Patent Publication Number: US-2020282789-A1

Title: Suspension assembly with a damper for an electric bus

Description:
TECHNICAL FIELD 
     The invention lies in the field of suspension assemblies for road vehicles. More precisely, the invention provides a suspension assembly with a shock absorber for a passenger vehicle. The invention also provides a vehicle such as an articulated low platform bus, and a bus assembling process. 
     BACKGROUND OF THE INVENTION 
     High capacity vehicles such as articulated buses are equipped with suspension assemblies in order to improve the passenger comfort. A suspension assembly with a damping device such as a shock absorber filters vibrations and controls oscillations of the swinging arms. Through this aspect, the damping device improves the contact between the wheel and the road. This advantage may be applied to driving wheels and to steering wheels. In curves and in braking situations, the wheels keep a homogeneous contact which reduces sideslip situations. Then, braking distances may be reduced, and turning radius may be respected as predefined. Thus, safety is provided due to the road handling. Last but not least, the perceived quality is improved since the noise is reduced, and vibrations felt by passengers—standing and sitting ones—varnish. 
     The document US2007/0018419 A1 discloses a wheel suspension arm mounting structure of a vehicle. It includes a lower suspension arm with two branches, namely a front member and a rear member, which are coupled to each other by a king pin support boss with a plate shape. 
     The document DE 28 35 865 A1 discloses a bus with a least six wheels. The wheels are connected to the chassis by means of pairs of arms. Gas springs and dampers are attached to the upper arms and to lower arms respectively. 
     The document WO2005/0303509 A1 provides a wheel supporting apparatus improving ride comfort for a vehicle. 
     Technical Problem to be Solved 
     It is an objective of the invention to present a suspension assembly, which overcomes at least some of the disadvantages of the prior art. The invention intends to improve the strength and the compactness of a suspension assembly. 
     SUMMARY OF THE INVENTION 
     According to a first object of the invention a suspension assembly is provided. The suspension assembly for a vehicle, notably a bus, the suspension assembly comprising: a transversal direction, a transversal wheel rotation axis, a wheel support for a wheel, an upper link pivotably joined to the wheel support, a damping device adapted for absorbing energy, a lower link comprising a portion of reduced thickness and two transversal branches, at least one of the two transversal branches being vertically thicker than the portion of reduced thickness and joining transversally the portion of reduced thickness to the damping device. 
     Preferably, the portion of reduced thickness comprises a plate and the transversal branches comprises two hollow rods 
     Preferably, the two transversal branches are longitudinally distant from each other and longitudinally joined by the portion of reduced thickness, the lower link comprising a vertical passage between the two transversal branches. 
     Preferably, the upper link comprises a longitudinal pivot axis which is across the damping device, preferably the damping device comprises an upper joint through which said longitudinal pivot axis is disposed. The current arrangement improves compactness. The damping effect is more gradual. Preferably, each of the two transversal branches is transversally longer than the portion of reduced thickness, and the portion of reduced thickness is longitudinally thicker than each of the two transversal branches. 
     Preferably, the suspension assembly comprises a wheel with a rim comprising an inner space in which the portion or reduced thickness is, at least partially, disposed. 
     Preferably, the suspension assembly comprises an electric engine adapted for rotating the wheel about the transversal wheel rotation axis, optionally said electric engine is vertically level with the damping device, the electric engine notably being an in-wheel engine. 
     Preferably, the portion of reduced thickness extends transversally along the whole electric engine, or along a portion of the electric engine. 
     Preferably, the damping device comprises lower fixation means joined to the transversal branches, and/or the portion of reduced thickness and the wheel support are joined by a ball joint notably disposed through the portion of reduced thickness. 
     Preferably, the lower link comprises an outer half joined to the wheel support, and an inner half joined to the damping device, said inner half being notably formed by the transversal branches, optionally totally formed by the transversal branches. 
     Preferably, the damping device comprises a tubular body projecting between the lower link and the upper link, and the damping device being a gas damper or an oil damper. 
     Preferably, the transversal branches comprise transversal notches in which the portion of reduced thickness is fixed, the lower link notably comprises a centre and a central segment at said centre which extends on at most the half of the lower link, the portion of reduced thickness and the transversal branches overlapping each other in said central segment. 
     Preferably, the suspension assembly comprises a hollow space around the damping device and extending at least on the half of the height of said damping device. 
     Preferably, the suspension assembly comprises a gas spring, notably a gas actuator, which is joined to the upper link, the suspension assembly comprises a separation, notably a transversal separation, between the gas spring, respectively the gas actuator, and the damping device. 
     Preferably, the upper link comprises an upper portion of reduced thickness to which the wheel support is pivotably linked, and two upper transversal branches extending from the upper portion of reduced thickness; the upper link and the lower link define a parallelogram. 
     Preferably, the lower link comprises two inboard pivot joints. 
     Preferably, at least one of the two transversal branches extend transversally along at least the half of said lower link. 
     Preferably, the plate is a solid plate. 
     Preferably, the transversal wheel rotation axis is disposed through the wheel support. 
     Preferably, the upper link and the lower link are similar. 
     each transversal inner end of the transversal branches of the lower link and/or of the upper link comprises a pivot joint. 
     Preferably, the damping system is joined to the lower link transversally at distance from the portion of reduced thickness. 
     Preferably, the rotation axis of the wheel is vertically between the upper link and the lower link. 
     Preferably, the rotation axes of the electric engine and of the wheel are colinear. 
     Preferably, the electric engine is disposed vertically between the upper link and the lower link. 
     Preferably, the electric engine faces transversally the damping device, notably between the upper link and the lower link. 
