WO2009017533A1

WO2009017533A1 - Modular light vehicle chassis

Info

Publication number: WO2009017533A1
Application number: PCT/US2008/007112
Authority: WO
Inventors: Dennis Palatov
Original assignee: Porteon Electric Vehicles, Inc.
Priority date: 2007-07-27
Filing date: 2008-06-06
Publication date: 2009-02-05

Abstract

A modular LV chassis comprises a Center Structure, a front End Structure and a rear End Structure, the latter two being substantially identical and interfacing to the Center Structure by means of a predetermined Mechanical Interface. The modular chassis can be readily configured to support a wide variety of vehicle types such as city car, resort car, flatbed delivery vehicle and the like without the need to re-engineer structural, suspension or drivetrain components.

Description

Modular Light Vehicle Chassis

Related Applications

This application claims the benefit of priority of U.S. Provisional No. 60/952,481 (Attorney

Docket No. 7823P002Z) filed on July 27, 2007, entitled "Modular Light Vehicle Chassis".

[0001] The present invention relates to design and construction of light vehicles, in particular city cars, light utility vehicles and the like.

Background of the invention

[0002] A wide variety of Light Vehicles, subsequently referred to herein as LVs, have been developed over the last several decades. The need for such vehicles is driven by many factors including limited operating space, urban congestion, cost or lack of availability of fuel, or in some cases, such as resorts, limited-access communities and factories, by noise and other environmental considerations. Examples of such vehicles range from the most basic such as golf carts to micro cars and so-called city cycles that are quite common particularly in Asian and also some European countries. The features such vehicles typically have in common are small size and light weight relative to that of conventional automobiles and modest performance which in many cases is specifically limited by regulations. This limited performance in particular prevents LVs from competing in the broad automotive markets. To make them appealing to buyers, LVs must therefore be targeted to very specific functions such as city car, resort car, delivery vehicle and the like. This in turn significantly fragments the already limited market and in many cases reduces production and sales volumes to levels where economies of scale are difficult to achieve. Yet since LVs cannot fully replace conventional automobiles, they must be low in cost both in terms of initial acquisition and maintenance. The conflicting realities of relatively low volume potential of each specific model of LV and the need for low cost make it difficult to produce and sell such vehicles profitably. A further difficulty in the present LV market is the fact that in many cases, particularly such as resort cars in remote locations, servicing and maintenance of the vehicles presents significant logistics challenges in spare parts distribution and availability.

[0003] What is needed is an LV chassis that can be readily adapted to a wide variety of niche markets while retaining maximum freedom in functionality and styling. At minimum, an effective LV chassis should support a resort car, a city car and a utility or flatbed delivery vehicle configuration. As many of the key mechanical components as possible should be made common to all versions of the LV for both economy of scale in manufacturing and efficiency in spare parts distribution and maintenance. The Modular Light Vehicle Chassis of the present invention fulfills this need.

Summary of the invention

[0004] A primary objective of the present invention is to provide a modular chassis design that can be readily configured to accommodate a wide variety of vehicle types without the need to re-engineer structural, suspension or drivetrain components. A second objective of the present invention is to enable the same parts such as suspension components to be used in multiple locations throughout the vehicle in order to improve economies of scale, manufacturing efficiency and ease of service. To achieve these objectives, the LV chassis of the present invention is separated into three basic functional modules. The Center Structure is the main structural component to which the body, the passenger accommodations and any ancillary equipment is attached. The two other modules are Front End Structure and Rear End Structure.

[0005] The front End Structure and rear End Structure each comprise a subframe, the respective suspension components, and are each configured to optionally receive a drivetrain. The optional inclusion of the drivetrain in front, rear, or both structures provides a ready means to configure the vehicle as front, rear or all wheel drive by simply including the drivetrain components in the assembly as appropriate. The front End Structure and the rear End Structure both attach to the Center Structure by means of a predetermined mechanical interface. The Mechanical Interface is identical for both front and rear End Structures, thereby enabling them to be substantially the same consistent with the second objective. Preferably the two modules are substantially identical and only vary in configuration, such as the inclusion of a steering mechanism in the front End Structure which is replaced by fixed control links in the rear End Structure.

