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Title:
ARTICULATED BUS WITH A SWIVELLING JOINT AND CONTROL PROCESS
Document Type and Number:
WIPO Patent Application WO/2021/037998
Kind Code:
A1
Abstract:
The invention provides an articulated bus comprising: a pivot joint (6), a first unit and a second unit coupled by the pivot joint. The pivot joint (6) comprises: a vertical pivot axis, a first structure (46) with a first horizontal plate (46P), a second structure (48) with a second horizontal plate (48P), a bearing (54) joining the first structure to the second structure (48). The first structure (46) comprises a first longitudinal section (46.1) with a first stiffness and attached to the bearing, and a second section with a second stiffness which is greater than the first stiffness. The stiffnesses depends on the thicknesses of longitudinal stiffeners. The invention also provides process of an articulated bus where the unit configuration is corrected in function of a measured stress and the inclination between the units.

Inventors:
HALLUNDBÆK JØRGEN (LU)
Application Number:
PCT/EP2020/074007
Publication Date:
March 04, 2021
Filing Date:
August 27, 2020
Export Citation:
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Assignee:
ALPHA EC IND 2018 S A R L (LU)
International Classes:
B60D1/62; B60D5/00; B62D47/02; B60W10/22
Foreign References:
EP0614797A11994-09-14
US20130062860A12013-03-14
EP2497701A12012-09-12
EP2692555A12014-02-05
DE10334971A12005-02-24
EP2738071A12014-06-04
EP0614797A11994-09-14
US20130006286A12013-01-03
EP2497701A12012-09-12
Attorney, Agent or Firm:
ROUSSEAU, Cyrille (LU)
Download PDF:
Claims:
Claims

1. Articulated bus (2) comprising: a pivot joint (6), a first unit (4) and a second unit (4) coupled by the pivot joint (6), the pivot joint (6) comprising:

• a first structure (46) notably with a first horizontal plate (46P),

• a second structure (48) notably with a second horizontal plate (48P),

• a bearing (54) which includes a vertical pivot axis (44) and which joins the first structure (46) to the second structure (48), the first structure (46) comprises a first longitudinal section (46.1) with a first stiffness and attached to the bearing (54), and a second longitudinal section (46.2) with a second stiffness which is greater than the first stiffness.

2. The articulated bus (2) in accordance with claim 1, wherein the first horizontal plate (46P) of the first structure (46) comprises a metal sheet exhibiting a constant thickness along the first longitudinal section (46.1) and the second longitudinal section (46.2); the constant thickness of the metal sheet is of at most 6 mm.

3. The articulated bus (2) in accordance with anyone of claims 1 to 2, wherein the first structure (46) comprises a longitudinal stiffener (56) protruding from the first horizontal plate (46P), the longitudinal stiffener (56) being thicker in the second longitudinal section (46.2) than in the first longitudinal section (46.1).

4. The articulated bus (2) in accordance with claim 3, wherein along the first longitudinal section (46.1) the longitudinal stiffener (56) comprises a constant thickness, and the longitudinal stiffener (56) comprises a constant width along the first longitudinal section

(46.1) and the second longitudinal section (46.2).

5. The articulated bus (2) in accordance with anyone of claims 3 to 4, wherein the longitudinal stiffener (56) comprises a first thickness T1 in the first longitudinal section

(46.1); and a second thickness T2 in the second longitudinal section (46.2) which is at least two times as thick as the first thickness T1.

6. The articulated bus (2) in accordance with anyone of claims 3 to 5, wherein along the second longitudinal section (46.2) the longitudinal stiffener (56) comprises a gradual longitudinal thickness variation with a thickness decrease toward the first longitudinal section (46.1).

7. The articulated bus (2) in accordance with anyone of claims 3 to 6, wherein the longitudinal stiffener (56) longitudinally extends on the majority of the first horizontal plate (46P).

8. The articulated bus (2) in accordance with anyone of claims 3 to 7, wherein the longitudinal stiffener (56) is a first longitudinal stiffener (56), the first structure (46) comprising a second longitudinal stiffener (56) and a transversal stiffener (58) linking the first longitudinal stiffener (56) to the second longitudinal stiffener (56), the first longitudinal section (46.1) optionally being free of transversal stiffeners (58).

9. The articulated bus (2) in accordance with anyone of claims 1 to 8, wherein the pivot joint (6) comprises a first sensor (60) in the first longitudinal section (46.1) adapted for measuring a stress data and/or a deformation data of the first structure (46).

10. The articulated bus (2) in accordance with claim 9, wherein the first sensor (60) is attached to the first horizontal plate (46P), and comprises a strain gauge sensor.

11. The articulated bus (2) in accordance with anyone of claims 1 to 10, wherein the first longitudinal section (46.1) extends on at least 10% of the length of the first structure (46), the combination of the first longitudinal section (46.1) and of the second longitudinal section (46.2) substantially extends at least on the longitudinal half of the first horizontal plate (46P).

12. The articulated bus (2) in accordance with anyone of claims 1 to 11, wherein the first stiffness comprises a first flexion stiffness, and the second stiffness comprises a second flexion stiffness about a transversal axis T, said second flexion stiffness being greater than the first flexion stiffness.

13. The articulated bus (2) in accordance with anyone of claims 1 to 12, wherein the first structure (46) comprises a third longitudinal section (46.3) with as third stiffness which is greater than the second stiffness, the second longitudinal section (46.2) being longitudinally between the first longitudinal section (46.1) and the third longitudinal section (46.3).

14. The articulated bus (2) in accordance with anyone of claims 1 to 13, wherein the first structure (46) comprises a first opening (460) and a first circular body (64) which is fixed in the first opening (460) and which is fixed to the bearing (54).

15. The articulated bus (2) in accordance with anyone of claims 1 to 14, wherein the pivot joint (6) comprises a first pivot linkage (50) with a transversal pivot axis (50A) and coupling the first structure (46) to a first superstructure (5) of the first unit (4), the corresponding stiffener (56) notably projecting from the first pivot linkage (50) .

16. The articulated bus (2) in accordance with anyone of claims 1 to 15, wherein the pivot joint (6) further comprises a pivoting floor (36) for passengers (PA) over the bearing (54), the pivoting floor (36) comprising two floor panels (40F; 40S) pivoting with respect to each z i other about the vertical pivot axis (44), said two floor panels (40F; 40S) comprising a flap (40S) with a horizontal pivot axis (42P) connecting one of the two floor panels (40F; 40S) to one of the units (4), the altitude of the pivoting floor (36) is of at most: 0,5 m, or 0,4 m.