     Preferably, the lower link comprises a lower face and an upper face, the wheel support and the damping device protruding on the upper face. 
     Preferably, the transversal branches are each inclined with respect to the transversal direction. 
     Preferably, the damping device is disposed in the parallelogram. 
     Preferably, the wheel support is a knuckle, notably a steering knuckle. 
     Preferably, the suspension assembly comprises a steering actuator coupled to the wheel support, respectively to the steering knuckle. 
     Preferably, at least one of the branches of the upper link and at least one of the branches of the lower link define a parallelogram. 
     Preferably, the portion of reduced thickness of the upper link and the portion of reduced thickness of the lower link define a parallelogram. 
     Preferably, the portion of reduced thickness transversally overlaps the electric engine. 
     Preferably, the notches transversally overlap the electric engine. 
     Preferably, the portion of reduced thickness protrudes from the inner space, and/or comprises an inner portion outside the inner space, respectively the wheel. 
     Preferably, the portion of reduced thickness transversally extends over a majority of the engine. 
     It is another object of the invention to provide a suspension assembly for a vehicle, the assembly comprising: a transversal axis; a damping device adapted for absorbing energy; a wheel support intended to receive a wheel rotating about the transversal axis; a lower link comprising a portion of reduced thickness attached to the wheel support, and two branches vertically thicker than the portion of reduced thickness and attached to the damping device and/or at least one of the two transversal branches being attached to the damping device. 
     It is another object of the invention to provide a suspension assembly for a vehicle, the assembly comprising: a transversal axis; a damping device; a wheel support intended to receive a wheel rotating about the transversal axis; a lower link comprising a plate attached to the wheel support and to transversal branches extending from the plate and being thicker than said plate, the damping device being attached to one of the transversal branches. 
     It is another object of the invention to provide a suspension assembly for a vehicle, the assembly comprising: a transversal axis; a damping device; a wheel support intended to receive a wheel rotating about the transversal axis; a lower link with a plate connecting two transversal branches; wherein at least one of the two transversal branches is vertically thicker than the plate and joining transversally the damping device to the plate. 
     It is another object of the invention to provide a suspension assembly for a vehicle, notably a bus, the suspension assembly comprising: a transversal direction, a transversal wheel rotation axis, a wheel support for a wheel, an electric engine, an upper link pivotably joined to the wheel support, a damping device adapted for absorbing energy, a lower link comprising a portion of reduced thickness and two transversal branches; at least one of the two transversal branches being optionally vertically thicker than the portion of reduced thickness, and joining transversally the portion of reduced thickness to the damping device; said portion of reduced thickness transversally overlapping the electric engine. 
     It is another object of the invention to provide a bus, notably an articulated bus, the bus comprising a suspension assembly in accordance with the invention, the suspension assembly being configured such that the transversal wheel rotation axis is movable, at least between an upper position and a lower position with respect to the chassis frame; preferably the bus comprises several units with identical suspension assemblies. 
     Preferably, the suspension assembly is a first suspension assembly, the bus further comprising a second suspension assembly, and a passenger platform between the first suspension assembly and the second suspension assembly which projects transversally over at least the half of the width of the bus. 
     Preferably, the bus comprises a wheel housing in which the suspension assembly is disposed 
     Preferably, the bus comprises a passenger capacity of at least one hundred passengers. 
     It is another object of the invention to provide a bus assembly process, the bus notably being a low platform bus, the bus assembling process comprising the steps of: providing a chassis frame for the bus, joining an upper link to the chassis frame; providing a wheel support, joining a damping device to the chassis frame; providing a lower link comprising two transversal branches and a portion of reduced thickness which is thinner than the transversal branches, joining the chassis frame to the wheel support and the damping device through the portion of reduced thickness and the transversal branches respectively; the upper link the lower link, the wheel support and the damping device notably forming a suspension assembly in accordance with the invention, and/or the bus being in accordance with the invention. 
     Preferably, the wheel support is joined to the portion of reduced thickness before the damping device is joined to at least one of the two transversal branches. 
     Preferably, the damping device and the upper link are joined to the chassis frame before the wheel support is joined to the upper link and the lower link, and/or the damping device and the upper link are joined to the chassis frame at the same time and/or together. 
     The different objects of the invention may be combined to each other. In addition, the preferable features of each object of the invention may be combined with the other objects of the invention, unless the contrary is explicitly mentioned. 
     Technical Advantages of the Invention 
     The invention provides a first technical advantage on the compacity of the suspension assembly by providing an optimized lower link. Indeed, the arrangement of the transversal branches and of the portion of reduced thickness copes with the available place in the wheels and bending stresses. The branches and the portion may have similar stiffnesses, however their shapes are adapted to their dedicated space. The weight distribution is optimised in order to limit the unbalanced weights. 
     In addition, the invention allows a cost reduction since the upper link and the lower link are similar. Thus, a single link model may be used for the whole bus model. The invention also promotes cooling of the damping device, which is notably relevant where an in-wheel electric engine faces said damping device. The position of the portion of reduced thickness along the engine improves the compactness, and optimizes the use of space. More place is available for the vertical swinging motions of the engine. 
     Moreover, the suspension assembly remains easy to assemble in a narrow wheel housing. Inspection and mounting remain user friendly. 