[0006] Within the context of the present invention, the term Center Structure refers primarily to the essential structural components which together interface mechanically to the front End Structure and rear End Structure. While bodywork, rollover protection, passenger accommodations and the like will typically be attached to these components to form a larger assembly, they are usually not essential to the structural function of the chassis and therefore are not considered herein except to show that a wide variety of such configurations can be accommodated. Many examples of vehicles with bodywork being mechanically distinct from the chassis are known in the art and are known as body-on-frame types. Alternatively, some components such as rollover beams, crash protection beams and some bodywork elements may be designed to perform an overall structural function in the chassis. In such cases these components are to be considered part of the Center Structure within the scope of the present invention. The Center Structure of the present invention is preferably of the backbone type although many other commonly practiced designs, including but not limited to ladder frames and space frames, may be used. The backbone design is preferable because it can be readily and efficiently manufactured in different lengths to accommodate varying vehicle wheelbase requirements.

Brief description of the drawings:

[0007] The present invention is described herein with reference to the following drawings:

[0008] Fig. 1 shows the modular LV chassis of the present invention comprising a Center Structure, a front End Structure and a rear End Structure.

[0009] Fig. 2 shows a front End Structure incorporating a front suspension, a steering mechanism and an optional drivetrain.

[00010] Fig. 3 shows a rear End Structure incorporating a rear suspension and an optional drivetrain.

[00011] Fig. 4 is an illustration of a Mechanical Interface between Center Structure and front or rear End Structure.

[00012] Fig. 5 illustrates a typical drivetrain that may be used in the chassis of the present invention.

[00013] Fig. 6 shows the modular LV chassis of the present invention used in a four-seat resort car configuration.

[00014]Fig. 7 is an illustration of a two-seat city car configuration

[00015] Fig. 8 shows a flatbed delivery vehicle configuration.

Detailed description of the embodiments of the invention [00016] The preferred embodiment of the modular LV chassis of the present invention comprises an aluminum extruded backbone 110 as the main component of the Center Structure 100. The backbone illustrated herein is of a rectangular cross-section but any number of shapes can be readily used. Such structural extruded shapes are well known in the art and need not be discussed herein. At each end of the backbone is the inboard part 505 of the predefined Mechanical Interface 500 to facilitate attachment of front End Structure 200 and rear End Structure 300. In the simplest form, the inboard Mechanical Interface 505 consists of a plurality of holes 506 drilled in a predetermined pattern. The complementary outboard part 510 of the Mechanical Interface consists of four L-shaped beams 515 in which matching holes 516 are drilled. To attach a front or rear End Structure to the Center Structure, the beams 515 are slidably received within backbone 110 so as to align the holes 506 and corresponding matching holes 516. A plurality of fasteners such.as bolts or rivets are then used in the holes to secure the components to each other. This particular implementation is only one of many possible types of Mechanical Interface and is not limiting. Many other types of Mechanical Interfaces are well known and will become readily apparent to those skilled in the art. The preferred embodiment calls for an interface utilizing threaded fasteners so as to facilitate disassembly for service if needed. However, riveted, bonded or welded interfaces are possible in cases where disassembly is not necessary, without departing from the teaching of the present invention.

[00017] In the preferred embodiment, the front End Structure 200 and the rear End Structure 300 are substantially identical and vary only in configuration, such as the inclusion of a steering mechanism 230 in the former and fixed control links 240 in the latter. In the context of the present invention, an End Structure comprises a structural subframe 210 and suspension assembly 220. Preferably an End Structure further comprises an attachment means to receive a drivetrain 250. The drivetrain 250 will typically consist of a motor 255, which may be of electric, internal combustion or hybrid type, coupled to a differential 256 and halfshafts 257 which transmit torque to the wheels. In some implementations either all or part of the drivetrain may be used as an integral part of the subframe 210, with suspension attaching at least in part directly thereto. Such designs are well known and are widely practiced particularly in racing vehicles such as Formula cars, Le Mans prototypes and the like. For example, the differential housing may be used as a structural part of the subframe, either as a bolt-in component or as an integrally cast feature. In the former case, when inclusion of drivetrain is not desired, a substitute structural component with identical mounting points and means may be used in place of the drivetrain. In the latter case when a drivetrain is not included in the End Structure assembly, only the housing is used while omitting internal drivetrain components. [00018] The subframe 210 of an End Structure of the present invention incorporates the outboard part 510 of the Mechanical Interface 500 which is configured to attach to the inboard part 505 of the Mechanical Interface of the Center Structure as previously disclosed. This common Mechanical Interface is a key feature of the present invention and facilitates the use of substantially identical front and rear End Structures. In the art the practice of attaching suspension and in some cases drivetrain to a subframe that is in turn attached to a chassis is common. Typically the purpose of using a subframe is to isolate noise and vibration from the chassis. The subframe is often mounted utilizing rubber bushings, although this is not usually found on Light Vehicles due to cost considerations. The common practice is to design the chassis and the suspension, then to design a subframe that supports and isolates the latter from the former. This design methodology results in either the use of a subframe at only the front or the rear, or the .use of substantially different and non-interchangeable subframes at the two ends. The increased parts count and attendant cost is what typically prevents such designs from being utilized in Light Vehicles. By approaching the chassis as a modular assembly the invention disclosed herein allows the use of common components throughout the vehicle and results in significant cost and logistics advantages.