17. Control process of an articulated bus (2) comprising: a first unit (4), a second unit (4) with a wheel module (7) equipped with : a wheel (8), an actuator system (73) associated with the wheel (8); a pivot joint (6) which connects the first unit (4) to the second unit (4), and which comprises: a vertical pivot axis (44), a first structure (46) including a first longitudinal section (46.1) with a first stiffness and a second longitudinal section (46.2) with a second stiffness greater than the first stiffness, a second structure (48), a bearing (54) coupling the first structure (46) to the second structure (48), a sensor (60) for measuring stress and/or deformations of the first structure (46), the control process comprising the steps: measuring (100) a deformation and/or a stress of the first structure (46); assessing (102) an inclination between the units (4), defining (106) a unit configuration reducing or suppressing the inclination between the units (4), varying (108) the mechanical effort of the actuator system (73) in the wheel module (7) in order to arrange the units (4) in said unit configuration such as to reduce the deformation and/or the stress of the first structure (46), the articulated bus (2) notably being in accordance with anyone of claims 1 to 16.

18. The control process in accordance with claim 17, wherein at step varying (108), the actuator system (73) generates a torque in the wheel module (7).

19. The control process in accordance with anyone of claims 17 to 18, wherein the wheel module (7) comprises a suspension system (74), a steering system (76), a braking system (78) and a driving system (80).

20. A computer program comprising computer readable code means, which when run on a computer (26), causes the computer (26) to run the control process according to any of claims 17 to 19, preferably at step defining (106) the unit configuration is defined in relation with a ground geometry, and the articulated bus (2) comprises a measuring module (25) adapted for measuring misalignments between the units (4).

Description:
ARTICULATED BUS WITH A SWIVELLING JOINT AND CONTROL PROCESS

Technical field

The invention lies in the field of connections between the carts of an articulated bus. More precisely, the invention provides an articulated bus with a hinged connection joining two adjacent units. The invention also provides a control process of an articulated bus.

Background of the invention

An articulated bus is generally equipped with a swivel joint between the carts. The passenger compartment extends along the whole vehicle, and comprises a gangway along the swivel joint. This complex mechanism transmits hauling efforts from one cart to another, while maintaining a comfortable space for passengers transported along the gangway.

An articulated bus is used to run on flat roads, but also on complex surfaces; which means on not purely planar roads. For instance, in cities on hills crossroads generate side tilting motions on the carts. When the carts tilt one after the other, the swivel joint, or pivot joint, suffers shear and torsion strains. These efforts may damage the pivot joint, and require a heavy construction. In addition, the life cycle is reduced, and a regular inspection is to schedule.

In the context of a low floor bus, the available space for mounting the pivot joint is narrow because the ground clearance must be preserved. Otherwise the pivot joint would risk to strike objects on the road, which would damage it severely.

Thus, there is a need for improving an articulated bus dotted with a rotating joint, while maintaining the steering capacity of the articulated bus. For instance, some road requires that the units are inclined of at least 35° with respect to each other about a vertical axis.

The documents EP 0614797 A1 discloses an articulated bus with a rotary junction coupling a front cart and a rear cart. The rotary junction comprises two supporting arms. Each arm 18 ends in an eye 20 which surrounds a bush 22 at the height of a recess 21 in a protrusion 19, which itself surrounds a shaft 23. The shaft 23 pivots with respect to the arms 18 about a transversal rotation axis in the bushes 22. Then, the rotary junction offers a resilient connection between the front and the rear vehicle. However, the bushes 22 present signs of wear over time. Providing bushes 22 at the left side and the right side limits the strength of the rotary junction.

The document US2013/006286 A1 discloses a swivel joint for a vehicle. The buffer device 100 receives a sliding buffer end 71, thereby forming a hydraulic damper. The front frame 3 is attached to the bearing 4 and physically separates the bearing 4 from the sliding buffer end 71.

The document EP 2497701 A1 discloses an articulated bus with a turning table between the front and the rear cart. A pivot joint is arranged between the turning table, and comprises a first joint element 4. The first joint element 4 exhibits a rigid design. Technical problem to be solved

It is an objective of the invention to present a device, which overcomes at least some of the disadvantages of the prior art. In particular, it is an objective of the invention to improve the pivot joint of an articulated bus.

Summary of the invention

According to a first aspect of the invention, it is provided an articulated bus comprising: a pivot joint, a first unit and a second unit coupled by the pivot joint, the pivot joint comprising: a vertical pivot axis, a first structure notably with a first horizontal plate, a second structure notably with a second horizontal plate, a bearing joining the first structure to the second structure, the first structure comprises a first longitudinal section with a first stiffness and attached to the bearing, and a second longitudinal section with a second stiffness which is greater than the first stiffness. Preferably, the first horizontal plate of the first structure comprises a metal sheet exhibiting a constant thickness along the first longitudinal section and the second longitudinal section; and possibly along the third longitudinal section and/or the fourth longitudinal section, the constant thickness of the metal sheet is notably of at most 6 mm.

Preferably, the first structure comprises a longitudinal stiffener protruding and/or projecting, for instance vertically, from the first horizontal plate, the longitudinal stiffener being thicker in the second longitudinal section than in the first longitudinal section. Preferably, along the first longitudinal section the longitudinal stiffener comprises a constant thickness, and/or the longitudinal stiffener comprises a constant width along the first longitudinal section and the second longitudinal section, and possibly along the third longitudinal section. Preferably, the longitudinal stiffener comprises a first thickness T1 in the first longitudinal section; and a second thickness T2 in the second longitudinal section which is at least two times as large as the first thickness T1.

Preferably, along the second longitudinal section the longitudinal stiffener comprises a gradual longitudinal thickness variation with a thickness decrease and/or reduction toward the first longitudinal section.

Preferably, the longitudinal stiffener extends longitudinally on the majority of the first horizontal plate.

Preferably, the longitudinal stiffener is a first longitudinal stiffener, the first structure comprising a second longitudinal stiffener and a transversal stiffener linking the first longitudinal stiffener to the second longitudinal stiffener, the first longitudinal section notably being free of transversal stiffeners. Preferably, the pivot joint comprises a first sensor in the first longitudinal section adapted for measuring a stress data or a deformation data of the first structure. Preferably, the sensor is attached to the first horizontal plate, and notably comprises a strain gauge sensor.

