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WO1999008889A1 - Moyens conferant de l'elasticite a des systemes de suspension - Google Patents

Moyens conferant de l'elasticite a des systemes de suspension Download PDF

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Publication number
WO1999008889A1
WO1999008889A1 PCT/CA1997/000576 CA9700576W WO9908889A1 WO 1999008889 A1 WO1999008889 A1 WO 1999008889A1 CA 9700576 W CA9700576 W CA 9700576W WO 9908889 A1 WO9908889 A1 WO 9908889A1
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WO
WIPO (PCT)
Prior art keywords
torsion bar
lever
control member
control
vehicle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CA1997/000576
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English (en)
Inventor
Peter R. J. Derviller
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Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to PCT/CA1997/000576 priority Critical patent/WO1999008889A1/fr
Priority to AU39352/97A priority patent/AU3935297A/en
Publication of WO1999008889A1 publication Critical patent/WO1999008889A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B35/00—Other machines for working soil not specially adapted for working soil on which crops are growing
    • A01B35/02—Other machines for working soil not specially adapted for working soil on which crops are growing with non-rotating tools
    • A01B35/10—Other machines for working soil not specially adapted for working soil on which crops are growing with non-rotating tools mounted on tractors
    • A01B35/12—Other machines for working soil not specially adapted for working soil on which crops are growing with non-rotating tools mounted on tractors with spring tools or with resiliently-or flexibly-attached rigid tools
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B35/00—Other machines for working soil not specially adapted for working soil on which crops are growing
    • A01B35/20—Tools; Details
    • A01B35/22—Non-rotating tools; Resilient or flexible mounting of rigid tools
    • A01B35/24—Spring tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G11/00—Resilient suspensions characterised by arrangement, location or kind of springs
    • B60G11/18—Resilient suspensions characterised by arrangement, location or kind of springs having torsion-bar springs only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
    • B60G17/025—Spring characteristics, e.g. mechanical springs and mechanical adjusting means the mechanical spring being a torsion spring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G3/00—Resilient suspensions for a single wheel
    • B60G3/18—Resilient suspensions for a single wheel with two or more pivoted arms, e.g. parallelogram
    • B60G3/20—Resilient suspensions for a single wheel with two or more pivoted arms, e.g. parallelogram all arms being rigid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G7/00—Pivoted suspension arms; Accessories thereof
    • B60G7/001—Suspension arms, e.g. constructional features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/10—Independent suspensions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/10—Independent suspensions
    • B60G2200/13—Independent suspensions with longitudinal arms only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/10—Independent suspensions
    • B60G2200/14—Independent suspensions with lateral arms
    • B60G2200/144—Independent suspensions with lateral arms with two lateral arms forming a parallelogram
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2202/00—Indexing codes relating to the type of spring, damper or actuator
    • B60G2202/10—Type of spring
    • B60G2202/13—Torsion spring
    • B60G2202/132—Torsion spring comprising a longitudinal torsion bar and/or tube
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2202/00—Indexing codes relating to the type of spring, damper or actuator
    • B60G2202/10—Type of spring
    • B60G2202/13—Torsion spring
    • B60G2202/134—Torsion spring comprising a transversal torsion bar and/or tube
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/10—Mounting of suspension elements
    • B60G2204/12—Mounting of springs or dampers
    • B60G2204/122—Mounting of torsion springs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/10—Mounting of suspension elements
    • B60G2204/14—Mounting of suspension arms
    • B60G2204/143—Mounting of suspension arms on the vehicle body or chassis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/40—Auxiliary suspension parts; Adjustment of suspensions
    • B60G2204/422—Links for mounting suspension elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2206/00—Indexing codes related to the manufacturing of suspensions: constructional features, the materials used, procedures or tools
    • B60G2206/01—Constructional features of suspension elements, e.g. arms, dampers, springs
    • B60G2206/10—Constructional features of arms
    • B60G2206/124—Constructional features of arms the arm having triangular or Y-shape, e.g. wishbone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2206/00—Indexing codes related to the manufacturing of suspensions: constructional features, the materials used, procedures or tools
    • B60G2206/01—Constructional features of suspension elements, e.g. arms, dampers, springs
    • B60G2206/70—Materials used in suspensions
    • B60G2206/72—Steel
    • B60G2206/722—Plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2206/00—Indexing codes related to the manufacturing of suspensions: constructional features, the materials used, procedures or tools
    • B60G2206/01—Constructional features of suspension elements, e.g. arms, dampers, springs
    • B60G2206/80—Manufacturing procedures
    • B60G2206/81—Shaping
    • B60G2206/8103—Shaping by folding or bending
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2500/00—Indexing codes relating to the regulated action or device
    • B60G2500/20—Spring action or springs

Definitions

  • the present invention relates to novel springing means for conferring elastic properties on a mechanical linkage between a sprung and an unsprung mass. More particularly, springing means of this kind are adapted for application in vehicle suspension systems.
