US 20100307842Al (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0307842 A1 Oriet et al. (43) Pub. Date: Dec. 9, 2010

(54) MOUNTED ELECTRIC, (22) Filed: Jun. 9, 2009 INDEPENDENT, OF A VEHICLE Publication Classi?cation

' _ _ (51) Int. Cl. (75) Inventors. Leo P. Or1et, Rochester Hills, MI B62D 9/00 (200601) (US); Andre Bocancea, Windsor B62D 3/00 (2006 01) CA ' ( ) (52) US. Cl...... 180/624; 180/400 Correspondence Address: NAVISTAR CANADA, INC. (57) ABSTRACT C/O NaViStal‘, 1116- A chassis frame (10) has a cross member (22) that bridges 4201 WINFIELD ROAD, P-O- BOX 1488 right and left side rails (18, 20). Right and left units (14, WARRENVILLE, IL 60555 (Us) 16) comprising respective right and left steered road (24, 26) are suspended from the frame by respective multi (73) Assignee: International Truck Intellectual link suspensions (33). A steering system (28) steers the Property Company, LLC, Wheels. An (34) and gear box (3 6) mounted on Warrenville, IL (U S) the cross member is coupled to the right and left Wheels by respective drive shafts (38, 40). The Weight of a system (21) Appl, No.1 12/480,923 (42, 44) for the Wheels is supported by the frame.

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FIGURE 2 US 2010/0307842 A1 Dec. 9, 2010