Preferably, the first longitudinal section extends on at least: 10%, or 20%, 30%, of the length of the first structure, the combination of the first longitudinal section and of the second longitudinal section substantially extends longitudinally on at least the half of the first horizontal plate. Preferably, the first stiffness comprises a first flexion stiffness, and the second stiffness comprises a second flexion stiffness around a transversal axis which is larger than the first flexion stiffness. Preferably, the first structure comprises a third longitudinal section with as third stiffness which is greater than the second stiffness, the second longitudinal section being longitudinally between the first longitudinal section and the third longitudinal section.

Preferably, the first structure comprises a first opening and a first circular body which is fixed in the first opening and which is fixed to the bearing.

Preferably, the pivot joint comprises a first pivot linkage with a transversal pivot axis and coupling the first structure to a first superstructure of the first unit, the stiffener notably projecting from the first pivot linkage toward the first circular body.

Preferably, the pivot joint further comprises a pivoting floor for passengers over the bearing, the pivoting floor comprising two floor panels pivoting with respect to each other about a vertical pivot axis, and a flap with a horizontal pivot axis connecting one of the two floor panels to one of the units, the altitude of the pivoting floor is notably of at most: 0,5 m, or 0,4 m.

Preferably, along the third section the stiffener comprises a constant thickness which is greater than the first thickness T1.

Preferably, the longitudinal thickness variation is a constant and/or continuous and/or monotone longitudinal thickness variation.

Preferably, the first structure comprises a section of reduced thickness; said section being the first section.

Preferably, the first structure comprises a fourth longitudinal section with as fourth stiffness which is greater than the first stiffness, the first section being between the fourth section and the second section.

Preferably, the articulated bus is a low floor articulated bus.

Preferably, the or each thickness is a vertical thickness.

Preferably, the third stiffness is a third flexion stiffness.

Preferably, the fourth stiffness is a fourth flexion stiffness.

Preferably, the metal sheet extends along the first section and the second section.

Preferably, the flexion stiffnesses are bending stiffnesses about transversal axes.

Preferably, the first longitudinal section is a longitudinal section of reduced stiffness.

Preferably, each of the first structure and the second structure being linked to the first unit and the second unit respectively. Preferably, the second longitudinal section is longitudinally at distance from the bearing.

Preferably, longitudinally along the vertical pivot axis, the first structure and the second structure are overlapping each other, possibly, the first plate covers the second plate.

Preferably, the first longitudinal section is a resilient section.

Preferably, the first thickness T1 and/or the second thickness T2 is/are maximum thickness(es) of their respective longitudinal sections.

Preferably, each of the two unit comprises driving wheels.

Preferably, the structures are similar and/or symmetric with respect to the vertical pivot axis. Preferably, along the third section the stiffener comprises a third average thickness which is higher than the average thickness along the second section.

Preferably, the first stiffness comprises the smallest stiffness of the longitudinal sections of the first structure, notably the smallest flexion stiffness.

Preferably, the first horizontal plate comprises a width variation with a width reduction toward the vertical pivot axis.

Preferably, the second structure is stiffer than the first structure, and/or comprise more stiffeners than the first structure.

Preferably, the first longitudinal section may be rigidly secured to the bearing; and/or physically in contact of the bearing.

Preferably, the first structure may be integrally formed and/or one piece; at least from the first longitudinal section to the second longitudinal section, preferably on its whole length.

Preferably, the second structure may be integrally formed and/or one piece.

Preferably, the bearing may be a main bearing, and/or a bearing device.

Preferably, the bearing may comprise a set of rotating elements, preferably rotating about vertical rotation axes.

The longitudinal sections are not essential features of the invention.

It is another aspect of the invention to provide an articulated bus, notably a low floor bus, comprising: a pivot joint, a first unit and a second unit coupled by the pivot joint, the pivot joint comprising:

• a vertical pivot axis,

• a first structure with a first horizontal plate,

• a second structure notably with a second horizontal plate,

• a bearing joining the first structure and the second structure, a longitudinal stiffener protruding from the first horizontal plate, said longitudinal stiffener comprising a first thickness T1 at a first area, and a second thickness T2 at the second area, said second thickness T2 being larger than the first thickness Tl, possibly at least: two or three time as large as the first thickness Tl. It is another aspect of the invention to provide an articulated bus, notably a low floor bus, comprising: a pivot joint, a first unit and a second unit coupled by the pivot joint, the pivot joint comprising:

• a vertical pivot axis,

• a first structure with a first horizontal plate and a longitudinal stiffener which form a first portion and a second portion thicker than the first portion,

• a second structure notably with a second horizontal plate,

• a bearing joining the first structure and the second structure,

• a sensor for measuring stresses and/or deformations in the first structure, and which is disposed in the first portion.

It is another aspect of the invention to provide a control process of an articulated bus comprising: a first unit, a second unit with a wheel module equipped with : a wheel, an actuator system associated with the wheel, a pivot joint which connects the first unit to the second unit, and which comprises: a vertical pivot axis, a first structure with a longitudinal section of reduced thickness, a second structure, a bearing coupling the first structure to the second structure, a sensor for measuring stress and/or deformations of the first structure, the control process comprising the step: measuring a deformation and/or a stress and/or a strain of the first structure; assessing an inclination between the units, defining a unit configuration reducing or suppressing the inclination between the units, varying the mechanical effort of the actuator system in the wheel module in order to arrange the units in said unit configuration such as to reduce the deformation and/or the stress and/or the strain of the first structure, the articulated bus notably being in accordance with the invention.

It is another aspect of the invention to provide a control process of an articulated bus comprising: a first unit, a second unit with a wheel module equipped with : a wheel, an actuator system associated with the wheel; a pivot joint which connects the first unit to the second unit, and which comprises: a vertical pivot axis, a first structure including a first longitudinal section with a first stiffness and a second longitudinal section with a second stiffness greater than the first stiffness, a second structure, a bearing coupling the first structure to the second structure, a sensor for measuring stress and/or deformations of the first structure, the control process comprising: measuring a deformation and/or a stress of the first structure; assessing an inclination between the units, defining a unit configuration reducing or suppressing the inclination between the units, varying the mechanical effort of the actuator system in the wheel module in order to arrange the units in said unit configuration such as to reduce the deformation and/or the stress of the first structure, the articulated bus notably being in accordance with the invention.