    
    
     
       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 
         FIG. 1  provides a schematic illustration of a side view of a bus in accordance with a preferred embodiment of the invention; 
         FIG. 2  provides a schematic illustration of an aerial view of a portion of a chassis frame in accordance with a preferred embodiment of the invention; 
         FIG. 3  provides a schematic illustration of side view of a wheel housing of a bus in accordance with a preferred embodiment of the invention; 
         FIG. 4  provides a schematic illustration of a longitudinal view of a suspension assembly in accordance with a preferred embodiment of the invention; 
         FIG. 5  provides a schematic illustration of a top view of a suspension assembly in accordance with a preferred embodiment of the invention; 
         FIG. 6  provides a schematic illustration of a longitudinal view of a suspension assembly in accordance with a preferred embodiment of the invention; 
         FIG. 7  provides a schematic illustration of a bus assembling 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. 
     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 bus in accordance with the invention is evidently controlled by a computer, even though such a computer is not explicitly referenced on the figures nor referenced in the description. 
     By way of convention, it may be defined that the word “longitudinal” refers to the longitudinal direction and may correspond to the main driving direction of the bus. It may be along the main central axis of the vehicle. The word “transversal” refers to the transversal direction and may be perpendicular to the longitudinal direction. It may be understood that the directions are not used in a strict meaning. Indeed, each direction used below may include a variation of at most: 5°, or 2°, or 1°, with respect to a strict meaning. The skilled in the art will understood that a longitudinal pivot axis may be inclined with respect to the longitudinal direction of the bus and/or the horizontal direction. 
     In the following description and claims, the mentioned length(s), width(s), and thickness(es) may be average ones. 
     It should be noticed that the present drawings generally provide configurations where wheels are substantially parallel to the longitudinal direction. The steering angle is of 0°. The vehicle may drive along a straight rajectory. However, the skilled in the art will be able to adapt the following teaching to situations where the steering angle of the bus is changed. 
       FIG. 1  shows a vehicle for mass transportation in accordance with a preferred embodiment of the invention. The vehicle is partially represented. 
     The vehicle is adapted for transportation of passengers in cities and may transport about one hundred passengers, for instance one hundred and twenty passengers. The vehicle may be a bus  2 , notably an electric bus  2 . The bus  2  may include electric driving engines and electric batteries (not represented) powering the electric driving engines. The bus  2  may be purely electric, in the meaning that it is free of combustion engine. 
     The bus  2  may be an articulated bus. It may comprise a first unit  4  and a second unit  4  (partially represented). Each unit  4 , may form a body, and/or may form a rigid element. 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 connection, for instance a hinged connection  6  enabling the units  4  to swivel 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 electric bus  2  includes three, four, or more units  4 ; which are articulated with respect to one another by hinged connection(s)  6 . 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 hinged connection  6 . 
     A bus formed of a single unit is also considered in the invention. 
     Each unit  4  may include several wheels  8  engaging the ground G. Pairs of symmetric wheels  8  may form axles, for instance four axles for each unit  4 . The axles and thus the wheels  8  may be distributed along the length of the bus  2 . At least one pair of wheels 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. The roof  10  may support an air conditioning system, and other systems as well. 
     The bus  2  may include a bus structure, notably a chassis frame  11 . The chassis frame  11  may distribute and/or support the weight of the bus, and load therein. The chassis frame  11  may include a roof  10 , and/or a passenger platform  12 , and/or 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 . They may form the bodywork of the bus  2 . They may cover transversally the wheels  8 . The bodywork may be part of the bus structure. The side walls  14  may receive windows  16  and doors  17  for passengers. Optionally, doors  17  are arranged in one of the two side walls  14 , notably between windows  16 . 
     For instance; the side walls  14  may close the wheel housings  18 . Optionally, at least one or each wheel housing  18  may receive two longitudinally spaced wheels  8 . The wheel housings  18  may form downwardly open boxes. The wheel housings  18  may be longitudinally at distance from the ends of the units  4 . The wheel housings  18  may be arranged below the windows  16 . The door  17  may be disposed between two wheel housings  18  of the corresponding unit  4 . 
     Generally, the or each wheel housing  18  may be understood a space in which at least one wheel is arranged. The or each wheel housing  18  may be a wheel cavity. The or each wheel housing  18  may be a wheel guard. 
     The bus  2  may comprise a gas supply  20 . 
       FIG. 2  provides an aerial illustration of the under structure  22  of the chassis frame  11  of a bus  2 , or from a unit  4  in accordance with a preferred embodiment of the invention. The longitudinal central axis L and the transversal direction TR are represented. The longitudinal central axis L may correspond to the longitudinal direction L, and may be horizontal. 
     The bus  2  and/or the unit  4  may correspond to those as described in relation with  FIG. 1 . Two pairs or wheels  8  are disposed in respective wheel housings  18 . The rotations axes  9  of the wheel are represented. The wheel rotations axes  9  may correspond to the axles when the wheels  8  are aligned at each side. It may be understood that the wheels  8  comprise toe-in or toe-out. Thus, the term “aligned” may be understood in the meaning of the environment of the invention. 
     The under structure  22  may form the platform  12  of the bus  2 . The platform  12  may be a passenger platform, and may include a passenger floor on which the passengers (not represented) may stand and walk. The chassis frame  11 , notably the under structure  22 , may comprise longitudinal beams, notably lower longitudinal beams  24 . The longitudinal beams, and possibly the lower longitudinal beams  24 , may extend on the whole length of the unit  4 , or at least on majority of the length of the unit  4 . The lower longitudinal beams  24  may delimit the wheel housings  18 . 
     The chassis frame  11 , notably the under structure  22 , may comprise transversal beams  26 . The transversal beams  26  project from one lower longitudinal beam  24  to the opposite lower longitudinal beam  24 . 
     The wheel housings  18  may comprise transversal bars  28 . The transversal bars  28  may form the longitudinal ends of the wheel housings  18 . The wheel housings  18  may further comprise upper longitudinal beams  30  at their transversal outer end. These upper beams  30  may form the side walls  14 . 