CHASSIS MOUNTED ELECTRIC, inertia of the suspension, making it unable to respond as INDEPENDENT, STEERING AXLE OF A quickly to rapid changes in a road surface. VEHICLE [0010] A vehicle that uses only battery-powered electric propulsion removes an internal combustion engine from a FIELD OF THE INVENTION vehicle’s poWerplant, making compliance With tailpipe emis sion and fuel economy requirements non-issues because the [0001] This invention relates to Wheeled vehicles, espe vehicle is a no emissions (NE) vehicle. cially large trucks and busses. [0011] The inventive chassis-mounted electric, indepen dent, steeringitruck axle to be described here provides a BACKGROUND OF THE INVENTION signi?cant reduction in the ratio of unsprung to sprung Weight in conjunction With independent steering, resulting in [0002] Dependent steering axle suspensions have been improved vehicle handling and performance, an improve consistently used in virtually all commercial trucks and ment that Would be quite bene?cial to oWners/operators of buses. Dependent steering axle suspensions physically link large commercial vehicles. right and left steered Wheels by a solid cast iron bar (axle) [0012] The inventive chassis-mounted electric, indepen under the front of the vehicle. The bar is suspended from the dent, steeringitruck axle accomplishes these improvements chassis by heavy leaf springs and shock absorbers. through a combination of independent features that include: [0003] Such a design is inherently subject to conditions that mounting the electric motorbetWeen the chassis frame rails to include but are not necessarily limited to: axle oscillation remove the contribution of the electric motor from the When one front Wheel hits a bump; gyroscopic torque about unsprung Weight and removing the Wheel from the the steering axis than tends to turn the axle from left to right unsprung Weight. When the vehicle is being forWardly propelled; axle inertia [0013] The inventive chassis-mounted electric, indepen ampli?cation of original motion from a road bump; substan dent, steeringitruck axle has a ?ve through eight-link tial unsprung Weight due to a heavy bar that requires heavy (multi-link) suspension With combinations of coil springs in linkages and leaf springs (i.e., unsprung Weight) for its sus systems for each Wheel. Each link pension; Wheel misalignment if the axle becomes bent; and performs a speci?c truck Wheel-locating task to ensure con poor, or non-existent, lateral control of axle bar location, a stant steering stability and superior handling amid changing signi?cant performance issue. road and load conditions While the Wheels can move indepen [0004] The internal combustion engine, typically a diesel dently of one another. This reduces truck and bus chassis engine, has consistently been the poWerplant of large com movement on rough surfaces in comparison to Walking beam mercial vehicles. HoWever, alternate types of poWerplants are articulations Where as much as about eighteen inches is gaining more Widespread usage in the broader automotive required in knoWn designs While maintaining optimal Wheel industry for various reasons, primarily emission- and fuel control at all times. related. [0014] The main mechanism, components, and features [0005] One type of alternate-poWered vehicle has electric include: Chassis Mounted Electric Motor; Chassis Mounted drive motors mounted directly into the Wheels. Such a pro Electric Brakes; Chassis Mounted Rack-in-Pinion; Electric pulsion system hoWever signi?cantly increases the ratio of Steering Rack-in-Pinion; Independent Suspension; Common unsprung to sprung Weight of the vehicle. Sprung Weight Axle Architecture for front and rear application; All Wheel comprises the Weight of that portion of a vehicle supported by Steer (AWS)4electronic all-Wheel steering. the springs, and unsprung Weight comprises the Weight of the [0015] Using the inventive chassis-mounted electric, inde springs and that of the remainder of the vehicle. Wheel pendent, steeringitruck axle in both front and rear of a mounted motors are also subject to severe impacts from road vehicle gives the vehicle all Wheel steering (AWS), and hence bumps during service, and such impacts can signi?cantly a reduced turning radius (about 30%) for buses With tWo shorten the life of these electric drive units. steering . [0006] In one hybrid commercial vehicle, an example of [0016] One general aspect of the invention relates to a Which is the Orion VII Hybrid Transit Bus, an electric motor vehicle chassis comprising: a chassis frame having a cross is coupled to the output of a and is mechanically member that bridges right and left side rails; right and left coupled to a heavy, rigid, conventional commercial truck rear Wheel units respectively comprising right and left steered axle. The Weights of both the electric motor and the diesel road Wheels suspended from the frame by respective multi engine are sprung because they are chassis-mounted. HoW link suspensions; a steering system for steering the steered ever, the rear suspension in this vehicle is a heavy, dependent Wheels; an electric motor and gear box mounted on the cross (i.e., non-independent) system, and the axle is a non-steering member and coupled to the right and left road Wheels by axle. respective drive shafts; and a brake system for the road Wheels [0007] In a de Dion tube suspension, the differential and the Whose Weight is supported by the frame. disk brakes are removed from the unsprung Weight by hang [0017] The foregoing, along With further features and ing them to the chassis. Such a design is sometimes called advantages of the invention, Will be seen in the folloWing chassis-mounted differential and brakes. disclosure of a presently preferred embodiment of the inven tion depicting the best mode contemplated at this time for SUMMARY OF THE INVENTION carrying out the invention. This speci?cation includes draW ings, noW brie?y described as folloWs. [0008] The present invention is a result of the inventors’ recognition of a number of factors relevant to commercial BRIEF DESCRIPTION OF THE DRAWINGS vehicle design, including the ones mentioned above. [0018] FIG. 1 is a top plan diagrammatic vieW of a vehicle [0009] Reducing the ratio of unsprung to sprung Weight is chassis frame having an electric, independent, steering axle vital for increasing truck and bus drivability and handling according to the present invention. performance because the greater the ratio, the greater the [0019] FIG. 2 is front vieW of FIG. 1. US 2010/0307842 A1 Dec. 9, 2010