Preferably, at step varying, the actuator system generates a torque in the wheel module.

Preferably, the wheel module comprises a suspension system, and/or a steering system, and/or a braking system and/or a driving system.

Preferably, the torque is about a horizontal axis. Preferably, at step assessing the inclination between the units may generally be an offset and/or a misalignment.

Preferably, at step varying, the actuator system reduces the driving torque on the wheel.

Preferably, at step varying, the actuator system generates a torque data in order to balance the longitudinal stress between the units, the actuator system notably being an in-wheel engine. Preferably, at step varying, the actuator system adapts a damping effect on the wheel.

Preferably, at step varying, the actuator system increases or reduces the braking torque on the wheel.

Preferably, at step varying, the actuator system changes the steering angle of the wheel.

Preferably, at step varying, the actuator system reduces the stress and/or the deformation of the first structure.

Preferably, at step assessing, the inclination between the units is an inclination about the longitudinal direction and/or about the vertical pivot axis.

Preferably, at step measuring, the stress and/or the strain and/or the deformation is measured within the longitudinal section of reduced thickness.

It is another aspect of the invention to provide a computer program comprising computer readable code means, which when run on a computer, causes the computer to run the control process according to the invention preferably at step defining the unit configuration is defined in relation with a ground geometry, and the articulated bus comprises a measuring module adapted for measuring misalignments between the units.

The different aspects of the invention may be combined to each other. In addition, the preferable features of each aspect of the invention may be combined with the other aspects of the invention, unless the contrary is explicitly mentioned.

Technical advantages of the invention

The invention offers a resilient solution. It still provides a tight joint between the units which is also adapted for supporting the turning floor. The pivot joint is able to swivel of at least 35° in both directions, and to twist of a few degrees about the longitudinal axis. The architecture in accordance with the invention remains thin. Thus, its compact character remains convenient to arrange in a vertically thin cavity.

The control process corrects and adapts the unit's configuration depending on the misalignment of the units and on the stress measured in the joint. Thus, the pivot joint is preserved, and may be designed in a lightweight fashion which, in turns, further fosters the resilient design of the invention. Brief description of the drawings

Several embodiments of the present invention are illustrated by way of figures, which do not limit the scope of the invention, wherein figure 1 provides a schematic illustration of a side view of an articulated vehicle in accordance with a preferred embodiment of the invention; figure 2 provides a schematic illustration of the rotary joint between two carts of an articulated vehicle in accordance with a preferred embodiment of the invention; figure 3 provides a schematic illustration of a top view of a pivot joint in accordance with a preferred embodiment of the invention; - figure 4 provides a schematic illustration of a longitudinal through cut of a pivot joint in accordance with a preferred embodiment of the invention; figure 5 provides a schematic illustration of longitudinal through cut of a bearing for a pivot joint in accordance with a preferred embodiment of the invention; figure 6 provides a schematic illustration of a wheel module connected to a control system in accordance with a preferred embodiment of the invention; figure 7 provides a diagram block of a control process in accordance with a preferred embodiment of the invention.

Detailed description of the invention This section describes the invention in further detail based on preferred embodiments and on the figures. Similar reference numbers will be used to describe similar or the same concepts throughout different embodiments of the invention. For example, reference 2 denotes different embodiments of the articulated bus in accordance with the invention.

It should be noted that features described for a specific embodiment described herein may be combined with the features of other embodiments unless the contrary is explicitly mentioned.

Features commonly known in the art will not be explicitly mentioned for the sake of focusing on the features that are specific to the invention. For example, the vehicle in accordance with the invention is evidently provided with an electric battery, even though such electric battery is not explicitly referenced on the figures nor referenced in the description. By convention, it may be defined that the word "longitudinal" refers to a longitudinal direction and may correspond to the main driving direction of the bus. It may be along the main central axis of the articulated bus. The longitudinal axis may be along the longitudinal direction. The same may apply to a transversal axis and a vertical axis. The word "transversal" refers to the transversal direction and may be perpendicular to the longitudinal direction. The current description uses the term "horizontal". However, the extend of this term must be adapted to the real slope of the ground, and should not be understood with a strict meaning. When the ground or the corresponding road exhibits a slope, the term "horizontal" may be interpreted as parallel to the ground, notably along the longitudinal direction.

In the context of the present invention, a bearing may be understood as a device that reduces friction between moving parts while constraining relative motions.

Figure 1 shows a vehicle for mass transportation in accordance with a preferred embodiment of the invention. The vehicle is partially represented. The vehicle is an articulated vehicle. The vehicle is actually an articulated bus 2. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus 2 are represented. They define a coordinate system with an origin O, said coordinate system notably being used for distance computation.

The articulated bus 2 is adapted for transportation of passengers in cities and may transport about one hundred passengers, for instance one hundred and twenty passengers. The articulated bus 2 may be an electric bus. The articulated bus 2 may be purely electric, meaning that it is free of combustion engine. It may be a hybrid bus, combining electric engines and a combustion engine. The articulated bus 2 may comprise a first unit 4 and a second unit 4 (partially represented). Each unit 4, also designated as "cart", may form a body in the meaning of a rigid entity. Each unit may comprise a superstructure 5. Each unit 4 may be a trailer and/or a tractor. The units 4 may be similar or identical. These units 4 may be joined by a mechanical connection, for instance a pivot joint 6. The pivot joint 6 may also be designated as hinged connection 6 or rotary joint 6. The pivot joint 6 allows the units 4 to swivel with respect to each other about the vertical axis V. The longitudinal axis L may be defined in a configuration where the units 4 are aligned, or in relation with one of the units 4.

The articulated bus 2 comprises a passenger compartment PC receiving passengers. The passenger compartment PC extends in each unit 4, and crosses the pivot joint 6. There, the articulated bus 2 may exhibit a gangway and a bellow 20 which are adapted to deform when the articulated bus 2 turns, and when the units 4 are inclined with respect to each other.

In the current embodiment, only two units 4 are represented, however it is contemplated in the current invention that the bus 2 includes three, four, or more units 4; which are articulated with respect to their neighbours by pivot joint(s) 6. Accordingly, the articulated bus 2 may be biarticulated or tri-articulated. Then, the passenger capacity may be of more than two hundred. Each unit 4 may be self-supporting. Thus, each unit 4 may move without the pivot joint 6.

