄. This allows limited movement of part 442 with respect to part 441 along axis X₄₄ and holds part 442 within the internal volume V₇₀ of the cover 70 when a sub- assembly 200 is constituted, as explained for the first embodiment.

A ball bearing 90 lies directly against an internal shoulder 74 of a cover 70. Even if no kingpin and no steering knuckle is represented, figure 6 shows an effort repartition corresponding to a case where sub-assembly 200 has been mounted on a steering knuckle.

An axial effort E₇₀ is exerted by shoulder 74 on the outer ring 96 of ball bearing 90 which transmits it, via its inner ring 92, as an axial effort E₉₀ to part 441. This effort is forwarded by part 441 to washer 80, as an axial effort E₄₄₁, and washer 80 applies a corresponding axial effort E₈o on part 442. This induces that shaft 44 can apply an effort E₄₄ similar to effort E₄₄ of the first embodiment within a recess of the kingpin when sub-assembly 200 is mounted on the lower end of a kingpin, as in the first embodiment. Therefore, the second embodiment works in a way similar to the first embodiment, the pressure effort transmission between cover 70 and shaft 44 being different because of the different location of washer

80.

As in the first embodiment, elastic washer 80 allows to limit the intensity of the pressure effort E₄₄ exerted by the pin 44 on the kingpin 12 and to compensate for variations in the dimensions of the kingpin, the steering knuckle, shaft 44, cover 70 and bearing 90.

As in the first embodiment, a measurement unit is formed by a permanent magnet 41 and a Hall effect cell 60, respectively supported by shaft 44 and a printed circuit board 62 immobilized within volume V₇₀ by screws 72 and/or a potting 120 of resin. A retaining ring 100 is used to hold items 90 and 44 within volume V₇₀.

The invention is represented on the figures with ball bearings 90. However, plain bearings, roller bearings or needle bearings could also be used. Ball bearings, roller bearings and needle bearings are examples of rolling bearings which are preferred in order to keep the friction low between cover 70 and shaft 44.

The invention can be used with any motor vehicle, in particular a truck or an articulated truck, where steering of some wheels is to be monitored.

Claims

1. A steering assembly (10) for a motor vehicle (T), said assembly comprising a kingpin (12), a steering knuckle (14) pivotably mounted around said kingpin and means (40) to determine a rotation parameter of said steering knuckle with respect to said kingpin, said means including a cover (70) which defines a housing (V₇₀) for a measurement unit (64), wherein said measurement unit comprises first and second magnetically coupled elements (41 , 60) and wherein said cover (70) is provided with first (62, 72) means adapted to hold the first element (60) with respect to said steering knuckle (14) and with second means (74, 80, 90) adapted to exert, on a support member (44) which holds said second element (41 ), an axial effort (E₉₀), parallel to a central longitudinal axis (X12) of said kingpin (12) and directed towards said kingpin.

2. Steering assembly according to claim 1 , wherein said cover (70), said first and second magnetically coupled elements (41 , 60), said first means (62, 72), said second means (74, 80, 90) and said support member (44) belong to a sub- assembly (200) mountable onto said steering knuckle (14) and said kingpin (12) in one step.

3. Steering assembly according to claim 2, wherein said cover (70) is provided with retaining means (72, 100) to hold at least said first and second magnetically coupled elements (41 , 60), said first means (62, 72), said second means (74, 90) and said support member (44) within an internal volume (V₇₀) of said cover.

4. Steering assembly according to one of claims 2 or 3, wherein said sub- assembly (200) can be mounted with respect to said steering knuckle (14) and said kingpin (12) by screwing of said cover (70) on said steering knuckle.

5. Steering assembly according to one of the previous claims, wherein said cover (70) is provided with a thread (79) adapted to cooperate with a corresponding thread (32) of said steering knuckle (14), in order to screw said cover on said steering knuckle.

6. Steering assembly according to one of the previous claims, wherein said surface (46) of said support member (44) and said corresponding surface (28) of said kingpin (12) are frustroconical and complementary to each other.

7. Steering assembly according to one of the previous claims, wherein said support member (44) and said cover (70) are respectively mounted on the inner ring (92) and on the outer ring (96) of a rolling bearing (90).

8. Steering assembly according to one of the previous claims, wherein an elastic effort transmitting member (80) is located between said cover (70) and said surface (46) of said support member.

9. Steering assembly according to claims 7 and 8, wherein said elastic effort transmitting member (80) is located between said cover (70) and said bearing (90).

10. Steering assembly according to claim 8, wherein said support member

(44) includes a first part (441 ) and a second part (442) which can move axially one with respect to the other and wherein said elastic effort transmitting member (80) is located between said first and second parts (441 , 442) of said support member (44).

11. Steering assembly according to claims 8 to 10, wherein said elastic effort transmitting member is an elastically deformable washer (80).

12. Steering assembly according to one of the previous claims, wherein said first means include a printed circuit board (62) immobilized within said cover (70), said first element (60) being mounted on and connected to said printed circuit board.

13. Steering assembly according to claims 12, wherein said printed circuit board (62) is held within said cover (70) by mechanical means (72) and/or overmoulded, at least on one side, within said cover (70).

14. A motor vehicle, in particular a truck (T), having a steered wheel (16) supported by a steering knuckle (14) pivotably mounted around a kingpin (12), wherein it includes at least one steering assembly (10) according to one of the previous claims.

15. A process for manufacturing a steering assembly (10) for a motor vehicle (T), said steering assembly comprising a kingpin (12), a steering knuckle (14) pivotably mounted around said kingpin and means (40) to determine a rotation parameter of said steering knuckle with respect to said kingpin, said means including a cover (70) which defines a housing for a measurement unit (64), wherein said process includes at least the following steps: a) mounting within said cover a holding means (62) which holds a first element (60), amongst two magnetically coupled elements (41 , 60) belonging to the measurement unit (64), b) mounting within said cover (70) a support member (44) which holds the second element (41 ), amongst said two magnetically coupled elements, and c) mounting said cover (70), equipped with said holding means (62) and said support member (44), on said steering knuckle (14) in such a way that said cover exerts, on said support member and parallely to a central longitudinal axis (Xi₂) of said kingpin, an axial effort (E₉₀) directed towards said kingpin, this axial effort pressing a surface (46) of said support member (44) against a corresponding surface (28) of said kingpin (12).