  • vehicle refers to a wheeled conveyance such as an automobile, all -terrain vehicle (ATV) , truck, bus, or trailer operating on a running surface such as a road, or over rough terrain.
  • ATV all -terrain vehicle
  • suspension system is meant the entire assembly of control arm linkages, spring devices, anti-roll bars ("sway bars”) and dampers ("shock absorbers”). All vertical forces and loads experienced by the vehicle are assumed to be reacted at the centres of the tire treads where they make contact with the running surface (i.e. "contact patches”) .
  • the operational characteristics of a suspension system are determined by the geometry of the mechanism for transferring motion between the sprung and unsprung mass through the use of combinations of control arms, links, sliding telescopic struts, pivots and rotating members, and by the resistance to deflection of the springs and dampers (shock absorbers) incorporated therein.
  • the elastic spring devices used in vehicle suspension systems are usually steel but may be of rubber, gas or advanced composite material.
  • the steel or composite spring may be configured as a "leaf" design to bend as it resists deflection, or as a torsion bar, either straight or coiled, designed to twist as it resists deflection.
  • spring rate The extent to which a spring deflects under load is referred to as its "spring rate” and is expressed in terms of force for unit deflection, i.e. Newton/millimetres (N/mm) or pounds per inch. The more resistant the spring, the higher or “stiffer” the spring rate is said to be.
  • the vertical deflection of the road wheel which results when the vehicle suspension system is subjected to static and dynamic loads is referred to as "compliance".
  • Resistance to deflection compliance under steady state conditions is primarily generated by the springing means, while the shock absorbers provide additional resistance (i.e damping) to the vibrations that are excited by transient forces.
  • the actual resistance to vertical deflection that the springing means exerts at the wheel is governed by the spring rate of the spring device itself, modified by the geometric relationship between the attachment points of the spring and the contact patch of the wheel .
  • the suspension system' s overall resistance to vertical compliance measured at the contact patch - termed the "wheel rate” - is expressed in terms of the unit force required to produce unit vertical deflection in N/mm or pounds per inch.
  • Very compliant systems are referred to as “soft”, while those which are highly resistant to vertical deflection are denoted “hard” or “stiff” .
  • a suspension system incorporates a mechanical linkage interposed between two mass assemblies whose relative motion is affected by the springs and dampers that are attached to the linkage.
  • the mass assembly including the passenger and cargo compartment, referred to as the "sprung mass” of the vehicle, is typically suspended by means of spring devices interposed between attachment points on the chassis of the vehicle and attachment points on the linkages which support the upright, hub carrier, wheel, brake, and axle assemblies, referred to as the "unsprung mass” .
  • a coil spring is a coiled torsion bar
  • the straight torsion bar has been used extensively in vehicle wheel suspension systems. Reference may be made, for example, to U.S Patents Nos. 2,972,489 (Collier et al . ) ; 3,178,200 (Backaitis et al . ) ; and 3,831,966 (Grosseau) .
  • the straight torsion bar used as a conventional single-acting springing means, is inherently of greater length and weight, requiring more space for installation in a given application, than is a coil spring.
  • any springing means for a suspension system including torsion bars, is that without exceeding its elastic limit, it must accommodate the maximum deflection required by the operational range of motion of a vehicle's suspension system, while at the same time maintaining a sufficiently high spring rate to react the expected static and dynamic loads at the wheel's contact patch.
  • the novel Differential Torsion Spring of the present invention is double-acting, in that its torsion bar spring element is coupled to two separate control members of the suspension system, from the angular motions of which there is derived a differential motion which drives the Differential Torsion Spring.
  • the Differential Torsion Spring of the present invention thus has no direct connection to the vehicle chassis, but reacts to the static and dynamic loads experienced by the suspension system by resisting deflection of the suspension from within the geometric linkage of the suspension.
  • This novel double-acting arrangement effectively decouples the factor of angular displacement of the suspension system from the factor of torsional stiffness, thereby making possible a simple and inexpensive suspension springing means, incorporating a wide range of adjustability and variability of spring rate, without the weight and size disadvantages of conventional (single- acting) torsion bar arrangements.