Each unit 4 includes several wheel modules 7. Each wheel module 7 supports the associated superstructure 5. Each wheel module 7 comprises a wheel 8 engaging the ground G. At least one pair of wheels 8 is formed of steered wheels. Optionally, each wheel 8 of the bus 2 or of at least one unit 4 are steered wheels and/or driving wheels. At least one wheel module 7 may comprise two wheels 8 disposed in a same wheel housing. According to another approach of the invention, each wheel 8 forms a wheel module 7. The ground G may correspond to the road, or the track on which the articulated bus 2 drives. In the current embodiment, the ground G is flat. However, the invention also accommodates uneven grounds G, with slope variations which are crossed by the articulated bus 2.

The articulated bus 2 includes a roof 10, a passenger platform 12, and side walls 14. The side walls 14 may be outer walls. Two transversally opposite side walls 14 may go down from the roof 10 to the passenger platform 12. The side walls 14 may receive windows 16 and doors 18 for passengers PA (only one represented in dotted lines). The roof 10, the passenger platform 12, and the side walls 14 may form the superstructures 5. The passenger platform 12 and the side walls 14 may extend up to the pivot joint 6.

The articulated bus 2 may comprise a self-driving system 22. The expression “self-driving” may be understood as an unmanned driving mode, where no human action is required for driving the bus 2 on its path.

The articulated bus 2 may comprise a control system 24. The control system 24 is connected to the pivot joint 6 and may obtain information, for instance angle information and strain information.

The articulated bus 2 comprises a computer 26, notably an inboard computer. The computer 26 may comprise a computer readable medium 28 and a processing unit 30. The computer readable medium 28 may store a source code for carrying out a control process, notably in accordance with the invention. The computer 26 may generally be a computing unit 26. The computer readable medium 28 is adapted for storing data.

The articulated bus 2 may comprise ground monitoring means 32 which may generally be environment monitoring means. The ground monitoring means 32 may comprise cameras. Several cameras may be distributed along the bus articulated 2, and possibly close to the roof 10. Thus, the cameras offer a precise view of the environment all along the bus 2. The cameras may be adapted to sense light of any wavelength, notably in the visible and invisible range. Providing several cameras at a same longitudinal end of the articulated bus 2 allows three-dimensional vision, which is useful for estimating the distance between the articulated bus 2 and ground variation.

The ground monitoring means 32 may observe the ground G in the environment of the articulated bus 2. Thus, the control system 24 may anticipate or estimate the inclination variations, and thus how the units 4 will tilt, lean and skew with respect to each other when the bus runs through the inclination variations. The control system 24 may comprise a measuring module 25 adapted for measuring the differential inclinations between the units about the longitudinal axis L, the vertical axis V and the transversal axis T. The measuring module 25 may also measure offsets between the units. The measuring module 25 may be arranged at the pivot joint 6, or may comprise optic means at distance from the pivot joint 6.

Accordingly, the control system 24 adapts signals on the wheel modules 7 in order to reduce stress on the superstructures 5, and on the pivot joint 6 as well. Thus, the pivot joint 6 may be simplified and lightened. Its lifespan is prolonged. As an alternative or in addition, the articulated bus 2 may comprises a geolocation system 34 such as a geolocation system 34 by satellite, for instance a global positioning system by satellite, which is generally referred to by the acronym GPS. The data obtained by the geolocation system 34 may provide information on road and notably information on road inclinations. Thus, inclination variations may be deduced and anticipated from a stored map.

The self-driving system 22, the control system 24, the ground monitoring means 32 and the geolocation system 34 may share resources. For instance, they share the computer 26. Their current location may be purely illustrative. They may be arranged at other location in the articulated bus 2.

Figure 2 shows the interface between two units 4 of the articulated bus 2. In the current interface, the units 4 are physically linked by a pivot joint 6. The articulated bus 2 may correspond to the one as described in relation with figure 1. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus 2 are represented. They may form a coordinate system attached to the articulated bus 2. The bellow is not represented for the sake of clarity.

The articulated bus 2 is represented through the facing ends of the units 4. The superstructures 5 exhibit portions forming the passenger platform 12. A passenger PA is standing on the pivoting floor 36, also designated as turning table 36. The pivoting floor 36 joins the passenger floor 38 in the units 4. The pivoting floor 36 forms the gangway 40, also designated as interconnecting passageway 40, between the units 4. The gangway 40 forms a distorted portion of the passenger compartment PC

The pivoting floor 36 may comprise a first panel 40F with a concave edge, a second panel 40S with a convex edge matching the concave edge. A third panel 40T may be fixed on of the units 4. The second panel 40S may be between the first and the third one. A hinged 42 with a transversal hinge axis 42P may join the second panel 40S and the third panel 40T. The concave edge and the convex edge may be circular. Thus, they allow pivot motions about the vertical pivot axis 44. The second panel 40S may be a flap.

The height H, or altitude of the pivoting floor 36 may be of at most: 50 cm, or 40 cm, in the driving configuration of the articulated bus 2. The height H is measured from the upper surface of the pivoting floor 36 to the ground G. The passenger floor 38 is at the same level. Thus, the whole floor of the articulated bus 2 is at the same level, which eases access to wheeled chairs. The articulated bus 2 may be designated as a low floor bus.

The pivot joint 6 comprises a first structure 46 and a second structure 48. They may be a front structure and a rear structure respectively. The first structure 46 and the second structure 48 are pivotably fixed to each other. They are adapted for turning about the pivot axis 44, which, in the current embodiment, is arranged along the vertical direction V. The structures 46 and 48 are hinged, and may swivel with respect to each other. The first structure 46 and the second structure 48 may overlap each other. By way of illustration, the first structure 46 overlaps the second structure 48. The first structure 46 covers partially the second structure 48. The contrary may be provided. They may be under the pivoting floor 36. At least one of the structures supports the pivoting floor 36. A device 47 may bear on the first structure 46 and maintain the second panel 40S. The device 47 may compensate for relative motions between the first structure 46 and the second panel 40S.