[00019] One of the logistics advantages enabled by the present invention is the ability to assemble a complete structural chassis in a production facility and deliver it to a customer. The non-structural components such as bodywork and the like can be supplied as a kit and may be manufactured at a separate facility, including locations that comply with local content laws. The non-structural components can then be assembled to the structural chassis at the customer facility creating a vehicle that is locally assembled while the control over performance and safety critical structural chassis is maintained by the manufacturer. Additionally, shipping costs are potentially reduced by only shipping the structural chassis rather than the complete assembled vehicle.

[0002O]In the preferred embodiment, the suspension that is incorporated in each End Structure is of double-wishbone type. Generally, this type of suspension is well known in the art. In departure from common practice, the preferred embodiment utilizes identical suspension arms in all locations (both upper and lower, at all corners), resulting in the use of eight identical parts per vehicle. Consistent with the objectives of the present invention this arrangement reduces the number of different parts that must be designed and manufactured while increasing the economies of scale in the manufacture of the common parts. To achieve desirable dynamic behavior and control suspension geometry, the suspension arms are arranged in a non-parallel, equal-length configuration. Suspension designs commonly practiced in the art usually utilize non-equal length wishbones which requires different parts to be used for upper and lower arms. Further, standard practice is to utilize different suspension designs for front and rear. This arises from customary chassis designs that are not modular but designed as a unit, thereby typically placing different packaging requirements on front and rear suspension components. The modular LV chassis of the present invention, by utilizing a Center Structure and two substantially identical End Structures, each of which incorporates a suspension, enables the use of identical suspension components throughout the vehicle, creating significant cost and logistics advantages.

[00021] From the above disclosure, it shall become apparent to one skilled in the art that a wide variety of specialized light vehicles can be built utilizing the modular LV chassis of the present invention. _ In one embodiment, a resort car is constructed. The requirements for a resort car are that four people including the driver be accommodated in a vehicle that is compact, low in cost, offers ease in ingress and egress. A resort car typically provides simple sun shade and rain protection by means of a canopy type roof but does not offer the complete protection from the elements that is expected in a conventional automobile. Such a car is illustrated in Fig. 6. The drawing shows how the backbone-type Center Structure 100 of the preferred embodiment is combined with front and rear End Structures 200 and 300 respectively, to form a simple chassis on which a resort car is configured. The Center Structure 100 is of an appropriate length to accommodate four occupants. Seats, a canopy style roof, a simple windshield and a lockable storage trunk are installed on the chassis. In one embodiment the roof, windshield and seats may be made detachable so that multiple chassis can be stacked upon each other for shipping, thereby reducing shipping costs. In another embodiment the chassis may be produced, assembled and tested at a central manufacturing facility and then shipped to destination with the balance of the components either shipped separately as a kit or produced locally in compliance with local content laws. The flexibility offered by the chassis of the present invention facilitates ready customization of the vehicles, including styling and cosmetic changes to accommodate customer branding or other aesthetic requirements. Further, some resort locations are remote and lack hard-surface roads. In such case all wheel drive may be desirable. The resort car based on the teaching of the present invention readily accommodates this by including a drive train in both front and rear End Structures. The commonality of components reduces the number of spare parts that has to be stocked and distributed. In the event that a vehicle is damaged, components from another vehicle can be used as replacements. A single vehicle when parted out can serve to provide parts for repairs on several other vehicles. This is a significant advantage for remote locations and allows the greatest proportion of a vehicle fleet to be maintained in running condition, unconstrained by parts delivery issues. [00022] Another embodiment of the preferred invention is a city car, as illustrated in Fig. 7. Recognizing that most city trips take place with only one or two persons onboard and that parking and road space is at a premium, the city car is configured as a two-person vehicle. The Center Structure is correspondingly shorter than the four-seat resort car previously disclosed. The extruded backbone design of the Center Structure 100 of the preferred embodiment facilitates easy and efficient changes in chassis length. A city car is expected to provide more protection from the elements and security than a resort car and so is configured with a hard roof, lockable doors and full glazing. Just as in the case of the resort car, a drivetrain 250 may be included in front, rear, or both End Structures to create front, rear and all wheel drive configurations as desired. In a city car an all wheel drive configuration may be desired in hilly terrain or if_winter operation in snow is expected. A further requirement of a city car design is the provision of bumpers 800 for impact protection. To facilitate this, each front and rear End Structure can be configured to provide a bumper attachment means such as a bracket of a predetermined design. Bumpers are routinely mounted by means of brackets and therefore the details of such an arrangement need not be disclosed herein. The substantially identical design of front and rear End Structures facilitates a common bumper design for both ends of the vehicle, further improving manufacturing efficiency and cost.