DESCRIPTION OF THE PREFERRED for a commercial truck or bus that operates on public streets, EMBODIMENT especially streets in a croWded urban environment. The brake system is effective on both front and rear axles, and either or [0020] FIGS. 1 and 2 show a truck chassis frame 10 having both axles can be driven by motor 34 and gear box 36. an electric, independent, steering axle 12 that comprises right [0029] While a presently preferred embodiment of the and left Wheel units 14, 16 each independently suspended invention has been illustrated and described, it should be from frame 1 0. The truck cab that mounts on the chassis frame appreciated that principles of the invention apply to all is not speci?cally shoWn. embodiments falling Within the scope of the folloWing [0021] Frame 10 comprises right and left side rails 18, 20 claims. running lengthwise of the frame and comprising respective What is claimed is: steel channels. Frame 10 comprises one or more cross mem 1. A vehicle chassis comprising: bers at locations along the frame length, such as the one a chassis frame having a cross member that bridges right marked 22. and left side rails; [0022] Right Wheel unit 14 comprises a spindle-mounted right and left Wheel units respectively comprising right and right Wheel 24, and left Wheel unit 16, a spindle-mounted left left steered road Wheels suspended from the frame by Wheel 26. The spindles have joumaled mountings in each respective multi-link suspensions; Wheel unit that enable the Wheels to turn about respective a steering system that includes a steering unit mounted on generally vertical axes as they are being steered by a steering the frame for steering the steered Wheels; system 28. an electric motor and gear box mounted on the cross mem [0023] Steering system 28 preferably comprises an electri ber and coupled to the right and left road Wheels by cally assisted rack-in-pinion steering mechanism 30 that is respective drive shafts; operated by the usual steering Wheel 32 Within the interior of and a brake system for the steered road Wheels Whose the vehicle and that is coupled With the respective Wheel units Weight is supported by the frame. to turn Wheels 24, 26 in unison to provide symmetric steering 2. A vehicle chassis as set forth in claim 1 Wherein the for the vehicle. The rack-in-pinion steering unit can be speed steering unit comprises a steering gear, and the steering sys sensitive, reducing steering effort at loWer speeds While tem comprises a linkage the steering gear With the increasing it at higher speeds to reduce the risk of undesired steered Wheels. incidents caused by inadvertent steering Wheel turning at high 3. A vehicle chassis as set forth in claim 1 Wherein the speeds. While a unit that provides symmetric steering is pre steering unit comprises a rack-in-pinion unit, and the steering ferred, a conventional poWer steering gear is contemplated as system comprises a coupling of the rack-in-pinion unit With an alternative. the steered Wheels that provides symmetric steering of the [0024] Each Wheel unit is suspended from frame 10 by a steered Wheels. multi-link suspension 33 that also includes elements provid 4. A vehicle chassis as set forth in claim 1 Wherein the ing damped elasticity. chassis frame comprises a further a cross member that bridges [0025] For delivering torque to each Wheel, an electric right and left side rails and is spaced from the ?rst-mentioned motor 34 is mounted on cross member 22 and coupled to the cross member; Wheels by a mechanism that includes a gear box 36 on motor right and left Wheel units respectively comprising right and 34 and drive shafts 38, 40 having universal joints coupling the left steered road Wheels suspended from the frame at the gear box With each Wheel. further cross member by respective multi-link suspen [0026] Wheel brakes 42, 44 are integrated With gear box 36 sions and steered by the steering system in coordination at the gear box output to each driveshaft. With the ?rst-mentioned right and left steered road [0027] With the construction that has been described, the Wheels. Weight of motor 34, gear box 36, and Wheel brakes 42, 44 5. A vehicle chassis as set forth in claim 4 Wherein the right becomes sprung Weight. The only unsprung Weight is that of and left steered Wheels at both cross members are coupled the independently suspended Wheel units and Wheels. With the gear box. [0028] The construction that has been described can be 6.A vehicle chassis as set forth in claim 5 Wherein the brake considered as a front axle that lacks a heavy metal bar that system is effective to brake the right and left steered Wheels at Would form part of the unsprung Weight. A vehicle may also both cross members. have a rear axle of comparable construction that also lacks 7. A vehicle chassis as set forth in claim 1 further including such a bar. Such a rear axle may have either non-steered road a passenger bus body mounted on the chassis frame. Wheels or steered road Wheels coupled With the steering sys 8. A vehicle chassis as set forth in claim 1 further including tem for steering in coordination With the front Wheels to a truck cab mounted on the chassis frame. provide AWS. The presence of tWo steering axles can be effective to reduce the turning radius of the vehicle, a bene?t * * * * *