Each of the structures 46 and 48 may be attached to one of the units 4. The first structure 46 and the second structure 48 may be attached to the superstructures 5 of the units 4, for instance to portions of the passenger platform 12. The first structure 46 and the second structure 48 may be attached to the superstructures 5 by means or pivot linkages 50. The pivot linkages 50 allow rotation about transversal pivot axes 50A. Thus, the units 4 are linked through threes pivot axes (44; 50A).

At least one or each transversal pivot axis 50A is longitudinally at distance from the transversal hinge axis 42P. The transversal hinge axis 42P is between the transversal pivot axes 50A of the first structure 48 and of the second structure 48. The transversal hinge axis 42P may be longitudinally along the first structure 46. There is a longitudinal gap 52 between the transversal hinge axis 42P and the transversal pivot axis 50A of the first structure 46.

Figure 3 provides a schematic illustration of a pivot joint 6 for an articulated bus. The articulated bus may correspond to those as described in relation with anyone of figures 1 to 2, and combination thereof. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus are represented. The pivoting floor is not represented for the sake of clarity. Longitudinal ends of the units 4 are represented through edges of the passenger platform 12.

Features detailed in relation with the first structure 46 may also apply to the second structure 48. The first structure 46 comprises a first plate such as a first horizontal plate 46P. The first horizontal plate 46P spans on substantially the whole surface of the first structure 46. The first horizontal plate 46P extends, at least, from the vertical pivot axis 44 to the associated transversal pivot axis 50A, namely the first transversal pivot axis 50A. The first horizontal plate 46P is generally triangular.

The triangular shape of the first horizontal plate 46P presents a width reduction toward the second structure 48, and a width increase toward the associated unit 4. The triangular shape may exhibit a section of constant width. This section receives the pivot linkages 50. The first horizontal plate 46P may exhibit a first opening 460 around the vertical pivot axis 44. A bearing 54 may be attached at the first opening 460. The bearing 54 may be a bearing device, or a bearing unit, or a bearing joint. As an option, the first structure 46 is strengthened. It possibly comprises stiffeners, for instance on the lower face of the first horizontal plate 46P. The stiffeners notably comprise longitudinal stiffeners 56. The longitudinal stiffeners 56 extend from the pivot linkages 50 toward the vertical pivot axis 44. At least one longitudinal stiffener 56 extends on the majority of the first structure 46. The longitudinal stiffeners 56 may have different longitudinal length. Each longitudinal stiffener 56 i z may have a constant width along the transversal direction T. As an option, the stiffeners comprise transversal stiffeners 58. The transversal stiffeners 58 may be connected to the longitudinal stiffeners 56. The transversal stiffeners 58 may extend on a transversal majority of the first structure 46. Thus, the stiffeners (56; 58) may form a grid pattern. The stiffeners (56; 58) may be adapted for allowing a torsion deformation about the longitudinal central axis X.

The second structure 48 may be similar to the first structure 46. It may exhibit a second horizontal plate 48P, longitudinal stiffeners 56 and transversal stiffeners 58. These stiffeners may be arranged below the second horizontal plate 48P. In addition, the second structure 48 may comprise upper stiffeners 56U which are above the second horizontal plate 48P. In a same way, the associated pivot linkages 50 may be arranged over the second horizontal plate 48P and may be attached to the upper stiffeners 56U. Then, the second structure 48 comprise more longitudinal stiffeners (56; 56U) than the first structure 46. It may be stiffer, for instance with respect to a flexion about the transversal axis T.

The pivot joint 6 may comprise sensors 60. The sensors 60 may be arranged on each structure (46; 48), or only on one of the structures, for instance the first structure 46. It may be disposed on the first horizontal plate 46P. The sensors 60 may comprise strain gauge sensors. The sensors 60 may be adapted for measuring deformations and stress of the structures (46; 48). Deformations of the horizontal plates (46P; 48P) may be obtained. At least one or each structure may comprise a first half and a second half, the second half enclosing the vertical pivot axis 44 and at least one or all the sensors 60 of said structure. Said second half may have the smallest transversal width.

A sensor 60 may be disposed within the first opening 460. It may sense vertical load on the pivot joint 6.

The different lengths of the stiffeners 56 may define different longitudinal sections 46.1, 46.2; each of said longitudinal sections having different stiffnesses.

Figure 4 provides a schematic illustration of a through cut of a pivot joint 6 for an articulated bus. The articulated bus may correspond to those as described in relation with anyone of figures 1 to 3, and combination thereof. The pivoting floor is not represented for convenience of the reader. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus are represented.

Features detailed in relation with the first structure 46 also apply to the second structure 48.

The bearing 54 is interleaved between the first structure 46 and the second structure 48. It may form their interface, and may be in physical contact of both.

The pivot joint 6 is essentially thin. It extends between the pivot linkages 50. The pivot linkages 50 may form the longitudinal ends of the pivot joint 6. They may be at the same vertical level.

The first horizontal plate 46P is flat. It exhibits a constant thickness on its whole longitudinal length and/or transversal width. The first horizontal plate 46P may have a thickness comprised between 5 mm and 7 mm values included. The first horizontal plate 46P may be a metal sheet, for instance of steel. Other alloys may be provided. The thickness may be of 6 mm. The metal sheet comprises a homogeneous material with increased ability against fatigue, under cyclic loading. Thus, it is adapted for enduring important deformations, and the lifetime of the first structure increases. The overall weight is also optimized.

This thickness range, in the context of an articulated bus, ensures a stiffness for supporting the gangway while allowing an inclination difference between the units about the longitudinal axis L. Thus, the pivot joint 6 remains resilient enough for reducing stress in the polymer bushings of the pivot linkages 50 and the bearing 54, which may endure more cycles.

Along the longitudinal direction, the first structure 46 comprises a first section 46.1 and a second section 46.2. The first and second section (46.1; 46.2) may be adjacent. In addition, first structure 46 may comprise a third section 46.3 and a fourth section 46.4, which may be at longitudinal ends of the first structure 46. The sections (46.1-46.4) are longitudinal sections. Each section extends from 10% to 35% of the length of the first structure 46, or of the first horizontal plate 46P. The first section 46.1 connects the fourth section 46.4 to the second one 46.2. The second section 46.2 connects the first section 46.1 to the third section 46.3.