     At least one wheel  8  is disposed in at least one wheel housing  18 . At least one or each wheel housing  18  encloses two wheels  8 . The wheels  8  may be received by pairs in the wheel housings  18 . The wheels  8  of each pair are adapted to run on the same wheel path. These wheels  8  may be transversally aligned. In each pair, the wheels  8  are longitudinally offset. A longitudinal distance  32  may separate them. The longitudinal distance  32  may be shorter than the transversal width W of the wheels  8 . The wheels  8  of each pair may be identical. 
     The width of the bus may be of about 2.5 m. Along and/or between the wheel housings  18 , the passenger platform  12  may extend at least on the half of the width of the bus  2 . At least one or each wheel housing  18  may extend on at most the quarter of the width of the bus  2 . This feature eases longitudinal circulation within the passenger compartment, and allows two pushchairs to cross each other between the wheel housings  18 . It also provides the technical effect of strengthening the platform  12 . 
     The bus may comprise at least one suspension assembly  34 , possibly several suspension assemblies  34 . The suspension assemblies  34  may be independent from each other mechanically. Each suspension assembly  34  may connect one of the wheels  8  to the chassis frame  11 , and/or to the corresponding wheel housing  18 . Each wheel  8  may be independently linked to its wheel housing  18 . 
     At least one or each suspension assembly  34  may comprise one or several links. In at least one or in each suspension assembly  34  the links may be parallel. The links may be pivotably linked to the longitudinal beams, for instance to the lower longitudinal beams  24 . The links may be pivoting links. The links may be swinging arms. The links may essentially project transversally. 
     In at least one or in each suspension assembly  34  the links may comprise a lower link (not represented) and an upper link  36  over the lower link. The upper links  36  may pivot about upper longitudinal pivot axes  38 . The upper links  36  and the lower links may be identical. In the current top view, each upper link  36  may mask the associated lower link. 
     At least one or each suspension assembly  34  may comprise an actuator, notably a gas actuator  40 . The gas actuators  40  may be joined to the upper links  36 . The gas actuators  40  may be in contact of the upper links  36 . The gas actuators  40  may comprise gas springs. The gas actuators may be in fluid communication with the gas supply  20 . The gas supply  20  may be arranged along one of the wheel housings  18 . 
     At least one or each suspension assembly  34  may comprise a damping device  64 . Each damping device  64  may be mechanically coupled to the chassis frame  11 . At least one or each damping device may be mechanically coupled to a lower link (not represented). At least one or each lower link comprises a portion of reduced thickness and two transversal branches. At least one or each transversal branch may be vertically thicker than the portion of reduced thickness and joining transversally the portion of reduced thickness to the damping device. The portions of reduced thickness may enter the wheels  8 , and the transversal branches may remain outside the wheels  8 , thus allowing a wheel size reduction while maintaining an important wheel vertical displacement. 
       FIG. 3  provides a schematic illustration of a side view of a bus portion in accordance with a preferred embodiment of the invention. The current side view may correspond to a side view of  FIG. 2 . The side view is centred on a wheel housing  18  within a chassis frame  11 . The wheel housing  18  may correspond to those as described in relation with any one of  FIGS. 1 and 2 . 
     The wheel housing  18  receives two wheels  8  which may be below the upper longitudinal beam  30 . The wheel housing  18  may comprise vertical bars  42 , which may project from the transversal bars  28 . 
     The lower longitudinal beam  24  may be a first longitudinal beam  24 . The wheel housing  18 , and more generally, the chassis frame  11 , may further comprise a second longitudinal beam  44  and a third longitudinal beam  46 . The second longitudinal beam  44  may be between the first longitudinal beam  24  and the third longitudinal beam  46 . These three longitudinal beams may be parallel. They may be above one another. They may define an inboard wall of the wheel housing  18 . The third longitudinal beam  46  may be the uppermost longitudinal beam of the wheel housing  18 . The beams ( 24 ;  30 ;  44 ;  46 ) and bars ( 28 ;  42 ) may be part of the chassis frame  11  of the bus  2 . Plates or sheets may be fixed to the beams and bars in order to strengthen the chassis frame  11 . Beams and bars may be tubular profiles. 
     The chassis frame  11 , notably the wheel housing  18 , may exhibit a vertical portion enclosing the first longitudinal beam  24 , the second longitudinal beam  44  and the third longitudinal beam  46 . This vertical portion may be an inboard portion. It may form a barrier or a wall. The chassis frame  11 , notably the wheel housing  18 , may exhibit a horizontal portion enclosing the third longitudinal beam  46  and the upper longitudinal beams  30 . The horizontal portion may form a top portion of the wheel housing  18 . The horizontal portion may receive a seat (not represented). The third longitudinal beam  46  and the upper longitudinal beam  30  may be connected by a transversal bar (here hidden by the upper longitudinal beam). 
     Each wheel  8  may be linked to the wheel housing  18 , respectively to the chassis frame  11 , by a dedicated suspension assembly  34 . Thus, the wheels  8  may oscillate between a lower position represented with dotted lines, and an upper position represented in plain lines. These positions may be respectively a first position and a second position, or a driving position and a boarding position respectively. The distance D between these positions may be measured at the summit of the wheels  8 . The longitudinal distance  32  between the wheels  8  in the wheel housing  18  may be the same in the upper position and in the lower position. Each suspension assembly  34  may be encircled by one of the wheel housings  18  in order to respect compacity requirements. 