[00023] A third embodiment is a flatbed delivery vehicle shown in Fig. 8. Such a vehicle typically requires maximizing the available load area while keeping the vehicle as compact as possible. The modular chassis of the present invention readily meets these requirements by allowing a cab-over design that accommodates a driver and a passenger while the flatbed load area is mounted to the backbone style Center Structure for maximum load carrying capacity. An additional advantage is that a large portion of the load can be placed inside the wheelbase, optimizing longitudinal weight and suspension load distribution. As in previously disclosed embodiments, a front, rear or all wheel drive configuration is readily achieved. A further advantage of an all wheel drive configuration in a delivery vehicle is that the available power is doubled by utilizing two powertrains, thereby increasing load carrying capacity in hilly terrain (gradability) for a given load.

[00024] It will be apparent to those skilled in the art that all three of the above described embodiments, as well as many others, can be readily built using the same set of End Structures and with only minor, easily implemented modifications to the Center Structure design to allow for different wheelbase lengths. [00025] As shown in the above disclosures, the modular LV chassis of the present invention achieves its objectives of facilitating multiple, distinct vehicle configurations from a common set of components. It enables improved economies of scale across multiple vehicle designs targeted at specific niche markets. The embodiments disclosed herein are illustrative and not limiting. Many other designs shall become apparent to those skilled in the art that can be practiced without departing from the teaching of the present invention.

Claims

ClaimsWhat is claimed is:

1. A light vehicle (LV) chassis comprising: a center structure; a front end structure; and a rear end structure, wherein said front end structure and said rear end structure are each mechanically coupled to said center structure by means of a mechanical interface that is substantially identical for both structures so as to render said front and rear structures mechanically interchangeable.

2. The LV chassis of claim 1 wherein said front end structure and said rear end structure further comprise respectively a front suspension having a first control arm and a rear .suspension having a second control arm, wherein the first control arm is identical to and mechanically interchangeable with the second control arm.

3. The LV chassis of claim 1 wherein said front suspension is a double-wishbone suspension comprising an upper suspension control arm and a lower suspension control arm identical to and mechanically interchangeable with the upper suspension control arm.

4. The LV chassis of claim 1 wherein said front end structure further comprises a drivetrain.

5. The LV chassis of claim 1 wherein said rear end structure further comprises a drivetrain.

6. The LV chassis of claim 1 wherein said front and rear end structures each further comprise attachment means for a bumper.

7. A method of manufacturing a Light Vehicle comprising:

(a) manufacturing a center structure having a first mechanical interface for attachment of a front end structure and a second mechanical interface identical to said first mechanical interface for attachment of a rear end structure;

(b) manufacturing the front end structure and the rear end structure identical to the front end structure;

(c) attaching the front and rear end structures to the center structure by means of the respective mechanical interfaces;

(d) attaching a front suspension to the front end structure;

(e) attaching a rear suspension to the rear end structure; and (f) installing a drivetrain in at least one of the front end structure and the rear end structure.

8. The method of Claim 7 further comprising attaching a steering mechanism to the chassis assembly.

9. The method of Claim 7 further comprising attaching bodywork, occupant accommodations and other non-structural components to the chassis assembly.

10. The method of Claim 9 wherein steps (d), (e) and (f) are performed at a first facility and the steps of attaching bodywork, occupant accommodations and other non-structural components to the chassis assembly is performed at a second facility distinct from the first facility. -

11. A method of delivering a Light Vehicle comprising:

(a) manufacturing and assembling a chassis comprising a center structure, a front end structure and a rear end structure identical to the front end structure, said end structures further comprising a front suspension and a rear suspension identical to the front suspension, respectively;

(b) manufacturing a kit comprising at least a plurality of non-structural components;

(c) delivering to a customer facility the chassis;

(d) delivering to the customer facility the kit; and

(e) assembling the kit to the chassis at the customer facility.