The first horizontal plate 46P extends along all the first to fourth section (46.1-46.4). At least one or several longitudinal stiffeners 56 extend along the first section 46.1, the second section 46.2, and optionally the third section 46.3. A longitudinal end of a longitudinal stiffener 56 may form the interface between the first section 46.1 and the fourth section 46.4. The bearing 54, or an accessory thereon like an adaptor, may mark this interface.

Along the first longitudinal section 46.1, at least one or each longitudinal stiffener 56 has a constant thickness. The thickness is measured vertically. The thickness may be a first thickness Tl. The first section 46.1 may be free of transversal stiffener. Thus, twisting deformation of the first section 46.1 imply less stress. Thus, the first section 46.1 remains the most resilient one of the first structure 46. Along the third longitudinal section 46.3, at least one or each longitudinal stiffener 56 has a constant thickness, notably a second thickness T2. Along the second section 46.2, the longitudinal stiffener 56 exhibits a thickness variation, for instance a gradual thickness variation. The thickness increase from the first thickness Tl to the second thickness T2. Therein, the stiffener 56 may form a parallelogram, with an inclined edge with respect to the horizontal direction HD. The thickness may reduce toward the bearing 54, and may increase toward the associated pivot linkages 50. The first thickness Tl may represent at most the half of the second thickness T2. Thus, the longitudinal stiffener(s) 56 may present a thickness variation of at least: +100%, or +150%, or +200%, between the thinnest and the thickest area. The first section 46.1 corresponds to the thinnest section of the stiffener 56, the third section 46.3 forms the thickest section, and the second section 46.2 forms a thickness transition. Accordingly, the first section 46.1 presents a first stiffness, for instance the smallest stiffness of the first structure 46. The second section 46.2 comprises a second stiffness which is larger than the first section 46.1. Further, the third section 46.3 comprises a third stiffness which is greater than the second stiffness, and the optional fourth section 46.1 exhibits a fourth stiffness which is greater than the first stiffness, and possibly the second stiffness.

The stiffnesses are adapted by means of the thickness of the stiffeners, but also by the number of stiffeners. The first section 46.1 comprises less stiffeners 56 than the second section 46.2. An interface between a first longitudinal section 46.1 and a second longitudinal section 46.2 may be formed by the end of a stiffener 56 extending on a fraction of the length of the corresponding structure (46; 48).

The considered first to fourth stiffness may be average stiffnesses, or maximum stiffnesses.

The considered first to fourth stiffness may each be flexion stiffnesses about a transversal axis T.

A dotted line represents the upper surface 46U of the first structure 46 under a deformation where all the sections (46.1-46.4) bend in the same fashion such that the upper surface 46U is convex. Another dotted line represents the upper surface 48U of the second structure 48 under a deformation where all its longitudinal sections are bent about transversal axes. In the current deformation, the upper surface 48U exhibits a curvature inversion, and show a convex area and a concave area.

The current deformations are represented along their whole corresponding structure. However, it may be considered that there is no, or negligible deformation in the fourth sections (46.4; 48.4).

The same consideration may be drawn for the third sections (46.3; 48.3). Since the second structure 48 receives the upper stiffeners 56U, some of its sections (48.1 - 48.4) may be split. As an alternative, the invention may merge some of its sections (48.1 - 48.4).

At least one sensor 60 is provided on the first structure 46. It may be arranged in the first section 46.1. It may be on the first horizontal plate 46P, or under. It may be arranged between longitudinal stiffeners 56. It may be at distance from the bearing 54.

At this location the sensor 60 perceives the deformations of the first structure 46. With the knowledge of the shape and material, the mechanical stress may be deduced.

The first structure 46 may be integrally formed. The first structure 46 may be monobloc, one-piece. The same may apply to the second structure 48. This improves the ability of each structure (46; 48) to resist to deformation cycles. Deformations are more predictable. The service life of the pivot joint is longer.

Figure 5 offers a schematic illustration of a bearing 54 in a pivot joint 6 for an articulated bus. The articulated bus may correspond to the one as described in relation with any one of figures 1 to 4, and combinations thereof. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus are represented. The bearing 54 forms the vertical interface between the first structure 46 and the second structure 48. The bearing 54 generally exhibits an inner ring, and outer ring, and an annular array of rotating elements between the inner ring and the outer ring. In the current embodiment the bearing 54 is a ball bearing. However, it could be replaced by a needle bearing or a roller bearing. Other technologies are considered.

The pivot joint 6 may comprise a first circular body 64 and possibly a second circular body 66. The first circular body 64 and the second circular body 66 each form a toroidal body. They are coaxial. They encircle the vertical pivot axis 44. They form stiff crowns that strengthen the fourth longitudinal sections 46.4 and 48.4. The first circular body 64 and the second circular body 66 are disposed outside and inside the bearing 54 respectively. They may be an outer crown and an inner crown. Due to their thicknesses and widths, they may be considered as stiffeners, for instance circular stiffeners. They may be thicker than the bearing 54 and the plates (46P; 48P).

The longitudinal stiffeners 56 extend toward the first circular body 64 and the second circular body 66. They may be at distance from these bodies (64; 66). However, at least one or several longitudinal stiffeners 56 may extend longitudinally along one of the bodies (64; 66).

The first structure 46 comprises a first opening 460. The first opening 460 is formed by an inner circular edge of the first horizontal plate 46P. Similarly, the second structure 48 exhibits a second opening 480 through the second horizontal plate 48P. The first circular body 64 is fixed in the first opening 460, and exhibits an outer circular edge mating with the inner circular edge of the first horizontal plate 46P. The second circular body 66 is fixed in the second opening 480, and exhibits an outer circular edge which is the complementary of the inner circular edge of the second horizontal plate 48P.

Thus, the structures 46 and 48; through their plates 46P and 48P and through the bearing 54; transmit longitudinal efforts to each other. Then, the units (not represented) are coupled to each other and may be kept at distance from one another.

The first structure 46 and the second structure 48 may comprise fixation discs 68. Each circular body 64 and 66 may be fixed to the associated plate 46P and 48P through the fixation discs 68 and fixation means 70 such as screws. The circular bodies (64; 66) and the bearing are disposed in the vertical space defined by the plates (46P; 48P). Thus, the current arrangement improves the compactness, notably the vertical compactness of the pivot joint 6.