  • the Differential Torsion Spring represents a particular improvement on prior torsion bar designs in those applications requiring light and compact mechanical construction, and precise control and location of the road wheel as, for example, in the design of front-wheel drive automobiles.
  • the Differential Torsion Spring is also suitable for applications requiring large suspension deflections, particularly where high wheel rates are additionally required.
  • the arrangement of the present invention by acting within the suspension linkage and having no direct connection to the chassis, permits isolation of the sprung mass from vibrations in the unsprung mass by means of conventional rubber bushings in the control arm pivots .
  • novel springing means for the mechanical linkage between a sprung mass assembly and an unsprung mass assembly in a suspension system comprises (i) a torsion bar coaxial with the pivot axis of a first control member of the suspension system, the torsion bar being torsionally secured near at least one end thereof to the first control member for co- rotation of said at least one end of the bar with the first control member about the pivot axis; (ii) a lever torsionally secured at an inner end thereof to the torsion bar at a selected intermediate position between the ends of the torsion bar and extending radially outwardly from that position to an outer end of the lever; and (iii) means for pivotally linking the lever to the second control member.
  • the Differential Torsion Spring may be incorporated in a wide variety of suspension linkages, particularly those requiring high spring rates, as in the trailing-arm or radius-arm suspensions typical in trailers.
  • novel springing means for the mechanical linkage between a sprung mass assembly and an unsprung mass assembly in a suspension system comprises (i) a torsion bar coaxial with the pivot axis of a first control member of the suspension system, the torsion bar being torsionally secured at both ends thereof to inboard branches of the first control member for co-rotation of both ends of the torsion bar with said first control member about its pivot axis; (ii) a lever torsionally secured at the inner end thereof to the torsion bar at a position equidistant from the two points of torsional securement to the first control member and extending radially outwardly from said position to an outer end of the lever; and (iii) means for pivotally linking the lever to the second control member.
  • novel springing means for the mechanical linkage between a sprung mass assembly and an unsprung mass assembly in a suspension system comprises (i) a torsion bar coaxial with the pivot axis of the first control member of the suspension system, the torsion bar being torsionally secured near one end thereof to the first control member for co-rotation of that end of the bar with the first control member about the pivot axis, the other end of the torsion bar being free of torsional engagement with the first control member, (ii) a lever torsionally secured at an inner end thereof to the torsion bar at a position near the free end of the torsion bar and extending radially outwardly from that position to an outer end of the lever; and (iii) means for pivotally linking the lever to the second control member .
  • a springing means for an SLA (Short-Long-Arm) or double wishbone type vehicle suspension system comprising a torsion bar coaxial with the pivot axis of one of the upper and lower control arms of the suspension and torsionally secured near one end thereof to that control arm for co-rotation therewith, the other end of the torsion bar being free of torsional engagement with that control arm; (ii) a lever torsionally secured at an inner end thereof to the torsion bar at a position near the free end of the torsion bar and extending radially outwardly therefrom to an outer end of the lever; and (iii) an adjustable-length tie-rod pivotally connected at a first end thereof to a selected attachment on the lever and pivotally connected at a second end thereof to a selected position of attachment on the other one of the upper and lower control arms of the linkage, so that a differential resultant of the angular motions of the first and second control arms produces in the to
  • Fig. 1 illustrates schematically a first embodiment of the Differential Torsion Spring in accordance with the present invention operatively connected to the control arms of a double vehicle wishbone-type suspension;
  • Fig. 2 schematically illustrates a second, preferred embodiment of the Differential Torsion Spring in accordance with the present invention, operatively connected to the control arms of a double wishbone-type vehicle suspension;
  • Fig. 3 illustrates the basic components of a Differential Torsion Spring according to the preferred embodiment
  • Fig. 4 illustrates the installation of the Differential Torsion Spring of Fig. 3 in a typical double wishbone vehicle suspension linkage showing the typical relative positions of chassis and suspension elements;
  • Fig. 5 schematically illustrates the installation of a Differential Torsion Spring according to the invention in an alternative independent wheel suspension system
  • Fig. 6 illustrates the use of a Differential Torsion Spring according to the invention as a trip-spring in a mounting structure for the support arm of a plough blade; and Fig. 7 is a schematic illustration of a further alternative independent wheel suspension system incorporating a Differential Torsion Spring according to the invention.