     Alternatively or in addition, the distance D may be measured by means of the rotation axes ( 9 L,  9 L) of the wheels  8 . In the lower position, the rotation axes  9 L are in lower positions, in the upper position the rotation axes  9 U are in upper positions. These positions are positions of the wheels  8  with respect to the platform  12 . In the lower position, the rotation axes  9 L may be vertically level with the platform  12 , notably within the thickness TH of the platform  12 . In the upper position the rotation axes  9 U may be above the platform  12 . In the upper position, the upper surface of the platform, for instance the passenger floor  12 F, may be at distance and below the rotation axes  9 U. Thus, in the lower position of the wheels  8 , the platform  12  is raised from the ground G, whereas in the upper position, the platform  12  approaches the ground G, and the ground clearance  48  reduces. The ground clearance  48 , in the first position and notably in the second direction, may be larger than the thickness TH of the platform  12 . The distance D between the upper position and the lower position may be greater than the vertical thickness TH, possibly the average thickness, of the passenger platform  12 . The distance D may be larger than the vertical thickness TH. 
     This implies that the thickness TH is reduced, and that the platform is a low floor platform which eases access to the passenger compartment  49 . The thickness TH may be of at most: 10 cm, or 7 cm. 
     The gas actuator  40  may comprise an upper bracket  50 . The upper bracket  50  may be a transversal upper bracket  50 . The upper bracket  50  may project transversally from one of the longitudinal beams, possibly from the third longitudinal beam  46 . 
     As a general aspect of the invention, it may be understood that the bracket  50  is an actuator support. 
     A vertical bar  42  of the wheel housing  18  may cross at least one longitudinal beam, for instance the second and/or the third longitudinal beam  46 . Thus, it may be considered that the corresponding longitudinal beam is segmented along the longitudinal direction L. However, the segments of the cut longitudinal beam may be aligned as in a single beam. 
       FIG. 4  provides a schematic illustration of a suspension assembly  34  in accordance with a preferred embodiment of the invention. The suspension assembly  34  may correspond to the ones as described in relation with any one of  FIGS. 2 to 3 . In the current figure, the wheel  8  is in the lower position. The suspension assembly  34  is in the lower configuration. 
     The suspension assembly  34  may be enclosed in the wheel housing  18 , wherein the wheel  8  is partially contained. Thus, the ground clearance  48  is preserved, at least in the driving configuration, and the suspension assembly  34  is less exposed to protruding surfaces of the ground which could damage it. 
     The wheel housing  18  may support at least one seat  52 , possibly a seat row of the bus  2 . The wheel housing  18  may support and/or receive and/or extend along at least three or four seats  52 . The seats may be identical. Each seat may comprise a seat base  52 B and a back rest  52 BR which may mate the side wall  14 . The seat base  52 B may substantially extend on the whole transversal width of the wheel housing  18 . The seat  52  may generally be a seat area  52 A. A seat area  52 A may be adapted for receiving a seated passenger. It may have a longitudinal length comprised between 0.4 m and 1 m. It may have a concave main surface, and/or rounded side edges. 
     At least one or each seat  52  on the wheel housing  18  may face the longitudinal centreline L of the passenger compartment  49 . Thus, the current arrangement adapts technically the suspension assembly  34  to a wheel housing  18 , and notably a chassis frame  11 , supporting seats  52  for passengers. 
     The suspension assembly  34  may comprise a lower link  35 . The lower link  36  may be parallel to the upper link  36 . The upper and lower link ( 36 ;  35 ) may define a parallelogram. They may have the same transversal width. As an option, the arms ( 36 ;  35 ) have different longitudinal lengths. The arms ( 36 ;  35 ) may form a first parallelogram in the lower position (illustrated by means the rotation axis  9 L) and in the upper position (illustrated by means the rotation axis  9 U) of the wheel  8 . The upper and lower link ( 36 ;  35 ) may generally be a first arm and a second arm, respectively. 
     The suspension assembly  34  may comprise a wheel support  54  for instance a knuckle. The wheel support  54  may be a steering knuckle. The wheel support  54  may be part of the first parallelogram. It may be joined, for instance pivotably attached, to the lower link  35  and to the upper link  36 . The wheel support  54  may comprise a kingpin. The wheel support  54  may rotate about a vertical pivot axis  55  due to an actuation of a steering actuator (not represented). The wheel  8  may be rotatably fixed to the wheel support  54 , and may rotate about its rotation axis  9 L. The vertical pivot axis  55  may be within the wheel  8  in order to lower steering efforts, and to shorten the steering radius. 
     The knuckle  54  may receive an engine  56  associated with the wheel  8 . The engine may comprise a rotor and a stator (not represented). The engine  56  may be an electric engine  56 . It may rotate the wheel  8  in order to drive the bus  2 . The engine  56  may be an in-wheel engine. The engine  56  may be arranged around the rotation axis  9 L of the wheel  8 . It may be smaller than the rim  8 R of the wheel  8 . It may be arranged between the lower link  35  and the upper link  36 , notably in the parallelogram that they form in order to improve compactness. 
     The upper link  36  may be joined to the second longitudinal beam  44 , for instance by means of an upper pivot which pivots about a longitudinal pivot axis  38 . The lower link  35  may be joined to the first longitudinal beam  24 , for instance by means of a pivot  60  which pivots about a lower longitudinal pivot axis  38 . 
     The suspension assembly  34  may comprise a gearbox (not represented). The gearbox may be housed in the wheel support. The gearbox may be coupled to the engine  56 . 
     The second longitudinal beam  44  may be closer to the third longitudinal beam  46  than to the first longitudinal beam  24 . Thus, the upper half of the wheel housing  18  is stiffer. In addition, the second longitudinal beam  44  provide an additional protection to passenger legs against side collisions from other vehicles. The longitudinal beams ( 24 ,  44 ,  46 ) may more generally be horizontal beams. They may be connected by at least one vertical bar  42 . 