Figure 6 provides a schematic illustration of a wheel module 7 for an articulated bus 2. The articulated bus 2 may correspond to the one as described in relation with any one of figures 1 to 5, and combinations thereof. The longitudinal axis L, the vertical axis V and the transversal axis T of the articulated bus 2 are represented. The wheel module 7 may comprise a wheel housing 72, also designated as wheel passage. The wheel housing 72 is joined to the passenger platform 12 and the side wall 14. The wheel housing 72 forms a casing on at least: two or four sides of the wheel 8.

The wheel module 7 comprises an actuator system 73 generating a torque on the wheel directly or on a control element linked to the wheel 8. The actuator system 73 is controlled by the computer 26; which depending on the signal received from the sensor 60, from the ground monitoring means 32 and the data from the measuring module 25; adapts the effort from ground G transmitted by the wheel 8 to the superstructure 5. It may also correct the positions of the units with respect to each other, and notably align them. Subsequently, the deformation in the pivot joint (not represented) sinks.

The wheel module 7 comprises at least one of the following systems: a suspension system 74, a steering system 76, a braking system 78 and a driving system 80. The systems 74-80 may share elements such as the wheel support 8S.

The suspension system 74 comprises at least one pivoting link 74L, such an oscillating arm, connecting the wheel support 8S while allowing vertical motions of the wheel 8 with respect to the passenger platform 12. A damper (not represented) may be provided for fdtering and absorbing reciprocating motions.

The actuator system 73 may comprise a suspension actuator 74 A, such as a bellow actuator, acting on the upper pivoting link 74L. It generates a torque on the pivot links 74L of the wheel module 7. This suspension torque is about a longitudinal axis L, or generally on a horizontal axis. Thus, the suspension actuator 74A may reduce or increase the vertical efforts of the wheel 8. The ground clearance 82 may be adapted locally. The torque may be about a horizontal axis.

The steering system 76 may comprise connecting rods controlling the orientation of the wheel support 8S, and thus of the wheel 8. Then, the steering angle may be controlled. The wheel support 8S may be a kingpin. The actuator system 73 may comprise a steering actuator 76A. The steering actuator 76A generates a torque on the wheel support 8S, and on the wheel 8. This steering torque is about a vertical axis 55. Changing the steering angle of the wheel 8 changes the path of the units 4, and permits to reach an alignment configuration reducing deformation in the pivot joint. Depending on the topology of the ground G, the control system 24 adapts steering in order to place the units 4 at locations reducing mechanical stress in the pivot joint.

The braking system 78 may comprise a disc brake rigidly fixed to the wheel rim. A brake calliper engages the brake disc in order to slow down the unit. The braking system 78 comprises an actuator (not represented) who actively acts on the brake disc. Thus, the braking system 78 generates a braking torque on the wheel 8 about the rotation axis 8A of the wheel. Adapting the braking torque may be used to correct the trajectory of the units 4 in order to reduce mechanical stress in the pivot joint. 7

The driving system 80 comprises a driving actuator 80A. The driving actuator may be an electric engine. It may be an in-wheel engine. It provides a driving torque on the wheel 8, and propel the articulated bus 2. Thus, the driving system 80 propel along the trajectory of the units 4 in order to reduce mechanical stress in the pivot joint.

Figure 7 provides a schematic illustration of a diagram representing a control process of an articulated bus in accordance with the invention. The articulated bus may correspond to those as described in relation with any one of figures 1 to 6, and combinations thereof.

The control process comprises the following steps, notably carried out in the following order:

• measuring 100 a strain and/or a deformation and/or a stress of the first structure;

• assessing 102 an inclination and/or an offset and/or a misalignment between the units,

• obtaining 104 a ground geometry,

• defining 106 a unit configuration reducing or suppressing the inclination between the units,

• varying 108 the mechanical effort of the actuator system in the wheel module in order to arrange the units in said unit configuration such as to reduce the strain and/or the deformation and/or a stress of the first structure, and more generally within the pivot joint.

At step measuring 100, the sensor(s) may provide a deformation signal. It may be transformed in a stress data upon calculation by the computer. During step measuring 100, the articulated bus may be driving or stationary. At step measuring 100, the first horizontal plate and/or the longitudinal stiffeners are elastically deformed.

Step assessing 102 may start on condition that the deformation or the stress is above a predefined threshold. At step assessing 102, the angles between the unit are measured. The angle variations may also be obtained.

At step obtaining 104, the geometry of the ground is obtained by the ground monitoring means while the articulated bus is driving. During motion, the ground monitoring means scan the surface of the ground and estimated the unevenness. It may identify the inclination variation, and their distance with respect to the bus. Thus, a map of the bus environment is established. As an alternative, a topology map may be stored in the computer of the articulated bus. By means of the geolocation system, the ground unevenness under the articulated bus are obtained.

At step defining 106, an inclination variation is defined in order to align the units, and to arrange them with the same orientation. Step defining 106 may also define correction signals provided to the actuator system. The correction signal may be computed on the basis of a previous signal, or on information from ground geometry. Thus, step obtaining is optional.

Step varying 108 the mechanical effort may operate on different systems of the wheel module. Step varying 108 may comprise the following steps:

• varying 110 a suspension effort in order to lower and/or to raise wheels with respect to the associated superstructure, • varying 112 a steering effort in order to drive the units on a planar surface,

• varying 114 a driving effort in order to propel the units and to reduce stress in the joint, and

• varying 116 a braking effort in order to reduce stress in the joint.

During step varying 108, the actuator system may exert a torque in the wheel module. By way or illustration, when an articulated bus is stationary with one wheel in a hole, said articulated bus twists along the longitudinal axis. Then, the pivot joint deforms. In order to correct this configuration, the control system sends a correction signal to the actuator system of the corresponding wheel module. The correction signal may consist in lifting the unit by means of said wheel. The suspension actuator pushes on the corresponding suspension link and generate a correction torque.

Further, the control system may foresee the contrary motion on the wheel at the opposite side of the wheel in the hole. Thus, the unit tilt such that the passenger platform becomes parallel to the ground. Then, stress and deformation in the pivot joint are minimized. The mechanical conditions are improved. During driving, the front unit drags the rear unit. The units are configured such that there is a tension between the units. The corresponding longitudinal effort is of about 100N. More generally, the longitudinal effort ranges from 10N to 1000N.

It should be understood that the detailed description of specific preferred embodiments is given by way of illustration only, since various changes and modifications within the scope of the invention will be apparent to the person skilled in the art. The scope of protection is defined by the following set of claims.