  • a Differential Torsion Spring according to the invention is particularly adapted for use in an SLA or double wishbone-type automotive suspension.
  • Schematically illustrated in Figs. 1 and 2 are embodiments of the Differential Torsion Spring of the invention in connection in use to the upper and lower control arms of a double wishbone suspension linkage.
  • the upper and lower control arms and associated elements of the double wishbone suspension linkage are identified by the same reference numerals in Figs. 1 and 2.
  • Fig. 1 schematically illustrates a first, "elementary" embodiment of the Differential Torsion Spring, comprising a torsion bar 1, a lever 2 torsionally secured at the central position of the torsion bar at its inner end 2a and pivotally connected at its outer end 2b to an adjustable-length tie-rod 4 by means of pivoting connection 6a.
  • Fig. 2 Schematically illustrated in Fig. 2 is a second, preferred embodiment of the Differential Torsion Spring, comprising torsion bar 1', lever 2' torsionally secured to one end of the torsion bar 1' at the inner end 2' a thereof and pivotally connected at its outer end 2'b to adjustable-length tie-rod 4' by pivoting connection 6' a.
  • Fig. 1 and Fig. 2 elements of the independent wheel suspension of the double wishbone variety in which upright member 7 is coupled transversely to the vehicle body by way of upper and lower control arms 3a and 3b, respectively.
  • These control arms are mounted to the vehicle chassis by means of convention metal/metal bearings or rubber/metal/rubber ("RB") bushings for pivotal motion about axes U and L, respectively.
  • RB rubber/metal/rubber
  • the double wishbone linkages arranged substantially in the manner of a quadrilateral link mechanism, with one link formed by the upright 7, the opposite link by the vehicle's structure and the lateral upper and lower links by the upper and lower control arms 3a and 3b.
  • the torsion bar 1 may be integrated into the pivotal axis of either the upper or lower control arm, but in the arrangement shown is integrated with the pivotal axis U of upper control arm 3a.
  • Flanges la may be machined onto the ends of the torsion bar 1 to serve as attachment means for fixedly attaching the ends of the torsion bar 1 to both bifurcation branches 3c of the upper control arm 3a.
  • Spindles lb may be machined onto the ends of the torsion bar 1 for free rotation in bushings or bearings in branches 3c of the upper control arm 3a, so that the spindles lb co-rotate with control arm 3a about axis U.
  • lever 2 is torsionally secured without slippage by means of a drive engagement profile, such as a spline or square drive, enabling the lever 2 to capture the torsion bar 1.
  • a drive engagement profile such as a spline or square drive
  • the torsion bar 1' may again be integrated into the pivotal axis of either control arm, being shown in Fig. 2 as integrated with the pivotal axis U of upper control arm 3a.
  • a single flange l'a may be machined onto one end of the torsion bar to serve as attachment means for fixedly attaching that end of the torsion bar to the associated branch 3c of upper control arm 3a.
  • a spindle l'b may be machined onto the opposite end of the torsion bar 1' , for free rotation in bushings or bearings in the other branch 3c of upper control arm 3a, so that the spindle is free to move independently of the rotation of control arm 3a. Adjacent the free end of the torsion bar 1', lever 2' is torsionally secured without slippage by drive engagement profile enabling the lever 2' to capture the torsion bar 1' .
  • torsion bar 1 the length in diameter of torsion bar 1, the length of lever 2 and the location on control arm 3b of the pointed attachment of tie-rod 4' are selected, such that when the suspension linkage deflects in use the differential rotation between the torsion bar 1 torsionally fixed to upper control arm 3a and torsionally coupled to the lower control arm 3b (via the pivoting linkage of lever 2 and tie-rod 4) generates a torsional reaction in the bar which resists a deflection of the suspension linkage.
  • torsion bar 1' the length and diameter of torsion bar 1', the length of lever 2' and the location on control arm 3b are selected so that a torsional reaction is generated in torsion bar by the differential rotation between that end of torsion bar 1' torsionally fixed to upper control arm 3a and the other end of other end of torsion bar 1' which is torsionally coupled by the pivoting linkage of lever 2' in tie-rod 4' to a lower control arm 3b.
  • Figs. 3 and 4 illustrate, respectively, the basic components of a differential spring according to the preferred embodiment of DTS and its installation in a typical double wishbone vehicle suspension linkage.
  • Differential Torsion Spring shown in Fig. 3 is a specific example of the preferred arrangement of torsion spring, lever and adjustable tie-rod discussed above in connection with Fig. 2.