     The vertical thickness of the first longitudinal beam  24  may be equal or similar to the thickness TH of the passenger platform  12 . The thickness TH of the passenger platform  12 , and notably the vertical thickness of the first longitudinal beam  24 , may be smaller than the ground clearance  48 . They may be thinner than 0.1 m. 
     The gas actuator  40  may comprise a lower element  40 L. The lower element  40 L may be fixed to the upper link  38 . The lower element  40 L may form the lower end of the gas actuator  40 . The lower element  40 L and the upper link  36  may be joined through a mechanical joint  40 J. The mechanical joint  40 J may comprise a pivot joint or a ball joint. It may allow a pivot about a longitudinal pivot axis  38 . 
     In the driving configuration and/or in the docking configuration where the bus is forcibly tilted toward the side of a bus stop, the altitude of the passenger floor  12 F may be smaller than: 0.5 m; or 0.4 m; or 0.3 m. The altitude may correspond to the addition of the ground clearance  48  and the thickness TH. 
     The gas actuator  40  may be vertically level with the wheel  8 . They may face each other. The tire  8 T of the wheel  8  may be vertically level with the lower element  40 L. The wheel rotation may foster an air flow within the wheel housing  18 , and thus cool the gas actuator  40 . Then, the working conditions of the gas actuator may be adapted. 
     The gas actuator  40  may comprise a pressurized enclosure  58 . The upper element and the lower element  40 L may comprise a plate, possibly a horizontal plate. By varying the pressure within the pressurized enclosure  58 , the height of the gas actuator  40  may be modified in order to move the wheel  8  within the wheel housing  18 . 
     Further, the gas actuator  40  may form a spring. Then, varying the pressure allows a stiffness evolution of the corresponding spring. This aspect adapts the suspension assembly  34  to the number of passengers in the passenger compartment, or more generally to the load in the bus even under a heterogeneous load distribution. 
     The upper link  36  may comprise an inner half  36 I and an outer half  36 O. The inner half  36 I and the outer half  36 O may be considered transversally. They may be considered along the transversal width of the upper link  36 . 
     The inner half  36 I may be joined to the wheel housing, notably to the second longitudinal beam  44 , by means of a pivot joint  60  which pivots about the longitudinal pivot axis  38  and which is fixed to the second longitudinal beam  44 . The outer half  36 O may be joined to the wheel support  54 , possibly through an outer mechanical joint  62 . A pivot joint and/or ball joint may form said outer mechanical joint  62 . 
     The gas actuator  40  may be connected to the upper link  36  at a location within the inner half  36 I of said upper link  36 . More precisely, the mechanical joint  40 J may be arranged within, and/or in contact of the inner half  36 I. Notably transversally, the mechanical joint  40 J may be closer to the pivot joint  60  than to the outer mechanical joints  62  of the upper link  36 . 
     The lower link  35  may be connected to the wheel housing  18  and to the knuckle  54  by a similar pivot joint  60  fixed to the first longitudinal beam  24  and a similar outer mechanical joint  62 . The outer mechanical joints  62  may define the vertical pivot axis  55  about which the knuckle  54 , and by way of consequence the wheel  8 , is steered. 
     The suspension assembly  34  may comprise a damping device  64 . The damping device  64  may be separate and distinct from the gas actuator  40 . The damping device  64  may be adapted for absorbing vibrations transmitted by the wheel  8  to the chassis frame  11  of the bus structure. It may convert mechanical energy into thermal energy. The damping device  64  may be inclined with respect to gas actuator  40 , notably in the upper and in the lower position. The damping device  64  may exhibit a centre line inclined with respect to the centre line of the gas actuator, notably in the upper and in the lower position. The centre lines may be lines along which the corresponding actuator or system works. Thus, the kinematics are different, and the mechanical resistances show different progressions in function of the inclination of the arms with respect the passenger platform  12 . The lower link  35  may comprise an inner half  35 I and an outer half  35 O. The damping device  64  may be joined to the inner half  35 I of the lower link  35 . 
     The damping device  64  may be joined to the lower link  35 . It may be at distance from the gas actuator  40 . The upper end of the damping device  64  may be joined to the second longitudinal beam  44 . As an option, the damping device  64  is joined to the upper pivot joint  60  of the upper link  36 . Thus, the upper link  36  may connect the damping device  64  to the gas actuator  40 . The damping device  64  may extend on the whole vertical thickness of the parallelogram defined by the links ( 35 ;  36 ). Thus, the use of the space in said parallelogram is optimised. The stroke and the inclination of the damping device  64  may be adapted to the cinematic of the parallelogram. 
     The upper end of the damping device  64  may be joined to the chassis frame  11 . The longitudinal pivot axis  38  of the upper link  38  may project through the damping device  64 , which implies that the suspension assembly  34  is compact. In addition, the position of the damping device  64  with regard to the pivot axis  38  implies that its motions from above are reduced. 
     The damping device  64  and the gas actuator  40  may be arranged above one another. They may be transversally at distance from each other. A transversal separation may be arranged between the damping device  64  and the gas actuator  40 . This separation may extend along the whole interface between the damping device  64  and the gas actuator  40 . 
     The lower link  35  may comprise a portion of reduced thickness and two transversal branches, at least one of the two transversal branches being vertically thicker than the portion of reduced thickness and joining transversally a portion of reduced thickness to the damping device  64 . 
     The upper link  36  may comprise a portion of reduced thickness and two transversal branches, the transversal branches being vertically thicker than the portion of reduced thickness. 
     The lower link  35  and the upper link  36  may be mirrored. They may be similar or identical. 