  • the preferred embodiment of Differential Torsion Spring comprises a torsion bar 10, a lever 12 torsionally secured to one end of the torsion bar at its inner end 12a and pivotally connected at its outer end 12b to an adjustable-length tie-rod 14 by pivoting connection 16a.
  • the independent wheel suspension system partly shown in Fig. 4 is of the aforementioned double wishbone variety.
  • a hub carrier 18 rotatably supporting a wheel 20 is coupled transversely to the vehicle body by way of a pair of upper and lower control arms 22a and 22b mounted to the vehicle chassis by means of metal/metal bearings or conventional RB bushings for pivotal motion about axes U and L, respectively.
  • Torsion bar 10 in the arrangement shown in Figs. 3 and 4 is integrated into pivotal axis U of upper control arm 22a.
  • a flange 10a is machined onto one end of the torsion bar to serve as attachment means for fixedly attaching that end of the torsion bar 10 to the associated branch of upper control arm 22a.
  • a spindle 10b may be machined onto the opposite end of the torsion bar, for free rotation in bushings or bearings in the other branch of upper control arm 22a, so that the spindle 10b is free to move independently of the rotation of control arm 22a.
  • Adjacent the free end of the torsion bar, lever 12 is torsionally secured without slippage by a drive engagement profile enabling the lever to capture the torsion bar.
  • the torsion bar has been machined over a short section of its length to a square cross-sectional profile 24 which engages with the walls of like- shaped apertures in lever 12.
  • Lower control arm 22b typically being a pressed steel member with an inverted "U" cross- section, affords a convenient surface for pivotal attachment 16b of tie- rod 14 to the lower control arm 22b.
  • Adjustable tie-rod 14 thus links attachment point 16a at the outboard extremity of lever 12 to attachment point 16b on the lower control arm.
  • torsion bar 10 the length and diameter of torsion bar 10, the length of lever 12 and the location on control arm 22b of the point of attachment of tie-rod 14 are so selected, that when the suspension linkage deflects in use the differential rotation between the end of the torsion bar torsionally fixed to upper control arm 22a and the end of the torsion bar torsionally coupled (by the pivoting linkage of lever 12 and tie-rod 14) to the lower control arm 22b, generates a torsional reaction in the bar which resists deflection of the suspension linkage .
  • the wheel rate at the contact patch and the rising or falling profile of the spring' s load-deflection characteristics throughout the suspension's operational range are dictated in part by design of the particular geometry of the suspension linkage in which the torsion bar functions as the pivotal axis of one of the control arms, as well as the torsion bar's material composition, diameter, length, lever length, lever angle at static load, and windup angle.
  • variations of the upper pick-up point can be made by providing lever 12 with a linear sequence 13a, 13b etc. of attachment locations for the upper pivoting connection 16a of tie- rod 14.
  • the tie-rod may be made adjustable in length by any of a number of conventional means, such as providing the tie-rod with female tapped ends to receive left and right-hand threaded Hiem joints (spherical bearings in housings with threaded shanks) . The tie-rod is then simply twisted about its axis to adjust its overall length. The Hiem joints are then locked in place by jamb-nuts .
  • the initial setting of the suspension linkage which determines the static ride height of the vehicle is coarsely adjusted by pre-setting at zero load, the attachment points of tie-rod 14 and the angular position of lever 12 relative to the control arm 22a to which the torsion bar is fixed, and finely adjusted by extension or contraction of the adjustable tie-rod.
  • the calculations which must be carried out to optimize the torsion bar characteristics and the geometric dimensions of the components of the Differential Torsion Spring in this application are specific to the given suspension system of the model of vehicle. They are, however, entirely conventional and within the ordinary skill of designers and installers of suspension systems .
  • the wheel rate that is called for in the vehicle in question defined as the vertical downward force required at the contact patch per unit upward vertical deflection.
  • the next steps are to lay out the Differential Torsion Spring's dimensions, and the geometry of its linkage relative to the suspension control arms, in a configuration that will yield an acceptable range of motion to accommodate these forces and give the suspension the required operational attributes such as wheel rate and force-deflection characteristics, within acceptable limits of stress in the torsion bar and other components .
  • the Differential Torsion Spring can accommodate the same forces, at an equal stress level, as a modern mass-produced conventional single- acting torsion bar of approximately twice its weight and more than three times its length.
  • Fig. 5 schematically illustrates the use of the Differential Torsion Spring of the invention in a typical independent wheel suspension for a trailer.
  • Wheel 26 is shown at position "A" with the suspension in full jounce as the wheel 26 follows a hump 28a on the road 28.
  • the action of the Differential Torsion Spring is entirely analogous to that in the double wishbone application, the only difference in geometry being that in this case control arms 30a and 30b are upper and lower trailing links which extend longitudinally of the chassis 32 rather than transversely.
  • Upper and lower trailing arms 30a and 30b are pivotally connected at their front ends to the chassis (i.e. the sprung mass assembly) and at their trailing ends are pivotally connected to a wheel knuckle 34.
  • Torsion bar 36 of the Differential Torsion Spring is integrated into either of the upper or lower trailing link pivotal axes, here that of upper trailing link 30a, with one of its ends flanged to its associated trailing link, so that trailing link 30a and the end of torsion bar 36 fixed thereto rotate as a unit, the opposite end of torsion bar 36 running in bushings or bearings so that it is free to move independently of the rotation of trailing link 30a.
  • Tie-rod 40 links a pivotal attachment point 42 on the outboard extremity of lever 40 to a pivotal attachment point 44 on the other trailing link 30b.
  • Differential Torsion Spring shown installed in the double trailing-arm suspension of Fig. 5 is essentially the embodiment of DTS illustrated in and discussed above in connection with Fig. 2.
  • the particular advantage of the double trailing-arm geometry is that it permits a low floor (there being no axle underneath it) .
  • the Differential Torsion Spring is "packaged" within the trailing arm assembly, requiring no additional spring mounting points on the trailer chassis.
  • a further contemplated application of this particular geometric arrangement is in a belt or chain tensioner. This can be visualized by replacing road surface 28 in Fig. 5 with a belt or chain. Conveyor belts, drive belts and chains often require tensioning and backlash absorbing devices, to which a Differential Torsion Spring could provide a simple, high energy and compact solution to the problem of finding physical space for such devices .
  • the static setting of the suspension system which determines the static ride height of the vehicle is coarsely adjusted by setting the attachment points of tie-rod 40 and the angular position of lever 38, at zero load, relative to trailing link 30a and finely adjusted by extension or contraction of adjustable tie-rod 40.
  • U.S. Patent No. 3,815,685 (Seifert, Jr.) is directed to a "trip spring" mounting structure for the support arm of a cultivating shovel (i.e. plough), whereby the support will yieldingly resist but be capable of being swung rearwardly and upwardly at its lower end so as to clear a ground obstruction.
  • An embodiment of applicant's Differential Torsion Spring is particularly suited to this application, which requires high spring rates and large deflections.
  • a trip spring mechanism must accommodate a larger range of angular deflection than most vehicle springs. If a single-acting torsion bar is used on a cultivator, as in the Seifert patent, it must therefore be long enough to twist through a large angular deflection without permanent deformation, while still sustaining an acceptably high spring rate. In fact, Seifert does illustrate a long and heavy bar, which would be unsuitable for use with an implement frame requiring many cultivating tools fairly closely spaced together. Moreover, long heavy torsion bars increase costs of manufacture and replacement as well as fuel, operating and maintenance costs .
  • a Differential Torsion Spring acts as a "trip-spring" to resiliently link the shank 46a of plough blade 46 to a transverse bar 48 fixed to the chassis 50 of a vehicle which draws the plough along the ground 52, from right to left in the drawing figure.
  • a plurality of these assemblies may be mounted on a single transverse bar 48.
  • the geometric linkage is in principle the same as the "trailing arm” arrangement of the previous example, except that the lower trailing link pivotally connected to the sprung mass at 56 is actually a linear extension of the shank of the plough blade.
  • Upper trailing link 58 torsionally engages one end of torsion bar 60 of the Differential Torsion Spring. Again, this may be effected by providing torsion bar 60 with a flanged end fixed to trailing link 58 for co-rotation therewith about its pivot axis and the opposite end of torsion bar 60 running in bushings or bearings so that it is free to move independently of the rotation of trailing link 58.
  • torsion bar 60 is torsionally engaged with lever 62 and is thence coupled to lower control link 46a by means of a tie-rod 64 linking a pivoting attachment point 66 to a pivoting attachment 68 of the lower trailing link 46a (i.e. the plough shank) .
  • the plough shank is of course directly connected to the "unsprung mass" of the plough blade 46.