     The transversal branches of the lower link  35  may be identical to the transversal branches of the upper link  36 . The portion of reduced thickness of the lower link  35  may be identical to the portion of reduced thickness of the upper link  36 . Their outer mechanical joints  62  may be identical. A same link model may be used for the upper one and for the lower one. Then an economy of scale is allowed. This advantage is offered whereas the links are coupled to different devices, namely the damping device  64  and the gas actuator  40 . 
     The rim  8  surrounds an inner space  81  in the wheel  8 . The inner space  81  in the rim  8 R may receive the portion or reduced thickness of the lower link  35  and/or of the upper ling  36 . These portions of reduced thickness may be partially in the inner space  81 . They may be encircled by the rim  8 R. 
       FIG. 5  shows an aerial view of a suspension assembly  34  in a preferred embodiment of the invention. The damping device  64  is represented in dotted lines for the sake of clarity. A portion of the chassis frame  11  is also represented in dotted lines for the same purpose. The represented portion of the chassis frame  11  may correspond to a longitudinal beam  24 . The transversal direction T, the longitudinal direction L and the vertical direction V are provided. These directions (T, L, V) may be perpendicular to each other. 
     The suspension assembly  34  may correspond to the one as described in relation with anyone of  FIGS. 2 to 4 . 
     The lower link  35  may comprise a portion a portion of reduced thickness  66 . The portion of reduced thickness  66  may comprise a plate. The plate may be solid. The portion of reduced thickness  66  may be flat. The portion of reduced thickness  66  may have a constant vertical thickness. The portion of reduced thickness  66  may form the outer transversal end of the lower link  35 . It may receive the outer mechanical joint  62 , for instance therethrough. The portion of reduced thickness  66  may be arranged below the wheel support  54 . 
     The lower link  35  may comprise transversal branches  68 . The transversal branches  68  may be inclined with respect to each other, for instance of an angle of at least 10°. The transversal branches  68  may be inclined with respect to the rotation axis  9  and notably to the transversal direction T. The transversal branches  68  may be symmetric with respect to the rotation axis  9  when the latter is aligned with the transversal direction T. The transversal branches  68  may be rods, for instance hollow rods as tubes. 
     Each transversal branch  68  may join the portion of reduced thickness  66  to the chassis frame  11 ; respectively the longitudinal beam  24 . The pivot joints  60  at the inner, or inboard, ends of the transversal branches  68  may comprise yokes, or forks, fixed to the chassis frame  11 . Then the transversal branches  68 , and thus the whole lower link  35  may pivot about the longitudinal pivot axis  38 . 
     The lower link  35  may comprise a recess between the transversal branches  68 . The lower link  35  may comprise at least one vertical passage  72  between the transversal branches  68 . The at least one vertical passage  72  may correspond to the recess. The vertical passage(s)  72  may cross vertically the lower link  35 . The vertical passage(s)  72  may communicate from the upper face of the lower link  35  to its lower face. It may be delimited by the portion of reduced thickness  66  and/or by the chassis frame  1 . It may extend all along the transversal branches  68 . 
     At least one or the two transversal branches  68  may be transversally longer than the portion of reduced thickness  66 , for instance at least two or three times longer. The portion of reduced thickness  66  may be longitudinally thicker than at least one or each of the two transversal branches  68 , for instance at least: three or five times thicker. Thus, this configuration optimises the stiffness and the lightness. 
     The damping device  64  may comprise lower fixation means  74 . The lower fixation means  74  may comprise a fixation axis projecting longitudinally. They may comprise a longitudinal link, for instance linked to the transversal branches  68 . The lower fixation means  74  may be fixed to at least one or to each of the transversal branches  68 . The lower fixation means  74  may comprise a pivot axis  70  about which the damping device  64  may pivot with respect to the lower link  35 . The lower fixation means  74  may cross longitudinally the vertical passage  72 . The lower fixation means  74  may divide transversally the vertical passage  72 . 
     The portion of reduced thickness  66  and the wheel support  54  may be joined by an outer mechanical joint  62 . The outer mechanical joint  62  may be a ball joint  76 . The ball joint  76  may be arranged within the portion of reduced thickness  66 , notably at distance from the transversal branches  68 . Thus, more space is provided to the wheel support  54  for pivoting about the vertical pivot axis  55 . 
     The damping device  64  may comprise a tubular body  78 . The damping device  64  may be a gas damper or an oil damper. The damping device  64  may be adapted for absorbing shocks from the road and transmitted by the wheel during driving. It may be adapted for resisting to its compression or rebound motions. It may generate a resisting effort which is proportional to its elongation variation speed. 
     The suspension assembly  34  may comprises a hollow space  80  around the damping device  64 . The hollow space  80  may extend at least on the half of the height of said damping device  64 , possibly substantially the whole height. The hollow space  80  may extend vertically from the transversal branches  68 , possibly up to the upper link (not represented). The hollow space  80  may extend transversally from the chassis frame  11 . The hollow space  80  may project on the whole longitudinal length of the lower link  35 . 
     The upper arm (not represented) may be similar or identical to the lower link  35 . They may comprise identical portions of reduced thickness  66 . They may comprise identical transversal branches  68 . They may comprise identical ball joints. They may comprise similar or identical vertical passages  72 . The engine (not represented) may extend longitudinally between the transversal branches  68 . 
       FIG. 6  shows a longitudinal view of a suspension assembly  34  in a preferred embodiment of the invention. The damping device  64  is represented in dotted lines for the sake of clarity. A portion of the chassis frame  11  is also represented in dotted lines for the same reasons. The transversal direction T, the longitudinal direction L and the vertical direction V are provided. These directions (T, L, V) may be perpendicular to each other. 