  • the linkage is completed by effectively coupling the rearmost end of upper trailing link 58 to the unsprung mass by bar link 70 linked to upper trailing link 58 and lower trailing link 46a at pivot attachments 72 and 74, respectively.
  • trailing link 58 would be bifurcated and the torsion bar 60 would be provided with flanged ends for fixing to both legs of the bifurcated trailing link 58.
  • the lever torsionally engaging the torsion bar would be secured at a point equidistant from the two points of attachment of the torsion bar to its associated trailing link.
  • the Differential Torsion Spring arrangement depicted in Fig. 7 allows for a rising or falling spring rate, as desired, whereas a single-acting torsion bar (connected as shown in the Seifert patent) would exhibit a fairly linear rate.
  • Selective arrangements of the Differential Torsion Spring geometry to give a falling rate for the cultivator application would be advantageous in that the larger the obstruction encountered by the plough blade, and hence the greater the angular deflection, the progressively easier it becomes to deflect the shank/trip- spring system, thereby relieving the stress on the blade, shank and the mounting structure.
  • the return torque of the Differential Torsion Spring becomes progressively higher, reaching a maximum at the point where the blade comes into contact with the soil surface.
  • the relatively short length of the torsion bar of the Differential Torsion Spring produces an assembly of much smaller transverse dimensions, thereby permitting the inclusion of a larger number of cultivator arms per unit transverse length of the implement frame.
  • Fig. 7 schematically illustrates a suspended wheel assembly applying the Differential Torsion Spring principle to a single swinging control arm, rather than a double wishbone or trailing arm geometry.
  • the wheel assembly shown in Fig. 7 is particularly suitable for installation on the undercarriage strut 75 of an aircraft where it offers the advantages of a light, simple and compact suspension spring that can accommodate large angular deflections at high wheel rates.
  • Wheel 76 is rotationally mounted on a swing-arm 78 pivotally connected to the aircraft fuselage at an undercarriage strut 75.
  • Swing-arm 78 serves as the first control member of this suspension linkage.
  • Concentric with the pivot axis of swing arm 78 is a torsion bar 80 which is anchored to swing arm 78 at one end and is free to rotate at the other end within the pivot bushing of the swing-arm.
  • the second control member of this suspension linkage is a telescoping lever 82, a conventional telescopic hydraulic damper, fixed at one end to the sprung mass of the vehicle or the aircraft's undercarriage strut 75. At its inboard end 82a, lever 82 is pivotally fixed to the sprung mass of the vehicle, i.e.
  • a torsion bar lever 86 is torsionally engaged at its inboard end to the free end of torsion bar 80 and at its outboard end is connected by pivotal attachment 88 to the outboard end of telescopic lever 82.
  • a tie-rod 90 pivotally connects the swing-arm 78, at pivotal attachment 92, to lever 82, at pivotal attachment 96.
  • a major benefit of this particular configuration is that substantially greater deflections in conjunction with higher spring rates may be achieved than with direct acting coil or leaf-spring systems.
  • the swing-arm suspension system incorporating a Differential Tension Spring is also very compact for the high spring energy levels that can be accommodated. Manufacturers of mass produced vehicles are concerned with reducing cost, weight, parts count and in improving performance.
  • a double wishbone or trailing link suspension linkage incorporating a Differential Torsion Spring meets these objectives, while precisely locating the road wheels at the front or rear of a vehicle, suspending the vehicle, and providing sufficient space and clearance for drive shafts and steering mechanism.
  • Vehicle suspension systems incorporating the Differential Torsion Spring as described above are capable of accommodating large deflections at the road wheel while maintaining a higher spring rate than is possible with an equivalent mass of leaf or coil springs .
  • Designers of specialized vehicles, such as military and off-road vehicles requiring unusually large suspension deflections will find that a Differential Torsion Spring provides a solution which uses the simplest and lightest possible springing mechanism.
  • the Differential Torsion Spring provides easier adjustability than convention sprung linkages.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Soil Sciences (AREA)
  • Environmental Sciences (AREA)
  • Vehicle Body Suspensions (AREA)
  • Springs (AREA)

Abstract

Moyens d'élasticité se présentant sous la forme d'une barre de torsion conçue pour un système de suspension, dans lequel les mouvements angulaires d'un premier et d'un deuxième éléments de commande de l'articulation de la suspension sont reliés respectivement à des points séparés de fixation sur la barre de torsion, ce qui crée une résistance élastique de torsion différentielle à des déplacements dans le système de suspension du véhicule. Ce dispositif à double action diffère des mécanismes classiques d'élasticité par barre de torsion à action unique dans lesquels un ensemble ressort est intercalé entre un point de fixation sur l'articulation de la suspension et un point de fixation sur le châssis du véhicule. Ce mécanisme d'élasticité à torsion différentielle permet d'atteindre des caractéristiques avantageuses de simplicité, de souplesse de réglage et d'économie de coûts, étant donné qu'il résiste à la déflexion de la suspension depuis l'intérieur de la géométrie de son système d'articulation.
PCT/CA1997/000576 1997-08-14 1997-08-14 Moyens conferant de l'elasticite a des systemes de suspension Ceased WO1999008889A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/CA1997/000576 WO1999008889A1 (fr) 1997-08-14 1997-08-14 Moyens conferant de l'elasticite a des systemes de suspension
AU39352/97A AU3935297A (en) 1997-08-14 1997-08-14 Springing means for suspension systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CA1997/000576 WO1999008889A1 (fr) 1997-08-14 1997-08-14 Moyens conferant de l'elasticite a des systemes de suspension

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WO1999008889A1 true WO1999008889A1 (fr) 1999-02-25

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Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB451490A (en) * 1933-02-19 1936-08-06 Porsche Gmbh Improvements in springing arrangements for vehicles
US2079899A (en) * 1934-11-26 1937-05-11 Packard Motor Car Co Motor vehicle
FR861484A (fr) * 1938-11-12 1941-02-10 Système de suspension stable pour véhicules
GB660443A (en) * 1949-08-26 1951-11-07 Salter & Co Ltd G Improvements relating to spring suspensions of vehicles
GB756026A (en) * 1952-05-09 1956-08-29 Motor Res Corp Improvements in and relating to spring suspension for motor vehicles
US2798419A (en) * 1954-05-04 1957-07-09 Harry Ferguson De France Disc tiller construction
US3137513A (en) * 1959-12-21 1964-06-16 Kleber Colombes Wheel suspension system for vehicles
FR1431874A (fr) * 1965-02-04 1966-03-18 Simca Automobiles Sa Dispositif de fixation de barres de torsion notamment pour suspension de véhicule automobile
DE1555348A1 (de) * 1962-03-02 1970-08-13 Armes De Guerre Fab Nat Drehstabfederung zum Federn von Fahrzeugen
US3815685A (en) * 1972-11-27 1974-06-11 E Seifert Torsion bar clamp
US4315549A (en) * 1978-06-05 1982-02-16 Lely Cornelis V D Soil working machine with interconnected displaceable supports which maintain orientation
GB2245234A (en) * 1990-05-15 1992-01-02 James Leslie Holden A suspension system for a vehicle
EP0783986A2 (fr) * 1995-08-24 1997-07-16 Delphi France Automotive Systems Système de réglage de roulis de véhicule

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB451490A (en) * 1933-02-19 1936-08-06 Porsche Gmbh Improvements in springing arrangements for vehicles
US2079899A (en) * 1934-11-26 1937-05-11 Packard Motor Car Co Motor vehicle
FR861484A (fr) * 1938-11-12 1941-02-10 Système de suspension stable pour véhicules
GB660443A (en) * 1949-08-26 1951-11-07 Salter & Co Ltd G Improvements relating to spring suspensions of vehicles
GB756026A (en) * 1952-05-09 1956-08-29 Motor Res Corp Improvements in and relating to spring suspension for motor vehicles
US2798419A (en) * 1954-05-04 1957-07-09 Harry Ferguson De France Disc tiller construction
US3137513A (en) * 1959-12-21 1964-06-16 Kleber Colombes Wheel suspension system for vehicles
DE1555348A1 (de) * 1962-03-02 1970-08-13 Armes De Guerre Fab Nat Drehstabfederung zum Federn von Fahrzeugen
FR1431874A (fr) * 1965-02-04 1966-03-18 Simca Automobiles Sa Dispositif de fixation de barres de torsion notamment pour suspension de véhicule automobile
US3815685A (en) * 1972-11-27 1974-06-11 E Seifert Torsion bar clamp
US4315549A (en) * 1978-06-05 1982-02-16 Lely Cornelis V D Soil working machine with interconnected displaceable supports which maintain orientation
GB2245234A (en) * 1990-05-15 1992-01-02 James Leslie Holden A suspension system for a vehicle
EP0783986A2 (fr) * 1995-08-24 1997-07-16 Delphi France Automotive Systems Système de réglage de roulis de véhicule

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