     The suspension assembly  34  in the current embodiment may correspond to the one as described in relation with anyone of  FIGS. 2 to 5 . 
     The portion of reduced thickness  66  and the wheel support  54  may be pivotably connected through an outer mechanical joint  62 . The outer mechanical joint  62  may comprise a ball joint  76 . A ball joint may be understood as a joint allowing rotation about three perpendicular axes. The ball joint  76  may be disposed through the thickness of the portion of reduced thickness  66 . It may comprise a body which crosses vertically the portion of reduced thickness  66 . The vertical pivot axis  55  may be through the ball joint  76 . 
     The portion of reduced thickness  66  may be transversally shorter than at least one, or each of the two transversal branches  68 , notably at least two times shorter. The vertical thickness of at least one or of each transversal branches  68  represent at least: 150%, or 200%, of the vertical thickness of the portion of reduced thickness  66 . The considered thickness of the portion  66  may be its average thickness. It may be the thickness of the plate forming said portion  66 . 
     The suspension assembly may comprise an electric engine  56 . The electric engine  56  may be arranged in a recess  81  of the wheel support  54 . The electric engine  56  may be adapted for rotating the corresponding wheel (not represented) about a transversal rotation axis  9 . It may participate to drive the bus. 
     The electric engine  56  may be an in-wheel engine. It may have a rotation axis which matches that of the wheel in order to improve compactness. The electric engine  56  may be vertically level with the damping device  64 . They may face each other transversally. The portion of reduced thickness  66  may overlap partially transversally thee electric engine  56 . The transversal branches  68  may be vertically, and notably transversally at distance from the electric engine  56 . 
     By way of example, the bus may comprise eight or sixteen wheels. Then, the bus may be driven by respectively, the eight or sixteen corresponding electric engines  56 . 
     The damping device  64  may comprise lower fixation means  74  joined to the transversal branches  68 . The lower fixation means  74  may be arranged in the thickness of said transversal branches  68 . Along the transversal direction T, the lower link  35  may comprises an outer half  35 O joined to the wheel support  54 , and an inner half  35 I joined to the damping device  64 . The inner half  35 I may be joined to the chassis frame  11  by means of the pivot joints  60  which oscillate about the longitudinal pivot axis  38 . The inner half  35 I may be formed totally by the transversal branches  68 , and optionally with the pivot joints  60  which are part of said transversal branches  68 . 
     The damping device  64  may comprises a tubular body  78 . It may be a gas damper or an oil damper. It may comprise a piston  82  which travels in a chamber  84  containing a damping medium (not represented) such as oil or gas. Such damping medium is well known from the skilled in the art and will not be discussed further. The flow of the damping medium through the piston  82  may brake the compression and the detent of the damping device  64 . 
     The transversal branches  68  may comprise notches  86 , for instance transversal notches  86 , in which the portion of reduced thickness  66  is fixed. Thus, the portion  66  and the transversal branches  68  overlap each other along the transversal notches  86 . Transversally, the lower link  35  may comprise a centre  88  and a central segment  90  at said centre  88 . The centre  88  may be the middle point. The central segment  90  may extend on at most the half or the third of transversal length of the lower link  35 . The central segment  90  may exhibit a constant thickness. The portion of reduced thickness  66  and the transversal branches  68  may overlap each other in said central portion  90 , which optimise the flexion stiffness of the lower link  35 . 
     The suspension assembly  34  may comprises a hollow space  80  around the damping device  64 . The damping device  64  may project through said hollow space  80 . The latter may extend at least on the half of the height of the damping device  64 , or along its whole height. The hollow space  80  may be disposed vertically between the upper link (not represented), and the lower link  35 . It may be transversally between the chassis frame  11  and the wheel support  54 . The hollow space  80  may be vertically level with the wheel (not represented). 
     Then the arrangement of the damping device  64  within its hollow space  80  fosters cooling. 
       FIG. 7  provides a schematic illustration of a bus assembling process, for instance with a suspension assembly. The suspension assembly may correspond to the ones as described in relation of any one of  FIGS. 2 to 6 . The bus may correspond to the ones as deduced from any of  FIGS. 1 to 6 . More generally, the bus assembling process may be a suspension assembly assembling process. 
     The process may comprise the following steps, for instance in the following order:
         providing  100  or manufacturing a chassis frame of the bus,   joining  102  an upper link to the chassis frame;   providing  104  a wheel support,   joining  106  a damping device to the chassis frame;   providing  108  a lower link comprising, along a transversal direction, two transversal branches and a portion of reduced thickness which is vertically thinner than each of the transversal branches,   joining  110  the chassis frame to the wheel support and to the damping device through the portion of reduced thickness and the branches respectively;   joining  112  a wheel on the wheel support.       

     At the end or during step joining  110 , the wheel support is joined to the portion of reduced thickness before the damping device is joined to one of the two transversal branches, or to each of the two transversal branches. 
     The damping device and the upper link may be joined to the chassis frame before the wheel support is joined to the upper link and to the lower link, for instance during step joining  106  a damping device, and/or during step joining  102 . 
     The damping device and the upper link may be joined to the chassis frame at the same time and/or together, for instance during step joining  106  a damping device, and/or during step joining  102 . 
     The damping device and the upper link may be physically in contact of the chassis frame, for instance through the pivot joints with longitudinal pivot axes. 
     It has been observed the portions of reduced thickness eases access to the damping device during assembly. Then, a faster and easier assembly is allowed. Besides this, inspection and maintenance are safer since removing the attached wheel, and optionally the wheel support, opens a wide lateral view on the damping device. 
     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.